NASA's Cassini space probe launched in 1997 to study Saturn, its rings and its system of moons. It concluded its voyage of exploration in 2017 with a spectacular final swan dive into Saturn's atmosphere. But Cassini is still yielding new discoveries as scientists go through the vast amount of imagery and other data that it sent back to Earth. According to Space.com, its latest posthumous discovery was evidence of fresh ice on the northern surface of Enceladus, Saturn's moon. A Little World With an Ocean Enceladus is a small world, only 314 miles in diameter according to NASA — which is only about a tenth the diameter of Titan, the giant of Saturn's moon system. Experts already predicted it had geysers, but Cassini was able to capture images of these during close passes. The images were surprising proof that Enceladus has an internal supply of liquid water. The source of this water supply, as EarthSky.org notes, is believed to be a subsurface ocean layer sandwiched between the moon's solid core and its icy surface. The gravitation interplay of Saturn's moon system provides an energy source that keeps this underground ocean from freezing solid. The geysers originally imaged by Cassini — more than a hundred of them, per Space.com — are clustered around the moon's south pole. Scientists believe that water from the underground ocean in this region is forced up through cracks in the surface ice. When it breaks through to the surface, it spurts into space, forming the geysers Cassini observed. Some of the water from the geysers vaporizes in the vacuum of space and is lost, but some falls back to the surface and freezes. This process is gradually "repaving" the surface of Enceladus' south polar region. Teasing Secrets Out of Images All of this was discovered during Cassini's mission, before its final swan dive into Saturn. But scientists have continued to examine the imagery that Cassini sent back, using image-processing software to tease out subtle details that could not be seen by simply looking at the images. These techniques led to the latest Cassini discovery: A research team combined visible-light and infrared images to examine the surface of Enceladus and found infrared heat signatures, such as "tiger stripes," that matched up with the location of the southern polar geysers. Now, this detailed search has also detected infrared signatures indicative of recent surface "repaving" in the northern hemisphere as well. The researchers do not yet know whether this repaving is produced by additional geysers, less powerful than the southern polar geysers and thus not dramatically visible, or by a more subtle seepage process. This might be equivalent to the hot springs that are commonly associated with geysers here on Earth, such as in Yellowstone Park. Looking for Life in Unexpected Places Will future space tourists take selfies standing in front of geysers on Saturn's moon? We don't know, but the scientists have more than just tourism prospects in mind. In 2018, as Chemical & Engineering News reported, another research team found that the water spurting from the geysers contains "large, complex organic molecules." These molecules resemble the building blocks of life, and while they are not by themselves proof of life , they certainly get the attention of biochemists. As a result, Enceladus has now emerged as one of the solar system's prime candidates for potential extraterrestrial life. This in itself is a remarkable discovery. Until recently, no one would have expected to find life anywhere amid the frigid reaches of Saturn's moon system (with the possible exception of Titan). A Solar System Full of Surprises But it gets better. Scientists are finding growing evidence for hidden oceans of liquid water beneath the surfaces of a variety of small- to medium-sized bodies scattered across the solar system, including two dwarf planets: Ceres in the asteroid belt and Pluto in the remote Kuiper Belt. The search for life, once almost wholly confined to Mars, is now spreading across the solar system. The more we look, the more surprises we continue to find.

More Geysers on Saturn's Moon Enceladus

This July, much of the world will be treated to a total lunar eclipse — the second of 2018 — according to Sky & Telescope. North America will be left out of July's upcoming eclipse, but never fear: North America will have a ringside seat next January, per Space.com. Perhaps it's time to step back and answer a few questions like, what is a total lunar eclipse? How does it relate to a solar eclipse? What do you see, and are there precautions to take in order to watch it safely? Cast a Giant Shadow Eclipses, both lunar and solar, are all about shadows. Both the Earth and moon cast shadows that extend far into space, in a direction away from the sun. The sun causes shadows when its light is blocked but does not cast a shadow itself — it produces light rather than blocking it. We pass into Earth's shadow every evening at sunset, but we don't really see it as a shadow — we just see the sun go down, hidden by Earth. Most of the time, the long shadows cast into space are not noticeable, because they fall only on empty space. But the long shadows cast by the Earth and moon become view-worthy when the sun, Earth, and moon are perfectly lined up. (See the Sky & Telescope's handy diagram.) If the moon is directly between the Earth and the sun, the moon's shadow (usually) extends just far across space enough to completely block the view of the sun from a small area on Earth. The result of this sun-moon-Earth shadow play is a total solar eclipse, according to NASA. This is one of nature's most spectacular sky shows. For a few minutes the blazing disk of the sun is entirely blocked, covered over by the moon. Deep twilight falls in the middle of day, and some animals will be tricked into thinking it is evening, said TIME. What is a Total Lunar Eclipse? But what happens if the lineup is sun-Earth-moon? Instead of Earth passing through the moon's shadow, the moon passes through Earth's shadow. For viewers on Earth, the moon is not blocked from view — unless we are on Earth's day side at the time, in which case, the moon is below the horizon and we wouldn't see it anyway. If the eclipse is total, the moon is blocked from direct sunlight. What would otherwise be a bright full moon goes dark, for up to more than an hour, according to NASA. Ghost Moon, Blood Moon  But even in a total lunar eclipse, the moon does not go entirely dark. The reason is that Earth's atmosphere bends (or refracts) some of the sunlight passing through it, so that a little sunlight still reaches the moon even within Earth's shadow. Exactly how this sunlight reaches the moon depends on weather conditions on Earth at the time of the eclipse. Sometimes the moon will be so dim it will be barely visible, and sometimes the eclipsed moon will be easier to see, per Space.com. On a few occasions during a total lunar eclipse, the moon will appear deep red — the so-called blood moon — because red light is more easily refracted by Earth's atmosphere than other colors. This is the same effect that often makes sunsets appear red, Space.com noted. Some conditions on Earth, as described by Space.com, including a major volcanic eruption that throws vast amounts of dust into the upper atmosphere, are especially favorable to a blood moon during a total lunar eclipse. There is no way to know in advance what effects refraction will have on an upcoming eclipse. You'll just have to go outside and find out for yourself. One bit of good news is that it is perfectly safe to look directly at a total lunar eclipse, unlike a solar eclipse, which requires special precautions for safe viewing. Step outside and enjoy!

What Is a Total Lunar Eclipse?

The last manned moon landing happened in 1972; humans haven't set foot on Earth's natural satellite for almost 45 years. Now, public agencies like NASA and private firms have announced plans for near-term, manned missions to Mars while the new federal administration pushes for travel to the moon. Which one is worth championing as mankind's next "giant leap?" Lunar Legacy Two years ago, NASA unveiled a proposal to shift away from Near Earth Objects to the Red Planet. As noted by Universe Today, NASA administrator Charlie Bolden responded "been there, done that" when asked about further moon exploration, a sentiment that matches popular opinion: The moon is a dry, dusty boring rock that doesn't offer anything unique or interesting. But is the moon really "been there, done that?" Maybe not.    Consider that we've mapped just 5 percent of the moon's surface, and the Apollo mission astronauts didn't stray far from their landing craft — the movements of Apollo 11's crew could fit into a regulation-size soccer field, the article explained. And while 2010 was a low point for lunar exploration when the Obama administration turfed the Constellation program, other space agencies continued to investigate Earth's nearest neighbor and discovered traces of water. According to National Geographic, further analysis of volcanic "glass beads" brought back by the Apollo missions and the discovery of widespread volcanic deposits suggests that there's a significant amount of water trapped under the moon's surface — some estimates suggest that liberating this water would produce a one-yard-deep (0.91-meter) ocean covering the moon's surface. In addition, volatile compounds were discovered at the lunar poles held there by "cold traps," while the moon environment itself offers the chance to test out new space suit, habitat and research technologies. Getting Ready   While NASA may be focused on Mars, other space agencies and private companies are preparing humans to live on the moon. As noted by Tech Crunch, volunteers at China's premier aeronautics university will live in a sealed, controlled environment for 200 days to simulate a lunar habitat. China was the third country to successfully complete a lunar "soft landing" and plans to put humans on the surface of the moon in 15 to 20 years. According to the European Space Agency, it is also testing out potential habitats to examine the impact of lighting changes on astronauts' circadian rhythms and abilities to function in a non-earth environment. Red Planet or Constant Companion?   So what's the best bet for mankind's next giant leap?   Mars is absolutely the "stretch goal" here — the stuff-of-dreams red planet that comes with potential discoveries of ancient life and could offer a viable "second Earth" scenario. But it comes with big challenges: At its closest, Mars is still around 35 million miles from Earth, meaning the trip takes at least six months using cutting-edge technology. And depending on the planet's position, communication with Earth could take anywhere from three to 22 minutes one-way, while dust storms could play havoc with machinery and communications. In an interview with New Scientist, social-media savvy astronaut Chris Hadfield explained that the moon is our best option largely because we've been there before and can control many of the variables, improving the chance of success.   Ultimately, the case for the moon comes down to three key benefits:    Science - From exploration of the surface to mapping the poles and obtaining more samples of lunar rock and regolith, there's "good science" to be done on the moon, according to Mike Seibert of NASA's Jet Propulsion Laboratory. Commercialization - Space tourism is just the start. The moon offers viable mining, machinery and eventually housing opportunities.  Technology - We need to develop technologies that allow humans to live off-planet indefinitely. Iteration and innovation can happen quickly when the moon is just a three-day trip; on Mars this simply isn't possible.   A trip to Mars? Or travel to the moon? It doesn't have to be either/or — but shooting for the moon offers the biggest short-term benefit. Image Credit: Pixabay 

Travel to the Moon or Mars: The Case for Humanity's Next "Giant Leap"

Jupiter's large moon Europa has been drawing attention for decades, ever since the first space missions to the giant planet sent back images hinting that an ocean of liquid water may lie concealed beneath its icy surface. So crucial is liquid water to life on Earth that detecting it anywhere else sets off alarm bells — or rather, excitement bells — in scientists' heads. Interest in the Jovian moon ratcheted up further in 2019 when scientists found evidence of sodium chloride — better known as ordinary table salt — on its frozen surface. If the underground ocean believed to exist on Europa is salty, like Earth's oceans, it must be exposed to rocky minerals that could provide the building blocks of living organisms. Now, new images indicate that Europa's salty ice surface may literally glow in the dark, potentially giving researchers a road map of its surface composition and further guiding the search for any Europan life. In an unusual twist, as Space.com reports, the images came not from Europa but from a lab in Maryland. What's more, they led to a completely unexpected discovery. The Heart of an Icy Moon of Jupiter According to NASA's Jet Propulsion Laboratory (JPL), a research team built a special instrument, intending to study the effects that Jupiter's powerful radiation field of charged particles might have on any organic compounds on the surface of Europa. The instrument is officially called Ice Chamber for Europa's High-Energy Electron and Radiation Environment Testing — a jawbreaker name that is much easier to remember as an acronym: ICE-HEART. To carry out the intended research, ICE-HEART was set up at a high-energy lab in Maryland. There, as Science News notes, the device cooled salty ice samples to around minus 173 degrees C (the temperature of Europa's surface), then bombarded them with radiation. When ICE-HEART was switched on, the ice samples started to glow. This in itself was not a huge surprise. While we usually associate glowing astronomical bodies with very high temperatures (think stars), a variety of radiation-related effects can make even cool objects, including living organisms, glow. When Serendipity Strikes But when the scientists varied their salty ice samples, they got a surprise. Salts, to a chemist, are a family of compounds with similar properties. Table salt, or sodium chloride, is one of these compounds. Epsom salt, or magnesium sulfate, is another. And it turns out that each of these salts produces a different glow when run through ICE-HEART. Ice containing sodium chloride glows less than pure ice with no salt, while ice with magnesium sulfate glows brighter than pure ice. In all the history of science, no one had ever previously tried the specific experiment of cooling salty ice to outer-solar-system temperatures, then bombarding it with electrons. So — until now — no one knew that each variety of salt produces its own distinct signature glow. NASA research team member Bryana Henderson detailed the moment of discovery: "When we tried new ice compositions, the glow looked different. And we all just stared at it for a while and then said, 'This is new, right?'" The researchers described this finding as a serendipity, a sheer good-luck discovery made by explorers who were looking for something else entirely. What Lies Beneath So, does the icy moon of Jupiter actually glow in the dark? We don't yet know. Earth-based telescopes can't get a decent view of the night side of Europa, and no space-based telescopes are currently in position for a good view. As Science News notes, the ICE-HEART samples were only exposed to a Jupiter-like radiation field for 20 seconds, not millions of years. Astronomer Jennifer Hanley told Science News that she wonders, "Is there ever a point where you might break down the salts, and this glow stops happening?" The only sure way to find out is to go out to Europa and look. Space.com reports that NASA's Europa Clipper probe, scheduled for launch about mid-decade, may give us our first chance to do just that. Scientists are currently examining whether its instruments should be able to detect the glow. If the glow of salty ice is detectable on Europa, it could provide a powerful tool for mapping the chemical composition of the surface and help to determine where a future Europa landing mission (now in preliminary planning) should go. If we do find life in the underground ocean of Europa, we may have the glow of salty ice to thank for the discovery. 

Jupiter's Moon Europa May Glow in the Dark

What does ordinary table salt have to do with Jupiter's moon Europa and the destination of NASA's upcoming Europa Clipper mission? As often happens in space science, the answer to this question is straightforward, but the implications are breathtaking. The detection of sodium chloride on the surface of Europa lends support to the theory that Europa not only has an underground ocean, but that this ocean contains the building blocks of life, and perhaps its own ecosystem of living organisms. All of which means that the Europa Clipper mission just might provide the first direct evidence that perhaps we are not alone. Misbehavior of the Gods First, a little background. As Space.com recounts, the four large moons of Jupiter, including Europa, were discovered by Galileo using his homemade telescope in January 1610. They are still collectively called the Galilean moons, but he simply numbered them. As Business Insider tells us, it fell to another astronomer to give them individual names. That astronomer, Simon Marius chose to name them for four of the Roman mythological god Jupiter's many romantic conquests. In order of distance from Jupiter, they are Io, Europa, Ganymede and Callisto. And as Business Insider also wryly notes, NASA is not above a little scientific mythology of its own. Another mission currently investigating Jupiter and its moon system is named Juno, after Jupiter's mythological (and very jealous) wife. Science Fiction Lends a Hand, and So Does NASA By the early 20th century, a new scientific mythology took form: science fiction. The moon and Mars usually played the starring role in early science fiction, but as Popular Science details, the four big moons of Jupiter, including Europa, got their share of attention. That is about where things stood until the 1970s, when space missions provided our first close-up views of these distant worlds — and spectacular views they were. As Space.com describes, each of the four big moons turns out to have very different surface features: from Io, the most volcanically active object in the solar system, to Callisto, the most heavily cratered. Jupiter's moon Europa does not have volcanoes and practically no craters. In fact, scientists determined that the surface of Europa cannot be more than about 160 million years old (even though Europa itself is nearly as old as the solar system, about 4.5 billion years). Some force, it seems, is continually "repaving" the surface of Europa. Not only is the surface being continually renewed; it is also almost completely flat. The most conspicuous surface features are linear markings, like scratches or cracks. A Hidden Ocean â€¦ One type of force, gravitational tides, turns out to account for both Io's volcanoes and Europa's flat, cracked surface. Tidal forces generated by Jupiter itself and the other moons subject all of the moons to flexing, which, over millions of years, heats them up internally. Thus, the inner moons, especially — Io and Europa — are much warmer internally than you would expect of worlds so far from the sun. When they formed, much of their material was water ice. The interior of Io is so hot that the ice long ago vaporized and escaped into space. Europa, not so close to Jupiter, only got hot enough to melt the ice. Per Geology.com, the result was and is a layer of liquid water believed to be as much as 60 miles deep — several times deeper than the deepest spot in Earth's oceans. A thin layer of ice, only a few miles thick at most, covers this ocean, which contains more water than all of Earth's oceans combined. â€¦ Of Salt Water All of which brings us back to that recent detection of sodium chloride (or in layman's terms, table salt) on Europa. Liquid water anywhere always gets the attention of researchers, because it seems to be an ideal environment for life. But water by itself is not enough: For life, you also need its building blocks and nutrients, most of which are to be found in rocks. If Europa's underground ocean is salt water, reports Phys.org, it must be in contact with rock, and surely contains many other dissolved substances, making the prospects for life that much stronger. And for a final touch, says Scientific American, these results indicate that liquid water must sometimes reach very close to the surface, or even break through before freezing, which could make detecting life on Jupiter's moon Europa that much easier. Interested in all things in outer space and exploration? We are, too. Take a look at open positions at Northrop Grumman and consider joining our team.

Jupiter's Moon Europa: A Moon With an Ocean — and Possibly Life

On Dec. 11, 2017, President Donald Trump reignited the nation's human space exploration program by signing Space Policy Directive 1. The executive order calls for NASA to work with commercial and international partners to create a sustainable space exploration program that will enable human travel to the moon and eventually to Mars. In effect, it creates a roadmap for humanity's next giant leap. Deliberate, Sustained Exploration  A core element of this new initiative, which NASA calls its Exploration Campaign, will be a Lunar Orbital Platform — Gateway, or lunar gateway for short. The Gateway will serve as a combination "base camp" for exploratory excursions down to the lunar surface, a laboratory to conduct experiments about the effects of prolonged space travel on humans, and a platform for assembling payloads and transport vehicles that will carry astronauts on to Mars. The Exploration Campaign, however, is far more than a retread of NASA's Apollo program. "During Apollo, we learned how to fly to the Moon, but we were limited logistically to relatively brief stays and short periods of exploration," explained Charlie Precourt, a former NASA astronaut who serves as vice president and general manager for the Propulsion Systems Division of Northrop Grumman Innovation Systems. "With Exploration, we're going to stay on the Moon longer, explore more extensively, and conduct more thorough research, not unlike scientists who spend time at McMurdo Station in Antarctica. The Moon can become a powerful stepping stone to Mars." NASA's campaign will help motivate advances in space technology, inspire a new generation of students to pursue careers in science, technology, engineering and mathematics fields, and position the nation to take advantage of financial opportunities that could emerge from exploration, Precourt added. Multi-Purpose Launch Vehicle Central to the Exploration Campaign will be NASA's new Space Launch System (SLS), a heavy-lift launch vehicle capable of carrying humans and large cargo to the moon in a single mission. According to NASA documents, "SLS offers more payload mass, volume capability and energy to speed missions through space than any current launch vehicle." NASA describes the vehicle as "flexible and evolvable," and claims that it may be also be used to support robotic scientific missions to the moon, Mars, Saturn and Jupiter. The SLS is a hybrid system based on space shuttle-derived components and heavy-lift rockets developed for Constellation, NASA's previous campaign to return humans to the moon. The rocket comprises a core stage powered by four shuttle-legacy RS-25 liquid propellant engines, two five-segment, strap-on solid rocket boosters (SRBs), and initially, a cryogenic upper stage derived from the Delta IV rocket program. SLS will use a version of the Constellation-era Orion crew vehicle to carry humans to the lunar gateway. Legacy Team, Innovative Approach Northrop Grumman, which produced the SRBs for NASA's shuttle program, is "remodeling" those original four-segment SRBs for use on SLS. "By going from four segments to five, we're giving NASA 25 percent more propellant and a little more thrust delivered over a longer period of time," said Mike Fuller, a senior business development manager. "The detachable SRBs provide a much more efficient way to lift the SLS off the Earth's surface to its initial orbit." NASA opted to reduce costs by going with an expendable version of the SRBs instead of recovering and reusing them for every mission, he added. Over time, NASA plans to evolve the SLS to meet increasingly complex human and cargo carrying requirements. First flight of the rocket, which will launch an uncrewed version of Orion around the moon, is expected in 2020. That initial flight will be used to test all aspects of the planned flight environment. The first crewed mission of the SLS is expected in 2022. Future versions of the SLS will feature a new, more powerful Exploration Upper Stage and be capable of carrying payloads of up to 45 metric tons (99,000 lbs.) to the moon. Gateway to Mars Ongoing travel to the moon and beyond will require development and deployment of the lunar gateway. According to NASA, this lunar-orbiting spaceship will serve as a temporary home and office for astronauts for up to three months at a time. It will include a power and propulsion element (PPE), a habitat module and logistics module capable of carrying pressurized and unpressurized cargo. The PPE will be used to maintain the Gateway's position in orbit, move it between orbits and provide power and communications for the spaceship. NASA plans to use the SLS to ferry major sections of the lunar gateway to orbit and assemble it in space. One of the more interesting aspects of the Gateway, explains Fuller, is its orbit. "Unlike the Apollo spacecraft, which orbited the moon at an altitude of about 60 miles, the lunar gateway will be placed in a highly elliptical orbit ranging from about 1,000 miles at its closest (perigee) to tens of thousands of miles at its farthest (apogee)," he said. "The high altitude of the orbit guarantees that the Gateway will remain visible to ground stations on Earth at all times, which will allow uninterrupted communication with crewed, cargo and robotic science missions." Reaching for the Stars There is much work yet to be done on NASA's Exploration Campaign, but an exciting future of human space exploration beckons. "We've learned through our experience with the International Space Station that humans can live for extended periods of time in low-Earth orbit," said Precourt. "With this campaign, we're ready to take on two more fundamental questions about the universe: is the human species truly sustainable off our planet ... and are we alone? The day we uncover hard evidence to answer these questions will be a game changer for our civilization." Ready to explore a universe of new opportunities? Check out careers at Northrop Grumman.

Travel to the Moon Returns to the Launch Pad

In the northern hemisphere, the full moon that occurs closest to the autumn equinox (when day and night are roughly equal around the world) is called the Harvest Moon. For several days in a row, the moon will rise near sunset to provide extra light, which farmers can use to harvest summer crops before winter arrives.   Many cultures — especially those at temperate latitudes — mark the occasion with evening festivities. In China and other Asian countries, the Mid-Autumn Festival is celebrated with paper lanterns and mooncake pastries. In 2021, the Harvest Moon was on September 20.   People often assume the Harvest Moon is bigger and brighter than other full moons, but that's not necessarily true. What makes it so special is that, when it rises above the horizon, an optical illusion makes the rising moon appear enormous.   Moon Basics   The moon travels around the Earth once every ~29.5 days, which is called a lunar month. The Earth travels around the sun once every ~365.25 days, which is called a year. Half the surface of both the Earth and the moon is illuminated by the sun at any one time, while the other half is (nearly) dark. The Earth also spins on its axis, making a full rotation every 24 hours, which gives us day and night. On Earth, the sun rises in the east and sets in the west. The moon also rises in the east and sets in the west, but the time of moonrise and moonset changes dramatically over the course of a lunar month.   When the moon is positioned roughly between the Earth and the sun, a person on Earth can only see the dark side of the moon — the part that is not illuminated by the sun. This is the New Moon, which rises in the morning and sets in the evening. As the moon continues its rotation around Earth, it will rise and set an average of 50 minutes later each day. As this occurs, you can see a larger and larger portion of the illuminated side of the moon. Halfway through the lunar month, the Full Moon rises at sunset and sets in the morning. As the moon continues its rotation, people on Earth will see a smaller and smaller portion of the illuminated side of the moon until it becomes a New Moon and the cycle starts over.   The Moon's Path Across the Sky   The Harvest Moon only occurs in the northern hemisphere. This is because: (1) The Earth is tilted 23.5 degrees on its axis as it travels around the sun (which gives us seasons), and (2) the moon's orbit around the Earth is tilted at a 5-degree angle relative to the equator, as EarthSky notes. As a result of these two tilts, the moon's path across the night sky changes throughout the year and appears different depending on the observer's latitude (distance from the equator).   The path of the Harvest Moon at moonrise is nearly parallel to the horizon, according to The Old Farmer's Almanac. This causes the moon to rise above the horizon at nearly the same time for a few nights in a row. This effect is most pronounced at northern latitudes and becomes less noticeable for observers closer to the equator.   Over the course of a year, the moon rises an average of 50 minutes later each day, but extremes occur during the Harvest Moon. Using information available on Time and Date, anyone with an internet connection can find the moonrise time for any city on a particular date. In the days surrounding the Harvest Moon in 2021, the number of days it took for the time of moonrise to change by 50 minutes was: 10 days in Helsinki, Finland (latitude of 60.2 degrees north), 5 days in London, England (51.5 degrees north), 4 days in New York City, New York, US (40.7 degrees north) and 3 days in Miami, Florida, US (35.8 degrees north). In contrast, on the night after the same full moon in Melbourne, Australia (37.8 degrees south), the moon rose 61 minutes later.   The situation is roughly reversed for the spring equinox, which occurs in late March. In the days surrounding the full moon closest to the spring equinox in 2022, it will take three days for the time of moonrise to change by 50 minutes in Melbourne, Australia (37.8 degrees south). In contrast, the night after the same full moon in Helsinki, Finland (60.2 degrees north), the moon will rise a whopping 94 minutes later.   The Moon Effect Optical Illusion   The Harvest Moon is celebrated for being big and bright, but it's not necessarily bigger or brighter than any other full moon. When the moon rises above the horizon, an optical illusion called the Moon Illusion makes it appear enormous, as explained by NASA.   Essentially, your brain is comparing the size of the moon to things it sees in the horizon, such as oceans, mountains, trees and buildings. Your brain knows that the moon is behind these big things, so the moon must be even bigger. As the Moon rises high in the sky, there are no Earth objects to compare it to, so the brain perceives it to be smaller.   People often describe a moon near the horizon as red or orange, which is not an optical illusion. When the moon is low in the horizon, you are viewing it through the thickest part of the atmosphere. Short wavelength blue light scatters when it travels through the atmosphere, which leaves mostly longer wavelength red and yellow light to reach your eyes.   Comparing Full Moons   The 2021 Harvest Moon was notable because it was the fourth full moon of the summer. Each season usually has three full moons, but because the moon's orbit around the Earth is not synchronized with the Earth's orbit around the sun, there's an "extra" full moon every two-and-a-half years. This lack of synchronization also means that the Harvest Moon can occur up to two weeks before or two weeks after the autumn equinox. Since the autumn equinox is September 22 or 23, the Harvest Moon is usually in September.   The moon follows an elliptical path around the Earth, causing some full moons to be closer to Earth than others. When measured from Earth, the closest full moons can be 14% bigger and slightly brighter than other full moons, according to NASA. This 14% difference pales in comparison to the perceived difference produced by the Moon Illusion.   EarthSky offers a comparison of some of the recent Harvest Moons: In 2021, it was an average-sized full moon. In 2020, it was the second-smallest full moon of the year. In 2019, it was the smallest full moon of the year. In 2015, it was a Super-Harvest Blood Moon, or the largest moon of the year combined with a total lunar eclipse.   With the great variety of ways that the Earth, moon and other celestial bodies travel through space, there is always something interesting to see.   Being on the forefront of change, especially regarding space, physics, and engineering has been part of the Northrop Grumman culture for generations. 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The Harvest Moon Lights the Night as Autumn Arrives

On Jan. 31st, 2018, a blue moon and a total lunar eclipse occured in tandem. The result of these celestial events colliding was a fairly rare occurance: an extra full moon in the month coinciding with a lunar ecplise, which as been nicknamed the blood moon for its often deep red coloring. The eclipse two years ago, visible over North America, was the first total eclipse of a blue moon in the region in 150 years, according to EarthSky.org. Blue moons and blood moons each have their own unique influences in culture, especially blood moons. But what are they? Are blue moons really that rare? Does a blood moon signal apocalyptic events for the poor humans here on earth and should people take care venturing out at night in a world lit crimson by the bleeding moon above? What are some popular blood moon superstitions? Let's find out.    Blue Bloods    Understanding what made the 2018 event so unique requires getting a handle on basic moon movement relative to the Earth and sun. First up? Blue moons. As noted by Space, a blue moon is "the appearance of an additional full moon within a given period." Historically, the blue moon referred to the rather infrequent occurrence of a third full moon in a season with four full moons, but the modern definition refers to a second full moon in one calendar month, said Space. This helps explain the phrase "once in a blue moon" to mean a rare occurrence.    It is worth noting that the moon rarely turns blue during a blue moon. According to NASA, "Most Blue Moons look pale gray and white, indistinguishable from any other Moon you've ever seen." The next blue moon is scheduled to appear on Halloween, October 31. 2020. A blood moon, meanwhile, is simply the result of a total lunar eclipse, which puts the moon entirely in Earth's umbra — the darkest part of its shadow. Although no sunlight can directly reach the moon during a total eclipse, light still passes around the edges of the Earth's atmosphere and is subject to what HyperPhysics explains is Rayleigh scattering; since blue light scatters more than red light, the moon takes on a reddish cast. The term "blood moon" may also refer to a sequence of four total lunar eclipses that happen within two years, known as a lunar tetrad, said NASA. The last tetrad occurred through 2014-2015 and the next won't happen until 2032-2033.         Enable targeting cookies to view this content.    Moon Madness    While a blue moon and a blood moon occuring at the same time is rare, blood moons themselves are more common. In fact, a lot of mythology has developed around them. Allen Kerkeslager, associate professor of theology and religious studies at Saint Joseph's University in Philadelphia, told Live Science that when blood moons occur, it's hard for us to overcome the "evolutionary tendency to try to explain this as the result of some kind of intentional action by some personal agent."    Popular blood moon superstitions include:      The Blood Moon Prophecy — In 2014, Live Science reports that several evangelical Christian ministers forwarded the idea of a "blood moon prophecy," predicting that the 2014-2015 tetrad would incite a "world-shaking" event. It didn't pan out.  "Crazy" Behavior — As noted by Seeker, the full moon has long been associated with "crazy" behavior. Doctors and police officers often have anecdotal stories about working shifts during a full moon. Supposedly the blood moon enhances these effects, but there's no evidence to back up either claim.   Starting Anew — According to Refinery 29, those of Wiccan faith consider any blood moon which occurs in October to be "a compelling time to build, to begin, to create" and also a good time to shed old habits. This is also called a "harvest moon" which isn't a true lunar eclipse but shifts red because of changing seasons.  Mythology — Cultures from all over the world have different explanations for lunar eclipses, according to National Geographic. "Marauding demons, murderous pets, and ravenous jaguars are just some of the culprits that cultures around the world have blamed for the moon's disappearance during lunar eclipses."     So what is a blood moon? It is a total lunar eclipse often colored red thanks to light scattering through atmospheric dust, but it's also the subject of stories, speculation and superstitions — take your pick.  Does learning about astronomy fascinate you? If so, consider making a career out of it.   

What Is a Blood Moon? Superstitions, Stories and Science

Future moon missions are at risk because of lunar soil. It seems harmless, but moon dust can actually damage scientific equipment and be harmful to human health: It is like a sticky powder made from shards of glass.   Neil Armstrong first stepped onto the moon 50 years ago, and his footprints in lunar soil will be there for million of years, according to NASA. There is no wind to blow the footprints away. When they returned to Earth, astronauts from the Apollo missions said that moon dust was sticky, abrasive and stinky.    The next astronauts who walk on the moon will have to contend with plenty of obstacles: the perils of space travel, exposure to high levels of radiation, and a lack of air, gravity, food and water. But dust is surprisingly high on the list of problems that need to be addressed for a successful visit to the moon.   Strange Properties of Moon Dust   The lunar surface is covered in regolith, a layer of powdery dust and broken rock, according to Britannica. Earth's soil is a mix of minerals, organic materials, air and water. It's a lovely layer of dirt where plants and animals thrive. The moon's soil, on the other hand, is mostly made up of silicate minerals.   Clingy   According to Popular Mechanics, the moon's lack of atmosphere makes it susceptible to solar wind. Unlike the breeze we experience at home — there's no air on the moon, after all — solar wind is a stream of charged particles from the upper layers of the sun. When these ions hit the moon, they make the soil electrostatically charged. Just like when clothing or hair has static cling on Earth, lunar soil clings to space suits.   Abrasive   The moon is frequently hit with meteorites, and with no atmosphere to soften the blow, their impact is more dramatic than here on Earth. Discover Magazine explains that billions of years of meteorite activity has kicked up lots of jagged dust. Grains of lunar dust are as small as the finest grains of sand— just 0.07 millimeters in diameter, on average. But grains of moon dust remain rough for a very long time because of a lack of erosion, so the dust is abrasive.   Dirty Problems on the Moon   Lunar soil causes a range of problems for astronauts and equipment. It can damage machines and scientific instruments. Discover Magazine points out that the first instrument placed on the moon, a seismometer on the Apollo 11 mission, quickly failed because dust caused it to overheat. More recently, China's Yutu rover died in 2014, and moon dust was the likely culprit of the vehicle's failure.   According to Wired, the "dusty dozen" Apollo astronauts tried to get rid of the pesky moon dust to keep the lunar module clean. After moon walks, they stomped their boots, brushed the dust off with bristle brushes and attempted to remove it with a vacuum cleaner. They wrapped garbage bags around their legs to try to contain the dust. On the Apollo 12 mission, astronaut Pete Conrad even stripped naked and stuffed his space suit into a pouch to keep the dust contained.   On the moon, dust is much more than a housekeeping chore. It is a dangerous feature of the landscape. In our brief visits during the Apollo era, it scratched astronauts' visors and weakened the seals on their pressure suits.   A Health Hazard for Astronauts   Astronauts who have been to the moon say it smelled like gunpowder or some kind of combustion. In addition to damaging their spacesuits, the dust made their eyes water and throats sore, according to The New York Times. Lunar soil could be toxic to humans. Apollo 17's Harrison Schmitt — the last person to set foot on the moon — described experiencing symptoms similar to hay fever after his moon walk. While it was only a mild allergic reaction, he was only there for 22 hours. Now NASA is preparing for much longer visits, which would expose astronauts and their gear to the abrasive dust for much longer.   A 2018 study suggests that prolonged exposure to lunar dust could put astronauts at risk for developing serious illnesses. The experiment published in GeoHealth by Stony Brook University exposed human lung cells and mouse brain cells to simulated lunar soil. They found that when inhaled, the dust damaged the cells at a DNA level. The researchers warn that prolonged exposure to lunar dust could impair airway and lung function, and lead to bronchitis, inflammation in the lungs and increased cancer risk.   Solutions for Dealing With the Dust   The success of future moon missions will depend, in part, on finding solutions for dealing with the moon's soil. According to Discover Magazine, researchers have proposed a special vacuum that uses magnets to catch the dust particles.   There aren't many solutions yet, but Popular Science reports that nine different institutions are now studying moon rock samples to learn about the moon's geology and chemistry. The samples have been sealed and stored for 50 years, and they are now being released for analysis with the latest technologies. Observations made on those samples will help guide future plans for visiting the moon. 

Lunar Soil Is a Dangerous Nuisance for Astronauts

The astronauts who brought back moon rocks half a century ago also revealed a lunar mystery that scientists have only recently begun to unravel. Unlike Earth, the moon today does not have a magnetic field, or magnetosphere, surrounding it. But when the rocks brought back by the Apollo astronauts were analyzed, NASA notes that researchers were surprised to find residual traces of magnetism. The Earth's magnetic field, which makes a magnetic compass work and produces spectacular aurora displays in high-latitude northern and southern skies, is believed to be produced by heat convection deep in Earth's molten iron core. But the moon, with a much smaller core, was not thought to have produced enough convection to magnetize any of its surface rocks. According to Space.com, some scientists speculated that the intense heat of asteroid impacts that produced the lunar craters might have produced short-lived magnetic plasma, enough to magnetize rocks near the impact. New Discoveries From Ancient Rocks Over the last few years, improved technology has teased new secrets out of the Apollo-era moon rocks — and shed new light on the long-vanished but now-confirmed lunar magnetosphere. Not only did the moon once have a magnetosphere, but it may have played a significant role in protecting Earth's atmosphere. The atmospheres of the solar system's inner planets are subject to erosion from the powerful solar winds of fast-moving particles. These particles collide with atmospheric atoms, hitting them with such force that they can exceed the planet's escape velocity and go hurtling through interplanetary space. The dense atmosphere of Venus has resisted such erosion, but Mars lost most of its atmosphere — along with the seas it once had, as the water either froze in the thin cold air or evaporated. Earth's atmosphere and oceans have been protected by its magnetic field, which deflects the charged particles from the sun, keeping most of them from hitting and eroding the atmosphere. A Complex History of Lunar Magnetism Scientists now believe that, in the early days of the solar system, the lunar magnetosphere contributed to this protection. Indeed, according to NASA, from about 4.1 to 3.5 billion years ago, the Earth's and moon's magnetic fields were linked, providing a duo of magnetic fields protecting the Earth-moon system. What's most surprising is that, in that era, the lunar magnetosphere was actually more powerful than Earth's is today, as MIT News reports. The current strength of Earth's magnetosphere is about 50 microteslas, while the ancient lunar magnetosphere may have pegged the needle at up to 100 microteslas in strength. By 2.5 billion years ago, this powerful field had faded to no more than 10 microteslas. And by the time the youngest moon rocks were formed — by an asteroid impact about a billion years ago — the magnetic field had faded to no more than 0.1 microteslas or possibly to nothing. This gradual and uneven fade suggests that more than one mechanism contributed to the early lunar magnetosphere. In the early period, when the field was strongest, the moon orbited much closer to Earth and was subjected to powerful tidal forces that could have kept the lunar interior churned up enough to produce a strong magnetic field. As the moon's orbit crept outward, these tidal forces weakened, but lunar vulcanism persisted, showing that the moon's interior had not yet fully crystallized and was still fluid enough to produce a weak magnetic field. Finally, the moon froze solid, and its magnetic field faded, leaving only the traces in moon rocks that puzzled Apollo-era researchers. But the fact that Earth once had a magnetic moon has implication for the search for life on extrasolar planets. The atmospheres of these distant worlds may have been protected not only by their own magnetospheres but also by the fields of any large moons orbiting them. And, closer to home, we can also wonder what other surprises the moon has in store, waiting for us to discover when we return.

What Ever Happened to the Moon's Magnetosphere?

Scientists at Cornell University recently estimated that the largest sea on Saturn's moon Titan reaches a depth of at least 1,000 feet, according to the Cornell Chronicle — but don't pack your diving gear just yet. Not that humans will travel to the sixth planet in the solar system anytime soon, but whenever we do take the 886-million-mile journey to Saturn (give or take several million miles depending on planetary positioning), we'll find that Titan's idea of an ocean is nothing like the ones found on Earth. This deep sea is made up of liquid methane — not exactly an ideal setting for swimming, surfing or scuba diving. It is conducive to exploration, though. In 2026, NASA plans to send a drone named Dragonfly to Titan, as Space.com points out, and there's talk of a submarine exploring the underwater reaches of the ocean. Until then, what is already known about this big sea is helping scientists understand Titan's landscape. By learning about the ocean's depth and makeup, they're getting an idea of the moon's hydrological system and any possible connection to Earth. A Moon With Earthly Water With the recent assessment of Titan's biggest ocean, Kraken Mare, there's no doubt it indeed lives up to its monstrous name. But unlike the sea monsters of Norse fables, this sea is real and observable to spacecraft. It's nearly the size of all five Great Lakes combined, as the Cornell Chronicle notes. That's how we are aware of its size. NASA's Cassini probe observed Saturn and its moons for 13 years before exhausting its fuel supply in 2017 and taking a final plunge into the planet's atmosphere. During its 294 orbits of Saturn, it took more than 450,000 photographs, many of them breathtaking images of a world that is, as NASA puts it, "ruled by raging storms and delicate harmonies of gravity." Cassini revealed "astounding worlds where methane rivers run to a methane sea and where jets of ice and gas are blasting material into space from a liquid water ocean that might harbor the ingredients for life," they continue. Outside of satisfying curiosity about Saturn's many rings, Cassini also explored the planet's icy moons. Scientists have long thought the moons offered conditions suitable to life, and that's why a close study of Titan captures attention. Titan is described as Earth-like because it is the only moon in our solar system that has a dense atmosphere and clouds, and it is the only moon with liquids in the form of rivers, lakes and oceans on its surface. NASA points out that Titan, the largest of Saturn's 82 moons, has an atmosphere composed mostly of nitrogen, just like Earth. However, Titan's surface pressure is 50% higher than our planet's. Its subsurface waters are of particular interest to scientists because they could contain forms of life with chemical compositions possibly unlike those found on Earth. No Ordinary Measuring Stick The search for life beyond Earth — a quest that drives NASA's Mars Exploration Program, as well as many other current and future space missions — is why the recent calculation about the depth of Titan's deepest ocean has significance. The more we learn about the building blocks of the planets and moons in our neighborhood, the more we understand how life on Earth came to be. Analyzing data gathered by a radar altimeter on Cassini as it flew 600 miles above Titan's surface in 2014, scientists and engineers from NASA's Jet Propulsion Laboratory were able to gauge the depth of Moray Sinus (an estuary at the north end of Kraken Mare) to be about 280 feet deep, the Cornell Chronicle reports. The estuary is shallower than the depths of the center of Kraken Mare, but the ocean itself was too deep for Cassini's radar to measure. So, the scientists and engineers devised a workaround. They discerned the depth of Kraken Mare by noting the radar's return time differences on the liquid surface and sea bottom, and they identified the sea's composition by the amount of radar energy absorbed during transit through the liquid. That's how they determined the depth of Kraken Mare to be at least 1,000 feet. "The depth and composition of each of Titan's seas had already been measured, except for Titan's largest sea, Kraken Mare — which not only has a great name, but also contains about 80% of the moon's surface liquids," Valerio Poggiali, a research associate at the Cornell Center for Astrophysics and Planetary Science (CCAPS), told the Cornell Chronicle. There's More Lake to Explore Scientists previously believed methane would dominate Kraken Mare because of its size and extension to the moon's lower latitudes. But the study of Cassini's data showed that the ocean's liquid methane composition is not much different from other northern seas on Titan. This finding excites scientists. As Poggiali told the Cornell Chronicle, Saturn's moon Titan represents a model environment of a possible atmosphere of early Earth. Knowing Kraken Mare has an abundance of liquid methane will only help to assess models of Titan's Earth-like hydrologic system, he said. As the New York Times observed, these findings represent more than complicated science. According to their reporting, Poggiali thinks of Titan partly as "a laboratory where, over millions of years, chemistry could have learned how to generate energy and store information." That has meaning for us Earthlings, and it's what makes the plan to send Dragonfly and a 20-foot-long submarine to closely examine Kraken Mare from below tantalizing. "These are processes that have happened on our planet too, but they left no traces," Poggiali told the Times. "As you probably see, we need to get back to Titan to better understand the mystery of life." Interested in all things in outer space and exploration? We are, too. Take a look at open positions at Northrop Grumman and consider joining our team.

A Lake on Saturn's Moon Titan Is More Than a Sea Monster

From space travel to the World Wide Web, email to nanoscale robotics, humanity's constant drive for improvement and innovation has changed the course of history. So hop aboard and get comfortable — the time machine is all fired up and ready to relive the greatest scientific discoveries of decades past. Let's go! First stop? Space-race technology from the 1960s that put humans on the moon and laid the foundation for computer development at breakneck speed: the microchip. To the Moon! Today, travel to the moon and Mars is the subject of governmental funding debates, executive orders and the drive to recapture public interest. But in the mid-1960s, the United States was fully committed to winning the space race against the Soviet Union, and NASA brought its A-game with Apollo 11. On July 20, 1969, NASA's Mission Control got its first message from the surface of the moon: "Houston, Tranquility Base here. The Eagle has landed." It was the culmination of a decade's worth of hard work, political one-upmanship and — perhaps most importantly — technological innovation. To reach the stars, NASA needed computer technology that was lightweight and scalable and that could out-perform anything on the market, but nothing like that had ever existed. At $10,000 a pound, it's astronomically expensive to put anything into lower Earth orbit, says Computer World. It was important to keep Apollo's weight low to reduce the amount of fuel needed and free up budget for other projects. Computing speed was also a big hurdle: According to NASA, Apollo required "a small, lightweight guidance and navigation unit that could process complex trajectory equations and issue guidance commands to the Apollo spacecraft in 'real time' during the flight." The Integration Generation In the late 1950s, transistor technology was struggling to stay ahead of shrinking device sizes, but a revolution was coming. In July 1958, electric engineer Jack Kilby realized that entire circuits — transistors and all — could be integrated onto silicon crystals, offering both better performance and significantly reduced size. Months later, Robert Noyce had the same idea, but he refined the chip by linking component parts with copper lines printed on an oxide layer to create a monolithic circuit, reports Computer History. On April 12, 1961, the first patent for an integrated circuit was issued. Harvey Cragon, Kilby's colleague, designed a demo computer for the U.S. Air Force showing that 587 integrated circuits could replace 8,500 transistors and deliver the same functionality. Noyce's company and MIT were chosen by NASA to build the Apollo Guidance Computer, says Computer World. While there's no doubt that integrated circuit technology from the 1960s helped the U.S. win the space race, microchips were just getting started. Innovation at Scale Much like the transistor technology that preceded it, microchip manufacturing took off, allowing companies to scale down the size of components and create computing products small enough — and cheap enough — for consumers. It's the natural second stage of the greatest scientific discoveries: leveraging what began as something revolutionary to drive mass production at scale. From microwaves to personal computers, portable cassette players to advanced touchscreen tablets, microchips are now the mainstay of electronic design. Consider smartphones. This computer-in-your-pocket revolution wouldn't have been possible without the use of tiny, high-performance microchips capable of carrying massive amounts of information at speed. Competition among manufacturers has led to increasingly small transistors and smaller chips. According to The Verge, scientists at the Lawrence Berkeley National Laboratory have managed to create a transistor that's just 1 nanometer long — a feat that pushes right up against the notion of what physical laws suggest is possible. Commercially, the result of integrated circuit innovation is stunning. As reported by Venture Beat, there are more than 3 billion smartphone users worldwide. Emerging products such as wearable devices and injectable microchips that can track bodily drug and alcohol levels, meanwhile, are helping to expand the microchip market in new (and sometimes worrisome) ways. Breaking Moore's Law Moore's Law was conceived in 1965 when Gordon Moore observed that the number of transistors on microchips doubled each year even as prices were halved. As noted by TechRadar, however, silicon is reaching its physical limits. The time it takes for chips to shrink is increasing — up to 18 months and counting. Threshold transistors won't work properly past a certain size because there isn't enough room for both "on" and "off" states. In addition, new devices and applications now require reduced latency, increased speed and enhanced light detection not possible with existing silicon chips. Is this the end for integrated circuits? Not quite. New, compound semiconductors made of elements such as gallium and nitrogen (GaN) could offer 100 times improvements to current silicon capabilities. While this (probably) won't break any immutable physical laws, it could bridge the gap between emerging device demands and existing circuit limitations. It All Starts Here There's no denying it: Microchip technology from the 1960s was not only the greatest scientific discovery of the decade but laid the groundwork for generations of human advancement, ingenuity and innovation. Ready for another ride? Flash forward to the disco-driven discoveries of the 1970s.

Microchips and Moon Landings: Technology From the 1960s

 Enable targeting cookies to view this content.   While the world was enjoying the rare "super blood wolf moon" earlier this year, a few observant spectators noticed an odd flash of light on the moon's surface. Planetary scientists have now confirmed that this was a meteorite impact.   A Triple Treat This was the first known sighting of a meteorite impact on the moon during an eclipse, according to New Scientist. Three astronomical circumstances aligned to make it happen. First, the moon was full, and it was as close to Earth in orbit as it gets, which made it appear to be larger than usual: a supermoon. Secondly, the moon passed into Earth's shadow for a total lunar eclipse. Then, while the moon appeared dark reddish in the shadow, a space rock crashed into its surface and emitted a bright light as it exploded.   Amateur stargazers around the world were watching the super blood wolf moon by simply looking outside or livestreaming the event online. Some viewers noticed a small flash, and they debated on Reddit whether it had been a meteorite. Meanwhile, scientists in at the University of Huelva in Spain aimed eight telescopes on different parts of the moon to try to observe a meteorite impact during a lunar eclipse and catch it on film for the first time in history.   "I had a feeling, this time will be the time it will happen," Jose Maria Madiedo told New Scientist.   After the eclipse, University of Huelva's software automatically pinpointed a flash in imagery recorded by several of their telescopes and helped confirm that it was a meteorite crashing into the lunar surface. According to National Geographic, Madiedo and his team estimated that the meteoroid that people witnessed during the super blood wolf moon was about the size of a football and it left a crater 23 to 33 feet wide. (Wondering about the difference between a meteoroid and a meteorite? Check out this terminology primer from NASA.)   How Often Do Meteorites Come Into Contact With the Moon?   National Geographic reports that similar meteorites hit the moon on a weekly basis. When meteoroids head toward Earth, they usually burn up in our atmosphere. But there is no air on the moon. So, when space debris comes into contact with the moon, some of the energy goes into heat that makes a crater, while a fraction of the energy creates a flash of visible light.    The challenge is that normally the moon is brightly lit, so it's hard to observe the flash of a meteorite impact (you're looking for light against a big backdrop of light). An eclipse darkens the moon and makes it easier to catch one of the tiny flashes in action, which is how people were able to witness the meteorite impact during super blood wolf moon.   What the Moon's Craters Reveal   One of the moon's most famous characteristics — its cratered surface — provides visible evidence of meteorite impact over many years. Scientists study the moon's craters to learn about the frequency of meteoroids so that we can anticipate them on Earth and eventually so that NASA can make forecasts to help spacecraft avoid being hit by flying rocks.    The moon's craters can also help us understand Earth's history. We're celestial next-door neighbors, so the meteoroids that fly past the moon should also fly past Earth at the same rate. Interestingly, Earth's gravity pulls in more meteoroids, but we only know of 180 craters on Earth. The most likely explanation is that Earth's craters have been covered up by erosion, tectonics and volcanism. There are thousands of visible craters on the moon because it doesn't have any of these crater erasers, so it is easier to see where meteorites have smashed into the lunar surface.   ScienceNews reports that approximately 290 million years ago, Earth and the moon both saw a sharp increase in impacts. Scientists can estimate the age of a crater because young craters on the moon are surrounded by rocks, which are debris from the impact. The young rocks absorb heat from the sun during the moon's daytime and radiate it back out at night, which can be observed by NASA. Older craters are surrounded by rocks that have become dust over time, so they don't glow as brightly as young craters.   On average, 73,000 pounds of meteorites hit Earth every day, according to Space.com, but the exact lunar impact rate is still uncertain because scientists just haven't observed enough meteorites impacting the moon to make a proper estimate.  

Did You Catch the Meteorite Impact on the Super Blood Wolf Moon?

As NASA ramps up preparations for Project Artemis to return astronauts to the moon, one of the many technical challenges it faces is providing an ultra-precise lunar map to use when astronauts are exploring the moon. Even small but unexpected surface obstructions could spell disaster for a landing spacecraft or a rover driving across the lunar surface. When Apollo astronauts went to the moon more than 50 years ago, their landing sites were carefully chosen for relative blandness. Bland was safer! But Artemis astronauts intend to visit the most interesting sites on the moon, not just bland ones. A Better Lunar Map Over the decades since Apollo, scientists have imaged the moon's surface features in enormous detail, so the Artemis lunar map team has far better information to work from than their predecessors had in the 1960s. As Space.com reports, the photographic imagery that is used to construct a lunar map has very high precision indeed, with one pixel covering less than one square meter of the surface. Thus, scientists can establish the latitude and longitude of a lunar feature to within a meter — accurate enough to support safe landing and driving on the lunar surface. But the laser altimetry that is used to establish the elevation of the lunar surface is far less precise, accurate only within about 100 meters. This is nowhere near good enough. There are existing methods for measuring shadows on the lunar surface to determine more precise elevation "fixes" for topographical mapping, but these are typically cumbersome. Not only are they computationally intensive, putting heavy demands on computers, they also require a great deal of estimating and fiddling that only highly trained people can do, but they must do so very carefully — and slowly. For the lunar map team, this was a severe bottleneck, but help was on the way. The Cliffs of Stevns Klint As the Artemis lunar map team wrestled with this challenge, a geophysics graduate student at the University of Copenhagen's Niels Bohr Institute also ran into a problem. Former grad student Iris Fernandes (per the University of Copenhagen, she has since earned her PhD) wanted to use photographic images of Stevns Klint — a dramatic and geologically important limestone cliff on an island in Denmark — to analyze surface patterns on the face of the cliff. Her problem, as Science Daily reports, was that the algorithm she was using to study the patterns was thrown off by complex interplay of sunlight and shading in the photographs. As Fernandes explains, "It created a bias in the model. We needed to find ways to remove the shades, in order to remove the bias." To mathematically cancel out the shading, Fernandes needed a test environment with varied rock forms, a lack of patterned colors, and where sunlight and shadow were the dominant features. Like many geophysicists, Fernandes was interested in the planets, and she was aware of a place that met her requirements well: the moon. Shades of Gray We may sing about the light of the silvery moon, but the lunar surface is almost entirely gray, with few small-scale patterns other than those produced by sunlight and shadow. This made it a perfect place for studying those shading patterns — and finding a way to cancel them out. As it happens, the human eye and the vision centers of the brain, shaped by millions of years of evolution, are extremely good at processing the shadings of light and shadow. As a result, even a good pair of binoculars can vividly display the shadows cast by lunar mountain ranges. Because this effect is most visible near the lunar terminator (the lines of dawn and dusk lie) where the sun is very low in the lunar sky and shadows correspondingly long, one effect is to make lunar mountains appear much more jagged in a telescope than they actually are. This capability of the human eye was crucial to the established methods for determining elevation from light and shadow. But the need for extensive human input and judgment was exactly what made these methods so cumbersome. Adding to the intrinsic complexity of these established methods was the wide range of variation in the quality of lunar imagery and laser altimetry data, which Fernandes had to deal with, similar to the Artemis lunar map team. Eyes on the Prize Faced with all this complexity, Fernandes and her PhD advisor, geophysicist Klaus Mosegaard, focused tightly on the underlying mathematics. They zeroed in on "inverse theory" — the mathematical process of getting from a result to the inputs that would produce that result — as well as the Sylvester Equation. As Fernandes explains in Science Daily, they set to work "basically, to see if this equation could solve the problem." "And it did," she adds. "You could say that we â€¦ found the mathematical key to a door that had remained closed for many years." The new mathematical method that Fernandes pioneered greatly reduces the amount of computation (and pre-computation "fiddling") required and takes out the guesswork. The variations in the quality of source data are automatically incorporated as inputs, producing not only a more precise output (such as a lunar map) but also one with a clearly specified precision level. Fernandes notes, "This method is fast, it is precise and it doesn't have to rely on any assumptions." Science: The Surprise Machine As Science Daily notes, scientific curiosity can lead you to surprising places. Fernandes and Mosegaard set out with the initial goal of canceling out the patterns of sunlight and shading on the cliffs of Stevns Klint, effectively eliminating light shading in order to reveal other patterns in the cliff rocks. They were not at all concerned with the challenges of elevation measurement and the limitations of laser altimetry, since the cliffs are right here on Planet Earth and can be surveyed as precisely as needed. For NASA, in contrast, the patterns of sunlight and shading on the moon's surface are the whole ballgame — the key to providing a topographical map with sufficient precision for human astronauts exploring the moon. And the same techniques can be applied to Mars, asteroids, outer-planet moons and other bodies with solid surfaces awaiting exploration. Meanwhile, Fernandes also sees other possible implications, such as using shading patterns to look for small, round stones on Mars as a sign that they might once have been exposed to water. Science as a human activity is, in no small part, the art of finding surprises and putting them to surprising use. Interested in all things in outer space and exploration? We are too. Take a look at open positions at Northrop Grumman and consider joining our team. 

Creating a Precise Lunar Map: When Sciences Collide

Even a quick glance into the night sky should inspire wonder about how humans found a foothold to the universe by stepping on the moon for the first time.  While space exploration has proceeded in fits and starts since then, the discoveries of Apollo 11 continue to present a greater understanding of the moon and Earth. As the 50th anniversary of the first moon exploration nears, scientists continue unlocking clues about our place in the universe by further studying the lunar samples collected by Neil Armstrong, Buzz Aldrin and the astronauts of five subsequent moon missions.  "I think people in general think, 'We've had the Apollo samples for a long time, so why are we still studying them?'" Ryan Zeigler, Apollo sample curator and manager of NASA's Astromaterials Acquisition and Curation Office, recently told Space.com. "There's real, new work that's being done on them that's not just repeating what was done decades ago."  Moon Discoveries Keep Providing Clues  It is lunar legend that on an otherwise by-the-book walk around the moon, the commander of Apollo 11 went a bit off script. After placing about 20 moon rocks into a collection box, Armstrong couldn't miss his ride; the lunar module that taxied him and Aldrin between the main spacecraft and the moon would soon leave. But believing his box didn't have enough samples, he decided to gather more soil, 5.9 kilos (13 pounds) worth.  Armstrong and the astronauts of other Apollo missions didn't realize it at the time, but some moon rocks wouldn't be studied until 2019. That's because NASA knew that the technology didn't exist during the Apollo program to properly study samples in a way that future scientific tools could. So, despite some remarkable research on lunar materials over the past 50 years, some of the 842 pounds of rock collected from the six moon missions have remained sealed, awaiting analysis.  Technology has indeed taken a giant leap since Armstrong jumped around on the moon. For one, NASA has a new X-ray CT scanner that identifies structures within objects, allowing scientists to see precisely where they should cut rocks to avoid destroying them. That should help scientists when they soon examine three samples for the first time: two vacuum-sealed cores and a long-frozen rock. Those studies can be performed just once — at the moment the samples are opened — so the scanner should provide guidance that wasn't available until now.  The results from the next experiment might prove as surprising as those from a 2014 study of lunar basaltic glasses brought back by the Apollo 15 and Apollo 17 missions. That research showed that traces of water in the recovered moon rocks might share a common source with water on Earth.  Apollo Findings Provided Answers  Despite relative technological limitations, NASA nonetheless studied many of the lunar samples in earnest as soon as the Apollo missions returned home. In fact, just six months after the moon exploration by Apollo 11, so many observations had already been made about the soil of Earth's satellite that Science published a special issue four times the size of a regular edition to cover all of the findings.  The importance of what the moon's materials have revealed can't be overstated. Prior to Apollo 11, no one could speak with certainty about the moon's provenance. Was it hot or cold? Could it support life?  Now we know it is a terrestrial planet with interior zoning similar to Earth and that it was formed from rocky material that took shape through meteorite crashes, volcanic eruptions and widescale melting. The Smithsonian National Air and Space Museum neatly encapsulates those findings and many others, including that the moon has no life forms, that it has a radiation history that helps understand climate change on Earth, and that lunar samples offer time scales for the evolution of Mars, Mercury and Venus.  A New Perspective and New Aims  Although Apollo 11 captured hearts and headlines, the other missions earned acclaim for either setting the stage for the first moon walk or by following the lead of Armstrong and Aldrin and making more moon discoveries.  Yet, it is argued that it was a single color photograph — not a scientific sample — that changed humans' perceptions of their place in space. Taken by Apollo 8 astronaut Bill Anders, "Earthrise" shows our blue and white globe climbing above the moon's horizon. For the first time, Earthlings had an understanding of what our world looked like from space, giving many an appreciation of life, science and, for some, the need to better care for our only place to live.  Now, as NASA and other public and private space agencies aim to return to our lunar cousin — and potentially use it as a springboard to Mars and beyond — Apollo's many discoveries are a reminder that the human quest to learn more about the universe should never cease for the simple reason that we'll never know what we'll find. 

Apollo 11 Showed That Moon Exploration Is Just the Beginning

Venus is in some ways the forbidden planet of our solar system. In size and mass, it is a near twin of Earth. Yet, it resembles the popular image of hell; its surface bakes at some 800 degrees Fahrenheit beneath a carbon dioxide atmosphere that's 90 times denser than Earth's with an endless rain of sulfuric acid. Space probes have survived there just long enough to send back images of Venus rocks scattered across a volcanic landscape. A Planet With a Past As Space.com reports, Venus may not always have been so hellish. Planetary scientists believe that conditions were much less extreme on early Venus. The dense greenhouse atmosphere with its blistering heat had not yet formed. While Venus, being closer to the sun, was always hotter than Earth, the sun itself was fainter in its early days. Thus, Venus may once have had liquid water — perhaps rivers and seas, possibly even life on its surface — before volcanic eruptions built up enough CO2 to trigger a runaway greenhouse effect and boil off any oceans it had. Indeed, according to National Geographic, recent tantalizing hints of the organic gas phosphine, high above the clouds, might even indicate that some form of life still hangs on there — all the more reason why scientists would love to know more about Venus's distant past. A Tough Place to Get To A lot of our questions could be answered if only we could obtain some Venus rocks for closer geological and chemical study. As Space.com notes, liquid water has distinctive chemical effects on rocks exposed to it, and these effects remain even after the water is long gone. The bad news is that bringing rocks back from Venus is so difficult that it's impractical with current space technology. A prospecting mission would not only have to recover Venus rocks from its hellish surface, but also launch itself back into space against Venus's gravity, which is nearly as strong as Earth's. The good news is that we might be able to find and examine Venus rocks without having to haul them back from Venus. Over the four and a half billion years since the solar system formed, planets have been hit multiple times by asteroids and comets. The most famous of these is the asteroid that hit Earth and wiped out the dinosaurs, but many others are known. These impacts blasted giant craters on the planets they hit, and some of the material was blasted out so fast that it escaped into space, going into orbit around the sun. In turn, some bits of this material eventually fell as meteorites on other planets. We know this because some of this debris landed on Earth, including a piece of Mars rock that ended up in Africa. Looking for Venus on the Moon If bits of Mars could fall onto Earth, so could bits of Venus. But searching for interplanetary debris such as stray Venus rocks on Earth has its challenges. While we got lucky with the Mars meteorite, Earth is not a good museum for preserving space fragments. Earth's active geology grinds down rocks with wind and water erosion or buries them under deep layers of sediment. A much better place to look might be Earth's nearest neighbor in space, the moon. Rocks on the moon have a much better prospect of surviving intact for millions or even billions of years than similar rocks on Earth. The heavily cratered lunar surface is a testament to a world that, since its formation, has not only been shaped primarily by space impacts but has also endured almost none of the same weathering forces that have "repaved" so much of Earth's surface. Thus, Venus rocks on the moon are much more likely to have survived intact. There is even a slight possibility that rocks collected by the Apollo astronauts already contain bits of Venus. But, in any case, future space missions will bring back additional lunar rocks for examination as we look to the moon to understand the second planet from the sun.

Venus Rocks! And Some May Have Ended Up on the Moon

Our closest neighbor in space, the Moon, is slowly drifting away from us. Researchers have calculated that the Moon's recession runs at around 1.5 inches (almost 4 centimeters) per year. Even though it's slow, this drift does impact life on our planet.
Over the centuries, we've built up an impressive array of knowledge about our satellite, but how many of us have wondered what would happen if the moon drifted away from Earth? Though it's unlikely to affect us in our lifetime, there are some major changes to expect with the Moon's departure.
Lunar Recession History
The Moon was born out of a massive collision of rocky material hurtling into our planet. The Atlantic describes that, when molten debris spun and formed into our satellite, the Moon's orbit was about 10 times closer, and a day on Earth ran at around four hours. It was also pulling away much faster — at around 8 inches (around 20 centimeters) per year.
From the time it formed to the present day, the Moon has been moving away from Earth. Astronomers suspected this but were able to confirm and measure the rate by bouncing lasers off mirrors installed on the Moon's surface during the lunar expeditions of the 1960s and 1970s.
The Conversation notes that the current rate is around 1.5 inches (3.8 centimeters) per year. From this rate, scientists initially calculated back to an initial impact date of around 1.5 billion years ago; however, other evidence showed that the Moon is much older with a creation date of around 4.5 billion years ago.
Rather than give in to "alternative" creation theories, the researchers turned to sedimentary rock analysis, which suggested variation in recession rates over the years. For example, around 2.46 billion years ago, the distance between Earth and Moon was 60,000 kilometers less than it is today, which shortened the day to only 17 hours instead of 24 hours.
Why Is the Distance Between the Earth and Moon Increasing?
Before asking what would happen if the moon drifted away from Earth, we first need to understand why this drift is happening. All bodies in space exert a force on each other, and the magnitude depends on a number of factors, including distance and size or mass. Closer objects exert more gravitational pull, and that increases if they are larger. Earth exerts a gravitational pull on the Moon, and vice versa.
The force that the Moon exerts on Earth shows up as our tides, with the oceans ebbing and flowing roughly twice each day. The gravitational pull of the Moon makes our oceans bulge outward along the direction of the pull; however, NASA notes that this pull is out of sync, since it takes some time to move water around. The tidal movements also slow Earth's rotational spin due to friction. This, in turn, impacts the speed at which the Moon orbits, letting it drift off into space.
What Are the Implications of This Drifting?
So, what would happen if the distance between the Earth and Moon increased? Most of this question can be answered by looking at what influence the Moon exerts on Earth, and as the Royal Museums Greenwich describes, it's mostly to do with the sea, as this is where lunar gravity has the most effect.
Interestingly, if the Moon was closer, its gravity would start tugging at Earth's crust. At even half the distance, Live Science describes that, not only would tides be eight times higher and slow down Earth's spin, but there'd also be more seismic activity and volcanic eruptions.
Increasing distance would also cause extinctions and climate upheaval. A more distant Moon would mean smaller tides, which would affect coastal ecosystems and ocean currents. Loss of coastal ecosystems and habitats for many species would seriously affect animals on land and sea that rely on them as part of the food chain.
Ocean currents drive and stabilize the weather, so we could expect more extremes of temperature and global climate disruption. The Moon's gravitational pull also helps stabilize Earth's tilt toward and away from the Sun, which causes the different seasons in each hemisphere. Less stability might completely abolish the seasons or perhaps lead to more extremes.
Being further away would mean less impact on Earth's rotation, with longer days and nights. There would also be less moonlight, as the Moon would seem smaller in the night sky. Predators that hunt at night wouldn't be able to locate prey so easily.
And with a "smaller" Moon in the sky, we'd lose an astronomical highlight — in 600 million years, the Moon will be too far away to completely block the Sun in a total eclipse.
Sweet Dreams, Moon
Another reason for the Moon's drift is tidal locking. On Earth, we only see one side of the Moon, but this wasn't always the case. Early on in its development, the Moon had its own rotational spin. However, since Earth was also exerting a gravitational pull and distorting its shape, energy dissipated and slowed the Moon's rotation down. Eventually, one lunar rotation took the same length of time to orbit the Earth, and the Moon became tidally locked with only one face presented to the planet. This energy dissipation also contributes to lunar drift.
As the two drift further apart, Earth will become tidally locked and have its own dark side compared to the Moon. In about 50 billion years, not only will the Moon be further away, but only one half of our planet will be able to see it each night. While that's quite a bit away, it's just one more reason to appreciate the Moon in the night sky while we can still see it.
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What Would Happen If the Moon Drifted Away From Earth?

Vodafone Germany and Nokia have teamed up to build an ultra-lightweight, space-worthy cellular network unit — a cellular tower to be placed on the moon. If all goes well, cell phone service will become available on the moon next year.    Why provide cell phone service on the moon? The last time anyone traveled to the moon was 1972, and at Northrop Grumman, we remember this well: Every human who went to the moon and back did so aboard parent company Grumman's Lunar Module. Cellular technology obviously didn't exist at that time, but today, it could solve some issues related to lunar missions.      Driving on the Moon   The lunar 4G network will be carried out next year aboard the spacecraft ALINA, which, according to Space.com, will become the first privately owned spacecraft to reach the moon. The name ALINA is short for Autonomous Landing and Navigation Module, and its payload will include not only the cellular network infrastructure, but also a pair of lunar rovers built by Audi. The four-wheel-drive rovers, designed using 3D printing, are built to handle difficult terrain and are equipped with solar panels.       Enable targeting cookies to view this content.   Established Technology, New Challenges   The ALINA mission was conceived and designed by a German-based organization, PTScientists. Rather than develop a special one-off communication system to link ALINA with its rovers, the team realized that it could reduce development costs by adapting established cell phone technology to provide a base station for communicating with and directing the rovers.   Of course, your cell phone is not rated to work in outer space, and most cellular towers are too heavy for a practical space mission. The ALINA mission, according to Space.com, will carry a space-rated version of Nokia's Ultra Compact Network — the lightest cellular station ever built, weighing in at 1 kilogram, or 2.2 pounds, slightly heavier than a quart of milk.   One Small Step for Lunar Infrastructure   As reported by Jason Daley at Smithsonian magazine, the lunar rovers carried by the ALINA mission will use their cell phone links to send back images and data more efficiently than conventional "analog" radio links would allow.   The objective of this initial mission, per Smithsonian magazine, will be to study an earlier model of the lunar rover — the one carried by Apollo 17 in 1972. The astronauts abandoned the rover, along with the landing stage of the Grumman Lunar Module that carried them there. (The astronauts were carried safely back to lunar orbit by the module's ascent stage.)   But if all goes reasonably well, there will be further missions — and further need for cell phone service on the moon, including handling phone calls by future lunar astronauts.   

Coming Soon: Cell Phone Service on the Moon

Fifty years ago, geopolitical chest-puffing spurned a competition between the United States and Russia to see who would land on the moon first. Today, a new race has commenced — this one driven primarily by the economics of moon mining. Water, rare elements and metals exist on the moon, according to NASA, and governmental and private space entities are betting on the potential profit of these space resources. They could be harvested for use on Earth, or they could help to build and power lunar habitats that could serve as way stations to nearby asteroids, as well as Mars and beyond. How companies might undertake such a venture and return high-value materials to Earth remains to be seen. But entrepreneurs from private and public agencies are making the case that moon mining could preserve our planet's own resources and create new opportunities for exploring the solar system. Moon Metals and More Black and white images from the first moon landing in 1969 show a cratered, seemingly barren landscape. But NASA's Lunar Reconnaissance Orbiter, launched in 2009, has revealed a surface rich in solar resources. Using several instruments to study the moon's surface — including ones that measure elevation, collect ultraviolet and visible light images, detect hydrogen and measure surface and subsurface temperatures and frost — the orbiter gathered data revealing the prevalence of important elements, minerals and water. It should come as no surprise that common minerals, including basalt, iron, quartz and silicon, have been detected on the moon, according to NASA. The more common resources could be turned into buildings, windows, stoneware, solar panels and more, reports Popular Science. Other scarce materials have also been discovered. Precious metals such as platinum, palladium and rhodium are highly conductive and could be used in electronics. In 2011, scientists reported that they had discovered titanium ore, 10 times richer than that found on Earth, says NASA. When mixed with aluminum or iron, titanium makes an alloy that is lightweight, corrosion-resistant, incredibly strong and resistant to extreme temperatures. It could be used to build a variety of items, such as engines, medical implants and structural frames. There are 17 rare metals that are scant to find on earth but may be found on the moon. These moon metals include scandium, ytttrium and others, which could be used in vehicle engines, to make glass or ceramics, electronic devices, radar systems, superconductors and more. Even rarer is helium-3, a gas that could be used as a clean and powerful fuel for nuclear fusion reactors. And then there's water. Thought to be trapped in lunar ice hidden deep in the shadow of polar craters, water could be turned into oxygen and rocket fuel. Robots, 3-D Printers and Optical Mining Earth's only natural satellite contains a wealth of possibilities. Getting there is another matter. According to IEEE Spectrum, new technology around rockets, reusable stages and crew capsules will need major funding. So, too, will lunar cargo landers that can pick up resources on the moon and return them to Earth. NASA has issued contracts for these machines to the companies Astrobotic Technology and Intuitive Machines. Eventually, building on the moon will require a range of technology that can construct everything from habitats to communications. Planning is underway. For the first time, the U.S. Geological Survey started seriously evaluating space resources for future mining. Last year, they began attending the Space Resources Roundtable held at the Colorado School of Mines in Golden, Colorado. There, they helped assess the location and value of minerals, energy and water on the moon, Mars and asteroids, reports Space.com. Private companies have also begun drawing up blueprints to start mining space resources, according to Yahoo Finance. Moon Express, for instance, received a license from the Federal Aviation Administration in 2017 to land on the moon and set up a commercial space station. It's now developing a family of scalable robotic explorers that could deliver scientific and commercial payloads to the moon or be chartered for expeditions to other worlds. Meanwhile, Planetary Resources, which is focused on asteroids, has planned data-gathering satellite missions to visit multiple near-Earth asteroids and assess their mineral and water content. Space.com notes that, in 2016, the company partnered with 3D Systems to demonstrate that metal extracted from a meteorite — the same material that would presumably be found on asteroids — could be 3D-printed into useful objects. Habitats could also be printed. In the meantime, NASA is investing billions of dollars in developing technology around space mining. This past May, the agency announced the winner of its 3D-printed Mars Habitat Challenge, showing it was possible to turn resources on the moon or Mars into shelters. In June, NASA announced it was moving forward with two mission concepts designed to explore lunar craters and mining asteroids. The first, called Skylight, proposes technologies to rapidly survey and model lunar craters. The second, called Mini Bee, aims to demonstrate a technique known as optical mining, which uses concentrated sunlight to forces gases out of asteroids and use them as rocket propellant. Benefits to All Humanity Although technology is a major aspect of exploring and mining space resources, some experts have raised concerns about the ethical consequences of such an undertaking. An April 2019 study published in the journal Acta Astronautica makes the case that the world should limit space development to one-eighth of the solar system and leave the rest "wild." Although that fraction may sound small, the scientists say that one-eighth of the iron in the asteroid belt is "more than a million times greater than all of the Earth's currently estimated iron ore reserves, and it may well suffice for centuries." Another group, called the Moon Village, launched in 2017 to establish an international consortium. Comprised of private industry members, government representatives and members of the public, the group seeks to ensure that the moon is developed in a sustainable, open and peaceful way. It was started by Giuseppe Reibaldi, who spent 35 years at the European Space Agency, and is run by many experts from the space community, including John Mankins, former Chief Technologist for Human Exploration and Development of Space at NASA, Jan Kolar, founder and director of the Czech Space Office, and Tai Sik Lee, a professor at Hanyang University and founder and CEO of the International Space Exploration Research Institute. In an opinion piece in The Conversation, bioethicist Evie Kendal raises questions around the exploration and settlement of the moon. They center on issues such as using the moon as a base for planetary defense, health and safety issues around tourism, conducting medical research there, worker safety, regulations around extracting resources and citizenship questions about babies born on the moon. Earth's rocky satellite has always served to inspire humanity. Its very existence has instilled a sense of discovery and desire to journey into worlds unknown. As the population grows on our home planet, it will be important to preserve its resources by seeking out alternate sources. But many technological and ethical issues must still be answered before humanity begins a serious effort to explore the moon and beyond. Establishing the groundwork for peaceful development now could go a long way toward bringing nations together under one, unified plan that benefits all humankind.

Why on Earth Should We Be Mining the Moon?

What is the dark side of the moon? Is it strictly the name of the classic 1973 Pink Floyd album, or is it a real phenomenon? The moon does indeed have a dark side. So does every other moon and planet in the solar system, including Earth. In fact, if you happen to be reading this at night, you are currently on the dark side of Earth. This is where things get confusing. When you look up at a crescent moon in the sky, you're looking at part of the dark side, though you don't usually notice it because it is, well, pretty dark. When people talk about the dark side of the moon they don't usually mean the side experiencing lunar night. They invariably mean the far side of the moon, which is indeed invisible from Earth, but gets just as much sunlight as the near side of the moon, the side we see, Wired reports. So what is the dark side of the moon? The Unchanging Man in the Moon  Still confused? Perhaps, says Space.com, some of the confusion can be blamed on Pink Floyd, and some of it is due to a cultural tradition of using dark to mean unknown. But the biggest culprit is likely the moon's rotation period, which is the same as its orbital period — a month. This is not mere coincidence, says Wired. The moon's rotation is "tidally locked" due to Earth's much greater mass, but the main effect is that the moon doesn't seem to rotate at all. The same side always faces Earth, its shades-of-gray surface features forming the familiar man-in-the-moon pattern. In fact, because the moon wobbles slightly as it orbits Earth — the technical term for this is libration — we can see a little more than half the moon's surface, though not all at the same time. But most of the lunar far side can never been seen from Earth, and remained totally unknown until the space age.  Seeing the Dark Side The far side gets just as much sunlight as the near side does — in fact a tiny bit more. During a total lunar eclipse, the sunlit "bright" side of the moon passes through Earth's shadow and for a couple of hours is temporarily darkened. On the lunar farside, where Earth is not visible in the sky, its bulk never blocks out the sun, so the farside cannot experience a lunar eclipse. As for the actual dark side of the moon, the side facing away from the sun, it never gets completely pitch dark there thanks to starlight (and any planets visible in the lunar night sky). The side facing Earth, meanwhile, also gets reflected earthlight. If you look at a thin sliver moon, a day or two before or after new moon, you can often see the faintly lighted dark side, an effect that NASA's Astronomy Picture of the Day describes as "the old moon in the new moon's arms." Even during a total lunar eclipse, when the moon is facing Earth's night side, our atmosphere bends a little sunlight into the shadow, sometimes producing the "blood moon" effect of a lunar eclipse. So as it turns out, even the actual dark side of the moon is not always quite dark. And since we are still in the dawn of moon exploration, the far side of the moon remains pretty mysterious, even though most of it is brightly sunlit for two weeks out of every month. Future Moon Exploration The 50th anniversary of the Apollo 11 landing helped call attention to all things lunar. Apart from current and upcoming NASA missions, China and India are both carrying out robotic moon missions. Indeed, China's Chang'e 4 mission made the first-ever landing on the far side of the moon early this year — an accomplishment that triggered a whole spate of headlines about the lunar "dark side."

What Is the Dark Side of the Moon?

Tricks of the light aside, for a celestial body to be seen during the day, it has to compete with the sun. Not many objects can outshine our main sequence star in its own system. A few supernovas have been so bright that they've been visible during the day. Meteors, if they are big enough, flare like giant torches as they burn through the atmosphere. And here and there across history, a comet rivaling the sun in brilliance has streaked across the sky, terrifying Earth-dwellers.
Then there is the moon. It breaks all the rules. Long before humans understood the orbital plane of the Earth and the stars, how many ancient people looked up at the moon and thought - what even is that thing?
Trickster or Rockstar
It's not hard to see why the moon had our species scratching their collective heads for millennia. It's nearly constant, phasing in and out every 27 days. But in most other ways, the moon makes less sense than anything else in the sky. How can it look as bright as firelight, but also seem solid? Why can we sometimes see the moon during the day, sometimes see it at night and sometimes not at all? What are those strange patterns across the surface, and why do they never change? Why doesn't the moon follow the same path across the sky as the sun, planets and stars? And why does it occasionally, seemingly out of nowhere, turn red?
In previous eras of human history, the amount of moon information possessed by modern eighth-graders would have made them legends. Or landed them in jail.
Around 600 BCE, Anaxagoras proposed to his fellow Athenians that the moon was not a deity but rather a rock — one that had been flung from the Earth. The sun, likewise, was solid and also burning. Rather than making its own power, the moon reflected the burning sun's light. This celestial setup allowed Anaxagoras and anyone of like mind to correctly predict that when the orbital planes of the three solid objects lined up, solar and lunar eclipses would be the result.
Seeing Is Believing
Suffice to say, Athenians were not entirely of like mind. Many ancients found it easier to imagine a god stationed in the sky than a highly reflective rock — one placed up there for unclear reasons by known forces. Why this rock never came down, why it continued to phase and how it remained unphased by weather seemed equally unfathomable. These days, basic knowledge of astronomy is a birthright. But 2600 years ago, it was simpler to arrest Anaxagoras for heresy than to understand that lunar phases are an optical illusion: that when the sun sets in the west as the moon rises in the east, the moon appears full only because we are standing in-between two distant, differently-sized bodies. Telescopes, invented more than a thousand years after Anaxagoras died in exile, allowed us to easily see craters, rocky planes and other imperfections in the sphere that was once believed to be a god.
Then, of course, we went there.
Post-Apollo, lunar knowledge is commonplace. Using a tennis ball and a flashlight, two school kids standing in a dark room can easily demonstrate phases of the moon. The child playing the sun stands still with the flashlight shining straight away from them. The other child playing the Earth faces the flashlight, trying not to squint too much. They hold the tennis ball in front of them with their left arm outstretched, then they rotate 90 degrees to the left. Presto: They can only see 25% of the illuminated moon. The moon/tennis ball is 50% illuminated, but the child only sees one illuminated quarter of it from their position. We see the same illuminated quarter from Earth during first-quarter moons.
Meanwhile, all the children standing around the child with the flashlight can see 50% of the moon lit up, as it always is. As the child with the tennis ball continues to rotate to their left, they will be able to see more of the moon lit up, too. It all looks the same from the sun's perspective. From the perspective of the child with the tennis ball, the day is going from noon to sunset, and the moon is waxing toward full as time fast-forwards through one whole week.
As the World Turns
Why can we see the moon during the day? Why is it crescent at dawn, first-quarter at noon and full at sunset? All this can be demonstrated in only a few minutes. But don't let the humbleness of the flashlight and the tennis ball fool you. Understanding this interaction of rotating bodies requires a surprisingly advanced appreciation of geometry. Entire civilizations rose and fell before simple demonstrations such as this were deemed more compelling than pantheons filled with drama, intrigue and interpersonal strife.
Speaking of which: The orbital plane of the moon relative to the Earth can be demonstrated with the same simple setup. If the moon's orbital plane were exactly the same as the one the Earth uses to travel around the sun, we would have lunar and solar eclipses every month. Instead, we only have them every so often. That's because the orbital plane of the moon is offset from Earth's orbital plane by about 5 degrees. To demonstrate this, instead of standing straight up, the child holding the tennis ball in front of them should slump a little to the left, as if one ear were heavier than the other. Or they could let their arm holding the ball wobble while they spin it. Either way, the ball should sink slightly below the line of the flashlight beam, then float slightly above it. As the child spins around in place with the tennis ball slightly offset, they'll create a solar eclipse only every so often, when their wonky orbit happens to dash directly in front of the flashlight beam.
New Gods
As easy as that, two lightly equipped children can blow eons of mythology out of the sky. At least, the part of moon mythology that explains how the sun is a god in a chariot, a dragon or any other mystical moon persona. In the era of lunar cam live-streams and satellite constellations, it's easier than ever before to see how the moon is 50% illuminated at all times. Yet, wherever you are on Earth, night or day, Northern or Southern Hemisphere, the same rules apply now as they did then. Whatever phase you are in — be it crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, waning crescent or new — you'll see the part of the half-lit moon that faces you now.
Thousands of years ago, even those who understood the physics of the Earth-moon-sun system could never have imagined how we see the moon today. How when clouds crowd the sky and snow falls on our rooftops, we can call up a perfectly clear view of the lunar surface. How, at any given moment, we can ask a glowing box in our hand to show us the crater Anaxagoras as seen by an orbiting spacecraft. Partly lit by the sun, partly concealed in shadow, the rock thrown into space continues to challenge us to rise above assumptions, superstitions and the comfort of not knowing, and to look back at the whole, imperfect form of the Earth as it hovers above the horizon.
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Tails From the Orbital Plane: Why We Can See the Moon During the Day

With NASA planning to bring astronauts back to the moon by 2024 and make lunar missions sustainable by 2028, the space race part two is on. The challenge this round? Go there to stay. In the drive to produce water, power, fuel and food, we're going to tap into every readily available resource: lunar soil, solar energy and even somewhat threadbare helium, neon and hydrogen atmosphere clinging to our moon's rugged surface. It's all up for grabs, but what can we do with it?
For starters: We can make oxygen on the moon.
Lighting Up the Night: Making Oxygen and Power on the Moon
Making something out of nothing usually involves breaking the laws of physics — making oxygen on the moon only involves using water to break up lunar soil.
To make oxygen on the moon, researchers at Nanjing University recently proposed using a process a bit like terrestrial photosynthesis. The process starts with lunar soil, which is rich in iron and titanium. Thanks to the presence of those elements, when scientists added water to lunar soil samples returned by the Chang'e 5 moon rover, it kicked off a very useful chemical reaction. As has been observed in some places on Earth, including Antarctica, iron in the water-hungry soil donated electrons to the oxygen and hydrogen in the water. The result: both O2 and H2 were released.
The research team noted that with this simple maneuver, the lunar samples readily produced not only breathable air, but also a potential source of fuel. In a future lunar base, carbon dioxide from astronauts' exhaled breath could be added to the H2 released by rehydrated lunar soil. Under the right conditions, H2 and CO2 create methane. Methane is a component of rocket fuel.
If future denizens of the moon's surface add even more oxygen and hydrogen to the methane mix, they might make methanol — which is toxic to humans if ingested, but also an excellent source of energy. If burned purely, methanol returns all of its original components in the form of water and carbon dioxide. This kind of combustion on Earth is the basis for gasoline engines, among other things. It could be used as a similar source of propellant on the moon or simply stored until more water and carbon dioxide are needed. If there are no leaks in the system, this kind of process would make a future lunar base more energy-independent than most homes in America.
This is one possible approach to making oxygen on the moon, and has the advantage of not requiring an external power source. In this reaction, the lunar loam itself acts as a battery. But this method of turning the moon's resources into humanity's air and water 238,855 miles (384,400 km) from home is not the only one, not by a long shot. Another approach involves cooking lunar soil instead of adding water to it.
An Alternative to Extraterrestrial Photosynthesis
Part of the reason that the iron in lunar soil is ready and able to give up oxygen when hydrated is that this iron is bound up with oxygen in the form of iron oxide. Another pairing, silicon oxide, the most abundant component of sand, is plentiful on the moon. Like iron oxide, silicon dioxide (SiO2 or silica) has been shown to release oxygen when heated. In previous eras, silicon dioxide was a problem for lunar explorers. It is fine, sticky and reactive. Silica from lunar dust clung to the Apollo astronaut suits, followed the crew into their cabins and even gave astronaut Jack Schmitt a nasty case of nasal congestion.
This time around, the gun-powder-smelling lunar dust could be a source of easier breathing instead of clogged sinuses. For this second process to successfully leach the O2 out of SiO2, it takes two steps instead of one, but, as a bonus, does not require adding precious water. Quite the contrary: it requires hydrogen and methane. As luck and science would have it, the first process described here, where lunar samples are rehydrated, produces both. So both processes could come in handy, depending on whether the lunar base is rich in water or rich in hydrogen at any given time. Both processes require carbon dioxide. Fortunately, owing to the respiratory efforts of every human being on the moon, future lunar bases are likely to be well-supplied with CO2.
Making Moonshine
The moon shines brightly in our sky partly because of the SiO2 its surface — SiO2 that tends to burn rapidly in the presence of oxygen or anything reactive. Last time we went to the moon, those same shining dust particles clogged up spacesuit visors, coated equipment and cut through all of the seals on the supposedly air-tight containers the Apollo astronauts used to collect lunar samples. Nothing on the moon was safe from it. This time, building habitats and life support systems that survive long-term with minimal support from Earth is going to require that we do more than survive the lunar dust. Settling on our nearest satellite for the long haul is going to require us to dig in and master it.
Cooking or hydrating lunar soil to make oxygen on the moon is not just a matter of breathing, but of using chemistry to turn the tables on one of the most confounding substances humankind as encountered in space to date. Neutralizing reactive lunar soil with water or heat converts an explorer's natural enemy into an invaluable friend: one that could fuel lunar exploration for generations to come.
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Using Lunar Soil to Make Oxygen on the Moon

Before any equipment or hardware is sent to space, it's usually rigorously tested to make sure it can withstand the extremes of space. From cold temperatures to radiation, space is hard on equipment, but hardware also functions differently in space than on Earth because of differing gravity. How, then, do organizations like NASA go about simulating zero gravity on Earth?
Astronauts test their mettle with the Neutral Buoyancy Laboratory (NBL), a giant pool that holds 6.2 billion gallons of water. Thanks to the size, astronauts can work with life-sized mockups to help them prepare for their journey into space. But the NBL is only for astronaut training, not for testing equipment to see how it would fare in space.
This begs the question — can we create zero gravity on Earth? And how reliable is it for testing equipment that will be sent into outer space? Let's find out.
Parabolic Flights Play an Important Role
Parabolic flights help with replicating zero-gravity conditions on Earth by providing up to 40 seconds of "freefall." The origins of parabolic flight to simulate zero gravity go back to 1950, when it was first proposed by researchers at Brooks Air Force Base in Texas. By 1959, pilots were able to achieve 10 to 15 seconds of freefall in a C-131B cargo transport, which was large enough to both train astronauts and test equipment. This was a part of the Air Force's Reduced Gravity Program, which started in 1957 and has been run by NASA since 1973.
These flights work by flying in the shape of a parabola. The aircraft begins accelerating, and then the pilot pulls up. When the plane is going up at a fast enough speed, the pilot performs a pushover, reducing thrust, which allows the occupants and equipment on the plane to fall at the same speed as the aircraft.
Parabolic flight is a low-cost and often-used method of simulating zero gravity on Earth (or to simulate gravity on the moon or Mars), but it is limited by duration.
Gravity Offload Systems Offload Weight
Gravity offload systems work by using an overhead crane-type device to offload the weight of a human or equipment to simulate zero gravity, lunar gravity and the gravity on Mars. The Active Response Gravity Offload System (ARGOS) is a large device located at NASA's Johnson Space Center. It actively tracks and follows motion using a cable angle sensor. This means that equipment and spacecraft can be moved around and interacted with, and ARGOS will maintain the simulated gravity level. Similar effects can be achieved with a complex weight and pulley system to offload the effects of Earth's gravity — a system that engineers used to test the James Webb Space Telescope.
While ARGOS is a large device, there are smaller gravity offload tables perfect for testing equipment. NASA's Goddard Space Flight Center has a table that consists of a large piece of polished and leveled granite. They're actually able to make test equipment "float" on top of the table thanks to the sled they're placed on — air bearings produce a thin layer of air underneath the sled, which makes it float on top of the table. "It's basically like an air hockey table in reverse," said Robotics Demonstration and Test Engineer, Joe Easley of NASA Goddard.
The downside to gravity offload systems is that they don't always offer the six directions you can move things in zero gravity — for example, the gravity offload table only offers three degrees of freedom, which can limit accuracy.
A Zero-G Research Facility Also Helps
NASA also has a specific Zero Gravity Research Facility at Glenn Research Center that's been in operation since 1966. It works by using a 467-foot-long steel vacuum chamber. A vacuum pump reduces the pressure to 0.05 torr. (For comparison, standard atmospheric pressure is 760 torr.) Then, a crane drops the equipment or experiment into the vacuum chamber and researchers have 5.18 seconds to study it in freefall. Like parabolic flight, the downside to this method is the short amount of time available, as well as a weight limit of 2,500 lbs.
Researchers are always looking for new ways to test hardware and experiments before sending them to space. But these days, as the costs of access to space get lower, the International Space Station is often used as a testbed for hardware rather than trying to figure out how can we create zero gravity on Earth.
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