Albert McKeon

Sep 21st 2022

With NASA’s James Webb Space Telescope, the Search for Habitable Planets Seems Hopeful


Our search for habitable planets that could support life just went to an entirely new level — one that extraplanetary beings might admire if we someday communicate with them.

After a successful launch in late 2021, NASA’s James Webb Space Telescope is now nearly one million miles away from Earth and completed an extensive commissioning process that included 17 scientific instrument modes coming online and innumerable tests. Now fully operational, the massive marvel of machinery is starting the first of many observations over a potential 20-year run in space. The telescope’s instruments aim to capture faint objects that could be more than 13.5 billion years away, including galaxies that started only a few hundred million years after the Big Bang.

While Webb looks for clues on the formation of the universe, it will also try to capture signatures of habitability in the atmospheres of exoplanets. What it finds is anyone’s guess, but considering it is the largest and most powerful telescope to launch from Earth, scientists are excited.

A Super Telescope Built for the Ages Will Have Its First Test

Webb is 100 times more powerful than what had been the largest optical telescope to travel into space: the Hubble Space Telescope. While Hubble orbits Earth at an altitude of about 354 miles, Webb is about 930,000 miles away. From that vantage point, Webb’s instruments can work mostly in the infrared range of the electromagnetic spectrum, relying on sensitivity cameras and a mirror that’s 21.3 feet in diameter. That primary mirror intercepts infrared light moving through space and bounces it to a smaller mirror, which then focuses the light to the telescope’s instruments for processing and study.

In one of Webb’s first tests, it’s setting its sights on the TRAPPIST-1 system, a group of seven rocky exoplanets that are 41 light-years away from Earth and are as large as three times the diameter of our planet. NASA says Webb’s findings will characterize the atmospheres of these planets and help scientists learn more about planetary formation and habitability. Yes, aside from seeing how the exoplanets formed, they’re also looking for signs that life may be able to exist.

Will NASA’s James Webb Space Telescope Find Indicators that could support Life?

Making sense of the TRAPPIST-1 system and other exoplanets could lead to indicators in the atmospheres that may support traces of life in the universe. As the SETI Institute observes, although distant objects in the images taken by Webb will appear as one-pixel dots, scientists can make a mountain out of this molehill of information. The ultraviolet light of distant planets and stars has been stretched by the expansion of the universe, but scientists can run the tiniest dots of such light through a high-tech prism and spread it into a detailed spectrum that can reveal what’s in a particular atmosphere.

Oxygen and other unique markers in an atmosphere can suggest biology on a planet. The SETI Institute offered one such example: Images of the atmospheres of Mars and Venus would show carbon dioxide to observers in other galaxies, while Earth would show not only CO2 but also the accumulation of exhaust gas from billions of years of photosynthesis — ample evidence of life.

However, the trick is sorting out true and false findings. Scientists can’t jump on a spaceship to confirm what the Webb telescope sees. To help NASA, several scientists recently published a study in the Proceedings of the National Academy of Sciences to say that Webb should be alert to the presence of methane in the search for alien life.

The Webb telescope will have a hard time detecting oxygen, but a prevalence of methane could point to the biological activity necessary to create the chemical compound, as the scientists explained in a press release announcing the study. Photochemical reactions destroy atmospheric methane, so its appearance in an atmosphere would mean it is constantly being replenished to maintain high levels.

Nonbiological sources wouldn’t be able to create a significant amount of methane without producing other clues to its origins, such as carbon monoxide. Yet, the scientists found that nonbiological sources can’t easily produce habitable planet atmospheres heavy in methane and carbon dioxide and with little carbon monoxide. So, if an abundance of methane is found in an atmosphere and other nonbiological sources can be ruled out, NASA can start to build on that evidence.

“One molecule is not going to give you the answer — you have to take into account the planet’s full context,” one of the scientists said in the press release. But methane will help to eliminate false positives and give NASA and other involved scientists a jump on determining whether distant planets did — or still do — serve as a home to biological, or as we say, “alien,” life.

Confidence Grows We’ll See Something, Someday

The stories that the Webb telescope could tell are tantalizing — so much so that scientists are starting to feel confident in the possibility of finding conditions for life in the outer reaches of space. Last year, a group of them led by NASA’s chief scientist proposed a framework to verify and communicate to the public the detection of biosignatures beyond Earth.

A biosignature is any characteristic, element, molecule, substance, or feature that can be used as evidence for past or present life. It also needs to be something that can’t be made without the presence of life.

The idea, as Scientific American reports, is to avoid false alarms and bogus claims by affixing findings to a scale from one to seven, with a claim making its way up the scale as studies confirm the work. Claims that reach the “final levels would represent robust follow-up observations solidifying a link to life.”

With the Webb telescope now perched in space, the joy of watching it work will come in the slow unraveling of the images it transmits home. We’ll hopefully see the strongest pieces of evidence of how the universe formed, and we’ll also hopefully see signs of habitable worlds carrying on millions of miles from here — creating a new set of scientific questions and prompting even more explorations of space.

Did you know that Northrop Grumman helped build Webb? If you’re interested in a career exploring space, please click here.