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Sheyna Gifford

Feb 4th 2022

Looking Better Than Ever: Vega Rockets and Earth Observation Satellites

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Sometimes, we look outward. Sometimes, inward. And sometimes, using an Earth observation satellite and a Vega rocket, we look downward, pinpoint a lost vehicle and rescue its passengers from 600 kilometers above the surface of the Earth.

Thanks to Pléiades Neo, a constellation of satellites that can image the planet in high resolution, and the Vega rockets they rode there, our views from above are about to get a whole lot better. As a result, everything for which we need real-time information to better understand how our world is changing — including global security, human safety, environmental monitoring, urban planning, climate data collection, weather tracking, search and rescue and so much more — will get a major boost.

Ridesharing to Space

Upping our tracking technology game to this level of detail was no small feat. It required new spacecraft, upgraded image acquisition and processing systems, and a specialized launch vehicle, the Vega rocket, to all come together.

The Vega series of launch vehicles has been hard at work for almost a decade. When Arianespace, an international company headquartered in Evry, France, began launching the ESA-funded Vega rockets out of French Guiana in 2011 and 2012, it was something of a breakthrough.

The location itself wasn’t new; launching from French Guiana has been happening since the 1970s. At only five degrees north of the equator, each rocket launching from French Guiana gets a 460 kph boost from being close to the equator. To boot, French Guiana doesn’t experience earthquakes, rarely has cyclones or hurricanes and is mostly covered in forest, making it a safe spot for rockets, a spaceport and people who need to keep clear of both. What was different was the rocket itself. It was a vision of the future of space exploration that built it.

Traditional, high-cost, heavy-duty, heavy-lift rockets — such as the Soyez, which also launches from French Guiana — can simultaneously blast 34 satellites into orbit. By contrast, Vega was designed to be a light-lift, low-cost system with two main purposes. The first was to inexpensively insert a single 1,000 kg satellite into orbit, and the second was to create a path to space ridesharing.

Using specialized internal structures (rather than carry one Vega 1,000 kg satellite into orbit), Vega can store one larger and four smaller satellites that weigh a combined 1,000 kg. This is exactly what occurred with Pléiades Neo 4. The August 2021 Vega rocket launch — the seventh in 2021 for Arianespace — was carrying five satellites that weighed just over 1,000 kg in total.

Contrast that with one of the most well-known satellites in the world, the Hubble Spaceflight Telescope (HST). The HST weighs an order of magnitude more (11,000 kg) than Pléiades Neo 4 and many GPS satellites, which typically weigh between 1,800 and 2,200 kg each. As satellites are getting smaller and their launches more frequent, the rockets that lift them into orbit are evolving. HST was taken into orbit on a space shuttle. Today, when the payloads are small enough, a single Vega can deploy dozens of satellites. In 2020, one Vega rocket put almost 50 satellites into a sun-synchronous orbit: 40-plus small CubeSats and seven microsatellites.

Satellite ridesharing leads to launch cost-sharing. Since the first Vega launched from French Guiana in 2012, lower surface-to-orbit costs have allowed Earth observation satellites to be launched from numerous single organizations, as well as countries outside of ESA, Russia and the U.S. In 2013, the VNREDSat-1A representing the Vietnamese Academy of Science and Technology launched on a Vega. In 2014, the Republic of Kazakhstan followed suit.

The four CubeSats that joined the Pléiades Neo 4 on its launch — the nineteenth mission for the Vega series — were taking advantage of the European space agency’s L3 Initiative: a light satellite, low-cost launch opportunity to hitch a ride into space at a fraction of the cost of most one-way trips into orbit. There’s a catch to this particular one-way trip, however: a satellite hitching a ride with Pléiades Neo is destined to travel not east to west but rather north to south.

Off-Axis Polar Express

If you want to image a feature on Earth as it changes day by day or even hour by hour, your orbit of choice is clear: a polar orbit and, more specifically, a sun-synchronous orbit. Satellites in sun-synchronous orbits (SSOs) move in a near-circle from north to south, revolving around the planet every 100 minutes. As they sweep through their orbits, the planet rotates below. This allows a single satellite in SSO to make a map of the sample place on the surface of the Earth at more or less the same local time every day.

SSOs are nearly circular in part because the Earth itself is not a perfect sphere. Making a perfect map of a less than perfectly round planet requires some extra planning. To avoid being thrown off by the bulge around Earth’s equator, Pléiades Neo 4’s inclination relative to Earth’s true north-south is a bit off-axis by about eight degrees.

Pléiades Neo 4 is joined in this slightly off-axis orbit by Pléiades Neo 3, which launched in April 2021. Though they are part of the same satellite constellation, the two satellites are set 180 degrees apart in their sweeps. Because they are half a world apart, when working together, Pléiades Neo 3 and 4 can map out every site of interest twice a day.

With this constellation in sun-synchronous orbit, up to two million square kilometers can be mapped every 24 hours. At that rate, the entire Earth can be mapped at ultra-high-resolution up to five times a year in different colors and multiple spectra, including the near-infrared and panchromatic.

Mapping the entire Earth in any color is an enormous gain in the amount of information we have about the surface of the planet we live on. Though we’ve been photographing the Earth from space since 1947, much of the planet still remains imaged in fairly low resolution. In part, this is because “high resolution” is a moving target. What was high-resolution in the 1980s was something in the area of 60 meters per pixel. Current standards for high-resolution imaging have each pixel representing 30 by 30 centimeters.

Another reason our whole-planet mapping technology lags behind is that giants of mapping, such as Google, have focused their efforts on where potential customers live, work and consume goods. Going into 2020, Google announced that it had mapped 10 million miles (or 16 million kilometers) of street view imaging but only 36 million mi (58 million km) of the planet — about 11% of the Earth’s surface. That’s not a dynamic map, either — that’s one and done, a picture of whatever was happening when the airplane, weather balloon or satellite flew over that area.

Find It First and Find It Fast

This generation of Earth observation satellites has a different approach in mind. Once the complete constellation of four Pléiades Neo satellites has rocketed from French Guiana into sun-synchronous orbit, geotracking weather patterns, ships at sea, downed aircraft, human convoys and even migrating animals should be possible in near-real time.

Among the four satellites in SSO, within 30-40 minutes of a tracking request, the event or object of interest should be findable by a Pléiades Neo satellite. The other three satellites will then sweep out that area when it passes below them. Within a day, the images of landmines, crews sent to clear debris from roads, flooding rivers and families seeking shelter on their roofs during the flooding will be available down to the scale of a soccer ball.

Such on-demand, high-resolution imaging of our home planet has been hovering just below the surface of commercial availability for some time. Now that it’s broken through, we’ll begin to see what’s possible when people who’ve been looking over the shoulders of mapping giants like Google start commissioning their own planetary imaging down to a minute scale.

But we know one thing is for sure: We have never seen the world like this before.

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