Tiny NEA Scout Solar Sail Mission to Chase Asteroid

NEA Scout will hitch a ride to an asteroid on the Artemis 1 Moon mission.

Tucked away on the long-awaited, historic launch of NASA’s Space Launch System (SLS) this April is a small, shoebox-sized mission mission that with use an innovative solar sail technology, to chase down a school-bus sized asteroid.

The mission is NEA (Near Earth Asteroid) Scout. Folded up and stowed away, the entire payload fits in a small 10 cm x 20 cm x 30 cm 6U cubesat. Once in space and unfurled, the tiny spacecraft will deploy solar panels for power, and four 7.3-meter long rods will support a 9.3-meter square sail for maneuvering and propulsion. Then, NEA Scout will use solar pressure to gradually depart the Earth-Moon system to the target.

The target asteroid 2020 GE is an intriguing space rock. Discovered on the night of March 12th, 2020 by the University of Arizona’s Catalina Sky Survey, the asteroid is in a 2.3 degree inclined orbit relative to the ecliptic, orbiting the Sun once every 368 days, meaning that 2020 GE visits the Earth every few years. It has two particularly close (<0.005 AU or 750,000 km, or 2.5 times the Earth-Moon distance) passes in the 21st century in 2024 and 2068. 2020 GE is 5-15 meters across, on the large end of the scale.

2020 GE
The orbit of asteroid 2020 GE. Credit: NASA-JPL.

“2020 GE chose us!” Principal Investigator Julie Castillo-Rogez (NASA-JPL) told Universe Today concerning the selection of a target for NEA Scout. “The pool of targets reachable for any launch window is small. There are a lot of NEOs, but those that can be accessed with our spacecraft need to meet a number of criteria. First, their position needs to be relatively well known (within a few 1000s of kilometers). We also need to encounter the target when it is less than 1 AU (astronomical unit) from Earth because our telecommunication system is limited in performance (small antenna). Lastly, our total mission duration needs to be shorter than 2.5 years because some the components we use in the flight system have a limited lifetime.”

“Thanks to the introduction of new observatories over the past decade and the help of the astronomical community, we’ve always had a couple of targets available for any launch window.”

The team plans to encounter 2020 GE during the September 8th, 2023 close pass for flyby, when the asteroid is 0.038 AU from the Earth. This will be the smallest target ever visited, and a 30 meters per second, the slowest asteroid flyby yet. This will also represent our first good look at a small near-Earth asteroid, in the pristine environment of space. This sort of approach and rendezvous technology could prove vital, should we ever have to deflect one of these space rocks out of harm’s way. A very similar-sized asteroid exploded over the Russian city of Chelyabinsk the day after Valentine’s Day in 2013.

“2020 GE is between 5-15 meters large, so one at least one order of magnitude smaller than Hayabusa’s target Itokawa (~210 meters in its smallest dimension).” Says Castillo-Rogez. “As another point of comparison, the OSIRIS-REx target Bennu is about 510 meters in its smallest dimension.”

NEA Scout was developed by NASA’s Advanced Explorations Systems Division at the Marshall Spaceflight Center, to test key technologies in a small package. The mission will carry a small camera (NEACam) with a resolution down to 10 cm (4 inches) per pixel, so we should get some pretty good images of 2020 GE, in an effort to understand if its a solid chunk of rock, or a ruble pile asteroid.

“NEAScout will carry a small imager. Its mass is about 1 lbs. Although it is very small, we demonstrated that its performance meets our requirements for science observations.” Says Castillo-Rogez. “We will launch in the Spring, spend a few months in the Earth-Moon region and start the interplanetary cruise in August 2022 (required to catch the asteroid). The flyby of the target will be in November 2023. We will start searching for it about one month prior to encounter. After the flyby, we will downlink the data in a few months (at least 3 and up to 6).”

A Brief History of Solar-Sailing the Solar System

Though the idea of solar sailing has long held promise, the road to practical use has been a tough one. The Planetary Society lost its very first effort at deploying a solar sail on the Cosmos 1 mission in 2005, when the Volna rocket launched from a Russian submarine failed shortly after launch. The Society fared better with Lightsail-2 in 2019. The Japanese Aerospace Agency (JAXA) also had better luck with IKAROS in 2010, deployed from the Venus-bound Akatsuki mission. The NanoSail-D mission in 2010 also showed the viability of using a solar/drag sail for a controlled reentry.

To be sure, Artemis-1 and the inaugural launch of SLS will be a historic one, and a first step in humanity’s return to the Moon. NEA Scout is one of 10 smallsat missions taking advantage of the Artemis 1 launch, headed out into cis-lunar space and back.

Artemis 1 orbit
Artemis 1 orbit and smallsat deployment phase. Credit: NASA

As of writing this, SLS is slated to launch in April 8th-22nd, with a backup window in May from the 7th-21st 2022. The NEA Scout and other smallsat payloads are tucked away inside the Orion stage ring adapter of the booster.

Ring of sats
Cubesats nestled inside the Orion ring adapter. Credit: NASA/Cory Huston

2022 also sees commercial Moon landing missions from Astrobotics and Intuitive Machines, as part of NASA’s Commercial Lunar payload Services (CLPS) program. NASA will also launch Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) in March, a pathfinder mission for the crewed Lunar Gateway platform, also part of the Artemis initiative.

Artemis 1
Stacking SLS for Artemis 1. Credit: NASA/Cory Huston

Things are about to get busy in cis-lunar space in 2022, and NEA Scout will be a mission to watch in the coming years.