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NASA’s massive moon rocket stowaways promise big science in small packages | Science

NASA is targeting August 29 for the first flight of its massive Space Launch System, seen here during a dress rehearsal in June.EVA MARIE UZCATEGUI/AFP via Getty Images

When NASA’s most powerful rocket attempts its maiden flight this month, its most visible payload will be three instrumented dummies, setting off on a 42-day journey beyond the Moon and back. They replace the astronauts that the 98-meter-tall rocket, known as the Space Launch System (SLS), is supposed to carry to the Moon as soon as 2025, as part of NASA’s Artemis program. But there will be other travelers for the trip when the SLS lifts off on August 29: 10 CubeSats, satellites no bigger than a small briefcase, to probe the Moon, asteroids and the radiative environment of deep space .

The investigators who built these satellites have more than the usual jitters at launch: half of them may not have enough power to begin their missions. Stuck in the rocket for more than a year due to launch delays, their batteries have depleted to such a degree that some may not be able to start up and deploy their solar panels. “The longer we wait, the greater the risk,” says Ben Malphrus of Morehead State University, principal investigator for Lunar IceCube, one of the CubeSats with power issues.

At stake is not just data, but a test of CubeSats as deep space probes. “We’re in the transition phase from being a curiosity and a training tool to a platform for real science,” Malphrus says. CubeSats are easy to assemble from standardized parts – from economical ion propulsion systems to small-sized radio transmitters – supplied by a growing commercial base. This allows researchers to focus on developing instruments capable of collecting new data, if they can scale it down to a CubeSat package.

Small size and standardization also make CubeSats cheap. At millions of dollars a pop versus hundreds of millions for a bigger, self-contained satellite on its own rocket, they can take on more risky missions, including hitchhiking on the unproven SLS. “When it comes to CubeSats, failure is an option,” Bhavya Lal, NASA associate administrator for technology, policy and strategy, said during a briefing earlier this month.

The CubeSats are positioned inside the Orion stage adapter which will be connected to the Artemis 1 rocket
Ten CubeSats will be ejected from an adapter ring that sits under the crew capsule of NASA’s new rocket.Cory Huston/NASA

Several SLS CubeSats will focus on lunar ice, which has intrigued researchers since NASA’s lunar prospector discovered a signal reminiscent of water in the late 1990s. Using a neutron detector, he has scanned the icy and permanently shadowed regions in the polar craters. In many of them, the probe detected a curious suppression of neutrons, best explained by an excess of hydrogen in the highest meter of the ground.

The researchers speculate that much of the hydrogen represents water ice delivered by ancient comet or asteroid impacts and trapped in the coldest and darkest lunar cavities. But hydrogen could also be implanted by the solar wind. When hydrogen ions from the wind hit oxygen-bearing minerals in the lunar soil, they create hydroxyl, which can be turned into water through further reactions. If the Moon contains enough water, it could be used for agriculture and life support, and split into hydrogen and oxygen for rocket propellant. “It will be more economical than bringing it in from Earth,” says Hannah Sargeant, a planetary scientist at the University of Central Florida.

The Lunar Polar Hydrogen Mapper (LunaH Map), an SLS CubeSat led by Craig Hardgrove of Arizona State University, Tempe, will attempt to improve Lunar Prospector’s maps with a bold orbit that dips just 12 to 15 kilometers above from the South Pole. During 280 passes with its neutron detector, the team hopes to map the excess hydrogen with a resolution of 20 to 30 kilometers, about twice as good as Lunar Prospector. “We can distinguish a [deep crater] another,” says Hardgrove. Craters lacking hydrogen, or enrichments outside glacial hideouts, could indicate a relatively recent impact that blew up the ice and redistributed it, he says.

Lunar IceCube will carry a spectrometer capable of detecting infrared fingerprints of water or hydroxyl. Since the device depends on reflected light, it will be more sensitive to signs of hydroxyl and water in sunny areas at lower latitudes. “They really look at the [effect of] the solar wind, day after day,” says Benjamin Greenhagen, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory.

Lunar Hitchhikers

When NASA launches its giant Moon rocket, it will also carry 10 small satellites beyond low Earth orbit. Some of the missions could have power issues on startup, after half of the satellites were not allowed to recharge their batteries.

NAME OBJECTIVE LEAD DEVELOPER BATTERY PROBLEMS
ArgoMoon Monitor the release of Cubesats, rocket stage The Italian space agency
BioSentinel Studying the effects of radiation on yeast NASA (Ames Research Center)
Cusp Study the solar wind and magnetic fields Southwest Research Institute X
EQUULEUS Terrestrial Plasmasphere Image The Japanese Space Agency
LunaH Map Study the lunar ice Arizona State University X
Lunar icicle Study the lunar ice Morehead State University X
MonIR Testing a new infrared spectrometer Lockheed Martin X
NEA Pathfinder Fly to an asteroid with a solar sail NASA (Marshall Space Flight Center)
OMOTENASHI Put a small lander on the lunar surface The Japanese Space Agency
Team Miles Test plasma thrusters Citizen Scientists of Miles Space X

Some of the CubeSats are heading beyond the Moon. Once the SLS leaves Earth orbit and frees the probes, Near-Earth Asteroid Scout (NEA Scout) will unfurl a thin solar sail the size of a racquetball court. Powered by photons, it will navigate to 2020GE, a miniature asteroid 5 to 15 meters in diameter. In about 2 years, it should sail up to 800 meters from the asteroid in 3 hours of flyby. Many larger asteroids are loosely bound piles of rubble, but NEA Scout will test the expectation that weak sunlight pressure has turned 2020GE too fast for it to hold rubble, says Julie Castillo-Rogez, Principal Investigator Scientist of NEA Scout at NASA’s Jet Propulsion Laboratory.

BioSentinel, led by Sergio Santa Maria, a biologist at NASA’s Ames Research Center, will transport yeast strains through hundreds of microscopic wells, NASA’s first test of the biological effects of radiation beyond Earth orbit. low since the last Apollo mission in 1972. Unprotected by Earth’s magnetic field, organisms are more vulnerable to DNA damage from solar explosions and galactic cosmic rays, a real concern for astronauts traveling to the Moon or Mars. From a perch orbiting the Sun beyond the Moon, optical sensors on BioSentinel will assess the health of yeast strains as they accumulate radiation damage by measuring cell growth and metabolism.

BioSentinel, NEA Scout and three other CubeSats were allowed to recharge their batteries during their long wait aboard the SLS. But five others were unlucky, including LunaH Map and Lunar IceCube. Some could not be reloaded without removing them from the rocket; in other cases, NASA engineers feared the process would trigger discharges that could damage the rest of the rocket. “We have to be very aware of the risk to the primary mission when interacting with these CubeSats,” says NASA chief exploration scientist Jacob Bleacher.

Hardgrove says LunaH Map’s battery reserve is likely at 50% and the threat to the mission is high, because at 40% the CubeSat will not be able to perform a set of initial operations and maneuvers before the solar arrays cannot deploy and start recharging the batteries. He says he pushed hard for the opportunity to recharge, but was pushed back by NASA officials. “You can’t agree to pick up stowaways and then kill them,” he said. Yet he realizes that the CubeSats are secondary payloads and resigns himself to rolling the dice. “It wouldn’t be a CubeSat mission if you weren’t anxious.”