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

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

The researchers who built these satellites have more launch worries than usual: Half of them may not have enough power to begin their missions. Stuck inside the rocket for more than a year due to launch delays, their batteries have depleted to a level where some may be unable to boot and deploy their solar panels. “The longer we wait, the more risk there will be,” says Ben Malphrus of Morehead State University, principal investigator of Lunar IceCube, one of the CubeSats with energy concerns.

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 being a platform for real science,” says Malphrus. CubeSats are easy to assemble from standardized parts, from inexpensive ion propulsion systems to pint-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 shrink it into a CubeSat package.

Small size and standardization also make CubeSats cheap. At millions of dollars a pop compared to hundreds of millions for a larger autonomous satellite on its own rocket, they can take on riskier missions, such as hitchhiking on the untested SLS. “When it comes to CubeSats, failure is an option,” Bhavya Lal, NASA’s associate administrator for technology, policy and strategy, said at a briefing earlier this month.

NASA is targeting Aug. 29 for the first flight of its mammoth Space Launch System, seen here in a general test from June.EVA MARIE UZCATEGUI/AFP via Getty Images

Several SLS CubeSats will focus on lunar ice, which has intrigued researchers since NASA’s Lunar Prospector discovered a telltale sign of water in the late 1990s. Using a neutron detector, he looked into the cold, permanently shadowed regions of the polar craters. In many, the probe detected a curious neutron suppression, best explained by additional hydrogen in the uppermost meter of the ground.

The researchers assume that much of the hydrogen represents water ice delivered by ancient comet or asteroid impacts and trapped in the colder, darker lunar recesses. But hydrogen could also be implanted by the solar wind. When hydrogen ions from the wind collide with oxygen-containing minerals in the lunar soil, hydroxyl is created, which can be transformed 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 propulsion. “This will be cheaper than bringing it 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 on Lunar Prospector’s maps with a bold orbit that dips just 12 to 15 kilometers above from the south pole Over the course of 280 passes with its neutron detector, the team hopes to map the excess hydrogen with a resolution of 20 to 30 kilometers, about twice that of Lunar Prospector. “We can distinguish one [deep crater] of another,” Hardgrove says. Hydrogen-free craters, or enrichments outside the cold hides, could indicate a relatively recent impact that dislodged the ice and redistributed it, he says.

Lunar IceCube will carry a spectrometer that can detect the infrared fingerprints of water or hydroxyl. Because the device relies on reflected light, it will be more sensitive to signatures of hydroxyl and water in sunlit regions at lower latitudes. “They’re really looking at the [effect of] the solar wind, day by day,” says Benjamin Greenhagen, a planetary scientist at Johns Hopkins University’s 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 problems at the start, after half of the satellites could not recharge their batteries.

ArgoMoon Cubesats launch monitor, rocket stage Italian space agency
BioSentinel Study the effects of radiation on yeast NASA (Ames Research Center)
CuSP Study the solar wind and magnetic fields Southwest Research Institute X
equestrian Image of the Earth’s plasmasphere Japan Space Agency
Map LunaH Study the moon ice Arizona State University X
Moon ice cube Study the moon ice Morehead State University X
LunIR Try a new infrared spectrometer Lockheed Martin X
NEA Scout Fly to the asteroid with a solar sail NASA (Marshall Space Flight Center)
OMOTENASHI Put a small lander on the lunar surface Japan Space Agency
Team Miles Try plasma thrusters Miles Space Citizen scientists X

Some of the CubeSats are headed beyond the Moon. After the SLS leaves Earth orbit and releases the probes, the Near-Earth Asteroid Scout (NEA Scout) will unfurl a thin solar sail about the size of a racquetball court. Powered by photons, it will navigate to 2020GE, a miniature asteroid between 5 and 15 meters in diameter. In 2 years, it should sail up to 800 meters to the asteroid in a 3-hour flyby. Many larger asteroids are loosely bound piles of debris, but NEA Scout will test the expectation that the weak pressure from sunlight has increased too quickly by 2020GE to contain any debris, says Julie Castillo-Rogez, principal investigator of science from NEA Scout to NASA Jet Propulsion. laboratory

BioSentinel, led by Sergio Santa Maria, a biologist at NASA’s Ames Research Center, will carry yeast strains in hundreds of microscopic wells, NASA’s first test of the biological effects of radiation beyond low-Earth orbit from from the last Apollo mission in 1972. No protection. because of Earth’s magnetic field, organisms are more vulnerable to DNA damage from solar flares and galactic cosmic rays, a real concern for astronauts traveling to the Moon or Mars. From a perch orbiting the Sun beyond the Moon, BioSentinel’s optical sensors will measure the health of yeast strains as they accumulate radiation damage by measuring cell growth and metabolism.

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

Hardgrove says LunaH Map’s battery reserve is probably at 50% and the threat to the mission is high, because at 40% the CubeSat will not be able to run a set of initial operations and maneuvers before the solar panels can deploy and start charging. the batteries He says he pushed for a chance to recharge, but NASA officials refused. “You can’t agree to take in stowaways and then kill them,” he says. Still, he understands that CubeSats are secondary payloads and is resigned to rolling the dice. “It wouldn’t be a CubeSat mission if you weren’t anxious.”

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