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Small satellites key to NASA's lunar search for water

IceCube, LunaH-Map and Lunar Trailblazer are three of many NASA missions that will study the presence of water on the moon -- and are using increasingly shrinking technology to do so.

By
Brooks Hays
The moon, in August 1999, as seen by NASA's Cassini spacecraft as it passed by en route to Saturn. Photo by NASA/JPL/Space Science Institute
The moon, in August 1999, as seen by NASA's Cassini spacecraft as it passed by en route to Saturn. Photo by NASA/JPL/Space Science Institute

Nov. 25 (UPI) -- Can shrinking satellites grow planetary science? NASA thinks so.

With a handful of CubeSat and small satellite science and space exploration missions already under its belt -- a couple even successfully having made the trip to Mars -- NASA is enlisting several new small satellites to study the moon.

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Often, rockets carrying larger payloads into space aren't at maximum capacity. Until fairly recently, that extra capacity went wasted. But over the last two decades, engineers and scientists have been able to miniaturize satellite technology, as well as the instrumentation that helps scientists observe the solar system's many objects.

"NASA is committed to using excess launch capacity to fly small satellite science missions," Carolyn Mercer, the agency's program executive for the Small Innovative Missions for Planetary Exploration program, told UPI.

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Currently, the SIMPLEx program has two lunar science missions in the works: LunaH-Map, a CubeSat mission to measure hydrogen concentrations on the lunar surface, and Lunar Trailblazer, a small orbiter that will map water ice deposits by using infrared instruments.

"LunaH-Map is pronounced 'Luna-Map' because it is looking for hydrogen, but the hydrogen is hidden. That's why the H is silent," Mercer said.

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But CubeSats and small satellites simply aren't an opportunity for creative names. They offer space scientists a chance to conduct research they might not be able to do otherwise -- and that could aid NASA's larger planetary exploration goals.

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LunaH-Map and Lunar Trailblazer are just two of many NASA science missions aimed at studying the presence of water on the moon. Studying the moon's resources is intrinsically interesting for planetary scientists.

"To understand the evolution and formation of the moon, you want to understand what the distribution of water, hydroxide and hydrated minerals is," Mercer said.

As part of the Artemis program, NASA officials are aiming to establish a permanent base on the moon -- an outpost for future deep space exploration missions like a mission to Mars. Naturally, those in charge of NASA's space exploration missions want to know where the moon's resources are, too.

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"There's a really good overlap between the interests of the scientists and the explorers," Mercer said. "If we can understand how much is on the moon, we can potentially go out and get it, and it would be a lot cheaper to manufacture that propellant in situ on the surface of the moon."

Instead of carrying a bunch of extra fuel on its initial launch from Earth, an expensive endeavor, a spacecraft headed for a deep space target could refuel on the surface of the moon, where gravity is much weaker.

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LunaH-Map is scheduled to be carried into space by the Space Launch System Artemis-1 mission, with liftoff scheduled for sometime in the middle of next year. The CubeSat will be joined by several other secondary payloads, including IceCube, another small satellite dedicated to studying the distribution and movement of water on the moon's surface.

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Several scientific surveys have confirmed the presence of water on the moon. Most of the lunar water deposits are found on the moon's poles, and yet, scientists suspect the only way water gets to the moon is via meteorites, which mostly strike near its equator.

IceCube's mission will examine this apparent contradiction.

"What we are interested in is how the water actually gets there," Dirk Grupe, an assistant professor of astrophysics and space systems engineering at Morehead State University in Kentucky, told UPI.

"How does the water get from the equatorial regions to the poles? To help scientists find out, we will look for hydroxyl signatures at different times during the day and at different angles," Grupe said.

Grupe helped design and build the IceCube satellite and its miniaturized instrumentation, the Broadband InfraRed Compact High-Resolution Exploration Spectrometer.

CubeSats don't just require smaller instruments. They also need entirely different propulsion systems. The mini satellites are too small to use the types of combustion systems employed by bigger spacecraft.

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"We are using an ion propulsion thruster, which is an innovative technology for CubeSats," Grupe said.

The electrical thruster will be the first to use iodine propellant. After Artemis 1 releases its load of CubeSats, IceCube will assume an elliptical orbit around Earth and be thrown like a slingshot toward the moon.

Its unique propulsion system will use small thrusts to push the CubeSat along the proper trajectory and into orbit around the moon.

"We have to take a low-energy approach to get to our target," Grupe said. "It will take about half a year to get to the moon."

Grupe says IceCube and the other CubeSats NASA and its partners are sending to the moon only mark the beginning of small satellite space science.

"I think we'll see more and more CubeSats in interplanetary space," he said. "This is just the first step."

All of the CubeSats headed for the moon in the immediate future will be working solo, but Grupe suspects later planetary science missions could utilize constellations of small satellites.

"In the future, we could do radio observations with a network of satellites," Grupe said. "You can do interferometry in space, so you can achieve higher resolution observations than you can with just one big satellite. I think when NASA goes to the moon again, they will do something just like this."

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Interferometry involves the measurement of wave interference between multiple wave sources, like radio waves from multiple members of a satellite constellation.

"Satellite constellations could help planetary scientists do simultaneous multipoint measurements," Mercer said. "That idea of doing that is very powerful."

Mercer said that because Earth scientists already have started to use satellites to study our own planet, the necessary technology will be well-tested when it comes time to deploy constellations of CubeSats on the moon or Mars.

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