When NASA’s shakedown Artemis 1 mission orbits the moon later this year, it will deliver a series of small research satellites as well — including one from ASU.
The Lunar Polar Hydrogen Mapper, or LunaH Map, is a briefcase-sized, 30-pound satellite complete with solar panels and iodine-powered ion thrusters.
“It's a very small spacecraft that includes all of the parts that you would see on a large spacecraft, just miniaturized,” said principal investigator Craig Hardgrove, a planetary geologist in ASU’s School of Earth and Space Exploration.
LunaH Map is one of several CubeSats that will hitch a ride on the mission. CubeSats’ reputation as simple, off-the-shelf, modular affairs is only partly accurate, especially when it comes to building a craft that must survive a trip to lunar orbit.
“I'd say it's a bit of a mix. In the case of the neutron detector, we absolutely had to build that from scratch, using some developments we've been involved with over the years in commercial companies,” said Hardgrove. “So I'd say we're a blend of traditional off-the-shelf CubeSat and something that absolutely needs to be customized for deep space.”
Fueling LunaH Map’s drive with efficient iodine instead of xenon let Hardgrove’s team shrink its propulsion system to tissue-box proportions but introduced challenges as well.
“It is corrosive when it interacts with oxygen. So in an oxygenated atmosphere, like ours on Earth, it will effectively rust very quickly. Any surface it binds to, it's also very sticky. And so you have to use iodine-resistant materials in a lot of the propulsion system,” said Hardgrove.
As LunaH Map orbits low over the moon’s surface — within five to 12 miles, far closer than previous missions — its spectrometer will detect neutrons that have interacted with lunar hydrogen.
“This will help for understanding how it got there, and it will also help for planning future landing sites,” said Hardgrove.
Neutrons “leak” from planets and moons across the solar system, released as cosmic rays bombard their surfaces.
“You get this sort of scattering around of these high-energy neutrons that are created from these interactions, and some number of them leak out,” said Hardgrove.
But the energy propelling those neutrons changes depending on their interactions with atoms on the lunar surface. That difference lets LunaH Map’s detector sniff out hydrogen, and do it at greater depth that many other instruments can manage.
“Unlike an optical instrument that really just gets you a micron to maybe a centimeter at most, we're really looking at the integrated depth of hydration down to about a meter,” said Hardgrove.
As for water, LunaH Map won’t be able to tell if the H it finds comes from H2O, but it can help future missions know where to look.
NASA plans to hold a dress rehearsal for its fully stacked Space Launch System and Orion capsule in mid-February, after which the agency will announce the Artemis 1 launch date, which likely will fall sometime in mid- to late March.
For Hardgrove, it’s been a long time coming.
“I've told the team, I'm going to the launch so I can see this thing go into space. I think it's been seven years since I wrote the proposal. And so, if nothing else, I want to see it go into space. I think it'll really hit home then.”
