LOGAN, Utah – Tiny cubesats, once a teaching tool to give engineering students hands-on experience developing simple spacecraft, are about to make the leap to serious science as a low-cost way to find and quantify deposits of water ice on the Moon for future human explorers to use.
Two presentations at a technical workshop held in association with the SmallSat 2014 conference here indicate that students, their professors and their industry suppliers have pushed cubesat capabilities beyond simple low Earth orbit exercises with little more capability than the first Sputnik. Both addressed what it would take to send cubesats to the Moon, and both are working to realize that goal.
A/Keck Institute for Space Science team is developing a set of "heavy" 6U cubesats that would smash into the Moon’s surface like the 2009 Lunar Crater Observation and Sensing Satellite (Lcross), kicking up enough material for a follow-on cubesat to analyze it for water ice and other volatiles before becoming a high-speed impactor itself, generating another debris cloud for another follow-on cubesat in a chain of them launched together.
Working separately, a group centered on Catholic University and’s is studying what it would take to send a Lunar Water Distribution (LWaDi) cubesat into a highly elliptical lunar orbit with an advanced, miniature near-infrared spectrometer to locate concentrations of water on the Moon, timing its orbit to gain the optimum illumination from the Sun.
"We already know that there’s water on the Moon [so] why bother," said Brendan Hermalyn, a planetary scientist at the University of Hawaii who is on leave to serve as senior imaging scientist and camera technical lead at Skybox Imaging. "We know that it exists on the Moon, but we don’t know the concentrations that it exists in other thermally interesting and potentially easier accessible sites."
While it is clear that water ice exists at the bottom of the deep, permanently dark craters at the Moon’s poles where temperatures hover near absolute zero, it may also exist in areas that would be easier to reach for in situ resource utilization (ISRU) someday. Hermalyn’s team believes that for $20-30 million, plus the cost of launch, it can send six cubesat impactor/analyzers to generate debris clouds that would help identify those regions where ISRU might be able to turn the ice into oxygen and hydrogen to support human exploration or commercial activities.
Hermalyn, who worked on the Lcross science team, has calculated that with the right angle and velocity of impact a 6U cubesat can kick up a debris cloud that presents a comparable target for spectral analysis as the 2009 mission. Potential instruments in the following cubesat could include a near-IR imager, a visible-light camera/interferometer, a neutron spectrometer, and a dust impacting mass spectrometer. The Lcross impact was observed by other ground- and space-based telescopes, and presumably similar arrangements would be possible with a series of cubesat impacts across the lunar surface.
The LWaDi cubesat would use an instrument already in development called Birches (Broadband IR Compact High-resolution Exploration Spectrometer) to map water vapor, liquid water, water bound to lunar minerals, ice and other potential sources. In keeping with a trend to larger cubesats over the initial 10-by-10-by-10 1U structures, a 6U cubesat would allow larger optics and easier packaging for the instrument, and would add only about $200,000 in launch cost over a 3U spacecraft for twice the volume and mass, according to team member Walter Holemans, chief engineer at Planetary Systems Corp. Launch opportunities include piggyback rides on NASA’s planned heavy-lift Space Launch System when it goes to distant retrograde lunar orbit on early flights, or on one of the Google Lunar X-Prize missions. Another possibility is launch as a hosted payload from a geostationary commercial communications satellite, using one of the solar-electric propulsion systems in early development for cubesats to move on to lunar orbit.
Editor's Note: TheResearch Center/Keck Institute for Space Science team has been corrected above.