Mapping the Distribution of Water on the Moon
When early astronomers looked to the Moon and saw the smooth expanses of the Lunar Maria, they believed that they were looking at deep, dark oceans. This belief is even reflected in the names of these features: Maria, the Latin word for 'seas'. As our astronomical understanding grew, we realized that these liquid water oceans were actually dry, smooth plains of basalt, left behind from the molten lava that formed the Moon. The more we learned about lunar history and geology, the more the prospect of water on the Moon seemed unlikely. However, recent developments and discoveries have challenged this image.
In recent years, much focus has been placed at the lunar poles, where deep craters harbor areas in permanent shadow. Without the touch of sunlight, these regions cool to frigid temperatures capable of holding onto large amounts of water in the form of ice. For this reason, current and future plans for the exploration of the Moon center on the Lunar South Pole, where permanent establishments can access and use the water ice for supporting life and producing fuel.
Data taken by SOFIA shows water present at latitudes away from the poles. This data represents the lunar surface in the vicinity of Clavius Crater. This chart comes from the paper "Molecular water detected on the sunlit Moon by SOFIA" (2020) by Honnibal et. al.
Honnibal et. al. (2020)
However, recent measurements from the SOFIA program have produced a more startling revelation. There is water across the entire lunar surface - even in the sunlit areas away from the poles. Although this abundance of water is likely stored in hydrated minerals instead of lakes and aquifers, its presence is transformative to the idea of the Moon as a bone-dry world. As we advance our exploration of the Moon, we must broaden our search for water: not just at the poles, but across the entire Lunar surface.
Aman Chandra
LunaCat is a proposed mission to map the distribution of water across the Moon's surface through both active and passive radar sounding. The primary instrument onboard will be a frequency modulation chirp radar system tuned to the 22-GHz water line.This type of radar can measure water even in very low concentrations with detailed range resolution. Combined with the movement of the spacecraft in orbit, this will allow the mission to produce a 3D map of the distribution of water on the surface of the Moon.
In addition to the active 22-GHz chirp radar, LunaCat will carry a cutting-edge 557-GHz water line receiver which it will use in combination with the 22-GHz receiver to passively scan for the presence of water, both on the surface through thermal emission and in the tenuous emissions percolating from the surface through absorption measurements against the backdrop of the Sun. LunaCat will also carry cameras to capture low and high resolution images of the lunar surface.
LunaCat will carry a large inflatable to increase the capability of its 22-GHz radar
Christopher Walker
This mission is designed to build off of the experience and technology developed from CatSat, from the student experience to the inflatable antenna. As of the proposal of LunaCat, we are excited to bring in old partner organizations, whose contributions were essential to the success of CatSat, as well as new partners, whose contributions will pave the way for the success of LunaCat.