When thirsty residents of a permanent community on the Moon take a swig of fresh water brought in from the lunar south pole, they’ll be enjoying the benefits of a 30-pound spacecraft known as the Lunar Flashlight that was assembled and tested at the Georgia Institute of Technology (Georgia Tech). Lunar Flashlight will use powerful lasers and an onboard spectrometer to search shaded areas of craters at the south pole for evidence of surface ice. Earlier NASA missions have shown that the Moon may have frozen water in these areas, and by orbiting close to the surface, the spacecraft will be able to identify locations that may be worthy of exploration by future missions.
Lunar Flashlight was developed by a team from NASA's Jet Propulsion Laboratory (JPL), NASA's Goddard Space Flight Center (GSFC), the University of California, Los Angeles (UCLA), Georgia Tech, and NASA's Marshall Space Flight Center (MSFC).
Researchers in Georgia Tech’s School of Aerospace Engineering worked with MSFC to develop the spacecraft’s propulsion system – a new technology that uses an improved environmentally-friendly propellant – and collaborated with the Georgia Tech Research Institute (GTRI) to assemble and test the Lunar Flashlight in a set of unique facilities in Atlanta.
Beyond studying the Moon’s ice, Lunar Flashlight will demonstrate that small spacecraft can have large capabilities. It will be the first CubeSat to use a green monopropellant propulsion system for orbital insertion at the Moon – and to change positions for aiming its instruments, radioing data back to Earth, and gathering sunlight to power its operations. The CubeSat, which is about the size of a desktop computer, will also be the first to use active laser spectroscopy to explore the Moon’s surface.
Until now, CubeSats – named for their use of standard-sized cubic modules – have mostly taken on tasks in Earth orbit and have not needed powerful propulsion systems. Lunar Flashlight will help demonstrate the ability of small and relatively inexpensive spacecraft to handle important space missions that had previously been reserved for larger vehicles.
Lunar Flashlight carries four powerful near-infrared lasers that operate at different wavelengths in the near-infrared spectrum. The lasers will be aimed at shadowed areas of craters and will operate in sequence to illuminate locations where ice may have been deposited and protected from melting. Water in the form of ice will absorb the laser light, while dry lunar soil – known as regolith – will reflect the beams back to the spacecraft’s spectrometer.
“By studying the light returned, the system will tell us whether water ice is present in these permanently-shaded areas,” said Jud Ready, principal research engineer at GTRI and the Lunar Flashlight project’s principal investigator at Georgia Tech. The Lunar Flashlight science team will interpret the CubeSat’s measurements along with data sets collected by other spacecraft to further understand the abundance and distribution of lunar ice deposits.
The lasers will be powered by a large lithium-ion battery that will be charged by the four solar panels on the spacecraft. The lasers, spectrometer, and battery take up about a third of the Lunar Flashlight’s total volume.
Data from the search for ice will be beamed to NASA’s Deep Space Network by a radio transmitter similar to those used in other NASA missions. The radio will also receive commands sent to the spacecraft from controllers on Earth; because of the time required for signals to be transmitted to the Moon, the commands will be stored and carried out at specific times. The data will come into Georgia Tech’s mission operations control center, located in the School of Aerospace Engineering, and be forwarded to UCLA for analysis and archiving in the NASA Planetary Data System. Spacecraft controllers at Georgia Tech will monitor the signals to make sure Lunar Flashlight is operating as intended.
Lunar Flashlight’s goal is to address one of NASA’s Strategic Knowledge Gaps: understanding the composition, quantity, distribution, and form of water and water ions – such as hydroxyl (OH) – in lunar cold spots known as “cold traps.” Previous NASA lunar orbiters and other missions have detected potential water ice deposits at high latitudes on the Moon. Lunar Flashlight will map a handful of those deposits at spatial resolutions of one to two kilometers, providing significantly more detail than earlier missions. Beyond confirming the existence of the frozen water, Lunar Flashlight will provide information that might help determine where future missions might land to sample the water and evaluate its potential use by humans.
Using the Moon’s own water resources for supporting human life and producing fuel could cut the cost of maintaining permanent lunar communities by reducing how much material needs to be launched from Earth. In addition to water, NASA hopes to use lunar materials to make oxygen and propellant for launching return flights.