Scientists at Washington University and a St. Louis startup, Impossible Sensing, have received a $3 million grant from NASA to develop a new sensor for future missions to the moon.
The sensor will be able to measure the chemistry and composition of rocks and soil, providing a better understanding of the moon’s geology, said Jeffrey Gillis-Davis, a research professor in Wash U’s physics department who is leading the development.
“It actually fires a laser that creates a little plasma,” he said. “So if you’re looking at it, you’d see a little blueish, grayish light, kind of like lightning.”
The instrument then uses a spectrometer to read the light that reflects back, which produces distinct peaks, Gillis-Davis said.
“The peaks are uniquely correlated with different elements, just like a fingerprint,” he said. “So we can measure the elemental concentrations of rocks and soils and even ices on the moon.”
The grant from NASA pays for three years of development to take the sensor from the laboratory to a flight-ready instrument via the Development and Advancement of Lunar Instrumentation Commercial Payload Service, or DALI program, said Gillis-Davis. By the end of that three-year period, the instrument will be ready to fly on board a Commercial Lunar Payload Service (CLPS), which is a program where private companies deliver payloads to the moon's surface for NASA.
“We know [this system] works. We know it’ll even work on the moon” Gillis-Davis said. “What we want to do is develop a really small, capable, low-cost, low-energy system that can measure element concentrations with very high fidelity.”
Scientists already have some understanding of the elements and minerals that make up the surface of the moon, thanks to the Apollo missions that brought back hundreds of pounds of samples, Gillis-Davis explained. But most of those were collected near the moon’s equator and on the side that faces the Earth, he added.
“As we explore the moon’s pole and the far side, we’re definitely going to learn more about the moon as we come across different rock types,” Gillis-Davis said. “That’s what we do as geologists—know how different minerals are mixed together to understand a rock and how it’s put together.”
Impossible Sensing founder Pablo Sobron, a co-investigator on the project, added a lot of the understanding of the moon’s composition since the Apollo missions comes from satellites orbiting it.
“The problem here is because you are far away, you are limited in your ability to see small features,” he said.
Gillis-Davis agrees, but this new instrument on a small rover could fill in those gaps.
“Sometimes the minerals are really small,” he said. “So we can actually detect those really small millimeter-sized minerals that you might not be able to see from a camera image or visually as an astronaut.”
This type of data may help scientists answer some of the enduring questions about Earth, like how the planet got its water, Gillis-Davis said. Plate tectonics and weathering mean the Earth’s surface is relatively young compared to the moon’s, which can offer a glimpse into the conditions of the very early solar system, he explained.
Gillis-Davis is particularly interested in the ice deposits at the moon’s poles.
“If those polar ice deposits formed and may have come out of lunar volcanoes, that would show the moon also formed with water,” he said. “If we see those ice deposits were added later, then it’s a better indication that Earth’s water would have come later rather than in its formation.”
Sobron argues this knowledge is also vital to discover given the interest from commercial companies in returning to the moon.
“We’re looking at creating a lunar economy,” he said. “We know the moon has all the elements and minerals that we need to build things like rockets and launch pads. We can extract fuels, oxygen [and] water.”
The development of this sensing technology can also be helpful for challenges on Earth because of the difficulty of engineering an instrument for space, Sobron said.
“One of the hallmarks of space: Every pound costs millions of dollars when you launch,” he said. “If you can cut down the volume, the size, the power consumption and how much human input you need to operate it, then you start seeing exponential cost reductions.”
And combined with the ability to withstand and operate in low gravity, massive temperature swings and intense radiation exposure means they can have meaningful applications on Earth, Sobron said. Those include things like measuring soil composition at individual plants on a farm or mapping the seafloor and the ecosystems and minerals that exist there, he said.
“The throughline is clear to me,” Sobron said. “If we unlock ways to study the moon, to study other planets and space in general, these technologies are automatically applicable to Earth problems.”
Both Gillis-Davis and Sobron emphasized the importance of St. Louis being the place where these scientific advancements are developed.
“These small companies in St. Louis that can do these types of high-tech projects are really unique,” Gillis-Davis said. “It doesn’t have to be Silicon Valley [or] Lincoln Labs in Boston.”
Having St. Louis known as a place for high-tech developments for exploration can inspire local people in college or even elementary school to remain in the region or attract people from across the country, he said.
Sobron added it builds on St. Louis’ legacy with space exploration, with McDonnell Aircraft producing the Mercury and Gemini capsules in the 1950s and '60s.
“This new grant really solidifies the leadership of St. Louis and Washington University in particular in moon science and exploration,” he said.
