NASA mission aims to study ice and water on the surface of the Moon

In the fall of 2023, an American rover will land on the south pole of the Moon. Its mission: to locate the water ice that scientists know lies within the lunar shadow, and which they believe could help sustain humans who may one day explore the Moon Or use it as a launching pad for more distant space exploration.

NASA recently selected Kevin Lewis, an associate professor in the Krieger School’s Department of Earth and Planetary Sciences, who has also served on the mission to Mars, as a co-investigator of the mission. Using part of the rover’s navigational system, he plans to explore the moon’s subsurface geology from his office at Olin Hall.

“I’ve been on other rover missions, but on Mars, so I’m a little new to the Moon,” Lewis said. “We’re going to be looking into shadows that have never seen the Sun, let alone seen by humans. So it could be a very different type of surface than other photos of the Moon’s surface.”

drier than the desert

Most of the Moon is completely without water. This is due to the way the satellite formed in a giant impact between a proto-Earth and a Mars-sized object. The temperatures were high enough not only to melt the rock, but to vaporize it, leaving a cloud of rock vapor orbiting Earth. The vapor eventually coalesced to form the Moon.

Those temperatures were also high enough to wash away any water, not even leaving appreciable traces trapped within rocks the way it is on Earth. But over time, water-ice meteors and comets bombarded the Moon, causing ice molecules to hover around the Moon’s surface.

The angle of the Sun at the poles of the Moon is straight, forming a long shadow. This means that some polar craters do not receive sunlight at all. When water molecules jump into one of those unspoiled regions whose temperatures are only tens of degrees above absolute zero, one of the coldest in the solar system, it dissipates their thermal energy and they stick to the surface. live.

“So, over time, you can accumulate ice in these permanently shadowed regions, which may basically be the only source of water on the entire Moon in useful amounts,” Lewis said.

moon spinning

The Volatile Exploring Polar Exploration Rover, or VIPER, is a golf cart-sized robot designed for the extreme and unknown of the Moon’s south pole. The rover, which will travel several kilometers over several lunar days — or about 100 Earth days — will assess things like what form the water is in, how much is in it, whether it’s frost on the surface or like ice at depth, and whether it Some areas have more than others.

Currently being assembled at NASA’s Johnson Space Center in Houston, VIPER has to be adapted to the specific conditions it will encounter at the Moon’s south pole. There is pottery soil with varying levels of compaction, which requires four independently controlled wheels that can handle slopes of 25 to 30 degrees.

During the day, the moon’s harsh temperature fluctuations range from 225 degrees Fahrenheit in the sun to -400 degrees in those permanent shadows; The boxy shape of the VIPER protects the equipment, and calibrations of high-precision technology are currently underway to protect against those swings.

There is darkness, which requires the first headlights used on the rover to illuminate places on the moon that have never seen sunlight.

And science and logistics have conflicting needs—science tells VIPER to spend its time in the shadows, but the rover will also need to exit the craters from time to time to recharge its batteries in sunlight. Most rovers have their solar arrays located on their roofs, but the polar sunlight angle requires VIPER arrays to be mounted on its sides instead.

Search

NASA selected eight new VIPER co-investigators to bring new ideas and expertise to the team. Lewis’ probe effectively gives the rover a new science tool to probe the Moon.

To track its position and orientation, the VIPER is fitted with accelerometers – instruments commonly used to determine changes in position and rover tilt. These are the tools Lewis plans to reuse for his research. Accelerometers are extremely sensitive; They can detect the slightest change in gravity you would experience if ore was deposited beneath the ground you are standing on.

“Gravity has been used for prospecting on Earth; you can see gravitational anomalies, and they will tell you something about subsurface geology,” Lewis said. “We’ve been able to do this on Mars and figure out the density of the subsurface rocks that we’re driving on. We’re going to do the same on the Moon, and trying to figure out the vertical density of the regolith and look for any geological anomalies.”

VIPER is part of NASA’s Artemis program, a multi-stage process to return humans to the Moon. The Artemis I will be the first test of the rocket that will eventually carry humans, and is scheduled to launch this year. Artemis II, scheduled for 2023, will orbit the Moon with humans. Artemis III plans to land humans on the surface of the Moon in 2024.

“Working on the VIPER mission in parallel with the human exploration side with the Artemis program is pretty wild,” Lewis said. “Even though those astronauts might not be drinking this water straight away, it’s really cool to do so against the backdrop of returning to the Moon.”

As a member of the science team, Lewis is not involved in the construction of VIPER, and he will not directly assume any control during the mission. But since joining the team, he has been involved in simulated operations, where the team exercises using the rover’s technology and makes decisions that would need to be made on the spot.

The mission is starting to feel real. “It’s really exciting to do prospecting for water that could someday potentially be used by human explorers,” Lewis said. “Finding water that they can drink a bottle of someday – that kind of blows your mind. And of course the geology side of it: the history of the Moon and the geologic and thermal evolution of its crust are very interesting questions as well.”