Will increased traffic to the Moon contaminate its precious ice?

With its mission to return lunar samples last month, China has launched a new wave of visitors to the Moon. At least eight spacecraft from countries including Russia, India, China, Japan and the United States are expected to land on the lunar surface over the next three years.

For the very first time, several of the upcoming missions will explore some of the Moon’s most scientifically intriguing and sensitive areas – those of its poles. Researchers are excited to study the frozen water in shaded craters in these regions. But they’re also worried that increased traffic to the Moon could contaminate the very ice they want to study.

Ice is important to scientists for a variety of reasons. Some want to analyze intact samples to find out how and when the Earth and the Moon accumulated water billions of years ago. Others want to harness the ice as fuel for rockets on future moon bases.

Explorers are now faced with a complicated choice. Do they start digging right away, to figure out the processes by which they’re going to extract the ice and convert it into fuel? Or do they proceed slowly, to carefully preserve the scientific records encoded in ice? “Right now we have scientists saying we can’t get close to it because we’re going to ruin it,” says Clive Neal, a geoscientist at the University of Notre Dame in Indiana. “And others say we need it, so we’re just going to go.”

These tensions must be resolved quickly – especially as NASA plans to send a series of missions to the Moon’s south pole, starting with robotic landers in 2022 and culminating a few years later with astronauts entering on the Moon for the first time since 1972.

Last week, a report from the influential U.S. National Academy of Sciences, Engineering, and Medicine (NASEM) argued that space agencies must prioritize the science they want from the poles. lunars in order to explore them effectively. The International Space Research Committee (COSPAR), which presents best practices in space exploration, is also assessing the situation and will decide in the coming months whether there is a need to publish new guidance for spacecraft traveling to on the moon. NASA is awaiting COSPAR’s decision and will likely update its own regulations on how to responsibly visit the moon.

As lunar exploration intensifies, “we have an obligation not to interfere with future scientific investigations,” said Lisa Pratt, NASA’s head of planetary protection based at the agency’s headquarters in Washington DC. The question is, “How can we do this right?”

Course collision

No spacecraft has ever directly probed the poles of the Moon and the ice hiding there. The only mission to come in close was the Indian lander Vikram, which crashed about 600 kilometers from the lunar south pole in 2019 instead of landing and surveying the surface. China is planning a Chang’e-6 mission that could visit the moon’s south pole, potentially picking up ice and rocks and sending them back to Earth as early as 2023. It would be the successor to Chang’e-5, who collected rocks on the mid-latitudes of the Moon last December. Japan and India have also discussed a robotic mission to the lunar south pole, as have Russia and Europe.

And then there is NASA. Under US President Donald Trump, the agency prepared a series of pole-focused moon missions. According to current plans, NASA would send two robotic landers to the South Pole in 2022, followed by a larger robotic robot, called VIPER, in 2023. It would drive its one-meter-long borehole into the lunar earth to extract gas. ice. . By the following year, humans would arrive and begin to explore the frozen craters. One of their goals could be to collect ice and fly it, still frozen, to laboratories on Earth for study, according to a NASA report released last month.

The possibility of explorers contaminating moon ice is a problem no one anticipated five decades ago, when Apollo astronauts became the first humans to walk on the moon’s surface. At the time, researchers thought the Moon was dry. It wasn’t until the last decade that they realized there was water in many places, including frozen in dark polar craters.¹. Scientists have even found water in at least one sunny spot on the Moon, contained in minerals contained in otherwise dry dirt.².

All of this water could have reached the Moon by means of water-rich asteroids or comets, or by the solar wind bombarding its surface. Some could come from inside the Moon, vomited during volcanic eruptions from a water-rich interior. Regardless of its source, the Moon’s water contains crucial scientific information.

Ice inside sunless craters at the Moon’s poles may have accumulated over billions of years. If so, it contains not only a record of the early history of the Moon, but also that of the Earth. The Moon likely formed when a giant object crashed into the newborn Earth about 4.5 billion years ago, lifting up debris that melted into the Moon and intertwining their stories. On Earth, geological activity, including plate tectonics, has erased much of the record of the early history of the planet. But the Moon does not have such activity – a perfect subject of study.

“The history of the Moon’s water provides a lot of clues as to how the solar system has evolved over time,” says Ariel Deutsch, planetologist at NASA’s Ames Research Center in Moffett Field, California.

Contamination station

Due to the importance of the moon’s ice, many researchers are reluctant to explore it. In particular, some have studied the possible contaminating effects of rocket exhaust gases on frozen caches.

Parvathy Prem, a planetary scientist at the Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland, and his colleagues recently simulated a medium-sized lander landing on the Moon at 70 ° south – a few hundred miles from the filled craters ice from the south pole. The simulation showed that even though a rocket wouldn’t release a lot of water, the water it releases would spread all around the moon and stay there for a while.³. Even after 2 lunar days – 2 months on Earth – about 30 to 40% of the rocket water would still be present, mostly frozen on the night side of the Moon. “The main thing to remember is that water vapor really goes everywhere,” Prem says. The moon’s polar ice has therefore already been contaminated by ancient explorers.

COSPAR, the international group, has asked hundreds of planetary scientists how concerned they are about lunar exploration that could interfere with science at the poles. More than 70% of respondents who responded to a survey in 2020 said they feared the contamination could compromise the scientific record held in the moon’s ice, said Gerhard Kminek, the agency’s head of planetary protection. space in Noordwijk, the Netherlands, and vice versa. – Chairman of the COSPAR planetary protection committee.

In a white paper submitted to NASA, 19 scientists, including Prem and Deutsch, propose what they call an “ origin-first ” mission to a shaded crater at one of the Moon’s poles. The goal would be to collect samples of reasonably intact ice before traffic to the moon resumes, to help scientists determine exactly how the ice has accumulated there over time. Such a mission would tell them exactly how valuable the ice science record is – and whether mining activities should be postponed, says Esther Beltran, a space scientist at the University of Central Florida at Orlando and co-author of the article. .

NASA does not currently have funds allocated for an “ origins first ” mission and continues to plan to send several spacecraft to the lunar polar regions. But the agency is listening to scientists concerned about getting it right and intends to act with caution, says Pratt, the agency’s planetary protection officer. “We have to balance the will to use resources with the need for scientific discovery and knowledge.” she says.

Meanwhile, if COSPAR adopts new guidelines for lunar exploration, NASA and space agencies in other countries likely will too. Current COSPAR guidelines require countries to keep a list of all organic materials – such as carbon composites, paints and adhesives – on board missions to the moon. Having that kind of list helps alleviate concerns about contamination, Kminek says, because it tells scientists exactly what kind of man-made material has entered the Moon’s environment. One possible change could be for future missions to also keep a list of the gases they would potentially emit from their rockets or life support systems. Relevant stakeholders, including the Chinese space agency and commercial companies such as SpaceX and Blue Origin, have been at the table with COSPAR to discuss these possible changes, says Kminek.

Ah, make decisions

However, as these discussions continue, some scientists are not too concerned about the contamination issues. Neal and others note that water vapor from rocket exhaust only settles in a thin layer on the highest part of the Moon’s surface – so it wouldn’t take much work to dig below to reach the undisturbed ice below. Last week’s NASEM report also notes that the risk of contamination from buried ice is low. And Kevin Cannon, a planetary scientist at the Colorado School of Mines in Golden, believes the small amounts of contamination introduced by exploring the moon’s ice are more than outweighed by scientific advances in determining where and how all the ice is. distributed. He mapped the largest and most accessible places of ice caches⁴ (see “Lunar Ice Caches”).

Others have put forward several ideas for protecting lunar ice. One proposal is to preserve one of the Moon’s poles for science while opening the other for mining and exploration. Another is to define an exclusion zone for some of the ice-filled craters. There are many such craters, originating from tiny pits smaller than a human hand.⁵ others that are 10 kilometers in diameter – and not all of them need to be explored, scientists say.

“One thing we have to do is make sure that we are clairvoyant,” Prem says. “Who knows what kind of science future generations might want to do?”