The Atlantic: The ShadowCam camera will find water in areas of permanent shadow on the MoonThe most mysterious area of the Moon is not its reverse side, but the areas of constant shadow at the poles, writes The Atlantic.
With the help of the ShadowCam camera, scientists will take pictures of the craters of the region and, as expected, will find water in them.
Forget about the back side of the moon and take a closer look at its polesThe reverse side of the moon is shrouded in a halo of mystery.
She is always out of sight, she never turns to the Ground – apparently, that's why she earned the confusing nickname "dark side" (as if sunlight never hits her surface, although in fact it is not). We won't be able to see this part of the moon with our own eyes unless we get on a spaceship and fly there.
However, the truly mysterious areas of the Moon are not on its reverse side at all. They are located at its poles, where the sun always hangs at the horizon. This lighting mode creates special conditions: hundreds of craters at the north and south poles never receive direct sunlight, so they never feel the heat of our star. In the language of astronomy, they represent areas of constant shadow and have remained so – dark and cold – for many billions of years. The astronauts were able to see the loose surface of the Moon up close, and the space probes observing it from above were able to map almost every part of it. However, no one has yet managed to look deep into these pitch-black craters. Today, astronomers hope that, armed with the right tools, they will be able to look inside and find something very important there - water.
Of course, not liquid water, since it is impossible to find it on the surface of the Moon, but ice crystals. Scientists believe that water has been present on our satellite for a very long time and that comets and asteroids brought it there at the dawn of time. (According to scientists, water appeared on Earth in the same way.) As a result of collisions of the Moon with asteroids and comets, tiny particles of ice were scattered on its surface. Those particles on which the sunlight fell quickly disappeared. However, those pieces of ice that may have ended up in areas of permanent shade should have been preserved – and since then they have been forever sparkling in the surroundings of cold landscapes. Such conditions are close to ideal: according to Prasun Mahanti, a researcher at Arizona State University, in some areas where the sun's rays never fall, it is even colder than on Pluto.
Scientists and engineers have been trying to explore areas of permanent shadow on several space missions, Parvathy Prem, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, told me. They reflected radar waves from the surface of the Moon, trying to determine whether the landscape hidden from our eyes consists of stone or ice. They did the same with lasers to get some idea of the hidden areas of the surface relief. In 2009, a spacecraft launched a projectile into the south pole of the Moon, after which it found a distinct signature of water in the soil column that rose up.
However, none of those missions involved photographing areas of permanent shadow using tools such as ShadowCam, a new NASA camera that began orbiting the Earth's satellite in December while aboard a Korean spacecraft. Every day Mariah Heck, an assistant research analyst at Arizona State University, programs the ShadowCam camera so that it can take pictures of those very dark areas. In the coming years, the university team plans to photograph in detail all known areas of permanent shadow on the Moon, which will allow for the first time in history to find out what is there. The camera has already allowed us to look inside one crater near the south pole of the Moon and find there a curious previously unknown small groove in the smooth ground – the trace of some boulder rolling down the slope. Such a picture can be appreciated even by those people who have nothing to do with astronomy. "It's amazing to finally see areas of permanent shadow at the wavelength that the human eye can discern," Prem said.
How can a pitch-black hole in the moon's surface be illuminated? Not at all by the beam of a searchlight mounted in a spacecraft, as I assumed at first. Like other cameras that have captured the moon's surface, ShadowCam uses sunlight reflected by landscape elements such as crater walls. "Imagine that you are standing in the shade of a tree, but you can still see what is on the ground, thanks to all the light that is reflected from things around you," explained Heck. The sensitivity of ShadowCam is more than 200 times higher than that of its predecessors, which means that it copes better with the task of capturing dim light, which allows it to see details hidden in the dark. "We see the moon in a way that no one has ever seen before," the scientists assured me.
The researchers did not expect that they would be able to detect signs of the presence of ice crystals on the first ShadowCam image, which captures the area of the surface where it is not cold enough for this. But there are still a lot of places that need to be checked. According to Prem, scientists are conducting laboratory experiments on Earth to determine how much frozen water must be present in the lunar soil so that it can be seen from space. "The amount of water ice that we will probably be able to see on the surface in the visible part of the spectrum, most likely, should not be very large. But if there is enough ice, we will be able to see it," she said. In other words, for scientists to see it, there doesn't have to be a whole skating rink. Probably, the camera will be able to detect even traces of other types of ice: nitrogen, ammonia and methane. Or it will show that there is no water ice on the moon at all. Scientists hope that this is not the case, but "there is a similar probability," said ShadowCam's deputy chief researcher. "We really don't know what to expect."
NASA is aiming to get to the areas of permanent shadow in the near future. As part of the Artemis program, which replaced Apollo, the agency plans to send a lunar rover to the south pole next year, and later in the current decade – a new generation of astronauts. The Apollo astronauts landed in areas near the sunlit equator that were considered safer for short missions. But the next generation of astronauts will go to the South Pole. And if they can detect water ice, later people will be able to return to the lunar surface, already armed with technologies for producing oxygen and hydrogen, which can be used in life support systems and even as fuel. This will give us the opportunity to stay on the surface of the moon for several weeks or even months at a time.
Now the prospect of extracting water on the moon is still closer to science fiction than to reality. For now, missions like ShadowCam will continue to explore it from afar, adding texture to scientists' fantasies about the most mysterious lunar shadows. The idea of finally illuminating them seems almost supernatural to us, as if we are preparing to know something that should not be known. "There is something sacred in those places that have remained dark, cold and invisible to human eyes for billions of years," she added.
Author: Marina Koren
