Science & Technology

AI provides clearer images of lunar craters containing water ice

The 17 newly studied craters and pits are located near Antarctica. The minimum (area 11) size of these areas is only 0.18 square kilometers, while the maximum (area 9) size is 54 square kilometers. Region 9 is not in the section of the Antarctic region shown here, but in the Schrodinger basin a little north. The lunar representation shown here is based on altimeter data from the Lunar Reconnaissance Orbiter.Credits: © MPS / University of Oxford / NASA Ames Research Center / FDL / SETI Institute

The permanently shadowed lunar craters contain water ice, which is difficult to image. Machine learning algorithms now provide clearer images.

In the polar regions of the moon, there are craters and other depressions that are not exposed to sunlight. Today, a group of researchers led by the German Maxplanck Institute for Solar Systems (MPS) presents the highest resolution images ever, covering 17 such craters. This type of crater can contain frozen water, making it an attractive target for future lunar missions. Researchers have further focused on the relatively small and accessible craters surrounded by gentle slopes. In fact, three of the craters turned out to be in the just-announced mission area. NASAVolatiles investigating the Polar Exploration Rover (VIPER), which is scheduled to land on the Moon in 2023. It is difficult to image the interior of a permanently shadowed crater, and previous efforts have relied on long exposures, resulting in smearing and low resolution. Researchers used reflected sunlight from nearby hills and new image processing methods to generate images 1-2 meters per pixel. This is close to or very close to the camera’s best capabilities.

The moon is a cold and dry desert. Unlike the earth, it is not surrounded by a protected atmosphere, and the water that existed at the time of the formation of the moon evaporates due to the influence of solar radiation and escapes to space. Nonetheless, polar craters and depressions provide several reasons for expecting limited water resources. MPS Scientist, Oxford University The NASA Ames Research Center is currently investigating some of these areas.

“Near the Moon’s North and South Pole, incoming sunlight enters craters and pits at very shallow angles and does not reach part of the floor,” said MPS scientist Valentin Bickel. Nature Communications,I will explain. In this “eternal night”, temperatures are so cold in some places that frozen water is expected to last for millions of years. Impacts from comets and asteroids may have caused it. Alternatively, it may have been outgassed by a volcanic eruption. Alternatively, it may have been formed by the interaction of the surface with the solar wind. In recent years, neutron flux and infrared measurements obtained by space probes have indicated the presence of water in these areas.Finally, NASA’s Lunar crater observation and sensing satellite (((Elcross) Provided direct evidence: Twelve years ago, the probe fired a projectile at the shaded Antarctic crater Caveus. As later analysis showed, the dust clouds released into space contained a significant amount of water.

However, scientific interest is not the only area that is permanently shadowed. Naturally occurring water is a valuable resource for humans staying on the moon for extended periods of time, and shaded craters and depressions are important destinations. NASA unmanned spacecraft Viper For example, Rover will explore the Antarctic region in 2023 and enter such a crater. Images from space probes are essential to obtain accurate images of topography and geology in advance, for example for mission planning purposes. NASA Lunar reconnaissance orbiter (((LRO) We have been providing such images since 2009.

However, it is very difficult to capture an image in the deep darkness of a permanently shadowed area. After all, the only light sources are scattered light that reflects off the Earth and surrounding terrain, and faint starlight. “Because the spaceship is moving, LRO Long exposures completely blur the image, “explains Ben Moseley of Oxford University, co-author of the study. With short exposure times, spatial resolution is much better. However, due to the low amount of light available, these images are noisy-dominated and it is difficult to distinguish the actual geological features.

Crater Antarctica without the name of the moon

An unnamed crater in the Antarctic region of the Moon. Located on the Leibniz Plateau, very close to the mission area covered by NASA’s Volatiles Investigating Polar Exploration Rover (VIPER). The image on the left is a photo taken by Lunar Reconnaissance Orbiter. The inside of the crater is almost invisible. The image on the right shows the same image after being processed by the HORUS machine learning algorithm.Credits: © Left: NASA / LROC / GSFC / ASU; Right: MPS / University of Oxford / NASA Ames Research Center / FDL / SETI Institute

To address this issue, researchers have developed a machine learning algorithm called HORUS (super-effective denoising U-net software) that “cleans up” these noisy images. I’m using over 70,000 LRO Calibration images taken on the dark side of the moon, as well as information about camera temperature and spacecraft orbit, distinguish which structures in the image are artifacts and which are real. In this way, researchers can achieve a resolution of about 1-2 meters per pixel. This is 5-10 times the resolution of all previously available images.

Using this method, researchers have now re-evaluated images of 17 shadow areas from the Moon’s Antarctic region, which are 0.18 to 54 square kilometers in size. In the resulting image, small geological structures of only a few meters can be identified much more clearly than before. These structures include rocks and very small craters found throughout the Moon. Due to the lack of atmosphere on the Moon, very small meteorites repeatedly fall to their surface, creating such mini-craters.

“With the help of the new HORUS image, we are now able to better understand the geology of the lunar shadow region than before,” explains Moseley. For example, the number and shape of small craters provide information about the age and composition of the surface. It also makes it easy to identify potential obstacles and dangers to rover and astronauts. At one of the craters under study on the Leibniz Plateau, researchers discovered a surprisingly bright mini-crater. “The relatively bright colors may indicate that this crater is relatively young,” says Bickel. Researchers suggest that this site may be an interesting target for future missions, as such fresh scars provide fairly unimpeded insights into the deeper layers.

The new image does not provide evidence of frozen water on the surface, such as bright patches. “Some of the areas we targeted may be a little too warm,” Bickel speculates. Lunar water may not exist at all as a clearly visible deposit on the surface. Instead, it can mix with regolith and dust, or hide underground.
To address this and other questions, the researcher’s next step is to use HORUS to study as many shadow areas as possible. “In today’s publications, we wanted to show what the algorithm could do. Now we want to apply it as comprehensively as possible,” says Bickel.

See also: VT Bickel, B. Moseley, I. Lopez-Francos, M. Shirley, “Peering into Permanently Shadowed Areas of the Moon by Deep Learning,” September 23, 2021 Nature Communications..
DOI: 10.1038 / s41467-021-25882-z

AI provides clearer images of lunar craters containing water ice AI provides clearer images of lunar craters containing water ice

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