Scientists studying the moon have made an unexpected discovery. Although we have good data on surface topography, we still do not know much about what is hidden under steep craters and dunes. A big crater in the southern polar region seems to contain a large deposit of material, maybe the remains of an old metal asteroid.
The region, known as the South Pole-Aitken Basin, is one of the largest known impact craters, measuring approximately 1,500 miles (2,500 kilometers) in diameter. Although larger than this (including on Earth), the immutable environment of the moon is far better at preserving the evidence of the moon. This distinction makes the South Pole-Aitken basin a subject of frequent research. The Chinese LG Chang & # 39; e 4 landed in the basin, specifically in a smaller crater called Von Kármán.
Researchers at Baylor University in Texas used data from NASA's GRAIL (Gravity Recovery and Interior Recovery) and LB (Lunar Reconnaissance Orbiter) missions to develop this new hypothesis about the origins of the basin. The GRAIL satellite has mapped the moon's gravity in 2011 and 2012. In parallel, the LRO has mapped the lunar surface for a decade. According to the new study, the two sets of data seem to present a disparity. Where should we expect gravity to drop slightly on the crater, it actually increases.
The main explanation for the gravitational anomaly, according to the researchers, is that the object responsible for the crater is still almost intact beneath the surface. So 4 billion years ago, an essentially metallic asteroid hit the the moon and remains anchored in the mantle to this day. Another possible explanation is that the region is naturally rich in oxides that formed during the cooling of the moon in the distant past. However, crater overlap and increased gravity seem a bit too practical.
If a large metal object is buried under the South-Aitken Pole Basin, it could tell us more about the inner moon. After 4 billion years, the iron and nickel remains of the asteroid would have dispersed into the mantle if the moon had been geologically active for a significant period of time.
Additional research and missions will be needed to confirm the presence of asteroid deposits under the South Pole-Aitken basin. Getting a sample is not very likely, however. The GRAIL data suggest that the asteroid nucleus is about 300 km below the surface.