Crater Reveals Ancient Surface of the Moon

By studying the images obtained of the lunar crust, geologists can now have a deeper look at the moon’s early history.
Crater Reveals Ancient Surface of the Moon
By seth
3/16/2010
Updated:
3/20/2010
NASA’s M3 (Moon Mineralogy Mapper) has discovered that a central part of the Apollo Basin could be showing a hidden portion of the ancient surface of the moon. By studying the images obtained of the lunar crust, geologists can now have a deeper look at the moon’s early history.

The Apollo Basin is a crater that lies inside the South Pole-Aitken (SPA) basin, and was formed by the impact of a 300-mile-diameter asteroid. Both craters are thought to be among the oldest of the lunar craters. The age of a crater is estimated by counting the number of smaller craters that cover up the old ones.

Since the moon has been bombarded with asteroids for billions of years, the true lunar surface has been covered with the remnants of the meteorites and solidified lava resulting from the impacts that formed the present surface. Because of this, it is very rare to find places where the original surface of the moon is seen, and it is even harder to find a view into the deeper crust.

“The asteroid that created the SPA basin probably carved through the crust and perhaps into the upper mantle. The impact melt that solidified to form the central floor of SPA would have been a mixture of all those layers. We expect to see that it has slightly more iron than the bottom of Apollo, since it went deeper into the crust. This is what we found with M3. However, we also see that this area in Apollo has more iron than the surrounding lunar highlands, indicating Apollo has uncovered a layer of the lunar crust between what is typically seen on the surface and that in the deepest craters like SPA,” said Noah Petro of NASA’s Goddard Space Flight Center in Greenbelt, Md., in a press release.

According to Petro, the lower surface of the moon that can be seen in the Apollo Basin survived the big impact that formed the larger crater in which it is located, because it was on the edge of it and thus several hundreds of miles from the impact area.

According to NASA, the heavier minerals on the moon, such as iron, are usually seen close to the core, while lighter minerals like potassium and sodium tend to move toward the top of the surface and end up forming the original lunar surface.