Our neighbour Mars is in a bit of a family problem. Long shallow groves along the surface of its largest moon, Phobos are early signs that this planetary satellite is on the verge of collapse, soon.
Orbiting around Mars, 6000 km above it's surface, the gravitational pull leads to about 2 meters of the moon to be disintegrated every 100 years. It is predicted that Phobos may no longer exist 30 - 50 million years from now.
“We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves,” said Terry Hurford of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The findings by Hurford and his colleagues are being presented Nov. 10, 2015, at the annual Meeting of the Division of Planetary Sciences of the American Astronomical Society at National Harbor, Maryland.
Before Hurford's study, many thought that the grooves were formed by material ejected from Mars. The gravitational pull between Mars and Phobos has formed stretch mark like grooves on its surface in the same way that the gravitational pull between Earth and the Moon causes tidal activity in oceans and seas.
Scientists thought that Phobos was constituted of solid material, but more recent thought has led to the belief that it may be a pile of rubble that is held together by a layer of powdery regolith.
The funny thing about the result is that it shows Phobos has a kind of mildly cohesive outer fabric,” said Erik Asphaug of the School of Earth and Space Exploration at Arizona State University in Tempe and a co-investigator on the study. “This makes sense when you think about powdery materials in microgravity, but it's quite non-intuitive.”
This probably explains why some grooves on the surface are younger than the others. Researchers predict the same fate for Triton, the moon of Neptune.
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