One day, Mars may have rings like Saturn does. The martian moon Phobos, which is spiralling inexorably closer towards the red planet, will disintegrate to form a ring system some 20 million to 40 million years from now, according to calculations published on 23 November. Other research suggests that long grooves on Phobos’s surface may represent the first stages of that inevitable crack-up.
Phobos may not be alone in its doom. Researchers have speculated that Neptune’s moon Triton might also be falling apart. And other, now-vanished moons elsewhere in the Solar System may have suffered a similar fate in the distant past, migrating towards their planet and shredding into a ring system before vanishing. Saturn’s iconic rings may have formed in this way too.
Watching Phobos in the first stages of its death throes is a rare chance for scientists to witness a process that could have been widespread in the early Solar System, says Benjamin Black, a planetary scientist at the University of California, Berkeley. He and his Berkeley colleague Tushar Mittal published the ring-system paper on 23 November in Nature Geoscience1.
By nearly any measure, Phobos is a bizarre place. It is tiny, measuring 22 kilometers across, and close to its planet — just 6,000 kilometers above the surface. Each year, Mars’s gravity pulls Phobos several centimeters closer, and scientists have long known that the moon would either plummet to its death intact or shred into a ring system before its doom.
To predict how Phobos’s death might unfold, Black and Mittal took information such as the density and strength of Phobos and compared it to a model used to estimate rock strength. They calculated that the weakest parts of Phobos would begin to spread out and form a ring about 20 million years from now.
Sourced through Scoop.it from: www.nature.com