Largest of Mars Two Moons Phobos is in Big Trouble
We are all familiar with tidal forces on Earth which affects the movement of our seas and the levels of the waves along any of our shorelines. That may be it’s simplest form but these forces could over an extended period deliver devastating consequences to moons like Phobos. With reference to new experimentation NASA believe that grooved markings showing up on Phobos are evidence that it is gradually being pulled apart.
According to NASA, the scar-like crevices that have long been visible on Phobos’ surface are evidence of an ongoing structural failure that will ultimately see the moon destroyed. The researchers say these grooves are like lunar “stretch marks” which reveal the effects of Mars’ gravity pull, and which will progressively shatter the moon over the next 30 to 50 million years.
“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 Centre in Greenbelt, Maryland.
Phobos’ distinctive markings had previously been thought to be fracture lines stemming from the lunar impact that created the Stickney crater – a truly massive collision that almost destroyed the moon. Another more recent theory was the grooves were caused by impacts of smaller material ejected from Mars.
However, new modelling presented this week at the Division of Planetary Sciences of the American Astronomical Society’s annual meeting suggests the deformations are instead caused by tidal forces. Interestingly, this theory was raised decades ago but was discounted after calculations – based on the assumption that Phobos had a solid core – negated the possibility that such fracturing could occur on a dense moon.
Now scientists believe Phobos is not dense but rather may have a rubble pile at its core, which is surrounded by a powdery surface regolith only about 100 metres thick.
image source: NASA/JPL-Caltech/University of Arizona