According to new evidence presented in Rome, Italy, Mars’ moon Phobos is made from rocks blasted off the planet’s surface in a catastrophic event, rather than the entrenched scenario that the satellite was captured by the planet’s gravitational pull and originated in the main belt of asteroids.
Phobos’ composition data was collected by the European Space Agency’s Mars Express spacecraft, which has been using its Planetary Fourier Spectrometer to gather thermal infrared wavelengths in order to match the rocks on Phobos’ surface with any chondritic-class meteorite. However, the results showed a poor match, seeming to support the ‘re-accretion’ scenario of a colliding space rock blasting chunks out of the planet, before having them re-clumped together by Mars’ gravitational forces.
“We detected for the first time a type of mineral called phyllosilicates on the surface of Phobos, particularly in the areas northeast of Stickney, its largest impact crater,” said Dr Marco Giuranna, from the Italian National Institute for Astrophysics in Rome. “This is very intriguing as it implies the interaction of silicate materials with liquid water on the parent body prior to incorporation into Phobos. Alternatively, phyllosilicates may have formed in situ, but this would mean that Phobos required sufficient internal heating to enable liquid water to remain stable.”
Image Credit: NASA/JPL-Caltech/University of Arizona