University of California, Santa Cruz | 2016 Aug 30
[img3="In this spacecraft image of Phobos, red arrows indicate a chain of small craters whose origin researchers were able to trace back to a primary impact at the large crater known as Grildrig. (Image credit: ESA/DLR/FU Berlin-Neukum, modified by Nayak & Asphaug)"]http://news.ucsc.edu/2016/08/images/pho ... rs-400.jpg[/img3][hr][/hr]Some of the mysterious grooves on the surface of Mars' moon Phobos are the result of debris ejected by impacts eventually falling back onto the surface to form linear chains of craters, according to a new study.
One set of grooves on Phobos are thought to be stress fractures resulting from the tidal pull of Mars. The new study, published August 30 in Nature Communications, addresses another set of grooves that do not fit that explanation.
"These grooves cut across the tidal fields, so they require another mechanism. If we put the two together, we can explain most if not all of the grooves on Phobos," said first author Michael Nayak, a graduate student in Earth and planetary sciences at UC Santa Cruz.
Phobos is an unusual satellite, orbiting closer to its planet than any other moon in the solar system, with an orbital period of just 7 hours. Small and heavily cratered, with a lumpy nonspherical shape, it is only 9,000 kilometers from the surface of Mars (the distance from San Francisco to New York and back) and is slowly spiraling inward toward the planet. Phobos appears to have a weak interior structure covered by an elastic shell, allowing it to be deformed by tidal forces without breaking apart. ...
Sesquinary Catenae on the Martian Satellite Phobos from Reaccretion of Escaping Ejecta - M. Nayak & E. Asphaug
- Nature Communications 7:12591 (30 Aug 2016) DOI: 10.1038/ncomms12591
