Mars Express spacecraft views of Phobos

Mars’ tiny moon Phobos has created a big stir among astronomers with the fly-bys of the Mars Express Spacecraft of the European Space Agency in early 2010. EarthSky spoke with Thomas Duxbury, on the science team collecting images of Phobos.

Thomas Duxbury: As we get higher and higher resolution of the images, we see more and more detail on the surface. It is just pockmarked with craters.

The biggest crater on Phobos is called Stickney.

Thomas Duxbury: And radiating from this crater are these long linear features that go all the way around to the backside of Phobos.

Duxbury said these features look like grooves you make in the snow when you’re building a snowman.

Thomas Duxbury: You start rolling balls of snow, and of course it gets bigger and bigger, you get these indentations in the snow.

Duxbury thinks that the grooves were created when an asteroid impact threw up large boulders that rolled from the crater.

Thomas Duxbury: You can actually see how these trails follow the topography. They go up and down the sides of craters and their path is actually diverted as they go around a crater wall. Sometimes they crisscross and then eventually they stop.

Duxbury added that these questions and more might be answered by a future mission in 2011 to collect samples of Phobos and return them to Earth. Thomas Duxbury spoke more about why scientists are studying Mars’ moon Phobos.

Thomas Duxbury: I believe that Phobos is an accretion of crater ejecta from Mars that was thrown into orbit about Mars, and then over time through gravitational pulls, formed the moon of Mars, Phobos, that we see today. So I believe when you look at Phobos, we are looking at Mars.

One of the goals of the Mars Express flybys of Phobos is to identify a landing site for a mission in 2011, called Phobos-Grunt, which will collect sample of the surface and return them to Earth, said Duxbury.

Thomas Duxbury: I am working with the Russians, who next year will launch a spacecraft to Phobos to gather samples and bring back to Earth. So one of the things we’re doing on Mars Express is we are exploring these possible landing sites. We want to pick a landing site that’s safe to land on, that has a wide range of chemical composition and geologic features, and that we have good communications with Earth, and that we can take these samples and safely lift off from Phobos and come back to Earth.