14 DAY TRIAL // Astronomers at the European Space Agency (ESA) announce that their orbiter, Mars Express, is about to begin its new campaign to survey the moon Phobos, one of the two companions the Red Planet has. The investigations will take place for about a month, with peak observations capabilities scheduled to be reached on March 3. At that date, the enduring orbiter will skim Phobos' surface at an altitude of just 50 kilometers, which will allow it to conduct a host of scientific measurements on the space rock, and determine more information about how it was formed, and what chemicals it's made of.
In fact, the campaign begins today (February 16), as the space craft passes some 991 kilometers above the Martian moon. The point of closest approach during this flyby was achieved at 6:52 CET (05:52 UT). Investigations will conclude around March 26, when the orbits of Mars Express and Phobos take the two far away from each other, out of the reach of the spacecraft's scientific instruments. Though the orbiter was primarily designed to investigate the Red Planet, ESA experts are confident that, given a chance to analyze the small space rock, it will not disappoint.
“Because Mars Express is in an elliptical and polar orbit with a maximum distance from Mars of about 10,000 km, we regularly pass Phobos. This represents an excellent opportunity to perform extra science,” explains Mars Express project scientist Olivier Witasse. He says that experts at the European Space Operations Center (ESOC), in Darmstadt, Germany, determined that a number of precautionary measures need to be taken for Mars Express, while the orbiter was flying in Mars' nightside. “That [50 kilometers] was the closest they would let us fly to Phobos,” Witasse adds, saying that this distance should also do for assessing the moon's gravitational pull.
If scientists manage to collect all the data they need, then they will also be able to map the internal structure of the body. This will further help them in determining whether Phobos was formed alongside Mars, or if it initially was a stray space rock that was captured by the Red Planet's gravity. A preliminary analysis of the moon showed that the density of Phobos is very small, which would seem to hint that it is hollow on the inside. The new observations will also allow astrophysicists to place this data to a more rigorous test.