On the 29th of December, 2013, the European Space Agency's (ESA) Mars Express spacecraft skimmed past Mars' moon Phobos at just 45 km above the surface.
An artists representation of the European Space Agency's Mars Express spacecraft. Credits: ESA, C. Carreau
The spacecraft flew so close to Phobos that it was unfortunately unable to take any images. Instead, the flyby was used to study how the solar wind interacts with Phobos, and to capture accurate measurements of the moon's gravitational field. Scientists will use this data to study the moon's internal structure.
The findings could provide important clues about the history and evolution of Phobos, and its role in the martian system. Scientists still don't know the origin of Mars' moons Phobos and Deimos. Some theories suggest they are asteroids captured by Mars, and others say the moons were formed by debris thrown from the planet by major impacts.
In an ESA press release issued on Dec 23, Mars Express project scientist Olivier Witasse commented, “By making close flybys of Phobos with Mars Express in this way, we can help to put constraints on the origin of these mysterious moons."
Mars Express Phobos flyby (Animation x1000 speed). Credit: ESA
Studying the relationship between Mars and its moons can help astrobiologists understand how the planet has changed since its formation, and whether or not the planet may have been habitable in the past.
ESA has also released a collections of videos that show what the trajectory of Mars Express looked like as it approached Phobos:
Mars Express flyby viewed from Phobos (Animation). Credit: ESA
Mars Express flyby as seen from Phobos (Animation). Credit: ESA
Mars Express closest-ever Phobos flyby (Animation). Credit: ESA
ESA is providing updates about the flyby on the Mars Express blog at: http://blogs.esa.int/mex/.