The main objective of Phobos-Soil (Phobos-Grunt) is to return Phobos regolith samples back to Earth for comprehensive studies in terrestrial laboratories – a historical first. The mission is also equipped for pioneering in situ measurements of the physical and chemical properties of the regolith at the landing site and for measurements of the bulk characteristics of Phobos from orbit. From its position in a quasi synchronous orbit with Phobos, it will study the near-Mars environment and will be the first spacecraft dedicated to the study of Phobos.

The mission's science objectives include:

• Study of the physical and chemical characteristics of Phobos in order to understand the origin of the Martian satellites, and possibly also the origin of satellite systems of other planets
• Detailed measurements of the orbit and intrinsic rotation of Phobos to aid the study of its internal structure and the evolution of its orbit
• Study of the near-Mars environment, including the charged particles and magnetic fields and interaction of the solar wind with the plasma environment in the region. This may also broaden our understanding of the history of water on Mars
• Remote studies of Phobos to study its origins, formation and evolution, orbit, internal rotation
• Characterisation of the Martian atmosphere

Mars Express obtained this image of Phobos, the largest of the Martian moons, when it flew by on 9 January 2011, passing at a distance of 100km. Superimposed on the HRSC-nadir image are 7 SRC-images with a resolution of about 3 m/pixel. The Super Resolution Channel images show more details of the surface of Phobos. Credits: ESA/DLR/FU Berlin (G. Neukum)