THE MARTIAN MOON PHOBOS AND ITS INTERACTION WITH THE SPACE ENVIRONMENT

Quentin Nenon –  IRAP

Phobos is a small moon of Mars which orbits only 6,000 km above the surface of the red planet. The origin of Phobos is a complete mystery: captured asteroid, co-accretion with Mars, or debris of a giant impact on the planet. To close this question, the JAXA Martian Moons Exploration mission is set to launch in 2024 towards Phobos and will return samples of the surface back to Earth in 2029.

However, remote observations and samples of the surface do not show the ‘pristine’ properties of Phobos, but properties processed by the interaction of the surface with the space environment, including micro-meteoroid bombardment and irradiation by space plasma ions. Surface modification by the space environment is known as ‘space weathering’.

In this presentation, we will highlight the contributions of IRAP to the study of space weathering of the surface of Phobos, including the analysis of Mars Express and MAVEN ion measurements, numerical simulations, and lab experiments. We will place these advances in the general context of space weathering at Phobos and at other airless bodies (the Moon, Mercury, asteroids…). The impact of our ongoing work on the scientific operations of JAXA MMX will be presented.