1,4,4,5,- 1University of Leicester, School of Physics and Astronomy, Leicester, United Kingdom of Great Britain – England, Scotland, Wales (ca337@leicester.ac.uk)
- 2Planetary Materials Group, The Natural History Museum, UK
- 3Institute for Space, Space Park Leicester, UK
- 4School of Engineering Maths and Physics, University of Kent, UK
- 5School of Natural Sciences, University of Kent, UK
JAXA's Martian Moon eXploration (MMX) sample return mission aims to solve the long-debated origin of Martian moons Phobos and Deimos [1]. This will be the first attempt to sample an object that either formed in the outer solar system and implanted [2,3,4] into the terrestrial planet region by a major dynamical process (the first origin scenario); or formed from a large impact and subsequently accumulated material from two, very possibly compositionally different, bodies, i.e. Mars and the impactor (the second scenario). In either scenario, impact processes by asteroids, meteoroids, as well as Martian ejecta have altered the surfaces of the Martian moons and require investigation into several aspects such as the crater formation and exposure of fresh sub-surface material, the comminution of surface boulders and regolith production, and the delivery of exogenous materials.
To provide a frame for the MMX data interpretation, a laboratory experimental campaign is conducted simulating the impact processes on Phobos. We used porous (50%) Phobos simulant materials obtained from the Exolith Lab. These were the PGI-1 and PCA-1 simulating the giant impact and captured asteroid scenarios and we studied the crater depth and diameter as well as the ejecta production as a function of speed and projectile mass.
In addition we simulated the Martian material contamination on Phobos surface. For this we performed impact experiments using olivine projectiles. Contamination was visible with naked eye and verified using RAMAN spectrometry.
Furthermore, we produced mixtures of Phobos and Martian simulant and recorded their NIR-FTIR spectra as a function of martian contamination and grain size of the sample. Measurements of simulant mixtures have shown variations in position and band depths of spectral features relative to the volume of Martian material present, in particular the Christiansen feature and 3-micron feature which will be observed by MMX’s miniRAD and MIRS instruments and play a critical role in identifying Martian material on Phobos’ surface.
Acknowledgements: We acknowledge CNES and STFC funding for initiating this work.
References:
[1] Usui et al. Space Science Reviews 216, Issue 4, article id.49 (2020).
[2] Levison et al. Nature 460, Issue 7253, pp. 364-366 (2009).
[3] Vokrouhlicky, Bottke, Nesvorny. The Astronomical Journal 152, Issue 2, article id. 39, 20 pp. (2016).
[4] Kegerreis et al. Icarus, Volume 425, id.116337 (2025).
How to cite: Avdellidou, C., Branagan-Harris, E., Spathis, V., Burchell, M., Finch, E., Tandy, J., Russell, S., Wozniakiewicz, P., and Alesbrook, L.: Support to MMX mission: Impact cratering and exogenous material contamination on Phobos simulants , Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1147, https://doi.org/10.5194/epsc2026-1147, 2026.
