Phobos, the larger of Mars’ two moons as seen by the High-Resolution Imaging Sciences
Experiment (HiRISE) on NASA’s Mars Reconnaissance Orbiter in March, 2008. The illuminated portion of the
image is some 21 km across and objects as small as some 6-meters across can be resolved. Courtesy of
NASA/JPL/University of Arizona.


A new study has been issued — Planetary Protection Classification of Sample-Return Missions from the Martian Moons – Phobos and Deimos. Currently, the Committee on Space Research of the International Council of Scientific Unions’ (COSPAR for short) planetary protection policy does not specify the status of sample return missions from Phobos or Deimos.

Although the moons themselves are not considered potential habitats for life or of intrinsic relevance to prebiotic chemical evolution, recent studies indicate that a significant amount of material recently ejected from Mars could be present on the surface of Phobos and, to a lesser extent, Deimos.

Robotic/human missions

Japan plans to launch the Martian Moons Exploration (MMX) mission in the mid-2020s to collect and return samples from Phobos (or Deimos) to Earth. Furthermore, the moons of Mars are potential targets for future human exploration.

Therefore, an understanding of the potential for life from Mars to persist on Phobos and/or Deimos is relevant to assuring astronaut safety on those missions.

These color-enhanced views of Deimos, the smaller of the two moons of Mars, were taken on Feb. 21, 2009, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. Deimos is about 7.5 miles in diameter.
Credit: NASA/JPL-Caltech/University of Arizona

Unrestricted Earth return

To lessen the scientific uncertainties concerning the planetary protection status of the martian moons, NASA and the European Space Agency (ESA) commissioned research to perform modeling and experimental activities to assess the extent to which material from Mars might be deposited on the planet’s moons.

The various steps of martian material transferred to Phobos (and inferred for Deimos). Teams undertook experimental studies and/or numerical modeling to study each distinct step in the chain
from the surface of Mars to that of its moons. The committee organized its report around the various steps outlined
above. Image taken from Japan’s JAXA report with permission.

One report focus is gauging the post-ejection environmental conditions that might inactivate potential martian life transported to Phobos and Deimos.

Tests of that idea have already included hypervelocity impact sterilization of relevant Earth organisms, as well as use of ionizing radiation and heat.

One bottom line of the report is that the committee carrying out the study recommends that samples returned from the martian moons be designated “unrestricted” Earth return.

Go to this informative website on Japan’s Martian Moons Exploration (MMX) mission at:

You can download the full report — Planetary Protection Classification of Sample-Return Missions from the Martian Moons — for free here:


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