Astronomers have proposed that we should search for life on Phobos instead of on Mars. Credit: NASA/JPL-CALTECH/UNIVERSITY OF ARIZONA

Martian Moons Could Hold Clues to Life on Red Planet

The satellites of the Red Planet may contain traces of life that was once present on the planet itself.

Scientists Ryuki Hedo and Tomohiro Usui of the Japan Aerospace Exploration Agency (JAXA) have published a promising paper, in which they propose a new way to search for traces of life on Mars. They believe that biomarkers should be looked for not on the planet itself, but on its satellites.

Traces of alien life on Phobos – how could it be possible?

Liquid water

The authors of the scientific article note that the studies of Mars over the past few decades have provided a large amount of evidence that liquid water was present on the surface of this planet at the very beginning of its existence.

Life could exist

With a high probability, the presence of liquid water also indicates that some form of life could exist on the Red Planet.


Modern research is focused on finding traces of this life. For example, this is one of the main tasks of the Curiosity rover, which has been studying the surface of Gale Crater since 2012.

Perseverance rover

This is also the main task of the Perseverance rover, which only recently began collecting samples for analysis for traces of life.


Previously, numerous hypotheses have been put forward about potential habitats on Mars, where, perhaps, there is still some kind of life, for example, microbial. At present, Mars is officially recognized as a “paleo-inhabited” planet, which reflects its ancient habitability.

The moons of Mars

In their new study, Japanese astronomers propose to shift the focus of the search from the Red Planet to its two small moons, Phobos and Deimos. Mars is known to have been hit by numerous asteroid impacts throughout its history. Some of them were so powerful that they ripped out some of the material and threw it into space. It is believed that some of the ejected material was delivered to the moons of Mars.

Life on Phobos

This means that the satellites of the Red Planet may contain traces of life that was once present on the planet itself. The authors of the work believe that Phobos is more promising for the search for ancient biomarkers. It is closer to Mars than Deimos, so more of the ejected planetary material should have remained on its surface. At the same time, scientists believe that the Martian inhabitants did not have a chance to survive.

No living microorganisms

Even if any organisms could survive the path to Phobos, it would be impossible for them to last in the environment without air and water. Moreover, the surface of the satellite is constantly under solar and cosmic radiation, which further makes it unlikely that there could be any living microorganisms.

SHIGAI Biosignatures

However, the researchers suggest that dead biosignatures may have survived on Phobos. In their work, astronomers gave them the name SHIGAI (Sterilized and Harshly Irradiated Genes, and Ancient Imprints – sterilized and highly irradiated genes and ancient imprints). In Japanese, this abbreviation means “dead remains”.


SHIGAI biosignatures can include any microorganisms that may have lived on Mars in ancient times, including potential DNA fragments. In general, the authors of the work declare that the Mars-Moon system is an ideal natural laboratory for studying the interplanetary transport and stability of SHIGAI on airless bodies of the solar system.

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Hyodo, R., & Usui, T. (2021, August 13). Searching for life on Mars and its moons. Science.
Kelvey, J. (2021, August 13). Phobos: Why the largest Martian Moon may Reveal alien life. Inverse.
Smith, A. (2021, August 13). Martian moon PHOBOS could be home to extinct alien life from an ancient lake. The Independent.
Yirka, B. (2021, August 16). The search for life on Mars expands to studying its moons.

Written by Vladislav Tchakarov

Hello, my name is Vladislav and I am glad to have you here on Curiosmos. As a history student, I have a strong passion for history and science, and the opportunity to research and write in this field on a daily basis is a dream come true.

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