American attention regarding space missions is, not surprisingly, focused primarily on NASA missions. But there is a lot more exploration underway, and we should know about it. This is a guest column by Elizabeth Tasker, an Associate Professor at the Japan Aerospace Exploration Agency, JAXA, and whose book, “The Planet Factory”, comes out in November in the USA. Here she explains the upcoming Japanese mission to the moons of Mars that will include sample return.
— Marc Kaufman
Illustration of Mars with its two moons, Phobos and Deimos. (NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.)
By Elizabeth Tasker
The global success rate for sending missions to land on the moons of Mars has hardly been impressive — coming in at zero out of three attempts. They were all led by the Russian (or former Soviet) space agencies, in collaboration with organizations ranging from the Chinese and Bulgarian space agencies to the Paris Observatory and the U.S. Planetary Society.
Now the Japanese space agency JAXA has approved its own mission to Phobos and Deimos, scheduled to launch from the Tanegashima Space Center in September 2024.
The Martian Moons eXploration (MMX) spacecraft will arrive at Mars in August 2025 and spend the next three years exploring the two moons and the environment around Mars. During this time, the spacecraft will drop to the surface of one of the moons and collect a sample to bring back to Earth. Probe and sample are scheduled to return to Earth in the summer of 2029.
Mars takes its name from the god of war in ancient Greek and Roman mythology. The Greek god Ares became Mars in the Roman adaptation of the deities. Mars’s two moons are named for Phobos and Deimos; in legend the twin sons of Ares who personified fear and panic.
Today, what the moons together personify is a compelling mystery, one regarding how in reality they came to be.
Both Martian moons are small, with Phobos’s average diameter measuring 22.2km, while the even smaller Deimos has an average size of just 13km. This makes even Phobos’s surface area only comparable to that of Tokyo. Their diminutive proportions means that the moons resemble asteroids, with irregular structures due to their gravity being too weak to pull them into spheres.
This leads to the question that has inspired a long-running debate: Were Phobos and Deimos formed during an impact with Mars, or are they asteroids that have been captured by Mars’s gravity?
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There are many worlds out there waiting to fire your imagination. This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.
The “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA's NExSS initiative, a research coordination network dedicated to the study of planetary habitability. Any opinions expressed are the author’s alone.