Japan Launches Historic Mission to Collect Samples from Martian Moon Phobos

TOKYO — Japan has launched its groundbreaking Martian Moons eXploration (MMX) mission, marking the first-ever endeavor to retrieve samples from Phobos, one of Mars' two small moons. The mission, expected to span five years, seeks to unravel the mysteries of how Phobos and its sibling moon, Deimos, came into existence and potentially gain insights into the evolution of life within the solar system.

The launch by the Japan Aerospace Exploration Agency (JAXA) on a new H-3 rocket underscores the growing international interest in Mars exploration, a field where the United States, China, and other nations are also pursuing ambitious goals, including potential crewed missions.

Acquiring samples from Phobos could prove invaluable for future Mars missions, potentially identifying the moon as a staging point for human expeditions to the Red Planet, according to MMX project manager Yasuhiro Kawakatsu. "Despite their potential importance, Martian moons have never been fully investigated," Kawakatsu stated, describing them as "the most important unclimbed mountains in the solar system." The international mission is spearheaded by Japan, with crucial equipment and communication support provided by NASA and other global space agencies.

Unraveling Martian Moon Origins

Since the 1960s, numerous missions have targeted Mars, yet its moons have remained largely unexplored. Phobos and Deimos, named after the Greek mythological figures representing fear and terror, have defied previous landing attempts, notably by Russia. Scientists are divided on their origin: some theorize they are fragments from a massive impact on Mars, while others suggest they are captured asteroids.

JAXA anticipates that Phobos soil samples will provide definitive answers. "We can almost certainly come to a conclusion by analyzing (Phobos) soil samples," said Kiyoshi Kuramoto, MMX principal investigator. Phobos was chosen due to its proximity to Mars and potential to contain Martian material, estimated by JAXA officials to be about 0.1% of its composition.

Phobos, approximately 20 to 30 kilometers in diameter, orbits Mars at about 6,000 kilometers, completing three orbits daily. Analysis of Phobos samples may also shed light on Deimos' origins, as the two moons are believed to share similar developmental histories. The MMX mission also includes a flyby of Deimos for observation.

A Three-Year Study of Phobos

The journey to the Mars region, which is 55 million kilometers from Earth at its closest point, will cover a flight distance of 500-600 million kilometers. The spacecraft is projected to reach the Martian vicinity in August 2027.

Once at Mars, MMX will spend three years orbiting and studying Phobos before commencing its return journey in 2031. The spacecraft comprises three modules: propulsion, exploration, and return. Only the return module, carrying the collected samples in a specialized capsule, will journey back to Earth.

The MMX is equipped with 13 scientific instruments. Notably, it carries the Idefix rover, a joint Franco-German development designed to land on Phobos. NASA contributed a sampling device and a gamma-ray spectrometer, while the European Space Agency provided a deep-space communication device. A Japanese radiation monitor will gather data pertinent to future crewed Mars missions.

Sample Collection on Phobos

The Idefix rover is slated to land on Phobos first, conducting a 100-day mission around 2029 to survey the surface and aid the subsequent sample collection by MMX. Following the rover's exploration, MMX aims to collect at least 10 grams of soil from two distinct sampling attempts, employing both U.S. and Japanese methodologies.

NASA's device utilizes pressurized gas to transfer surface dust into a container, while JAXA's coring technique will extract samples from approximately 2 centimeters below the surface. The initial landing will attempt to collect both surface and subsurface samples using both methods, with a second landing planned for additional subsurface samples.

Scientists believe that collecting samples from multiple locations increases the likelihood of discovering any potential traces of past microbial life on Mars. The collected samples will be housed in a heat-shielded capsule designed to withstand atmospheric reentry, with a planned landing in Australia before transport to Japan.

This mission builds upon Japan's previous successes with its Hayabusa asteroid sample return missions, which successfully brought back extraterrestrial material in 2010 and 2020.

Navigating Phobos' Low Gravity

A significant challenge for the MMX mission is Phobos' extremely low gravity, which is about one-two thousandth of Earth's. The spacecraft must identify a suitable landing site, characterized by smooth, level terrain, based on data from the rover. Sample collection must then be completed within a two-hour window.

To mitigate bouncing upon touchdown, the MMX's exploration module is equipped with a four-legged landing gear system featuring shock absorption. The Idefix rover is designed with wheels optimized for traction in low gravity, the ability to self-right if it tips over, and a slow, deliberate movement, according to JAXA.