Japan's probe has embarked on a five-year journey to collect sand and rocks from Mars' moon Phobos. The spacecraft is scheduled to land on Phobos in 2029, collect samples, and return to Earth in 2031. If successful, this will mark the first instance of humanity retrieving samples from the vicinity of Mars. Japan aims to utilize its asteroid sample retrieval technology to clarify the origins of Phobos and secure technology for future Mars exploration.
According to the Yomiuri Shimbun, the Japan Aerospace Exploration Agency (JAXA) launched the MMX spacecraft aboard its H3 rocket from the Tanegashima Space Center in Kagoshima Prefecture at 4:41 a.m. on October 20. The MMX separated from the rocket approximately 1 hour and 11 minutes after launch and entered a trajectory toward Mars.
Japan is targeting Phobos, a small moon with a diameter of about 20 to 30 kilometers, rather than Mars itself. This choice aims for a world-first achievement, distinguishing Japan's mission from previous Mars explorations by the U.S. and China. The Yomiuri reported that the U.S. has halted its Mars sample return plans due to rising costs, while China plans to launch a probe around 2028 with a goal of sample retrieval by 2031. In contrast, Phobos has been the subject of several failed Soviet missions, leaving it largely unexplored.
Technical feasibility was also a consideration. Asahi Shimbun noted that retrieving samples from Mars requires the probe to land through the atmosphere and then launch back against strong gravity, increasing the need for equipment and fuel. Phobos' weak gravity reduces the fuel burden for landing and takeoff. Japan can also draw on its experience from the Hayabusa and Hayabusa2 missions, which successfully returned samples to Earth.
The primary goal of MMX is to collect over 10 grams of sand and rocks from Phobos to clarify the moon's origins. According to the Yomiuri, there are two leading hypotheses: the 'asteroid capture theory,' which suggests that an asteroid was captured by Mars' gravity, and the 'giant impact theory,' which posits that debris from a massive collision with Mars coalesced to form the moon.
If the samples contain minerals or organic materials with water, it would support the asteroid capture theory. Conversely, if the samples include materials mixed with Martian crust components, the giant impact theory would gain credibility. Kiyoshi Kuramoto, a professor at Hokkaido University overseeing MMX's scientific research, stated, "The expected chemical compositions and mineral combinations from the two hypotheses are completely different. Analyzing the samples will definitively clarify their origins." Satellites like Phobos are believed to have formed in the early solar system, and understanding their origins could provide insights into the solar system's formation.
There is also interest in Martian materials that may be present on Phobos' surface. While U.S. rovers have collected and analyzed Martian rocks, none have been brought back to Earth. Asahi reported that if the samples collected from Phobos contain particles from Mars, it would represent the first instance of such materials being returned to Earth.
MMX plans to enter orbit around Mars in August 2027, conduct observations, and land on Phobos twice in early 2029. The mission will also involve using robotic arms to collect samples and observing Mars' other moon, Deimos. The spacecraft is set to leave the Martian vicinity in November 2030 and return to Earth in July 2031, dropping a capsule containing the samples in the Australian desert. The one-way flight distance exceeds 500 million kilometers.
Despite the successful launch, challenges remain. Japan previously experienced a setback with the Nozomi Mars probe, which failed to enter Mars' orbit after its launch in 1998. According to the Yomiuri, the most significant hurdle for the MMX mission will be landing on Phobos. The moon's gravity is only about 1/2000th that of Earth, which, while advantageous for conserving fuel, poses risks of the probe bouncing or tipping over upon landing. MMX is equipped with four shock-absorbing legs and employs technology to determine its current position and automatically adjust its trajectory based on terrain images. This technology was demonstrated during the landing process of Japan's lunar probe, SLIM, in 2024.
This mission also serves as preparation for future crewed Mars exploration. The Yomiuri reported that JAXA aims to secure technology for round trips to Mars and communication with Earth, while also verifying whether Mars' moons could serve as relay points for future crewed missions and cargo transport. Hiroshi Yamakawa, JAXA's director, stated at a press conference on the day of the launch, "We want to secure technology that will lay the foundation for future exploration activities."
Asahi noted that MMX was initially scheduled for launch in 2024 but was delayed by two years due to the failure of the first H3 test rocket. Due to the positions of Earth and Mars, opportunities to head toward Mars occur only about every two years. With this launch, the H3 rocket's success rate has increased to 80%. According to the Nihon Keizai Shimbun (Nikkei), the Ministry of Education, Culture, Sports, Science and Technology and JAXA are in discussions to transfer launch operations to Mitsubishi Heavy Industries by 2027, aiming to reduce costs and secure demand for overseas satellite launches by having a single company handle everything from manufacturing to launch.
* This article has been translated by AI.
Copyright ⓒ Aju Press All rights reserved.