Japan’s Upcoming Mission to Phobos
The Japan Aerospace Exploration Agency (JAXA) has plans to launch a spacecraft on Tuesday that will embark on a five-year journey to Phobos, one of Mars’ moons. This mission aims to collect the first-ever rock and soil samples from a moon of Mars.
Kawakatsu Yasuhiro, who manages the Martian Moons Exploration Mission (MMX), stated that this mission could significantly enhance our understanding of the solar system’s formation, perhaps even shedding light on the origins of life. It may also set the stage for using Phobos as a potential base for future manned missions to Mars.
“Despite their potential importance, Martian moons have never been fully investigated. They are known as the most important unclimbed mountains in the solar system,” he remarked.
Phobos, which is the larger of Mars’ two moons—Deimos being the other—is relatively small compared to Earth’s Moon. It measures just 17 miles at its widest point and has a rapid orbit, completing three revolutions around Mars each day. A prominent feature of its surface is Stickney Crater, a large dent formed by a meteoric impact that nearly shattered the moon.
Landing on Phobos presents its own challenges. The Russians made several attempts to send probes to Phobos between 1988 and 2011, but only one, Phobos-2, reached Martian orbit before it suffered a catastrophic failure just before landing in 1989.
The MMX mission is a collaborative effort, led by JAXA with support from NASA, which is providing a gamma ray and neutron detection instrument called MEGANE. This tool, designed by the Johns Hopkins Applied Physics Laboratory and Lawrence Livermore National Laboratory, could offer insights into the origins of Phobos and Deimos.
Since the discovery of Mars’ moons in 1877, they’ve puzzled astronomers. The prevailing inquiries have revolved around whether these moons originated from Mars itself or if they are captured asteroids.
“What are these little space potatoes? We can’t explain Phobos or Deimos right now. They shouldn’t exist, but they do. They’re super weird, super small, and super puzzling,” claimed Dr. Abigail Fraeman from NASA’s Jet Propulsion Laboratory. She added that while previous missions have provided data about Phobos and Deimos, none has been entirely consistent with any theories surrounding their beginnings.
The MEGANE system aims to decode this mystery by analyzing neutron and gamma ray energies from Phobos, potentially confirming whether the moons share the same material composition as Mars—almost like conducting a DNA test to trace ancestry.
David Lawrence, a planetary scientist at APL, explained the process: “If you had a giant impact, what happens is the materials get very hot, and you will cook off these volatile elements. In contrast, lots of asteroids have higher abundances of these volatile elements.”
The spacecraft will initially deploy a small rover named Idefix onto Phobos’ surface. This tiny rover, developed by the German Aerospace Center and the National Center for Space Studies in France, will assist in identifying the most suitable landing site for a larger lander that the MMX spacecraft carries.
Given Phobos’ low gravity, the mission plans to drop the lander from just under 350 feet, allowing it to bounce onto the surface. The lander itself is about the size of a case of beer, while Idefix looks like a small toy. There are plans to make two lander drops on opposite sides of Phobos due to the observed differences in composition between the moon’s dark and light sides. The lander has an American-made system to collect surface dust using pressurized gas, along with a Japanese system designed to dig about an inch into the moon’s surface for samples.
By obtaining samples from multiple areas on Phobos, the mission hopes to address ongoing questions about the origins of life in our solar system and whether any form of life ever existed on Mars. If Phobos originated from Mars after an ancient cataclysm, it could hold a snapshot of the planet’s past. Conversely, if it’s primarily a captured asteroid, it may contain chemicals from distant regions of the solar system.
The MMX mission is set to reach Mars in about a year, orbit Phobos for around three years, perform a close flyby of Deimos, and then return to Earth within another year. It’s anticipated that the sample capsule will splash down off the coast of Australia in 2031, aiming to bring back less than half an ounce of materials.
Moreover, the MMX mission is working to complete its objectives before China’s Tianwen-3 sampling mission arrives on Mars later in 2031.
