The Japan Aerospace Exploration Agency (JAXA) has officially initiated a groundbreaking interplanetary endeavor to investigate the Martian satellites and transport extraterrestrial material back to Earth. The Martian Moons eXploration (MMX) initiative lifted off from the Tanegashima Space Center situated in Kyushu, Japan, at 4:41 a.m. JST on Oct. 20. The primary objective is to survey Phobos and Deimos, culminating in a sample retrieval from Phobos scheduled for 2031.

Orbiting the Red Planet are two diminutive, heavily cratered, and non-spherical bodies. Phobos, the larger of the pair, spans roughly 14 miles (23 kilometers) across as a potato-shaped mass circling just 3,700 miles (6,000 kilometers) above Mars, completing its circuit in under eight hours. Positioned further out lies Deimos, a smaller, irregular moon that requires approximately 30 hours for a complete Martian orbit.

JAXA's MMX probe will journey toward the Martian system, deploying a payload of 13 dedicated scientific instruments to analyze the geological makeup and genesis of these minor celestial bodies.

A core scientific puzzle the MMX project seeks to resolve is the exact formation history of Phobos and Deimos. Researchers remain divided, with competing hypotheses suggesting either gravitational capture by Mars or accretion from debris spawned by a colossal ancient impact.

This ambitious undertaking represents a cooperative global venture led by JAXA in partnership with international space organizations, including NASA, France's CNES, and Germany's DLR.

What The MMX Mission Will Do

Upon reaching the Martian neighborhood, MMX will first establish a planetary orbit before transitioning into a quasi-satellite trajectory surrounding Phobos. This configuration enables continuous, close-range observation via specialized cameras and scientific gear. These extensive surveys will facilitate detailed studies of the moon's surface composition while identifying an optimal, secure touchdown zone for the probe.

Executing a landing on Phobos presents one of the venture's most formidable engineering hurdles. Due to the moon's exceptionally feeble gravity, the spacecraft must execute a precise, delicate touchdown to harvest regolith from the terrain. Engineers designed the probe to make one or two descents utilizing dual sampling mechanisms, including a pneumatic gathering system, to secure at least 10 grams of matter. Additionally, the mission will deploy the compact IDEFIX rover—engineered collaboratively by Germany's DLR and France's CNES—to autonomously traverse and study the surface.

Following the completion of operations at Phobos, MMX will execute several close flybys of Deimos to contrast the two bodies and extract further clues regarding their origins. The spacecraft will subsequently depart the Martian environment, housing its acquired samples inside a specialized return capsule. If projections hold true, this capsule will parachute down into the Australian desert by 2031, yielding the very first material ever brought to Earth from the Mars system.

Alongside the physical specimens, the landing capsule will transport ultra-high-definition visual data chronicling Mars and its satellites from unprecedented perspectives. Japan’s public broadcaster, NHK—which previously flew an HD sensor on JAXA’s 2007 Kaguya lunar orbiter and filmed 4K footage of Earth from the International Space Station—has engineered an 8K-capable Super Hi-Vision camera expressly for this flight. Because transmission bandwidth limitations prevent direct 8K broadcasting from Mars, select 4K and 8K images will be beamed back during transit, while the master high-resolution footage travels home safely alongside the Phobos samples inside the sealed MMX return capsule.

Japan’s Heritage In Spaceflight And Sample-Return

In January 2024, Japan cemented its status as the fifth nation to achieve a soft lunar landing through JAXA's SLIM (Smart Lander for Investigating Moon) project. Furthermore, the nation boasts a proven track record in asteroid sample recovery. Most notably, the Hayabusa2 probe gathered material from asteroid Ryugu in 2019 and successfully parachuted it to South Australia in 2020. JAXA also previously retrieved samples from asteroid Itokawa in 2010 following the Hayabusa spacecraft's initial 2005 rendezvous.