Japan launches robotic spacecraft to collect samples from Martian moon Phobos

Japan launched an ambitious robotic mission to explore the Martian moons and return surface samples to Earth. Led by the Japan Aerospace Exploration Agency (JAXA) with international contributions, the Martian Moons Exploration (MMX) mission lifted off from the Tanegashima Space Center. The spacecraft climbed into space aboard a Japanese H3 rocket powered by four solid-propellant strap-on boosters and two hydrogen-fueled first-stage engines.

Following two upper-stage engine firings, the 9,900-pound probe separated to fly on its own. The launch was witnessed by international dignitaries, including Australia's ambassador to Japan, representatives from France and Germany, and the deputy ambassador from the United States, alongside NASA officials.

Mission Objectives and Origins Theories

The primary scientific objective of the MMX mission is to resolve a long-standing debate regarding the origin of Mars's two irregularly shaped moons, Phobos and Deimos. Phobos measures about 17 miles across at its widest point, while Deimos is less than half that size. Both resemble asteroids in appearance, leading to competing hypotheses among researchers.

Scientists debate whether the moons are asteroids captured by Martian gravity or if they formed from debris ejected during a giant impact early in the history of Mars. Thomas Statler, who helped oversee NASA instruments aboard the spacecraft, noted that while the moons resemble outer asteroid belt objects, other evidence points toward a giant impact origin.

"By going to the Martian moons, studying them up close and bringing samples back to Earth, we'll be able to determine whether Phobos material is more consistent with an asteroid composition or with debris created by a collision involving Mars."

Thomas Statler, NASA, via CBS News

Researchers also hope the mission will clarify how inner planets acquired water and organic compounds, and whether Phobos contains ancient material ejected from the surface of Mars that could hold evidence of early development.

Timeline and Trajectory

Event	Date	Location / Details
Launch	Monday afternoon	Tanegashima Space Center, Japan
Mars Arrival	August / September 2027	Brake into orbit around Mars
Rover Deployment	Early 2029	Phobos surface (German/French rover)
Sample Collection	2030 timeframe	Phobos touch-downs by MMX mothership
Departure from Mars	November 2030	Return journey to Earth
Earth Return and Landing	July 2031	Woomera, South Australia

After travelling for roughly one year, the spacecraft is scheduled to brake into orbit around the red planet, flying in lockstep with Phobos. MMX will spend three years in the Martian system, conducting remote observations of both Phobos and Deimos while studying chemical and mineral compositions.

International Partnerships and Technology

The mission brings together space agencies from around the world. NASA contributed the Mars-moon Exploration with Gamma rays and Neutrons (Megane) spectrograph to study the surface of Phobos, as well as the pneumatic sampler technology demonstration designed to collect surface material. NASA's Deep Space Network will provide communications and navigation support.

Additionally, the French and German space agencies supplied a 55-pound rover slated for deployment onto Phobos in early 2029. Because the gravity of Phobos is roughly one-thousandth as strong as Earth's, the rover lacks braking rockets. Instead, it will bounce and tumble to a stop before righting itself to capture images, fire laser beams into the soil to analyze minerals, and monitor surface temperatures.

JAXA and NASA personnel emphasize that the round trip serves as a vital stepping stone for future human exploration of Mars. Nicky Fox, associate administrator for NASA’s Science Mission Directorate, stated that the samples will generate paradigm-shifting science as NASA prepares to send the first humans to Mars.

Sample Collection and Return

Approximately a year after the rover deployment, the MMX mothership will touch down on Phobos once or twice. Using devices built by JAXA and NASA, the spacecraft aims to collect a minimum of 10 grams of sand and rock from a depth of about 2 centimeters, navigating the challenges of extremely weak gravity.

Yaji Kentaro of the MMX project team noted that dealing with low gravity has presented significant engineering hurdles, requiring specially designed landing legs to ensure stability. Once samples are secured and remote observations of Deimos conclude, the spacecraft will depart the Martian sphere in November 2030.

The probe will head back to Earth, releasing an aerodynamic, heat-resistant re-entry capsule containing the sand and rock. The capsule is scheduled to land in Woomera, South Australia, in July 2031, where a waiting recovery team will retrieve the contents for analysis by an international team of researchers.