Martian Moons eXploration facts for kids

Quick facts for kids
Martian Moons eXploration

An artist's concept of the Mars Moons eXploration spacecraft
Mission type	Sample-return mission
Operator	JAXA
Mission duration	5 years (planned) 1 day, 2 hours, 14 minutes (elapsed)
Spacecraft properties
Manufacturer	JAXA
Launch mass	4,480 kg (9,880 lb)
Dry mass	2,100 kg (4,600 lb)
Start of mission
Launch date	19 October 2026, 19:41:03 UTC (20 October, 04:41:03 JST)
Rocket	H3-24L, Flight 10
Launch site	Tanegashima, LA‑Y2
Contractor	Mitsubishi Heavy Industries
Phobos lander
Landing date	2029 (planned)
Return launch	2031 (planned)
Sample mass	≥10 g (0.35 oz)

Martian Moons eXploration (MMX) is an exciting robotic space adventure led by Japan. The main goal of the mission is to travel to Mars and land on its largest moon, Phobos. It will collect pieces of space rock and bring them back home to Earth! The mission launched into space in October 2026 from the Tanegashima Space Center in Japan. Scientists want to study these moon rocks to learn how the moons of Mars formed billions of years ago.

The Japan Aerospace Exploration Agency, known as JAXA, designed and built the robot probe. Several other world space agencies are helping out with amazing scientific tools. The spacecraft carries a small wheeled robot called the Idefix rover. It also plans to fly near the other Martian moon, Deimos, to take colorful photographs. This special flight is a sample-return mission, which means it must travel far away and come back safely.

What Is the Martian Moons eXploration Mission?

Phobos, the rocky and cratered moon of Mars

Mars is famous for being the red planet, but it also has two tiny, lumpy moons named Phobos and Deimos. They look a lot like giant floating potatoes in outer space! For a long time, astronomers have wondered where these moons came from. Did Mars capture two loose asteroids with its gravity? Or did a giant space rock crash into Mars long ago and blast out chunks that formed the moons?

The MMX mission was designed to solve this giant mystery. By scooping up dirt from the surface of Phobos, scientists can test the rocks in laboratories on Earth. If the dust matches Mars, they will know a collision happened. If the dust looks like deep-space asteroids, it means Mars trapped them with its gravity. The mission helps us understand how planets and moons grow across our solar system.

Traveling to Mars and Phobos

The trip across the solar system takes many months of quiet cruising through space. The spacecraft must fire its engines carefully to steer toward Mars. Once it arrives near the red planet, it will enter orbit around Mars. Later, it will slowly change its path to match the orbit of Phobos.

Because Phobos is so small and light, its gravity is very weak. A normal satellite cannot circle it in a regular orbit like the Moon circles Earth. Instead, the spacecraft will use special flight paths called quasi-satellite orbits. These clever paths allow MMX to float close to Phobos for many months without drifting away into deep space.

The Journey Home to Earth

After completing its work on the moon, the probe will fire its engines to lift off. It will fly past Deimos to snap clear pictures of its craters and hills. Then, it will make the long journey back toward our planet. When it reaches Earth, it will release a tough heat-resistant capsule.

This sample capsule will zoom through Earth's atmosphere and land safely with a parachute in the deserts of Australia. Scientists will rush out in helicopters to collect the box. Inside, they hope to find at least 10 g (0.35 oz) of untouched dirt from Phobos. This makes it one of the most exciting space adventures of our time!

How the Spacecraft Works

An illustration of how the spacecraft parts fit together

Building a probe that can fly to Mars and return home is a massive engineering challenge. The MMX spacecraft had a total mass of about 4,000 kg (8,800 lb) when it sat on top of the rocket. Nearly half of that weight was liquid rocket fuel needed for steering and braking. The spacecraft is made of three main modules joined together like building blocks.

• The propulsion module carries the heavy engines and rocket fuel tanks needed to push the craft to Mars.
• The exploration module contains all the scientific cameras, computers, radios, and landing legs.
• The return module includes the small capsule that will keep the moon rocks safe on the way home to Earth.

Scientific Instruments on Board

To study the moon from above, MMX carries a full toolkit of high-tech instruments. Each tool has a special job to do while hovering over the surface.

• TENGOO is a powerful telescopic camera that can spot tiny details and rocks on the ground.
• OROCHI is a wide-angle camera that takes colorful images of the moon landscape.
• LIDAR shoots a harmless laser beam down at the moon and measures how fast the light bounces back. This helps scientists map out hills, mountains, and flat plains.
• MIRS is an infrared camera made by France's space agency CNES to study what minerals are inside the rocks.
• MEGANE is a sensitive detector that studies invisible particles called neutrons and gamma rays. It was built by NASA to count elements like iron, silicon, and oxygen. In Japanese, the word "megane" means eyeglasses!
• CMDM is a dust monitor that counts tiny specks of space dust flying around Mars.
• MSA is an instrument that measures tiny charged particles called ions in the space air around the planet.

Ultra High-Definition Cameras

JAXA worked with Japan's national television network, the Japan Broadcasting Corporation, to build a special camera system. This device combines 4K and 8K super high-definition video cameras. It is the very first time that any spacecraft will record Mars and its moons in crisp 8K resolution!

Some pictures will be sent back through space using radio signals. However, high-definition videos have so much data that sending all of them through space would take years. Because of this, the original memory cards will stay inside the return capsule. When the capsule lands on Earth, scientists and movie makers will get to watch crystal-clear videos of Mars!

The Rover Named Idefix

The small Idefix rover designed to roll across Phobos

Before the big MMX spacecraft lands on Phobos, it will drop a tiny helper robot called Idefix. This brave little rover was built by space scientists in France at CNES and Germany at the DLR. It weighs less than 30 kg (66 lb), which makes it about the size of a small backpack.

The rover is named after Idéfix, the cute little white dog from the famous comic book series Asterix. In English books, this dog is called Dogmatix. The comic book character loves nature and trees, and the robot rover will explore wild new worlds in space!

Rolling in Low Gravity

Driving on Phobos will be very strange because gravity is thousands of times weaker than on Earth. If an astronaut jumped on Phobos, they might fly right off into space! The rover has four specially designed wheels that turn very slowly. It has to creep along carefully so it does not bounce off the ground and float away.

The rover carries four tiny cameras. Two cameras look forward to find a safe driving path, while two other cameras look down at the wheels. This allows engineers to see how the soft dirt behaves when the wheels roll over it. It also carries a mini-radiometer to measure how hot the surface gets in the sunlight.

Helping the Mothership Land

The main job of Idefix is to test the ground before the big MMX spaceship touches down. It will study whether the surface is hard rock, slippery gravel, or thick soft powder. By sending this information back up to the mothership, Idefix will help the team choose the safest spot to land.

The rover will also test the soil using a tool called a Raman spectrometer. This instrument shines a light on the ground to detect different minerals. If there are any interesting organic molecules or signs of ancient water, Idefix will help find them.

Collecting Moon Dust from Phobos

A cutaway model of the sample coring mechanism

Landing on another world is dangerous, so the spacecraft must work very quickly. In fact, the entire sampling job is scheduled to take only about two and a half hours! To make sure it grabs plenty of soil, MMX has two completely different sampling tools.

The first tool is the Coring Sampler, which uses a long robotic arm. When the spacecraft lands, the arm will shoot a tube into the ground to collect dirt from more than two centimeters below the surface. It uses a clever spring made of a shape memory alloy that snaps forward with great force. This mechanism can grab more than 10 grams of underground rock.

The second tool is the Pneumatic Sampler, which is built right into the foot of the landing leg. When the leg touches down, it fires a puff of high-pressure air into the soil. The blast pushes a cloud of dust straight into a collection cup. Having two different tools means that even if one gets stuck, the other can still collect moon dust!

Once the samples are safely locked inside metal jars, the robot arm lifts them into the return capsule. The capsule seals shut tightly so no air or dirt from Earth can contaminate the rocks later. Scientists hope these precious grains will contain ancient clues about the beginnings of our solar system.

International Teamwork in Space

Space exploration is a huge adventure that brings people from all over the world together. While JAXA is in charge of running the mission, many different countries are sharing their best technology to help it succeed.

• The United States and NASA provided the MEGANE gamma-ray and neutron spectrometer instrument. Scientists from the Johns Hopkins Applied Physics Laboratory helped build and test this equipment.
• France and CNES built the infrared camera and worked with Germany to construct the Idefix rover. French engineers also helped calculate the tricky flight paths needed to land on the moon.
• Germany and the German Aerospace Center helped design the rover and built special sensors for its scientific tests.
• The European Space Agency provided powerful deep-space radio transmitters to keep in touch with the spacecraft. ESA is also using its worldwide network of giant satellite dishes, known as the Estrack network, to track the probe as it travels through deep space.
• Australia will provide the wide, open landing zone in its outback desert where the sample capsule can touch down safely.

Working together allows scientists to share the costs and build the most advanced spacecraft possible. When the samples return to Earth, researchers from all of these countries will get to study the rocks in their own laboratories.

Launch and Mission History

A half-scale model of the MMX spacecraft displayed in Japan

The idea for the MMX mission was first shared with the public in June 2015. Japanese scientists worked for years drawing blueprints, testing computer software, and building scale models. In February 2020, the Japanese government gave the project final approval to begin building the real spacecraft.

In early 2026, the finished spacecraft was carefully packed into a shipping container and moved to the Tanegashima Space Center. This rocket launch base is located on a beautiful island in southern Japan. Engineers spent several months running final checkups on the engines, computers, and solar panels to make sure everything was in working order.

The spacecraft was placed inside the nose cone of a brand-new H3-24L rocket built by Mitsubishi Heavy Industries. On 19 October 2026, the rocket engines roared to life, blasting the spacecraft high into the sky. The launch was a complete success, and the spacecraft separated from the rocket stage to begin its long voyage across the solar system!

See Also

• Phobos program
• Fobos-Grunt
• Mars sample-return mission

Images for kids

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  U.S. and Japanese team members with the gamma-ray spectrometer portion of the MEGANE instrument at Johns Hopkins APL.