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Japan's MMX Is Off to Grab Dirt from Mars's Potato Moon!

2026-10-19 · Watch on YouTube

Summary

A spacecraft from Japan called MMX just blasted off on a five-year round trip to Phobos, the tiny, lumpy, potato-shaped moon of Mars. Find out how it will scoop up moon dirt, carry a little wheeled rover along for the ride, and fly its treasure all the way back to Earth to solve a big space mystery!

Transcript

0:00Blast Off!

Imagine a moon so small you could drive across it in about half an hour, and so lumpy it looks like a giant space potato. Right now, a spacecraft from Japan is zooming toward it to grab a scoop of its dirt and bring it all the way back to Earth! The spacecraft is called MMX. That stands for Martian Moons eXploration, which is a fancy way of saying 'let's go visit the moons of Mars.' It blasted off on a huge rocket called H3 from a launch site on a small island in southern Japan. Picture the countdown. Three, two, one... WHOOSH! Fire, smoke, and a roar so loud you could feel it in your tummy. In just a few minutes, the rocket punched through the sky and into space. Here's a wow-fact to start us off: this trip will take about five whole years, there and back. If you're eight years old right now, you'll be about thirteen when the dirt lands on Earth! That's a long time to wait for a souvenir. But why would anyone fly all the way to Mars just to pick up some dirt? Stick with me, because the answer is a real space mystery.

0:57Mars and Its Moons

First, let's meet Mars. Mars is the fourth planet from the Sun. It's red because its dust is full of rust, the same orange-brown stuff you see on an old bike chain. Our Earth has one big round Moon. But Mars has two tiny moons, and they don't look anything like ours. Their names are Phobos and Deimos. Deimos is the smaller one, and it circles far out. Phobos is the bigger one, and it hugs close to Mars. Now, when I say 'bigger,' I only mean bigger than Deimos. Phobos is still super small. It's only about twenty-seven kilometers across at its longest point. Our Moon is more than one hundred times wider than that! Here's the wow-fact: Phobos is so close to Mars that it zips all the way around the planet three times every single day. Imagine if our Moon zoomed across the sky three times between breakfast and bedtime! And Phobos isn't round at all. It's lumpy, bumpy, and covered in dents, just like... you guessed it... a potato. But a potato with one very, very big dent. Want to see it?

1:56The Potato Moon

Let's zoom in on Phobos. It's dark gray, almost like a lump of charcoal. Its surface is sprinkled with craters, which are round holes made when space rocks bumped into it long, long ago. The biggest one is called Stickney Crater, and it's huge. It's about nine kilometers wide, which is about a third of the whole moon! If Phobos were a potato, Stickney would be the spot where someone took a giant bite. Phobos also has long lines running across it, like scratches or grooves. Scientists are still figuring out exactly how those got there. Now here's a wow-fact that's going to make you giggle. The gravity on Phobos is super weak. Gravity is the pull that keeps your feet on the ground. On Phobos, it's so gentle that if an astronaut jumped, they might float up and up and take a very, very long time to come back down. A strong jump could even send them sailing off into space! So landing there is tricky. You can't just plop down. You have to land like a feather. But before we talk about landing, let's solve the big mystery. Where did this potato moon come from?

2:56The Big Mystery

Scientists have two big ideas, and they're like detectives with two suspects. Idea number one: Phobos used to be an asteroid. Asteroids are rocky leftovers floating around in space. Maybe, a long time ago, Phobos was drifting past Mars, and Mars's gravity caught it, like a goalie catching a ball. And it's been going around and around Mars ever since. Idea number two: Phobos is actually a piece of Mars itself! Maybe a giant space rock smacked into Mars billions of years ago, and a huge spray of rock and dust flew up into space. Over time, some of that spray clumped together, like a snowball rolling and growing, and made Phobos. So which idea is right? Here's the wow-fact: the answer is hiding in the dirt. Rocks and dirt carry clues, kind of like fingerprints. Dirt from an asteroid would have one kind of fingerprint. Dirt from Mars would have a different one. If scientists can get a scoop of Phobos dirt into their labs on Earth, they can study it with super powerful tools and finally crack the case. And that's exactly what MMX is built to do. So let's take a look at this amazing machine.

4:02Meet MMX

MMX is like a three-part space train. It has three big sections joined together, and each one has its own job. The first section is the going-out part. It has powerful engines that push MMX away from Earth and slow it down when it reaches Mars. The second section is the explorer part. This is where the landing legs, the cameras, the science tools, and the dirt-grabbing arm are. The third section is the coming-home part. It has its own engines and a special little capsule that will carry the precious dirt back to Earth. MMX also has big wings covered in solar panels. Solar panels turn sunlight into electricity, so the spacecraft can power itself with the Sun, a bit like how a plant uses sunlight to grow. And get this wow-fact: when MMX left Earth, it weighed about as much as three cars put together, and lots of that weight was fuel! Here's the clever part: when a section finishes its job, it can drop away, making MMX lighter, like taking off a heavy backpack after a hike. But MMX isn't traveling alone. It has a tiny passenger tucked inside.

5:08The Little Rover

Meet the rover! A rover is a robot car that drives around on another world. This one is about the size of a microwave oven, and it has four wheels. Teams of scientists and engineers from France and Germany built it, and they worked together with Japan. That's teamwork across the whole planet! When MMX gets close to Phobos, it will gently let the rover go. Remember how weak the gravity is? The rover will drift down slowly, maybe bounce a few times, and then flip itself right side up. Then it will start driving. Its job is to test the ground before the big spacecraft lands. Is the dirt soft like flour? Crunchy like sand? Hard like a sidewalk? The rover's wheels and cameras will find out. Here's the wow-fact: this will be the first time ever that a wheeled rover drives on a moon of Mars! Driving on Phobos is a little like driving on a bouncy castle, because the gravity is so tiny. The rover has to go super slow, about as fast as a snail, so it doesn't hop off the ground. That's a cool little robot! But first, MMX has to get to Mars, and Mars is really, really far away.

6:12The Long Journey

Mars and Earth both travel around the Sun, like two runners on different tracks. Sometimes they're close together, and sometimes they're on opposite sides of the Sun. Space scientists wait for the perfect moment to launch, when the planets line up just right. That way the trip is shorter and uses less fuel. Even then, MMX has to travel hundreds of millions of kilometers. That's like driving around the whole Earth thousands of times without a single bathroom break! The trip to Mars takes about a year. During that time, MMX cruises quietly through space, checking its systems and keeping its solar panels pointed at the Sun. When it finally reaches Mars, it fires its engines to slow down, so Mars's gravity can catch it. Then it carefully moves into a path that travels right alongside Phobos. Here's a wow-fact: MMX will spend about three years near Mars. It will map Phobos from top to bottom, snap tons of pictures, and even fly past the other little moon, Deimos, to take a peek. Scientists will use all those maps to pick the perfect landing spot. And once they've picked it, it's time for the most exciting part of the whole mission.

7:21Scooping Moon Dirt

Touchdown time! MMX slowly, slowly drifts down toward Phobos, like a leaf falling on a calm day. Its landing legs are springy, so they can soak up the bump, just like your knees bend when you hop down from a low step. Now MMX gets to work. It has a robotic arm with a special tool on the end called a corer. A corer is like a hollow tube that gets pushed into the ground. When it pulls back out, the tube is full of dirt, like when you dip a straw into a drink, cover the top with your finger, and lift it out. MMX also has a second tool that uses a little puff of gas to blow dirt into a container, like a tiny leaf blower filling a jar. Here's the wow-fact: scientists hope to collect at least ten grams of Phobos dirt. That's about as heavy as two grapes. It might not sound like much, but to a scientist, that's a treasure chest full of clues! Grabbing dirt from a bit deeper down is important, because the top layer has been baked by sunlight for ages. The deeper dirt is fresher, like the soft inside of a loaf of bread. Then the dirt is sealed safely inside the return capsule. Now comes the long trip home.

8:28The Trip Home

With its treasure tucked safely away, MMX lifts off from Phobos. In such weak gravity, taking off is easy peasy. It's more like stepping off a curb than blasting off from Earth. Then MMX waits near Mars for the planets to line up again, and fires its engines to head for home. The trip back takes about another year. As it gets close to Earth, the spacecraft lets go of the small capsule, and the capsule falls toward our planet all by itself. Here's the wow-fact: when the capsule zooms into Earth's air, it's moving so fast that it glows like a shooting star! A special heat shield on the outside keeps the dirt inside nice and cool. Then a parachute pops open, and the capsule floats gently down to the ground. Teams on Earth will be waiting to find it and carry it carefully to a super clean lab. The plan is for the capsule to come home around the year 2031. Scientists will study every tiny grain. Some of the dirt will even be saved for the future, so scientists who are kids right now, like you, can study it someday with even better tools. Maybe one of those future scientists will be you! So let's look back at everything we've discovered.

9:37Recap and Challenge

Wow, what a mission! Let's do a quick recap of the coolest things we learned. Mars has two tiny moons, and Phobos is the lumpy, potato-shaped one that zooms around Mars three times a day. Scientists aren't sure if Phobos is a captured asteroid or a chunk of Mars itself, and its dirt holds the clues. MMX is a three-part spacecraft from Japan, carrying a little wheeled rover from France and Germany that will be the first to drive on a moon of Mars. It will scoop up dirt with a corer and send it home in a glowing capsule around 2031. Now here's a fun challenge to try at home, with a grown-up's help. Grab some play dough or clay in two or three different colors. Squish them into flat layers and stack them up like a sandwich. Then take a clear straw and push it straight down through all the layers. Pull it out, and look! You'll see all the colors inside the straw, just like MMX's corer will see the layers of Phobos dirt. And here's a cool fact to share with your family at dinner: Phobos is slowly inching closer to Mars, by about the height of a grown-up every hundred years. Keep looking up, keep asking questions, and I'll see you on our next adventure!

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Series: science (English)