Mars, the red planet, has two tiny moons. One of them is called Phobos. It is shaped like a potato!
In October 2026, a spacecraft from Japan set off to visit it. Its real name is MMX, but let's call it Emmy. Emmy's job: scoop up some Phobos soil and bring it home to Earth!
๐ Tap the glowing circles. Tap ๐ Read to me to hear the story. Press Next โถ to keep reading, or jump straight to the game.
Our Moon is round and big. But Mars's moons are small and lumpy, like potatoes. Their names are Phobos and Deimos.
Phobos is the bigger one, and it is very close to Mars. ๐ Tap the planet and the moons.
๐ Phobos is only about 22 km across. A car on a highway could drive past it in about 15 minutes! Our Moon is about 160 times wider.Phobos is a speedy moon! It goes all the way around Mars in about 7 and a half hours. That's about 3 times in one Mars day.
Deimos is far away and slow: it takes more than a day. ๐ Run one Mars day and count!
๐ From the ground on Mars, Phobos rises in the west and sets in the east, the opposite way from our Sun and Moon. It moves so fast it passes Mars's turning!
Riku and his mom woke up very early to watch. On October 20, 2026, before sunrise, a big H3 rocket lifted off from Tanegashima Island in Japan, carrying Emmy!
"3, 2, 1... Liftoff!" ๐ Count down with Riku.
๐งณ Emmy weighs about 4,500 kg, as heavy as three cars. Most of that is fuel for the long trip there and back.Mars is very far away. Emmy can't fly straight there. It goes around the Sun in a big curve, and meets Mars when Mars comes around.
The trip takes about 10 months. Emmy should reach Mars in August 2027. ๐ Fly the curve!
๐ฏ It's like throwing a ball to a friend who is running: you throw to where your friend will be, not where they are now.Here is a mystery: nobody knows where Phobos came from! Scientists have two big ideas.
Idea 1: Phobos was an asteroid that flew too close, and Mars caught it. Idea 2: Something huge crashed into Mars long ago, and the pieces that flew up stuck together. ๐ Watch both ideas.
๐ The soil can tell! If it's made of the same stuff as Mars, Idea 2 wins. If it's like asteroid rock, Idea 1 wins. That's why Emmy is bringing some home.Phobos is so small that it hardly pulls on anything. On Phobos, Riku would feel super light, as light as a handful of paper clips!
If he jumped as hard as he can on Earth, on Phobos he would float up hundreds of meters, about as high as Taipei 101, and take many minutes to come down. ๐ Jump in both places.
โ ๏ธ That's why landing is tricky! Land too fast, and you bounce away. Emmy has to come down very, very gently.
Emmy has a little friend on its back: a rover named Idefix! It was built by France and Germany.
Before Emmy lands, it lets Idefix go. Idefix has no landing legs. It just drops, then bounces, boing... boing... until it stops. Then it stands up and drives, very slowly. ๐ Tap around.
๐ฌ Idefix weighs less than 30 kg. It will look at the soil with its cameras, and check if Phobos is a safe place for Emmy to land.
Emmy lands for just a few hours. Time to scoop! It has two ways: an arm that pushes a tube into the ground to dig, and a gun that puffs air to blow soil into a box.
Emmy needs at least 10 grams, about as heavy as two or three sugar cubes. ๐ Help Emmy collect it!
๐ The whole scooping job is planned to take about 2 and a half hours. Then Emmy takes off again, gently!Look at that giant hole! It is a crater called Stickney, about 9 km wide. Something hit Phobos so hard it almost broke apart!
And here is a surprise: Phobos is very, very slowly getting closer to Mars. One day, millions and millions of years from now, Mars may pull it apart into a ring. ๐ Explore Phobos.
๐ Phobos comes closer to Mars by about 2 meters every 100 years. That's much slower than a snail!
After exploring, Emmy flies back toward Earth. Near home, it drops a small capsule with the soil inside.
The capsule zooms through the air, glowing hot. Then, pop! A parachute opens, and it lands softly in the desert of South Australia, in 2031. ๐ Tap around.
๐ฏ๐ต Japan has done this before! The Hayabusa2 capsule landed in the same desert in 2020, with soil from the asteroid Ryugu.Emmy's whole trip takes about 5 years. When the Phobos soil lands in Australia, how old will you be?
Maybe one day, you'll be the scientist who looks at the Phobos soil and solves the mystery! ๐ Pick your age.
๐ 2026: liftoff ยท 2027: reach Mars ยท 2027 to 2030: explore Phobos (and visit Deimos) ยท 2031: the capsule comes home.Phobos is a tiny, potato-shaped moon that zips around Mars. Its gravity is super weak, so landing has to be gentle. Emmy (MMX) will scoop its soil and bring it to Australia in 2031, to find out where Phobos came from.
๐ง Quick Quiz!