NASA has launched its latest mission to the red planet.
The huge Atlas rocket took off in California on Saturday morning (local time), the first interplanetary mission launched from the West Coast of the United States.
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The rocket is carrying the InSight probe which, it's hoped, will discover what Mars is made of, and how it was made in the first place.
It will take more than six months to reach Mars. Once it's there, the probe will carry out a series of tests over the next two years. This will include digging almost five metres underground to take the planet's temperature - deeper than any previous Martian mission.
The probe will also use a seismometer to try to measure 'Marsquakes', which occur on the planet every million years.
If successful, this could reveal how the underground rock of Mars is layered, which will then be compared with Earth in order to reveal more about the formation of the planets some 4.6 billion years ago.