NASA's $850-million mission to Mars is about to launch — here are 13 incredible facts you probably didn't know about the red planet

NASA is about to launch InSight: a new, $850-million Mars lander that will probe the red planet's secrets like never before.

InSight is slated to lift off on Saturday, which is one day after International Space Day, on May 4. But it's just one of dozens of robotic and satellite missions that humanity has rocketed to Mars over the decades.

These spacecraft have beamed back dazzling photos, inspired sci-fi movies like "The Martian", and even helped give Elon Musk, the founder of SpaceX, the idea to colonize the red planet with the Big Falcon Rocket.

While scientists readily admit they have much to learn about Mars, including the planet's internal structure (a mystery InSight will try to solve), what we have found out so far is incredible.

Here are 13 fascinating facts about Mars and our robotic exploration of the red planet.

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Volcanoes

Olympus Mons is more than twice as high as Hawaii's Mauna Loa, the tallest mountain on Earth from top to bottom.

Canyons

Compared to the Grand Canyon on Earth, Valles Marineris on Mars is nearly five times deeper, about four times longer, and 20 times wider.

Mars quakes

The red planet doesn't have plate tectonics, which is what causes most quakes on Earth. But rising plumes of magma could trigger Mars quakes, as could meteorite impacts and the contraction of the world due to cooling. InSight will listen for them with its seismometer.