Humanity has sent dozens of probes and satellites to Mars over the decades.
But how much do you really know about Earth’s next-door neighbour?
Even though humans have yet to arrive and there are still plenty of mysteries to solve, scientists have figured out a great deal about Mars.
From what it’s like on the surface to the most impressive landmarks to the presence of an ancient ocean (and tsunamis!), keep scrolling to learn 12 incredible facts about Mars you probably didn’t know.
Mars has almost as much surface as Earth has land -- but that doesn't account for the 71% of Earth that's covered in water.
The average surface temperature on Mars is -81˚F, 138 degrees chillier than on Earth.
The Martian atmosphere is 61 times thinner than Earth's, and it consists almost entirely of carbon dioxide, which makes up just 0.04% of Earth's atmosphere.
Valles Marineris is nearly five times deeper, about four times longer and 20 times wider than the Grand Canyon.
Mars once had oceans, but adding them up would give you just 1.5% of all water on Earth.
If aliens existed on Mars, they might have lived in oasis-like pools. These pools would have been habitable for life, just as they are on Earth.
Martian oceans also had tsunamis like those on Earth. The tallest may have reached as high as 400 feet, just slightly shorter than the London Eye.
Like Earth, Mars has ice caps at its poles. The northern cap is up to 2 miles deep and covers an area slightly larger than Texas.
Olympus Mons is more than twice as high as Hawaii's Mauna Loa.
Missions to Mars have become much rarer -- after 23 launches in the 1960s and 1970s, we've launched just 10 in the new millennium (so far).
Getting to Mars is hard: About a third of the missions launched have failed.
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