Air on Mars
Written by Fraser Cain
Trust me, one of the last things you want is to be kicked out onto the surface of Mars without a spacesuit. The cold will freeze you quickly enough, but the bigger problem is the air on Mars.
There's very little of it, and you wouldn't want to breathe it anyway.
Compared to Earth, the atmosphere on Mars barely exists. The average air pressure on the surface of Mars is about 600 pascals (0.6 kilopascals). That sounds like a big number, but it's actually less than 1% the atmospheric density of Earth. So there's very little air pressure.
Furthermore, the composition of the Martian atmosphere is 95% carbon dioxide, 3% nitrogen, 1.6% argon and then trace amounts of oxygen and water vapor. And carbon dioxide is absolutely something you can't survive on. You need more than trace amounts of oxygen, you need the same levels we have here on Earth to breathe.
Although the atmosphere on Mars is very thin, it actually extends to an altitude of 11 km above the surface of the planet. This is higher than Earth's atmosphere goes, because of its lower gravity.
Astronomers think that the atmosphere on Mars used to be much thicker, but the planet never formed a magnetic field. Without the magnetic field, the Sun's solar wind was able to buffet the planet, and blast away its atmosphere into the outer Solar System.
It's also possible that Mars cooled down and locked its atmosphere away beneath the surface of the planet in large deposits. This might be good news for future attempts to terraform Mars by warming it up.
More information on the Martian atmosphere from David Darling's Encyclopedia of Science.
Here's an interesting video, where Russian volunteers test out breathing air on Mars.
Finally, if you'd like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.
Filed under: Astronomy
