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Wind on Mars

Air and fluids · level 1, lesson 6 of 6

A question to start

On Mars, there are spinning winds that pick up dust and carry it high into the sky. Rovers have watched them go past. What is the wind like on Mars?

The idea

Mars has air, but it is very thin: there is far less of it than on Earth. It still blows as wind, and the wind carries dust.

  • Dust devils are spinning winds, like small whirlwinds, that lift dust as they go. In its first 216 Mars days, the Perseverance rover spotted 91 of them.
  • Dust storms fill the sky with dust. Some years, a storm spreads around the whole planet. That happens about once every three Mars years.
  • The dust in the air makes Mars's sky look orange and pink.
dust devilrover
Wind and air Mars Earth
Air above each square metre of ground about 170 kg about 10,300 kg
Strongest winds 17 to 30 metres each second, in a dust storm up to 100 metres each second
Dust storms that cover the whole planet about once every three Mars years never

Because the air is so thin, even a strong Mars wind gives only a soft push. NASA says it could not tip over big machines. But the fine dust it carries gets everywhere, and it can cover a rover's solar panels.

Worked examples

1. A dust devil Perseverance saw. It was about 25 metres wide and at least 118 metres tall: wider than a tennis court is long, and taller than a 30-storey building.

2. A global storm. In 2018, a dust storm spread over the whole of Mars. It blocked the sunlight that the Opportunity rover needed for power.

3. Three Mars years. A Mars year is almost two Earth years, so a global storm comes about once every five or six Earth years.

Try it

  1. What is a dust devil?
  2. Why does Mars's sky look orange and pink?
  3. Is Mars's air thicker or thinner than Earth's?
  4. Why could dust storms be a problem for a rover?
Answers
  1. A spinning wind that lifts dust as it goes.
  2. There is fine dust in the air.
  3. Much thinner.
  4. The dust can cover its solar panels and block the sunlight it needs for power.

Common mistake

"Mars storms would blow you over." Mars winds can be fast, but the air is so thin that they push much less hard than winds on Earth. The danger is the dust, not the push.

Where it leads