3 ms·
Wind forces are defined by dynamic pressure q, which is proportional to speed squared divided by density. At 1% the Earth's air density, a 100m/s wind on Mars (
by jojobas 6y ago
Wind forces are defined by dynamic pressure q, which is proportional to speed squared divided by density. At 1% the Earth's air density, a 100m/s wind on Mars (half the speed of sound!) exerts the same force as 10m/s breeze on Earth.
So far the fastest winds observed on Mars are about 30m/s.
So, the thin air that makes it hard to fly on Mars makes it safe to stay on the ground.
- pengaru 6y agoDoesn't the suspended dust carried in these wind storms need to be taken into consideration? I presume they contribute significantly to the density.
- jojobas 6y agoIt's said that during dust storms Martian air carries some 100-1000 dust particles of 1-10um per cm^3. Running the worst case numbers, 1000 10um particles per cm^3 adds up to about 1/3 the air density. Realistically it's maybe 10% of density increase.
- tobmlt 6y agoI remember from my flying days that: “The addition of water vapor to air (making the air humid) reduces the density of the air, which may at first appear counter-intuitive. This occurs because the molar mass of water (18 g/mol) is less than the molar mass of dry air.” (Not sure I like the language above but that’s how Wikipedia says it) Is this potential effect accounted for in your numbers? I.e. What happens to the molar mass of Martian atmosphere when Martian dust is suspended in it? At any rate, dust is bad for the moving parts of flying machines.
- jojobas 6y agoThis is about gaseous water, not water droplets. Water droplets (fog) increase density (again, not by much). Dust doesn't have a meaningful vapour pressure and can't influence air density this way.
- codeduck 6y ago10m/s is a pretty fresh breeze.