Random question: Is it silent on Mars? I'm looking at this picture and can't help but wonder what it sounds like. Just curious if Martian weather tends to be windy or calm.
Good question! No, it is not. See http://sprg.ssl.berkeley.edu/marsmic/sound.html for an experiment, carried on the Mars Polar Lander, which would have attempted to record the sounds of Mars. Sadly the instrument was lost along with MPL.
> Just curious if Martian weather tends to be windy or calm
Another good question. Mars is quite windy. I don't have a reference handy, but Spirit and Opportunity recorded numerous dust devils on the Martian surface. IIRC, they sometimes saw more than one a day!
> But the atmosphere is thinner, so this makes it harder to
> hear? Or quieter?
Sound intensity for a plane wave is given by the equation $I = \xi^2 \omega^2 c \rho$. Here $\xi$ is the particle displacement (the amplitude of our wave), $\omega$ is the angular frequency, and $c \rho$, typically called $Z$, is the characteristic acoustic impedance, where $c$ is the speed of sound and $\rho$ is the density of the medium.
Given that the speed of sound is roughly independent of pressure, and keeping all other variables equal, as $\rho$ decreases, $I$ also decreases. So yes, on Mars, sounds are much quieter.
I knew my bait would bring someone smarter than me out of the woodwork! Thanks, very informative. Can I ask what's your background that led you to this?
There are winds. The wind is what would clear dust off the solar panels of the other rovers. I think that is what allowed them to run so long - the winds were stronger than expected, and cleaned off the solar panels better than expected, so more power was available. If I'm not mistaken, the engineers originally expected the solar panels to get covered by dust in a matter of months, at which point the rovers would stop working.
