Spirit Parachute Nov '06 to Sept '07, Anim from HiRISE |
Spirit Parachute Nov '06 to Sept '07, Anim from HiRISE |
Nov 21 2007, 09:18 PM
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Saw a new HiRISE image up of Gusev earlier and wondered if the 'chute had moved given the strong winds.
The top of the 'chute moved between Nov-22 and Dec-12 '06, and then back again May-10 '07. I'm not sure how much is lighting and brightness/contrast within photoshop - but I think the last image, the chute is possibly dirtier than the other. Off to hunt at Meridiani now Doug |
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Nov 24 2007, 03:04 PM
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
The molecular weight (and temperature) affect the speed of sound, and therefore the resonant frequencies in a cavity such as the human voice box or a tin whistle. This is what makes the helium-breather's voice go high. However there is no change in frequency of the sound once emitted, as a result of travel through the atmosphere - any atmosphere. The same number of wave-fronts must pass each observer in a given time interval, therefore sounds that are emitted by mechanical vibration such as a tuning fork will be heard at the same pitch on any airy planet. The only way to change the perceived frequency is via the doppler effect when relative motion is involved.
However it is the case that different atmospheres could attenuate different frequencies differently. That could affect the 'colour' of white noise such as might be produced by a rustling fabric. Any difference would be minimal at close range, increasing with distance. I have no details on this. |
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