QUOTE (djellison @ Jul 16 2006, 03:32 PM)
...primative CFD of the topography might help find particularly windy spots to really get the best chance of a good dust-down.
According to this:http://powerweb.grc.nasa.gov/pvsee/publica...cpec2/dart.html
wind velocities above 35m/sec (126km/hr) are required for martian dust removal.
"5. Dust Removal And Abrasion by Wind
...experiments show that a wind velocity of at least 35 m/sec was required before significant amounts dust removal was achieved by wind. Measurements of surface winds was done at both Viking landing sites . The daily peak wind was about 7 m/sec at Viking-1 site, and about 3.5 m/sec at the Viking-2 site. Winds over 15 m/sec occurred less than 1% of the time. Over 100 days of operation, the peak gust velocity observed at the Viking 1 site was of 25 m/sec. Thus, these experiments suggest that it is unlikely for significant amounts of dust to be cleared from the array surfaces by wind. However, it was observed by Viking that the light surface coating deposited on rocks after the major dust storms (attributed to fine dust coverings) disappeared with time, indicating removal of the dust layer by wind [15,16]. This indicates that it must be possible for some clearing of array surfaces to occur. Most likely, this clearing occurs by brief gusts of high wind. This is confirmed by the observation by Pathfinder of localized "dust devil" lifting of dust .
The wind velocity is believed to be higher on sloped terrain, and global meteorological models of Mars suggest that surface wind velocities near the Martian equator may be quite high."
Spirit is near the equator and on somewhat higher/sloped terrain so chances are slightly improved for a cleaning event (in the spring).
Are we absolutely sure "gust angels" are the only mechanism for cleaning?http://www.unmannedspaceflight.com/index.p...ost&p=55502
"Adler also noted that there are advocates of a process whereby sublimation of CO2 ices lifted the dust off the panels. I was a bit incredulous over that one, but he insisted that it is being given serious consideration as a possible cleaning cause."
I haven't seen anything further on the CO2 sublimation mechanism. Any idea how that might work? Would it be more of a SH winter or SH spring phenomenon? Preferred locations? (Google didn't help any)
Looking at Helvick's Power Chart Spirt needs a cleaning event soon and needs to learn how to manage <280 whrs for 100-150 sols. (Thanks Helvick, great chart)
Newbie question - CFD=Computational Fluid Dynamics?