The Storm, Dust storm of 2007 |
The Storm, Dust storm of 2007 |
Jul 5 2007, 05:57 PM
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Member Group: Members Posts: 710 Joined: 28-September 04 Member No.: 99 |
Oh no...This is getting bad:
The new and potentially bleak outlook is a stark shift from the prognosis earlier this week. The dusty squall has reduced direct sunlight to Mars' surface by nearly 99 percent, an unprecedented threat for the solar-powered robotic explorers. If the storm keeps up and thickens with even more dust, officials fear the rovers' batteries may empty and silence the robotic explorers forever. Opportunity's energy-gathering ability has been slashed to a dangerous 280 watt-hours-enough power to light only three 90-watt light bulbs. "The worst-case scenario is that enough dust in the sky decreases solar energy to the point that we have to shut down too many things to save power," Lemmon said. "The rovers keep their battery alive by keeping their electronics alive." "The reality of the situation is that we're limited as to what we can do from the ground by cutting power use," Callas said. "If it continues to worsen and stay that way, it's a survivability issue for Opportunity. If Mars wants to kill the rovers, it can." http://www.space.com/news/070705_dusty_rovers.html |
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Jul 18 2007, 10:19 PM
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
QUOTE Well unless the array power was less than the minimum 'do nothing loads', particuarly with the sholder heater, in which case the battery is not going to charge anyway. The issue is: do you want to conserve power in the battery or do you use every drop trying to stay alive.. This is close to happening. IIRC the stuck heater draws 15 watts unless she is in Deep Sleep mode. With Tau between 5.2 and 5.5 she's would generate ~ 120-150 Watt hours over the entire 12 hours of sunlight with a peak output around 18-22 watts. That doesn't leave much to go around for basic housekeeping, let alone to top off the batteries, take images and phone home. Edited to add: Just noticed Doug's comment re the heater. Doh!, I'd forgotten that and it is quite likely that the temperature is high enough around the middle of the day to keep it off so that's a relief. Also with reference to James Canvins comment regarding the wakeup current - I thought that wake up current was 2.0 amps which would keep it asleep until quite late in the day. I don't know what the panel output voltage range is but assuming it is only 10v then it would only just rise above 2A at the moment. |
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