Dust Storm- Opportunity EOM, the end of the beginning of a new era in robotic spaceflight |
Dust Storm- Opportunity EOM, the end of the beginning of a new era in robotic spaceflight |
Jun 5 2018, 03:05 PM
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#1
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Expect a quiet few sols - http://www.lpl.arizona.edu/~lemmon/mars-tau-b.html
SOL TAU 5097 0.65 5098 0.64 5099 0.67 5100 0.64 5101 0.60 5102 0.60 5103 0.61 5104 1.55 5105 **** 5106 2.12 |
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Jun 15 2018, 07:19 PM
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#2
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
On the 22 WH just to keep the clock alive, maybe that number is accounting for the stuck IDD heater?
From the paper - "The Mission Clock in the MER rovers uses a custom hybrid crystal oscillator from Q-Tech Corporation. " which however is proprietary, at least at the time the paper was published. The skew of +-10s over 10 sols with temperature is pretty reasonable for a typical +-50 ppm crystal oscillator. (~900,000s for 10 sols, so about +- 10ppm with 10s drift). To get better PPMs clocks in your phones use temperature compensation, ie they adjust the voltage based on temp, with <2 ppm or less commercially available. Of course, that costs power too (~mA), and isn't space rated. A COTS RTC (real-time clock, think wrist-watch in a tiny package) without temperature compensation can be < 1uA though, again not space rated. -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Jun 15 2018, 10:26 PM
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#3
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
On the 22 WH just to keep the clock alive, maybe that number is accounting for the stuck IDD heater? I don't see how, that heater is turned off when the battery controller is turned off, that being the whole point of deep sleep. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Jun 17 2018, 02:31 PM
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#4
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
I don't see how, that heater is turned off when the battery controller is turned off, that being the whole point of deep sleep. Yes, but when the rover wakes up to phone home/listen, the IDD current draw could be a factor then if the temp is low enough to turn it on uncommanded. -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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