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: 14431 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 17 2018, 02:34 PM
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#2
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Senior Member Group: Members Posts: 4245 Joined: 17-January 05 Member No.: 152 |
I guess the question is: how does the rover decide if it's midday? One idea would be exceeding some minimum power level. More elaborate would be to take several power level samples over at least a day and fit a sinusoid. If it's something like the former it may get stuck thinking it's not midday until tau drops sufficiently.
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Jun 17 2018, 03:41 PM
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#3
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Senior Member Group: Members Posts: 2502 Joined: 13-September 05 Member No.: 497 |
More elaborate would be to take several power level samples over at least a day and fit a sinusoid. Perhaps, but this kind of elaborate solution that requires state to be recorded and used from sol to sol is usually not used in deep fault responses, because it's really hard to test all the possible permutations. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Jun 17 2018, 06:57 PM
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#4
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Member Group: Members Posts: 507 Joined: 10-September 08 Member No.: 4338 |
...solution that requires state to be recorded and used from sol to sol is usually not used in deep fault responses... Not to mention the fact that flash memory is unavailable, so only measurements from a single Sol could be considered, and the CPU would have to stay on throughout the Sol. In principle, the rover might be able to autonomously reset its clock if there was enough energy to take images of the sun position but (as the previous post points out) such complex algorithms would be unlikely in fault protection. Waking up every 4 hours is a simple and seemingly adequate solution. The biggest danger I see from the dust storm is a poor dust factor going into the winter season leading to desperate measures. If I recall, the issue with Spirit was precipitated by over-winter issues that upset the original plan of driving along Home Plate. Hopefully we will get cleaning after the current dust storm but we may also get a second dust storm in the current summer season. |
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Jun 18 2018, 12:11 AM
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#5
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Senior Member Group: Members Posts: 2502 Joined: 13-September 05 Member No.: 497 |
Not to mention the fact that flash memory is unavailable, so only measurements from a single Sol could be considered... While the flash is not available, the rover also has 11MB of EEPROM thst could be used to store state information. I think, for example, that this is where Earth position as a function of SCLK is kept. Without time reference, no HGA comm will work until this can be updated. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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