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Dust Storm
SpaceListener
post Jun 13 2018, 04:31 PM
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Are the solar panels able to raise up? I say this when MER traveled thru the space, the solar panels was inside in compact mode before it landed.
During the process of closing (raising) and opening (lowering) solar panels might shake due to the motor vibration or also due to the slope, some
dust will slip down.
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Explorer1
post Jun 13 2018, 04:35 PM
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No, those were a one-time use, though good thinking outside the box!

Telecon starting now....
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djellison
post Jun 13 2018, 05:52 PM
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People should think of their TV screen. It has dust on it. It's vertical. The dust just sits there.
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Art Martin
post Jun 13 2018, 06:22 PM
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The news conference was upbeat. They expect the rover to survive based on observations so far. Good news is this is happening during the summer so battery temps aren't as much of a concern. (I was unaware there were warming plutonium sources inside the battery compartments). Very little power is required to run the onboard clock and even if it stops, the rover can awake again from new solar input and go into a search mode to contact Earth. Fascinating. Such amazing engineering and staff.
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MahFL
post Jun 13 2018, 10:48 PM
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QUOTE (SpaceListener @ Jun 13 2018, 05:31 PM) *
Are the solar panels able to raise up? I say this when MER traveled thru the space, the solar panels was inside in compact mode before it landed.
During the process of closing (raising) and opening (lowering) solar panels might shake due to the motor vibration or also due to the slope, some
dust will slip down.


The wind blows the panels clean from time to time.
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mcaplinger
post Jun 13 2018, 11:24 PM
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The good news from the press conference is that the low-power fault state is basically the same thing as deep sleep, which they use all the time.

I don't know two things: first, how long it has until it loses its mission clock, which complicates the situation, and second, how the stuck-on IDD heater that deep sleep was added to get around will affect the recovery -- since that's a 0.5A load that will start as soon as the battery controller comes up.


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PaulH51
post Jun 14 2018, 12:35 AM
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ICYMI : Here is a link to the YouTube recording of the 'Dust Storm' teleconference: https://youtube.com/watch?v=fIKxdRFx2Wo#


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serpens
post Jun 14 2018, 02:13 AM
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The extent of this dust storm seems to be emulating the 1971 Mariner global dust storm. That storm lasted over three months so we could be in for a long wait as the atmospheric transfer between poles slows down and the dust settles.
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jccwrt
post Jun 14 2018, 02:55 AM
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Another potential alternative is the 1977 dust storms observed by Viking. There was an early season storm that followed the Acidalia storm track (started in Mare Acidalium, crossed south across Chryse and Thaumasia, and exploded in the southern hemisphere) that cleared by mid-summer, followed by an even more intense storm in late summer originating from the Hellas Basin.
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marsophile
post Jun 14 2018, 03:17 AM
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QUOTE (mcaplinger @ Jun 13 2018, 03:24 PM) *
...how long it has until it loses its mission clock, ...

If it gets no power from the solar panels, is there a ball-park figure on how long the pre-existing battery charge could keep the clock going? Days or weeks?

[EDIT: Based on figures here:
https://trs.jpl.nasa.gov/bitstream/handle/2...400/05-3884.pdf
and some assumptions, my own rough estimate is 8 days if zero power from the solar panels.]
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elakdawalla
post Jun 14 2018, 03:27 AM
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Because a lot of questions being asked here were answered in the press briefing, I'm going to break my usual practice and link to my own writing, in this case a single-page version of all my live tweets of the press briefing.


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mcaplinger
post Jun 14 2018, 04:09 AM
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QUOTE (elakdawalla @ Jun 13 2018, 07:27 PM) *
Because a lot of questions being asked here were answered in the press briefing, I'm going to break my usual practice and link to my own writing...

John Callas said "If rover is generating less than 22Wh, then it won't have enough power to maintain clock". I'm not sure how to parse this. AFAIK, the mission clock is powered directly from the batteries during sleep and will presumably drain them down to some minimum voltage cutoff. 22Wh per sol would be a little under 1 watt of power, which is a heck of a high power draw for a simple clock.

At any rate, I think it's safe to assume that over the next few days there will be essentially no power generated.


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Explorer1
post Jun 14 2018, 04:33 AM
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The main thought I keeping coming back to is that Oppy has been out of contact for much longer stretches of time during conjunctions (though obviously this is a very different circumstance in other respects!) We know the rover won't suffer some cold-related issue as Spirit did; it's just a matter of crossing our fingers and waiting it out...
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mcaplinger
post Jun 14 2018, 03:05 PM
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https://trs.jpl.nasa.gov/handle/2014/43244 "The effects of clock drift on the Mars Exploration Rovers" is an interesting paper about the MER clock architecture. It didn't really have anything germane to the issue of losing time reference but it has a lot of detail about how the mission clock works.


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mcaplinger
post Jun 14 2018, 03:11 PM
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QUOTE (Explorer1 @ Jun 13 2018, 08:33 PM) *
The main thought I keeping coming back to is that Oppy has been out of contact for much longer stretches of time during conjunctions...

During conjunction the rover has still been powered, of course. The most worrisome thing about this is whether there's some issue associated with losing the mission clock (go back through all the Spirit status reports after loss of comm for lots of discussion about various permutations there). We can assume that Spirit just got too cold, but there's no proof of that I'm aware of. And then there's the possibility that the panels will be so dusty after the storm clears that they won't produce a useful amount of power (although I think that's probably unlikely.)


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