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The Storm, Dust storm of 2007
climber
post Aug 2 2007, 09:14 PM
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QUOTE (Stu @ Aug 2 2007, 10:23 PM) *
(This topic gets the award for 'Most Depressing For A Long Time" I reckon...)

Yep, and already over 41000 hits in less than a month. I guess it's a record, isn't it ?
sad.gif


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Reckless
post Aug 2 2007, 10:45 PM
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Hi all

I remember those pathfinder days of watching and waiting, imagining that Sojourner was driving round and round the Sagan memorial station in the hope of getting a signal.
These days of waiting out this storm are bad but not as bad as back then .......yet

Watching and waiting with you lot pancam.gif

Roy
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Mark Adler
post Aug 3 2007, 02:48 AM
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QUOTE (imipak @ Aug 2 2007, 12:57 PM) *
So the question is, how long do you carry on looking for a signal? More to the point, how long do the actual JPL team carry on looking for a signal? Actually, that now starts to look like a rather less positive scenario - Oppy clings to life, bravely recovers, calls home - and is ignored...

In this case, you'd have to be more active than just looking for a signal. You would likely have to send commands to get the rover to transmit.

QUOTE (djellison @ Aug 2 2007, 01:04 PM) *
I think Pathfinder is a good basis on which to guestimate that... several weeks of daily efforts. Then a few weeks of less-regular efforts, and then a occasional, perhaps once a week, efforts for a couple of months.

How long and how hard you try is directly related to how futile you think your efforts are. In the case of Pathfinder, after a week or two they were pretty convinced it was futile. In the outlined scenario, there is good reason for hope for as long as there is limited light. Once you've had a few weeks with what appears from orbit to be good sunlight, then you'll start thinking futility. Even then, you might figure that you're just waiting for that wind gust to clear off the panels.

The other constraint on how long you try is money. Commanding every day can be made relatively cheap by having the procedure be completely routine. One mission controller could send commands and listen for a beep every sol, or every few sols. One other person on the project could have a small additional duty to generate the Earth times at which to do that and schedule the mission controller shifts and DSN antennas. The project will be funded for about year after the end of mission anyway for data analysis and archiving, so a little commanding every now and then to search for a lost rover would probably be considered worthwhile.

Of course, this is all hypothetical. Naturally the rovers will come out of this storm fully operational. They're tough little buggers.

Mark
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ElkGroveDan
post Aug 3 2007, 03:19 AM
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QUOTE (Mark Adler @ Aug 2 2007, 06:48 PM) *
Naturally the rovers will come out of this storm fully operational.

Thank you Mark for that upbeat note. As a taxpayer who advocates for continued funding of these kinds of projects that's the attitude I like to hear. You guys and your project is money well spent.


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fredk
post Aug 3 2007, 03:28 AM
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Thanks for the insights, Mark.

A bit of humour on Lemmon's site:
QUOTE
OK, I had to virtually come in to resolve a problem handling the B/1252 downlink--but that's OK, since it means there was a B/1252 downlink.
Some numbers too. Oppy still at 4.7 (1250), Spirit down to 3.9 (1271).
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CosmicRocker
post Aug 3 2007, 05:04 AM
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QUOTE (Reckless @ Aug 2 2007, 05:45 PM) *
...Watching and waiting...
This is totally OT, but those words are one of my favorite verses from an ancient Moody Blues song. They were particularly poignant to me in these dark times.

QUOTE (Mark Adler @ Aug 2 2007, 09:48 PM) *
... They're tough little buggers. ...
My sentiments, exactly. Thanks for noting that. smile.gif

QUOTE (fredk @ Aug 2 2007, 10:28 PM) *
... Some numbers too. Oppy still at 4.7 (1250), Spirit down to 3.9 (1271).
...and those appear to be pancam Tau measurements, not estimates based on panel output. I'm trying to correlate these numbers to the published Themis images, which we seem to get earlier than the every-three-days Oppy data. I'll go way out on a limb and say Opportunity will see some improvement on sol 1251, but that's as far as I'll guess.

Another bit of humor from the good doctor's site was, "Never planned this to be a long list ... ." biggrin.gif

Don't worry.
Be happy.

"They're tough little buggers." Damn tough, in my opinion...


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nprev
post Aug 3 2007, 05:45 AM
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I'm very impressed by the quite well thought-out recovery procedures, both on the ground & aloft; pretty robust systems engineering for a 90-day mission! smile.gif

Mark, silly question: How much voltage is required to hold the flash memory, and is there a little teeny backup battery dedicated to this function?


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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mcaplinger
post Aug 3 2007, 06:20 AM
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QUOTE (nprev @ Aug 2 2007, 10:45 PM) *
Mark, silly question: How much voltage is required to hold the flash memory, and is there a little teeny backup battery dedicated to this function?

Flash memory requires no power at all to retain its contents.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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djellison
post Aug 3 2007, 06:58 AM
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Updated
Attached thumbnail(s)
Attached Image
 
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nprev
post Aug 3 2007, 07:57 AM
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QUOTE (mcaplinger @ Aug 2 2007, 11:20 PM) *
Flash memory requires no power at all to retain its contents.


Really! smile.gif Good news, thank you...gotta research this. Wondering right now why we even bother with FPGAs, then, unless this is a related technology and/or flash is rad-vulnerable.

Doug, thanks for the update...not great news, but guess it could definitely be worse.


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akuo
post Aug 3 2007, 09:42 AM
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I'm wondering why the turning on of the emergency heaters would be so bad? Is it so that they cannot be otherwise turned on, except automatically when the low temperature limit is reached? Is there a particular reason to run other electronics instead of the heaters, which I would think would be most efficient in warming the WEB?


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Antti Kuosmanen
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mchan
post Aug 3 2007, 10:10 AM
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QUOTE (nprev @ Aug 3 2007, 12:57 AM) *
Wondering right now why we even bother with FPGAs, then, unless this is a related technology and/or flash is rad-vulnerable.

For high logic element density, SRAM-based FPGA's have advantage over non-volatile FPGA such as anti-fuse. SRAM-based FPGA's are typically configured from a separate flash device so you can power off your board and the FPGA will reconfigure from the flash after power is restored. Over the last few years, lower density FPGA's have been introduced with an integrated flash to store the FPGA configuration. These are typically targeted at replacing larger CPLD's.

For rad-hard, anti-fuse based FPGA's are sometimes or even usually used. The disadvantage is you only get to burn one configuration. You need a new part if you want a new configuration. With SRAM-based FPGA's, you can change the configuration up to 100,000 times by reprogramming the flash.
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Oren Iishi
post Aug 3 2007, 12:56 PM
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I remember reading somewhere that the rover had small Uranium heaters installed at critical position in the rover to keep them at an acceptable temperature. Does anyone know what good these heaters can do in these dire straits?
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djellison
post Aug 3 2007, 02:14 PM
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There are 8 of them as I understand it - 6 on the battery, 2 on the REM. They each chuck out abotu 1W of heat. They've been doing so since the day they landed - and - except for decay - will carry on doing so for some time to come. Essentially they're there making a bad situation slightly less bad than it might be. they wont keep an entirely dead rover warm enough for survival - they just shave a bit off the heating requirements.
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tedstryk
post Aug 3 2007, 02:46 PM
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Here are both HST July observations (July 23 and 27).



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