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#440
by
robertross
on 06 Aug, 2012 06:38
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#441
by
iamlucky13
on 06 Aug, 2012 06:39
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There is a margin, but I didn't think it was that big.
There's an update to this paper (this one is 2006), but I can't find it at the moment:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090007730_2009006430.pdf
Page 13 says the +/- 3 sigma fuel consumption should be between 284.2 kg and 312.8 kg. That should have left 77.2 kg to 105.8 kg to spare.
I updated my comment from earlier - probably not a good idea in a fast moving live thread.:
Going from memory, 4 thrusters at 800 lbs each (3200 lbs) and hydrazine Isp at ~230 gives about 14 lbs/sec (6.4 Kg/sec). So, they had about ten seconds of propellant left. Seems about right. Certainly NOT 1.4 kg.
Not sure on these numbers, but think they are close.
It will be throttled down, not max rated thrust. The touchdown descent rate is constant velocity, so thrust should be right around m*g (750 lbs rover + weight of descent stage that I don't know).
If JPL expected no more than 105 kg back in 2006, and mass went up a bit since (I think), I really can't imagine they'd have ended up with more than that.
I agree though. 1.4 kg seems implausibly low. Maybe that was relative to a nominal remaining?
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#442
by
robertross
on 06 Aug, 2012 06:39
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"The rover is made in the USA"
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#443
by
Stardust9906
on 06 Aug, 2012 06:39
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Charles Elachi and Grunsfeld
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#444
by
robertross
on 06 Aug, 2012 06:41
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"A priveledge to lead such an event"
"as easy as it looked tonight, it's because of those in the blue shirts here tonight"
"words cannot state the kind of work that they have done"
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#445
by
Stardust9906
on 06 Aug, 2012 06:42
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#446
by
robertross
on 06 Aug, 2012 06:42
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I especially want to thank the man to my right, Richard Cook" . "We would not have been succesful without him"
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#447
by
robertross
on 06 Aug, 2012 06:43
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Richard Cook
"I have now done this 4 times, and it never gets old"
"Pathfinder was great, but we were young and stupid"
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#448
by
robertross
on 06 Aug, 2012 06:45
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#449
by
robertross
on 06 Aug, 2012 06:46
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Richard: "Say something profound" (to Adam as he gets emotional)
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#450
by
robertross
on 06 Aug, 2012 06:48
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Adam:
"To work with such a great group of talent...is truly an honor"
"we are toolmakers, agriculturalists, and pioneers"
"I want to say 'thank you', to the blue shirts"
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#451
by
anonymous1138
on 06 Aug, 2012 06:52
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There is a margin, but I didn't think it was that big.
There's an update to this paper (this one is 2006), but I can't find it at the moment:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090007730_2009006430.pdf
Page 13 says the +/- 3 sigma fuel consumption should be between 284.2 kg and 312.8 kg. That should have left 77.2 kg to 105.8 kg to spare.
I updated my comment from earlier - probably not a good idea in a fast moving live thread.:
Going from memory, 4 thrusters at 800 lbs each (3200 lbs) and hydrazine Isp at ~230 gives about 14 lbs/sec (6.4 Kg/sec). So, they had about ten seconds of propellant left. Seems about right. Certainly NOT 1.4 kg.
Not sure on these numbers, but think they are close.
It will be throttled down, not max rated thrust. The touchdown descent rate is constant velocity, so thrust should be right around m*g (750 lbs rover + weight of descent stage that I don't know).
If JPL expected no more than 105 kg back in 2006, and mass went up a bit since (I think), I really can't imagine they'd have ended up with more than that.
I agree though. 1.4 kg seems implausibly low. Maybe that was relative to a nominal remaining?
Good point - they were probably throttled back somewhere around 50%, plus or minus. And, yeah IF they said 1.4 (which I don't think they did) maybe it was a delta off what was expected to be remaining. For all that it matters. :-)
Will be very interesting if they can image the descent stage and see how far away it landed. What a great engineering accomplishment.
Looking forward to possible snapshots of MSL during descent from HiRISE, and to the HD descent images.
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#452
by
robertross
on 06 Aug, 2012 06:53
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406 science team members
no greater inspiration to middle school members.
The #hits on the internet is astounding
about the cost being that of a movie:" that's a movie I want to see"
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#453
by
Jason1701
on 06 Aug, 2012 06:55
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Confirms total fuel reserves at touchdown 140 kg. 400 to start with.
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#454
by
robertross
on 06 Aug, 2012 06:55
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Craig (American Space): tell us about the landing
-Looked extremely clean
-Touchdown in the more benign side of our nominal expectation
-Very nominal
-Remarkably good navigation error (low side)
-Powered flight appears to be good
-(confirmation) landed with 140 kg fuel reserves (of 400 kg)
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#455
by
Kaputnik
on 06 Aug, 2012 06:55
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140kg confirmed by Adam
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#456
by
robertross
on 06 Aug, 2012 06:55
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Landed in a beautiful spot
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#457
by
PeterAlt
on 06 Aug, 2012 06:55
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Notice the nationalistic hype at the conference... Bolden referencing the "four nations" that have been to Mars, but it was the US that made those nation's missions possible.... Later the reference that only the US has successfully landed on Mars... Not that I have a problem with it... Just found it a little odd... Could be because of the Olympics....
I counted... Not only are we the only nation to successfully land... But we did it SEVEN times! Is that count correct? Viking 1, Viking 2, Pathfinder, MER-1, MER-2, Polar Lander, Curiosity
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#458
by
Artyom.
on 06 Aug, 2012 06:56
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#459
by
robertross
on 06 Aug, 2012 06:56
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Asking about file type & compression
No idea