Preparing for launch |
Preparing for launch |
Jun 29 2011, 10:46 AM
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#16
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
I have few of questions about the desent stage thrusters.
Are all 8 used in the landing ? Why are the thrusters in each pair pointing in different directions ? What happens if the thrust is not enough ? Thanks. Also I read the thrusters run at 107 %, which seems an odd figure to me. |
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Jun 29 2011, 11:20 AM
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#17
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Member Group: Members Posts: 562 Joined: 29-March 05 Member No.: 221 |
Yes
For stability Lithobraking 100% is the original engine rating. 107% represents a 7% performance increase over the original design spec. |
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Jun 29 2011, 11:29 AM
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#18
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
I assume safe landing could be made with less than 100 % thrust, and any extra needed then would be available ?
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Jun 29 2011, 01:05 PM
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#19
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
I have few of questions about the desent stage thrusters. Just going by the animation, all eight thrusters are firing at release from the back-shell but the four inner ones shutdown shortly thereafter. I only see the outer four thrusters firing from then on even at descent stage flyaway. I also don't see any movement of the nozzles so their orientation looks fixed. But all I know is what I see in the video. |
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Jun 29 2011, 01:51 PM
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#20
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
I have few of questions about the desent stage thrusters...... This document has much of the info you require... it has been linked to before from this forum. Anyone serious about understanding MSL EDL would find it via google quite easily. http://trs-new.jpl.nasa.gov/dspace/handle/2014/41629 In particular "Beginning at an altitude of approximately 50 m above the surface, the PDV begins the constant deceleration segment. During this sub-segment, the PDV is decelerated from 20 m/s to 0.75 m/s. This is done at a constant deceleration rate roughly equivalent to 90% throttle setting...... Throttle Down At this point in the landing sequence, more than half of the initial 400 kg of fuel has been consumed. In order to maintain thrust equal to weight, the MLEs would need to be throttled back to thrust levels on the order of 20-25%. Since the MLEs operate less efficiently at these throttle settings, four of the MLEs are throttled back to their near- shutdown condition of 1%. This allows the four remaining MLEs to function in the more efficient range of 50% throttle. The transition from eight to four MLEs introduces disturbances to the system. Therefore, a 2.5 second period of time is allotted for the disturbances to settle allowing for predictable and stable conditions for the next major segment of the landing: Sky Crane." QUOTE What happens if the thrust is not enough Then the project doesn't get through Preliminary Design Review. That was about 5 years ago. What a strange question. 107% sounds like the Space Shuttle thrust level. Where did you read that the MSL MLE's would be running at 107%? |
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Jun 29 2011, 02:52 PM
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#21
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
It was a wrong assumption by me the thrusters would be running full tilt all the time.
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Jun 29 2011, 03:05 PM
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#22
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
How could that possibly work anyway - the vehicle is always getting lighter and needs to come to a near hover for the sky-crane phase.
Even Phoenix, which had constant thrust engines, pulsed them to manage the total 'thrust' provided. |
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Jul 18 2011, 06:28 PM
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#23
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Newbie Group: Members Posts: 9 Joined: 23-June 09 From: Leyland U.K. Member No.: 4834 |
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Jul 29 2011, 07:40 PM
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#24
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
Mars Science Laboratory's page is slightly changed. Changes are not great, but quite important.
http://mars.jpl.nasa.gov/msl/ If anyone did not noticed, here is the most important fragment of new page. Seriously, I did not know that the launch date is so precisely determined. 118 days, when will it be? Nov 24 ? -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Jul 29 2011, 08:00 PM
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#25
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
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Aug 2 2011, 07:54 AM
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#26
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Junior Member Group: Members Posts: 29 Joined: 11-May 09 Member No.: 4772 |
The first and Centaur stages of the Atlas-V rocket (to be used for the MSL launch) have arrived at KSC.
Pictures available at the KSC gallery page http://mediaarchive.ksc.nasa.gov/ |
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Aug 2 2011, 03:37 PM
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#27
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Junior Member Group: Members Posts: 79 Joined: 11-September 09 Member No.: 4937 |
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Aug 4 2011, 11:25 PM
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#28
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Member Group: Members Posts: 293 Joined: 29-August 06 From: Columbia, MD Member No.: 1083 |
Just got to see and stand near MSL's engineering model at JPL and it is AWESOME! Beast of a thing.
Was interesting to find out that it's actually run off the batteries the whole time and the RTG just keeps the battery fully charged. Tour was by Scott Maxwell and one of the project scientists...the scientist said 14-16 years of operations is certainly possible...as is driving OUT of Gale. Now let's just launch and land this thing |
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Aug 7 2011, 01:05 PM
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#29
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Member Group: Members Posts: 153 Joined: 4-May 11 From: Pardubice, CZ Member No.: 5979 |
Whose was this idea? Somebody we know here?
Bender as "Official Unofficial MSL Mascot" at KSC Payload Hazardous Servicing Facility. Good choice, I love it ! |
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Aug 8 2011, 04:45 PM
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#30
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Member Group: Members Posts: 133 Joined: 29-January 05 Member No.: 161 |
Video of Curiosity flight hardware being prepared for launch at KSC with detailed views of the arm and mobility system: http://www.youtube.com/watch?v=aEhfEZZhKa0
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