MSL EDL Hardware, Its state & fate |
MSL EDL Hardware, Its state & fate |
Aug 7 2012, 06:17 PM
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#1
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Junior Member Group: Members Posts: 46 Joined: 14-January 06 Member No.: 645 |
Looking at the HiRISE imagery of the descent stage, does the distribution of the debris field represent the disintegration of the stage from impact only, or is it possible that some or all of the 140+/- kilos of Hydrozine exploded and expanded the debris field? [I understand the darker albedo material is from below the surface]
Does the thin martian atmosphere contain enough oxygen to support combustion/explosion? [guessing No, but my chem is insufficient] Were the hydrazine cells sufficiently designed to survive impact intact? I couldn't find anything on the net or in the specs, any ideas? |
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Aug 7 2012, 11:54 PM
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#2
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Member Group: Members Posts: 705 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
I seem to remember there was some concern that Opportunity's camera optics got contaminated during its visit to the heatshield, so they might be more careful with Curiosity.
John |
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Aug 8 2012, 01:46 AM
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#3
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Forum Contributor Group: Members Posts: 1374 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
I seem to remember there was some concern that Opportunity's camera optics got contaminated during its visit to the heatshield, so they might be more careful with Curiosity. John Remember MSL's heat shield had a suit of senors built in to measure temperatures, g forces and how much material ablated away, so they will know how well it performed anyway. |
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Aug 8 2012, 07:34 PM
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#4
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Junior Member Group: Members Posts: 96 Joined: 11-February 04 Member No.: 24 |
Remember MSL's heat shield had a suit of senors built in to measure temperatures, g forces and how much material ablated away, so they will know how well it performed anyway. The instrument package embedded in MSL's heat shield is called "MEDLI". Refer to the following if you want to learn more about it: http://msl-scicorner.jpl.nasa.gov/Instruments/MEDLI/ For the Thermal Protection System (TPS) community, this is a Big Deal. Mars Pathfinder had an instrumented heat shield and the results were extremely useful in designing future heat shields. The folks behind MEDLI had to fight hard to get MSL's heat shield instrumented. MSL's Entry Descent and Landing (EDL) was the first in the history of Mars exploration where a heat shield's boundary layer went turbulent. This made designing the heat shield very tricky. The originally selected heat shield material SLA-561V was found to be inadequate due to the turbulent heating and had to be replaced with Phenolic Impregnated Carbon Ablator (PICA). PICA was first used for the Stardust reentry vehicle (fastest reentry in the history of Space Exploration). The Stardust aeroshell was NOT instrumented. This lack of instrumentation caused much weeping and gnashing of teeth in the TPS community and was a prime argument for instrumenting MSL. |
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Aug 8 2012, 08:00 PM
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#5
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Junior Member Group: Members Posts: 89 Joined: 27-August 05 From: Eccentric Mars orbit Member No.: 477 |
...PICA was first used for the Stardust reentry vehicle (fastest reentry in the history of Space Exploration). Stardust was the fastest reentry at Earth, and I guess only entries at Earth can be called 're'entries, but the Galileo probe was far faster (~60km/s entry speed). /pedantic |
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Aug 8 2012, 09:27 PM
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#6
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Junior Member Group: Members Posts: 96 Joined: 11-February 04 Member No.: 24 |
Stardust was the fastest reentry at Earth, and I guess only entries at Earth can be called 're'entries, but the Galileo probe was far faster (~60km/s entry speed). /pedantic Yeah, Stardust was the fastest reentry at 12.45 km/sec [relative frame at 134.4 km], 12.78 km/sec [inertial frame]. The Galileo Probe was the fastest entry at 47.4 km/sec [relative frame at 450 km altitude], 59.83 km/sec [inertial frame]. The Galileo Probe's entry was ridiculously difficult (almost as crazy as MSL and the Space Shuttle) and only possible because carbon-phenolic was used as the thermal protection system (TPS) material and Jupiter has a hydrogen-helium atmosphere. If the Galileo Probe had hit the Earth's nitrogen-oxygen atmosphere going at 47 km/sec, it would have vaporized in a flash. Likewise if the Galileo Probe had hit the Earth's atmosphere going at Stardust's speed, very little of the heat shield would have ablated (kinetic energy scales as velocity squared). There's been some conversation about doing Saturn return reentries at 16 km/sec. When TPS guys hear that sort of talk, they smile and quickly change the conversation. We could probably do it if someone was willing to invest $300 million dollars on new TPS technology (yeah right, that's going to happen some time soon). |
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