Mars Sample Return |
Mars Sample Return |
Apr 7 2006, 07:32 AM
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#501
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Member Group: Members Posts: 370 Joined: 12-September 05 From: France Member No.: 495 |
Next phase reached in definition of Mars Sample Return mission
http://www.esa.int/esaCP/SEMJAGNFGLE_index_0.html |
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Mar 31 2024, 03:45 PM
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#502
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Junior Member Group: Members Posts: 99 Joined: 17-September 07 Member No.: 3901 |
There are a lot of details about the MAV design as of 2022...larger design with more mass margin...sounding-rocket-based flight test on slide 15. That March 2022 IEEE Aerocon presentation was previously seen in Post #424 (the "Presentation" link in the post text, not the link in the quote from 2021). Slide 15 says that Stage 2 of the MAV would be tested at a high altitude over Earth, "to replicate Martian surface environments." But Stage 2 needs to function at high altitude over Mars, without Mars surface atmospheric density. Also in Post #424, the full paper corresponding to the 2022 presentation says it would be desirable to flight test the whole MAV.Re "a lot of details," should we worry that 3D CAD has made it too easy for design concepts to look like finished engineering? Agree that larger and more mass margin could be helpful, but how big can the Mars lander be, to deliver the MAV? |
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Mar 31 2024, 07:10 PM
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#503
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Senior Member Group: Members Posts: 2520 Joined: 13-September 05 Member No.: 497 |
That March 2022 IEEE Aerocon presentation was previously seen in Post #424 (the "Presentation" link in the post text, not the link in the quote from 2021). Slide 15 says that Stage 2 of the MAV would be tested at a high altitude over Earth, "to replicate Martian surface environments." But Stage 2 needs to function at high altitude over Mars... Sorry, the link I found was a PDF and the original link was a PPT so I missed that it was already discussed. There also seems to be some confusion on the NTRS web site, as I often can't find MAV work with a search on NTRS, only via other search engines. You'd think there would be more recent papers by now, but I haven't found them. Maybe I'm just not using NTRS correctly. Slide 15 is confusing IMHO by showing the whole vehicle "Notional Qualification Test Article" and then showing what seems to be just the interstage and Stage 2 in the lower right, but it's hard to say for sure. Since the avionics and RCS are in the interstage, perhaps they are using the sounding rocket's upper stage as a mass surrogate for the test. I'd like to believe that Marshall has a justification for proposing this. Previous work has mentioned balloon tests but I'm not going to bother to track those down. It's unclear to me what the real cost drivers with MSR are, but I maintain that if it's the MAV, they are not yelling that from the rooftops that I can see. It's a bit sad to go through this very long thread and see my optimism wax and wane about whether MSR will ever happen, but I am definitely in a trough at the moment. All we can do is wait from the MIRT report. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 31 2024, 07:48 PM
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#504
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Member Group: Members Posts: 237 Joined: 14-January 22 Member No.: 9140 |
At the risk of being overly reductive (but with the intention of being pretty reductive!) I think that on an abstract level the gist of the matter is:
• When NASA attempts a new flight architecture, unproven, the probability of it working is pretty good, but understandably not perfect. Let's call the probability of success of a new untested flight architecture Ps (surely not the same for all kinds of effort). Maybe that's 85%? . • MSR requires a few new flight architectures all to succeed. Some of those, if they fail, would permit a second try, but some would not, and would destroy, disperse, or otherwise lose the samples if they failed. Let's say there are 4 of those. • The probability of a catastrophic failure for MSR, then, is something like 1-Ps^4, which is disturbingly high for an investment so vast. In a sense, this is nobody's fault, just a really ambitious project. They made up for this level of risk with Apollo by having lots of iterative development with many launches and space tests before the real thing. So to have a mission architecture with lots of untested success-critical steps tested all at once is simply unprecedented. If they just went ahead and tried it, it might work (60%? 40%?), but the risk of a colossal unrecoverable failure is really worrisome. Of course, none of this is news. It seems like the source of the angst is that at times along the way, the tension has simply been ignored by the program. |
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Mar 31 2024, 08:30 PM
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#505
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Senior Member Group: Members Posts: 2520 Joined: 13-September 05 Member No.: 497 |
MSR requires a few new flight architectures all to succeed... Let's say there are 4 of those. Which ones are you thinking of? Mars EDL and Earth EDL are well-proven at these scales, and the ERO seems pretty straightforward, leaving the MAV as the major new element. I'm not as pessimistic about the MAV as John is, but it's certainly new and doesn't get as much attention as it deserves. Surprisingly to me, the program seems to have run aground on issues less fundamental than these. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Mar 31 2024, 10:45 PM
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#506
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Member Group: Members Posts: 237 Joined: 14-January 22 Member No.: 9140 |
I would add that docking in Mars orbit is something new. That would make Mars EDL and Mars orbit docking new.
Agreed, almost nothing here seems truly new, but some aspects, like ERO, are operations that have been accomplished before, but have new parameters in this case. Rather than say that there are four completely original actions required here, it's more like six or seven that have been done before but have some new element or factor here. Is ERO from Mars orbit really harder than from an asteroid? Seems like no – just a little. And given that two sample returns to Earth have had technical issues, it highlights that none of this is without significant risk. It really seems like it's all quite doable – just a lot of new and newish risks in a sequence that has to be pretty infallible or those Perseverance samples end up somewhere we'd never get them back. |
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