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PBS's "Nova" and MER
bob wrote: Did anyone else find the simulation of the failed landing as disturbing as I did? The one where the landing airbags popped? Yes, I cringed at that one. Pat |
#12
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PBS's "Nova" and MER
On Mon, 05 Jan 2004 07:43:54 GMT, Brett Buck
wrote: Scott Ferrin wrote: This is also why I fear the day when the "cheap access to space"/X-Prize types actually try to launch. I imagine the big companies do too. They'll look pretty stupid if Rutan succeeds. Succeeds in winning the X-Prize? Who the hell cares? You guys are really something. Maybe you could explain to us why they need the "levelest and flatest floor in the world" just to line up the friggin' boosters on the Delta IV. Hell the sections of a drive shaft on a Nimitz class carrier need to be lined up just as well and they use a CRANE in a shipyard. Then maybe you could explain why the ATF program was able to produce two types of fighters (YF-22 and YF-23) both of which had far more new technology at a FAR cheaper price than this "new technology" little spaceplane NASA wants to build. The fact of the matter is that NASA does go way down the diminishing returns curve when comes to precision, complication, and materials all for CYA and because they're stuck in this mentality of "we're NASA so it all needs to be gold plated". The X-prize is not even on the radar screen to Lockheed, TRW, or Boeing, and whether or not anyone wins or not, it won't make a whit of difference to the majority of the industry. It could have been done in 1960 if anyone had cared to, and you took out the "no government money" clause. Nobody wanted to, because then as now, it doesn't really lead anywhere or advance the state of the art in any way. Far more capable plans were well on their way to succeeding in that era, but were derailed, once again based on "lack of need" that persists to this day. If there is a lack of need then why the X-34, 37, 38, and 40? Why the tiny spaceplane NASA wants to build? The X-20 didn't get cancelled because of no need, it was cancelled because of $$$$$. Rutan has a backer with money, I applaud him for taking on the task, and I expect that eventually he will make the X-prize requirements (before or after the deadline). Coefficient of relevence to space technology is negligible. A newly designed launch vehicle and manned rocket for far cheaper than a "lifeboat" that all it needs to do is glide back to earth? Something of which they've already been doing for DECADES?. First manned use of hybrid rockets? Totally new way of reducing speed when returning to earth? Yep, you're right, no relevence whatsoever. I will grant that it will make sci.space.policy "true beleivers" ecstatic, but that's really not much of a goal. Brett Spoken like a true believer in unnecessary complexity, precision, and gold plating. |
#13
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PBS's "Nova" and MER
In article ,
Pat Flannery wrote: This to me STRONGLY suggest that such probes need more time and funding thrown at them in the future; if even for a few million dollars and a extra month or so leading up to launch; looking at this, one can certainly see a distinct downside to BFC in that these were all serious problems that were being addressed at the last moment via lots of hard work, sleepless nights, and just plain dumb luck. Are you under the impression that such things never happened on the old slower/costlier/worse projects? If so, you are sadly mistaken. It's easy to say that a bit more money and time would fix these things, but in practice, that's not what the money and time get used for -- they get used to make the mission more ambitious instead. The most telling argument against "more money would make these problems go away" is that we have plenty of evidence that *it doesn't*. I will not even comment on the idea to launch the probes before their landing software was completed; and then uploading it to them in-flight... There's nothing particularly wrong with that, if you think of software uploads as routine practice rather than as a dire emergency measure. or the extremely young average age (by engineering standards) of the people involved in the MER program as shown in the special, after Dan Goldin's scythe cut down all the old pros at NASA. Most of the old pros have hit retirement age anyway. The problem goes back much farther than Goldin -- it's a consequence of post-Apollo contraction and the accompanying hiring freezes. And actually, young is good. An unfortunately large fraction of the middle-aged people at JPL, and NASA in general, are viewgraph engineers whose net contribution to a fast-paced results-oriented project would be negative. (If memory serves, the people picking the Mars Pathfinder team carefully excluded them.) -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
#14
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PBS's "Nova" and MER
In message , Pat Flannery
writes Our local PBS station ran a special tonight on the MER spacecraft and their rovers design, testing, and launch (as well as the successful landing of #1) The show was chock-full of info on the rovers and what they can do;Which if they work right is very impressive- but in my opinion showed a major flaw in the program timeline that led up to their launch...in the last few months before the launch, the MER team runs into no less than _5_ unexpected problems, any one of which is a complete show-stopper if not fixed: 1.) An attempt to use a Pathfinder type parachute for the descent of the rovers fails after a helicopter drop, as it is not structurally strong enough to take the extra weight of the MER probes. 2.) A redesigned chute fails to open properly in wind tunnel tests. Its central hole is too large and this makes it "squid" as it attempts to open, due to too much airflow out of the top. The test that fixes this flaw is done by sewing in a constraint around the top hole; and holding the chute reefed via two guys in the wind tunnel with a cord at the apex of its shroud lines; as there is neither time nor money to do another test ejection from its canister. The chute is found to have been built to the wrong specifications, and a redesigned one has to be made in short order to correct the flaw. 3.) One of the landing airbags ruptures during a bounce test. Again unexpected...again fixed with a few months to go. Beagle 2 had the same set of problems, but sadly it doesn't seem to have survived them. I will not even comment on the idea to launch the probes before their landing software was completed; and then uploading it to them in-flight- There's a precedent for that. One of your probes (NEAR ??) was being tested for millennium compliance in mid-flight. -- Rabbit arithmetic - 1 plus 1 equals 10 Remove spam and invalid from address to reply. |
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PBS's "Nova" and MER
On Mon, 5 Jan 2004, Pat Flannery wrote:
Our local PBS station ran a special tonight on the MER spacecraft and their rovers design, testing, and launch (as well as the successful landing of #1) I missed this, alas, but a check of the pbs.org site showed that my local station is repeating it on Tuesday the 6th, and twice again next Sunday. If you missed it too, and you are within reach of a U.S. PBS station, poke around the site and ask it when *Nova* episodes are shown in your town. -- Bill Higgins | They can have my World Almanac Fermilab | when they pry it from my cold, dead fingers. Internet: | Or when next year's edition comes out, whichever is first. | --Lois A. Fundis |
#16
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PBS's "Nova" and MER
Bill Higgins wrote:
Our local PBS station ran a special tonight on the MER spacecraft and their rovers design, testing, and launch (as well as the successful landing of #1) I missed this, alas, but a check of the pbs.org site showed that my local station is repeating it on Tuesday the 6th, and twice again next Sunday. If you missed it too, and you are within reach of a U.S. PBS station, poke around the site and ask it when *Nova* episodes are shown in your town. Beter yet, follow this link: http://www.pbs.org/wgbh/nova/schedule-local.html -- Dave Michelson |
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PBS's "Nova" and MER
i think we have to cut some slack to the developement for the hasty work
created by the astonomy (once every 26 month mars/earch minimum approach). It was not a case of FBC, just a deadline that was impossible to work around. I was not worried about the youth of the crew: it was unavoidable given the all at once surge of the 60's (it takes several generations of more even funding that NASA has ever had to even things out, and organizational cultural transmission of experience is the best we could hope for. Given the level of change in technology, this is probably not as important as we think. Finally, i worried not at all about loading software after the hardware went up. Software is just that, soft. They had the device here, software can be tested. If the hardware is designed correctly, software follows the form. I design software for a living, and I know who's boss: reality, not me. bob |
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PBS's "Nova" and MER
Scott Ferrin wrote:
Maybe you could explain to us why they need the "levelest and flatest floor in the world" just to line up the friggin' boosters on the Delta IV. Hell the sections of a drive shaft on a Nimitz class carrier need to be lined up just as well and they use a CRANE in a shipyard. Well, you are utterly and completely *wrong*. The crane is used to install the segments into the hull. Once in the hull all of the bearings have adjustments to align and center the drive shaft, and lasers and micrometers are used to ensure that the alignment is spot-on perfect. D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
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PBS's "Nova" and MER
Henry Spencer wrote: Are you under the impression that such things never happened on the old slower/costlier/worse projects? If so, you are sadly mistaken. I was concerned about the compressed timeline that was being used; when you are within six months of launch, and your parachute system hasn't been successfully tested yet, things seem too rushed. It's easy to say that a bit more money and time would fix these things, but in practice, that's not what the money and time get used for -- they get used to make the mission more ambitious instead. As I stated in the original posting, they had five "iffy" things to fix (six if you count the IR scanner with no existing spares that they shock-tested); any one of these things doesn't get fixed on time, and you have to push the launch back to the next Earth-Mars launch window a couple of years down the road. Even a few extra weeks would have helped. And you can do as ambitious of mission as you want, but the primary key to it is that the ambition be balanced against it's odds of success, otherwise all you've accomplished is flushing a lot of time and money down the toilet, MPL and Beagle style. The most telling argument against "more money would make these problems go away" is that we have plenty of evidence that *it doesn't*. Pioneer 10 & 11 had time and money on their sides; both worked great. Viking 1 & 2 had lots of money and time; both worked great; both the orbiters...and landers. Voyager 1 & 2 had lots of money and time; both worked great. The only big-budget long-span program semi-flop we have had was Galileo; and its problems were as much due to a hurried redesign of its launch method and trajectory as anything else, and it still got a lot of its job done at Jupiter. In comparison to this, our lower-cost fast timeline missions are running around 50% as to success rate. I will not even comment on the idea to launch the probes before their landing software was completed; and then uploading it to them in-flight... There's nothing particularly wrong with that, if you think of software uploads as routine practice rather than as a dire emergency measure. What happens if you launch them, and then run into some software-spacecraft compatibility problem that can't be fixed before the time that the software is needed, due to a compatibility problem that can't be fixed in-flight; but could have been found via ground testing of the systems and software on the ground prior to launch? If that had happened on the two MER flights they would have had no way to get them ready for landing. or the extremely young average age (by engineering standards) of the people involved in the MER program as shown in the special, after Dan Goldin's scythe cut down all the old pros at NASA. Most of the old pros have hit retirement age anyway. The problem goes back much farther than Goldin -- it's a consequence of post-Apollo contraction and the accompanying hiring freezes. And actually, young is good. An unfortunately large fraction of the middle-aged people at JPL, and NASA in general, are viewgraph engineers whose net contribution to a fast-paced results-oriented project would be negative. (If memory serves, the people picking the Mars Pathfinder team carefully excluded them.) But some of the old guys might have pointed out that you may want to put a method on the outside of one or more of the three MER lander petals that would let you get the rover out if you needed to work on it without firing the pyros; that wasn't well thought out. This team has now learned that lesson; how many more do they need to learn? Pat |
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PBS's "Nova" and MER
Bill Higgins wrote: On Mon, 5 Jan 2004, Pat Flannery wrote: I missed this, alas, but a check of the pbs.org site showed that my local station is repeating it on Tuesday the 6th, and twice again next Sunday. At least the Tuesday one will have the latest images from the lander... it's a very interesting show; one thing they go into is just what a small area of Mars MER can operate in due to the need for sufficiently thick atmosphere to slow the probe's parachute sufficiently, and the need to have the sun almost overhead for the solar panels. It's only a thin band around the equator, minus any highlands. Pat |
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