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PBS's "Nova" and MER
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. 4.) A failure of a circuit board in both of the rovers to come up to spec requires that it be replaced _after_ they have been sealed in the landers; this requires firing the pyros on the landers to open the petals so that they can be reached. 5.) The possibility that firing the pyros leaves them in an electrically shorted configuration that will burn out the resistors in their firing system- so as to make them non-functional on the two spacecraft- has to be examined...this means digging up the fired and replaced pyros with no paper trail on them.. they are finally tracked down one-by-one after a exhaustive search; which is good, as there is no way to replace the resistors in question inside of the launch window. 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. 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- 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. In another ten years or so, this team will be old pros...but it seems stupid to have to re-learn how to do interplanetary flight all over again. We got away with it this time; but this is one hell of a poor way to run a planetary exploration program, in my opinion. Pat |
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PBS's "Nova" and MER
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. That's just the way real space projects go. I've never seen one that didn't. The technology and missions are so unforgiving that even tiny problems have to be addressed, and beaten to death. That takes time and money - there's no getting around it. It should be taken into account up front. You are correct that cheaping out or funding or schedule, or simply ignoring this essential fact, is exactly why there are so many failures in all sorts of aerospace projects. This is also why I fear the day when the "cheap access to space"/X-Prize types actually try to launch. It's not just a trade-off, it's that most "space buff" types involved actively sneer at the idea of spending the time it actually takes, or don't know enough to be worried about it. Those "dinosaur" aerospace companies actually know some things about how to conduct projects that lead to their "exorbitant" bids. Whenever you ignore the rules, you get in trouble - FIA, MPL, continual pressure on the shuttle to cheapen up operations, all lead to the sorts of results that have been demonstrated. Most of the proposed budgets for the "stunts" like Roton aren't enough to cover even the contingencies that will arise, much less the entire program. That's why they fail. Brett |
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PBS's "Nova" and MER
On Mon, 05 Jan 2004 06:34:10 GMT, Brett Buck
wrote: 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. That's just the way real space projects go. I've never seen one that didn't. The technology and missions are so unforgiving that even tiny problems have to be addressed, and beaten to death. That takes time and money - there's no getting around it. It should be taken into account up front. You are correct that cheaping out or funding or schedule, or simply ignoring this essential fact, is exactly why there are so many failures in all sorts of aerospace projects. 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. |
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PBS's "Nova" and MER
Pat Flannery wrote:
snip 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. As a computer programmer, I think I realize that there are "gotchas" just waiting in the wings. I have seen computer programs run for years without fail, then one day, some "gotcha" enters the system and causes the program to puke. As far as the "plain dumb luck", there seems to be an insane amount of it in this mission. While your post pointed out lots of possible problems, gladly they didn't happen. My favorite peice of dumb luck is landing in a place with enough interesting rocks, but not so many that driving is going to be a problem. AIUI, as long as the solar arrays stay fairly dust free, this mission will have some lasting power. With any more dumb luck, we will have a ton of interesting reading coming our way "Real Soon Now". Sam |
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PBS's "Nova" and MER
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. 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. 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. I will grant that it will make sci.space.policy "true beleivers" ecstatic, but that's really not much of a goal. Brett |
#6
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PBS's "Nova" and MER
I thought that the rover project was not FBC. It only built upon the FBC
pathfinder experience, but after polar lander retrenced and refocused. I must say though, that as a fan of FBC, the NOVA program did give me pause. If a slower more expensive probe had this kind of trouble, and this many near show stoppers, one marvels at the luck of the pathfinder, and can quickly understand some people's scoffing of Beagle's chances. Did anyone else find the simulation of the failed landing as disturbing as I did? "Pat Flannery" wrote in message ... 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. 4.) A failure of a circuit board in both of the rovers to come up to spec requires that it be replaced _after_ they have been sealed in the landers; this requires firing the pyros on the landers to open the petals so that they can be reached. 5.) The possibility that firing the pyros leaves them in an electrically shorted configuration that will burn out the resistors in their firing system- so as to make them non-functional on the two spacecraft- has to be examined...this means digging up the fired and replaced pyros with no paper trail on them.. they are finally tracked down one-by-one after a exhaustive search; which is good, as there is no way to replace the resistors in question inside of the launch window. 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. 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- 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. In another ten years or so, this team will be old pros...but it seems stupid to have to re-learn how to do interplanetary flight all over again. We got away with it this time; but this is one hell of a poor way to run a planetary exploration program, in my opinion. Pat |
#7
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PBS's "Nova" and MER
as long as the solar arrays stay fairly dust
free, this mission will have some lasting power. Do they have any way to clean them? Didnt some old probe have a duster f some sort that would blow a gas on he panels for dusting? just like my home even on mars dust can be a problem. of course we both have dogs. |
#8
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PBS's "Nova" and MER
bob wrote on Mon, 05 Jan 2004 12:29:39 GMT:
:b Did anyone else find the simulation of the failed landing as disturbing as I :b did? Oh yeah, that was disturbing and yet fascinating all at the same time, probably just like watching a train wreck would be. Seeing that rip in the airbag during the test as well as the failed parachute tests sure reminded me of just how close to the edge we are operating while sending these spacecraft to Mars. Either of those two failures would have caused the loss of the spacecraft. It makes me wonder just what happened to Beagle II. I'd hapilly volunteer to lead the seach party to go find the remains of Beagle (or Mars Polar Crasher, for that matter...). Jim. Jim Scotti Lunar & Planetary Laboratory University of Arizona Tucson, AZ 85721 USA http://www.lpl.arizona.edu/~jscotti/ |
#9
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PBS's "Nova" and MER
Brett Buck wrote: That takes time and money - there's no getting around it. It should be taken into account up front. You are correct that cheaping out or funding or schedule, or simply ignoring this essential fact, is exactly why there are so many failures in all sorts of aerospace projects. About the time they started talking about sending the finished landing software to the spacecraft _after_ they launched, a feeling of deja-vu hit me; the first thing that came to mind are all those wonderful Microsoft products that get released before they are debugged, knowing that people are expected to promptly start downloading the fixes after getting them...but another bell went off in regard to that and also the whole frenzied pace of the last few weeks before launch as shown in the Nova show...the MER program seemed to be operating under Deming's "Just In Time" technique of manufacturing; thing were only finished at the last minute...this may work fine in say the manufacture of automobiles; where the company has decades of experience building basically the same machine, and can take a very good guess at how long things will take to be completed- but to extrapolate that concept to building spacecraft that are produced in ones and twos is to me an unsound idea. One of the instruments on the rovers is a infrared imager intended to observe the IR signature of rocks so that the ones that are possibly water-related can be picked for closer study by the rover; the program showed the MER team in a real quandary- they had exactly two of these instruments, and they wanted to do a stress test on one to assure that it could take the force of the landing impact...but do they dare do it? Both of the instruments are to be put on the rovers, and if they break one, they don't have the time or money to replace it...so maybe its first all-up test should be the landing itself. That is a horrible situation to put the team in...zero back-ups. They do test it, and it doesn't break- but again, is this anywhere near how things should be done in the future? Pat |
#10
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PBS's "Nova" and MER
Sam Seiber wrote: My favorite peice of dumb luck is landing in a place with enough interesting rocks, but not so many that driving is going to be a problem. AIUI, as long as the solar arrays stay fairly dust free, this mission will have some lasting power. The landing area appears to be near ideal: enough rocks to examine; but not so many or so large as to block the rover's free movements...these looks like the least rocky of the four landing sites we've seen from the surface. I still remember the looks on the team at Mission Control when they got their first images of where Viking 2 had landed- the boulder field that they had thought was a smooth and safe landing area. With any more dumb luck, we will have a ton of interesting reading coming our way "Real Soon Now". Which should be fun. Pat |
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