Crap Throwing Monkey Posted July 6, 2006 Posted July 6, 2006 Interesting point. When the shuttle was proposed in the late 60's/early 70's, it's failure rate was estimated to be between 1 in 100 and 1 in 100,000 flights. A bit generous, don't you think? Can you guess which figure was proposed by the engineers and which was championed by NASA management? After Challenger, Feynmen pointed out that the logic used to justify this figure was flawed. He emphesized the fact that management used decreasing strictness of criteria with respect to launches, a symptom that has not gone away even now. Actually, "estimated" is the wrong word to use. The engineering staff calculated a failure rate of around 1 in 100. Management overrode the engineers and guessed the failure rate would be around 1 in 100000. And therein was Feynman's beef about it: the shuttle managers used absolutely no empirical evidence or methodology, they just made sh-- up as they went along. Their risk assessment was non-existent, and their risk analysis was criminal ("Well...the o-ring leaked last time, and the shuttle didn't blow up...so a leaking o-ring's not a problem!") And THAT particular symptom has gone away. For Challenger, shuttle management was wilfully ignorant - they specifically chose not to understand the technical risks, and ignored the empirical reality right in front of their eyes. Now they have a much better understanding of the technical risks - they just choose to ignore them, or prioritize them as acceptable. Which, actually, I find perfectly reasonable...as long as the people whose asses are on the line (the astronauts) have the absolute final say. If the shuttle commander says "Yeah, we recognize a risk of dying...we want to go for it anyway" that's one thing. If a project manager in an air-conditioned office in Houston says that, that's entirely different. Your reliability factor is fairly accurate. I say fairly only because it does not take into account management's alarming tendancy to rewrite launch protocols... 719144[/snapback] My reliability factor is fairly accurate because it's from memory off the top of my head. I could calculate it, using the same methodology NASA engineers do, and it would be dead-on accurate regardless of management stupidity...because it's a technical measure, not a psychological one. The shuttle has about a 96% technical reliability, plus or minus two. When I get back from lunch, I'll put three decimal points on it for you...
GoodBye Posted July 6, 2006 Posted July 6, 2006 Hmmm...well that is pretty interesting, cause my information tells me the ISS passed over your area at about 9:41 pm last night, a little less than halfway up in the sky. Unless you have an excellent view of the horizon, you might not get to see ISS until after the 15th. It is supposed to be visible for you about 15 degrees high, about 10:07 tonight... http://spaceflight1.nasa.gov/realdata/sigh...n&city=Portland 718884[/snapback] Wasn't able to see the ISS last night. Too much cloud coverage...
SDS Posted July 6, 2006 Posted July 6, 2006 Wasn't able to see the ISS last night. Too much cloud coverage... 719207[/snapback] Ahhh... Taco Bell night in the LanaK6 household I assume.
ajzepp Posted July 6, 2006 Posted July 6, 2006 Ahhh... Taco Bell night in the LanaK6 household I assume. 719218[/snapback] lol...she's definitely had some excretory issues as of late
Crap Throwing Monkey Posted July 6, 2006 Posted July 6, 2006 You guys are horrible...and a bunch of turds! 719232[/snapback] Well, that would go a long way towards explaining your excretory problem then...
GoodBye Posted July 6, 2006 Posted July 6, 2006 Well, that would go a long way towards explaining your excretory problem then... 719238[/snapback]
TheMadCap Posted July 7, 2006 Posted July 7, 2006 SHUTTLE UPDATE - DAY FOUR Discovery Damage - Images have been acquired that show serveral areas of damage to TPS (Thermal Protection System) tiles and blankets on Shuttle Discovery. While all of the damage is small, the images are currently being poured over by engineers to confirm Discovery will not require any repair work, and will be cleared for re-entry next week - as expected. Leonardo module installed on ISS - The Multi-Purpose Logistics Module (MPLM) has been unloaded from Shuttle Discovery's payload bay, and docked on to Node 1 of the International Space Station (ISS) - at the start of Flight Day Four for STS-121. The container, called Leonardo, more than two tons of equipment, supplies, spare parts, crew supplies and experiments. More to come...
TheMadCap Posted July 8, 2006 Posted July 8, 2006 Just saw Discovery and the ISS fly overhead. Pretty awesome...
Pete Posted July 8, 2006 Posted July 8, 2006 Just saw Discovery and the ISS fly overhead. Pretty awesome... 720012[/snapback] Got to love Heavensabove. Have you seen an Iridium flare during the day yet?
GoodBye Posted July 8, 2006 Posted July 8, 2006 Just saw Discovery and the ISS fly overhead. Pretty awesome... 720012[/snapback] Me too....
TheMadCap Posted July 9, 2006 Posted July 9, 2006 One step closer to authorizing one final Hubble mission... With the official word from NASA, that STS-121 is the "cleanest" ever, administration is one step closer to authorizing STS-115, the final service mission to the HST. The issue is that this will be the only mission where safety on the ISS will not be an option. So if something goes wrong with the launch, like a major damage incident to the thermal protection system, the astronauts are dead...
AJ1 Posted July 10, 2006 Posted July 10, 2006 One step closer to authorizing one final Hubble mission... With the official word from NASA, that STS-121 is the "cleanest" ever, administration is one step closer to authorizing STS-115, the final service mission to the HST. The issue is that this will be the only mission where safety on the ISS will not be an option. So if something goes wrong with the launch, like a major damage incident to the thermal protection system, the astronauts are dead... 720365[/snapback] Another example of the short sightedness of the Shuttle design. Someone should have thought about it once in the last 10 years---the need for a transfer stage to be able to shift orbital angle between HST orbit and ISS. Bet it could have been done if it had been planned for. Too late now.
Crap Throwing Monkey Posted July 10, 2006 Posted July 10, 2006 Another example of the short sightedness of the Shuttle design. Someone should have thought about it once in the last 10 years---the need for a transfer stage to be able to shift orbital angle between HST orbit and ISS. Bet it could have been done if it had been planned for. Too late now. 720533[/snapback] Actually, it's not that easy. HST and ISS are in significantly different orbits; orbital physics pretty much prohibits going from one to the other. No one's thought about it in the past ten years because they know physics. And there was a component designed for the shuttle to carry extra OMS or SSME fuel in the cargo bay, for significant (not drastic, like HST-to-ISS) orbital changes or high-orbit launches. They scrapped it after Challenger because it was somehow decided it was "unsafe" to put liquid fuel in the cargo bay...
Crap Throwing Monkey Posted July 10, 2006 Posted July 10, 2006 One step closer to authorizing one final Hubble mission... With the official word from NASA, that STS-121 is the "cleanest" ever, administration is one step closer to authorizing STS-115, the final service mission to the HST. The issue is that this will be the only mission where safety on the ISS will not be an option. So if something goes wrong with the launch, like a major damage incident to the thermal protection system, the astronauts are dead... 720365[/snapback] That HST service mission is worth the risk. The astronauts would probably agree with me as well. HST is one of the most successful scientific devices of the past 40 years. Scientific American had a "Top Ten Discoveries of the HST" this month. It's amazing to see what the program has accomplished.
TheMadCap Posted July 10, 2006 Posted July 10, 2006 Another example of the short sightedness of the Shuttle design. Someone should have thought about it once in the last 10 years---the need for a transfer stage to be able to shift orbital angle between HST orbit and ISS. Bet it could have been done if it had been planned for. Too late now. 720533[/snapback] The HST is nearly twice as high as the ISS, so it is either one or the other. There is no way to lift a shuttle from the ISS to the HST anyways, what would be the point? It is easier to go all at once, or just don't go at all. Tom, I believe you refer to the Centaur upper stage rocket. In the beginnings of the shuttle program, it was decided to use the shuttle as a carrier for launching deep space missions (ie, Galileo) and DoD missions by raising the rocket in the payload bay before liftoff. There was a huge amount of debate about the dangers of such a mission, it is just not a good idea to have cryogenic propellents in the shuttle's payload bay. Discovery and Challenger were modified to carry the Centaur, and they were ready to begin launching at the time the Challenger was lost. They would have flown out of Vandenburg for polar orbit missions. That is another problem, in order to reach polar orbit, the shuttle has to launch from Cali, and fly over land. So it something goes wrong, we get what happened over Texas in February 2003. When Challenger went down, the DoD pulled out of the project, the Centaur was scrapped, as was the nearly complete shuttle facility at Vandenburg. It took nearly two years to launch Galileo, and they used the lower powered upper stage type launcher from Atlantis on STS-34...
TheMadCap Posted July 10, 2006 Posted July 10, 2006 Actually, it's not that easy. HST and ISS are in significantly different orbits; orbital physics pretty much prohibits going from one to the other. No one's thought about it in the past ten years because they know physics. And there was a component designed for the shuttle to carry extra OMS or SSME fuel in the cargo bay, for significant (not drastic, like HST-to-ISS) orbital changes or high-orbit launches. They scrapped it after Challenger because it was somehow decided it was "unsafe" to put liquid fuel in the cargo bay... 720593[/snapback] Actually, they ended up using the Centaur as the upper stage on the Titan IV up until last year's final flight. After Challenger, the new saftey rules prohibited a risky launch of a LOX/LH rocket from the shuttle...
Crap Throwing Monkey Posted July 10, 2006 Posted July 10, 2006 Actually, they ended up using the Centaur as the upper stage on the Titan IV up until last year's final flight. After Challenger, the new saftey rules prohibited a risky launch of a LOX/LH rocket from the shuttle... 720641[/snapback] I know about Centaur...but there was also a design on paper for an internal fuel tank that would take up a third of the cargo bay. I believe it would have carried LOX/LH2 for the SSME's...which, as you say, is why it was scrapped. It was intended more for very high orbit missions (i.e. to provide an extra couple minutes thrust past ditching the EFT), but I suppose with some planning it could have been used for a large trans-orbit burn.
TheMadCap Posted July 10, 2006 Posted July 10, 2006 I know about Centaur...but there was also a design on paper for an internal fuel tank that would take up a third of the cargo bay. I believe it would have carried LOX/LH2 for the SSME's...which, as you say, is why it was scrapped. It was intended more for very high orbit missions (i.e. to provide an extra couple minutes thrust past ditching the EFT), but I suppose with some planning it could have been used for a large trans-orbit burn. 720673[/snapback] hmmm...interesting. I'll check on this and get back to you guys. BTW, if you care to know technical details of the shuttle check out Dennis Jenkins' book. It is extremely thorough and complex, should be a good read for you...
TheMadCap Posted July 10, 2006 Posted July 10, 2006 I know about Centaur...but there was also a design on paper for an internal fuel tank that would take up a third of the cargo bay. I believe it would have carried LOX/LH2 for the SSME's...which, as you say, is why it was scrapped. It was intended more for very high orbit missions (i.e. to provide an extra couple minutes thrust past ditching the EFT), but I suppose with some planning it could have been used for a large trans-orbit burn. 720673[/snapback] Oh ok, you must be refering to the Orbital Manuvering Module, which evolved from the "space tug" concept. It used LOX/LH2, was transported to the space station via the shuttle, and was used to launch satelites into higher orbit trajectories. The concept evolved around the time of Space Station Freedom, and was the first budgetary elimination of the project (in FY91-ish). The idea was that Freedom could use the OMV to deploy and retrieve spacecraft from LEO. The shuttle, or SDV, would return with fuel as needed to keep the OMV running. There was also an interesting proposal to use a shuttle stack without a payload unit called the "low-value cargo vehicle", proposed in 1989. The idea here was to attach two beat-up SSME to the ET, and use normal SRBs to deliever propellents to orbit, for use in other space craft. Since the vehicle was much lighter than the traditional shuttle stack, the SSMEs would not use much propellent, and approximately 163,000 pounds of fuel could be sent to the space station. However, this concept didn't really gather much steam because NASA was trying to get Shuttle-C flying, and focused most of thier efforts there...
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