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#1
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How many shuttle flights per year without Challenger accident?
In retrospect we know that the O-ring issue that destroyed Challenger
was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. That said, let's say it doesn't ever happen. Maybe because it's diagnosed, or NASA and Thiokol listen to Boisjoly and require a certain outside temperature for launches, or NASA just never schedules a launch on that cold a day. Without Challenger, shuttles would have continued to carry commercial and DoD payloads. Discovery would be dedicated to SLC-6 launches. Additional American politicians are likely shuttle passengers, as well as senior military leaders like Pete Aldridge and more foreign dignitaries (Prince Andrew, perhaps?). The Journalist-in-Space program would have joined Teacher-in-Space; Artist-in-Space was likely next, and perhaps Writer-in-Space and even Boy Scout-in-Space. In such a scenario it seems more likely than not that Dennis Tito would have been able to persuade NASA to take him up, and quite possibly for a price more akin to the $40,000 McDonnell Douglas paid for each of Charles Walker's three flights rather than the $20 million to Russia. NASA flew nine shuttle flights in 1985, a rate it would never hit again although it flew eight per year several times in the 1990s. Without losing Challenger, how many flights could NASA have expected to have flown a year? I understand it was contemplating perhaps two dozen a year with the four shuttles; was such a pace feasible? If not that many, a dozen? 15? Would the agency order a fifth shuttle with such demand? -- URL:http://www.pobox.com/~ylee/ PERTH ---- * |
#2
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How many shuttle flights per year without Challenger accident?
On Feb 10, 4:15*am, Yeechang Lee wrote:
In retrospect we know that the O-ring issue that destroyed Challenger was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. That said, let's say it doesn't ever happen. Maybe because it's diagnosed, or NASA and Thiokol listen to Boisjoly and require a certain outside temperature for launches, or NASA just never schedules a launch on that cold a day. Without Challenger, shuttles would have continued to carry commercial and DoD payloads. Discovery would be dedicated to SLC-6 launches. Additional American politicians are likely shuttle passengers, as well as senior military leaders like Pete Aldridge and more foreign dignitaries (Prince Andrew, perhaps?). The Journalist-in-Space program would have joined Teacher-in-Space; Artist-in-Space was likely next, and perhaps Writer-in-Space and even Boy Scout-in-Space. In such a scenario it seems more likely than not that Dennis Tito would have been able to persuade NASA to take him up, and quite possibly for a price more akin to the $40,000 McDonnell Douglas paid for each of Charles Walker's three flights rather than the $20 million to Russia. NASA flew nine shuttle flights in 1985, a rate it would never hit again although it flew eight per year several times in the 1990s. Without losing Challenger, how many flights could NASA have expected to have flown a year? I understand it was contemplating perhaps two dozen a year with the four shuttles; was such a pace feasible? If not that many, a dozen? 15? Would the agency order a fifth shuttle with such demand? -- URL:http://www.pobox.com/~ylee/ * * * * * * * * *PERTH ---- * it might have been a wonderful experience. as long as a high flight rate didnt cause a different loss. i think that should be the premise of your question. without any major accident what could the flight rate have been? i seem to rember post challenger findings of lots of killer type issues being found and fixed. perhaps like apollo one a accident improved the program? |
#3
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How many shuttle flights per year without Challenger accident?
On 2012-02-10 09:15:13 +0000, Yeechang Lee said:
In retrospect we know that the O-ring issue that destroyed Challenger was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. That said, let's say it doesn't ever happen. Maybe because it's diagnosed, or NASA and Thiokol listen to Boisjoly and require a certain outside temperature for launches, or NASA just never schedules a launch on that cold a day. The relatively simple joint heaters would have been enough to resume flying while the field joint was redesigned, I think. NASA flew nine shuttle flights in 1985, …and came 15 seconds away from a tenth on December 18, 1985. a rate it would never hit again although it flew eight per year several times in the 1990s. Without losing Challenger, how many flights could NASA have expected to have flown a year? If Challenger had not been destroyed (say, the windshear did not cause the leak to reopen at altitude), and the severe damage of the o-rings was found after SRB recovery, this should have been sufficient for Thiokol's engineers to effectivdely force a moratorium on Shuttle launches until the joint heaters could be implemented, resuming flying say in 1987. During that time, the Shuttle program could well have caught its breath and built up a stockpile of spare parts that would have made meeting the flight rate somewhat easier (this was done after Challenger.) I think realistically the program would have topped out around 15-16 per year, 12 from KSC and 3 or 4 from SLC-6. I understand it was contemplating perhaps two dozen a year with the four shuttles; was such a pace feasible? No. External Tank production would probably have peaked around 18 per year. Michoud could handle a little more, but I doubt they would have really pushed that hard. They'd have reduced the flight rate to keep things under control. If not that many, a dozen? 15? Probably, if they funded a third OPF at KSC (without sacrificing SLC-6.) Would the agency order a fifth shuttle with such demand? No, they would have backed out of the commercial market anyway, relieving pressure on the 24-per-year goal. Arianespace would have taken more commercial payloads regardless of Challenger. Brian |
#4
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How many shuttle flights per year without Challenger accident?
"If not that many, a dozen? 15? Would the agency order a fifth shuttle with such demand? Someplace I have a zerox of a US Senate Letter detailing the proposed Shuttle Capabilities - $10M per launch, 2 week turnaround, 66 launches a year. Sixty Six launches a year means Florida's weather would have had to really cooperate. There were artists pictures of shuttles being loaded by a crane and three ground crew. Just like a 474 freighter going out of Kennedy Airport. Everything would go up on shuttles, They never came close. The Air Force was to have two dedicated vehicles, which were never built as they ducked out of the program partially blaming serious faults at SLC-6 that had been incorporated to keep the environmentalists happy, and finally the Challenger disaster that really denied them required access to space. The Titan IV motto was "Assured Access to Space". The shuttle program was doomed from the start by the great expectations of our politicians who wouldn't spend the real dollars required and a NASA who went along. But even if all went well as planned, Enterprise was refurbished for space (but is was too heavy), NASA bought 1 more and the Air Force Bought 2, and Challenger didn't explode - so you'd only have about twice as many - all with the same faults. Val Kraut |
#5
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How many shuttle flights per year without Challenger accident?
" In retrospect we know that the O-ring issue that destroyed Challenger was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. Supposedly there were partial burn throughs on recovered boosters - but NASA didn't wake up to the real potential until they actually lost a vehicle. There was an interesting article on the mind set people get into - Hey worked the last 24 times we did it - we're on a roll! And on Colombia, some said let's get one of the Recon birds to look at the tiles - and again it was dismissed. Go back and look at how long some satellites sat at SLC-4 being proscessed - this itself would have impacted the same satellites if they were launched at SLC-6 Val Kraut |
#6
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How many shuttle flights per year without Challenger accident?
On 2012-02-11 18:44:14 +0000, Val Kraut said:
"If not that many, a dozen? 15? Would the agency order a fifth shuttle with such demand? Someplace I have a zerox of a US Senate Letter detailing the proposed Shuttle Capabilities - $10M per launch, 2 week turnaround, 66 launches a year. I've never seen a reference to more than 50 launches per year, which was (and still is) widely reported as "almost once a week". But even 50 was impossible with the Shuttle design and infrastructure as it was actually built, because Michould could crank out no more than 20-22 External Tanks per year, so there were certainly never serious plans for once-a-week flights. This is all perfectly acceptable, because there was never the slightest chance there would be more than 50 payloads per year requiring launches, nevermind two or three payloads on each of those 50 launches. Even if Ariane had never gotten a foothold. Getting a good read on how many Shuttle Orbiters NASA wanted, and when, is pretty hard. Numbers ranged from 10 to 4. But once construction started, NASA had to fight just to get four Orbiters. Discovery and Atlantis were not finally approved until late 1979, the threat of not getting the lighter Discovery and Atlantis drove the decision to upgrade STA-099 instead of OV-101 as the second spaceworthy Orbiter. But even if all went well as planned, Enterprise was refurbished for space (but is was too heavy), Enterprise would have been about the same as Columbia, maybe a little lighter. It could easily have handled Spacelab and HS-376 deployment missions, just as Columbia did. And note that despite being the heaviest Orbiter, Columbia actually launched the heaviest payload of the Shuttle program: the Chandra AXAF/IUS. But everything useful was yanked out of Enterprise and installed in Challenger, so there really was no point to refurbishing Enterprise once the decision was made to move to STA-099 (renamed OV-099 Challenger) in 1978. |
#7
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How many shuttle flights per year without Challenger accident?
I've never seen a reference to more than 50 launches per year, which was (and still is) widely reported as "almost once a week". But even 50 was impossible with the Shuttle design and infrastructure as it was actually built, because Michould could crank out no more than 20-22 External Tanks per year, so there were certainly never serious plans for once-a-week flights. This is all perfectly acceptable, because there was never the slightest chance there would be more than 50 payloads per year requiring launches, nevermind two or three payloads You have to remember the early dreams of shuttle utilization that included much more manned operation and things like large space structures, beam builders, orbiting power stations etc that were being seriously studied at the time. The Shuttle was supposed to privide really cheap access for major new space programs. Grumman, as an example, actually had a working prototype beam builder that would ride in the shuttle bay and extrude and spot weld long lightweight beam assemblies. Val Kraut |
#8
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How many shuttle flights per year without Challenger accident?
On 2012-02-11 18:53:22 +0000, Val Kraut said:
" In retrospect we know that the O-ring issue that destroyed Challenger was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. Supposedly there were partial burn throughs on recovered boosters - but NASA didn't wake up to the real potential until they actually lost a vehicle. There was an interesting article on the mind set people get into - Hey worked the last 24 times we did it - we're on a roll! Not "supposedly", it is well documented. My point is that STS-51L nearly got away with it. The o-ring failure did not cause the disaster alone. Had the windshear at T+55 seconds or so not reopened the leak (this was the strongest windshear the Shuttle has ever experienced, before or after Challenger), Challenger might have squeaked by and survived. But that level of damage, with *both* o-rings having failed (a first) would certainly have given the engineers the ammunition they needed to suspend flights until a fix could be implemented. NASA would have screamed bloody murder about missing the Galileo and ISPM deadlines, but they would have been out of their "the backups kept us safe" counter-arguments. The engineers would finally have their evidence that the design was unsafe, which is what they didn't have in hand on the night of January 27-28, 1986. An interesting what-if. Brian |
#9
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How many shuttle flights per year without Challenger accident?
Brian Thorn wrote:
Not "supposedly", it is well documented. My point is that STS-51L nearly got away with it. The o-ring failure did not cause the disaster alone. Had the windshear at T+55 seconds or so not reopened the leak (this was the strongest windshear the Shuttle has ever experienced, before or after Challenger), Challenger might have squeaked by and survived. But that level of damage, with *both* o-rings having failed (a first) would certainly have given the engineers the ammunition they needed to suspend flights until a fix could be implemented. The other possibility, Thiokol could have stuck to their guns about not launching in under 51 deg F conditions. 51-L would have been delayed a few days until the weather warmed up, then they might not have had any O-ring failures. NASA and Thiokol might have continued operating within uncertain zones of reliability until the next time a limit was pushed. However IIRC, the joint design was under review and a parallel effort was underway to fix it. It is an interesting speculation that had Thiokol management stood by their engineer's original higher temperature limit recommendation at the telecon, if that alone would have been enough to buy enough time to allow the fix to be implemented w/o a disaster. Given the NASA mindset at the time however, it seems likely it would have just moved the Crit-1 failure from SRB case joints to somewhere else. Dave |
#10
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How many shuttle flights per year without Challenger accident?
On Feb 10, 7:56*pm, Brian Thorn wrote:
On 2012-02-10 09:15:13 +0000, Yeechang Lee said: In retrospect we know that the O-ring issue that destroyed Challenger was inevitable. It had almost happened in earlier flights and would likely have happened on some winter day sooner or later. That said, let's say it doesn't ever happen. Maybe because it's diagnosed, or NASA and Thiokol listen to Boisjoly and require a certain outside temperature for launches, or NASA just never schedules a launch on that cold a day. The relatively simple joint heaters would have been enough to resume flying while the field joint was redesigned, I think. NASA flew nine shuttle flights in 1985, …and came 15 seconds away from a tenth on December 18, 1985. In calender year terms, Brian. They actually flew 10 missions within a one year span from STS-51-C launched on January 24, 1985 to STS-61-C which launched January 12, 1986. Had STS-51-L not been delayed by STS-61-C, it would have been 11 in 12 months, and Challenger would have been launched in warmer weather, thus a launch failure would not likely have occurred. Also along similar thinking; Discovery, which launched four times in 1985, actually had launched six times in a one year period from first flight on August 30, 1984 to it's last pre-Challenger flight on August 27, 1985. So theoretically you could have orbiters doing 4-6 flights a year, if dedicated OPFs were available. Say one OPF at Vandenburg, and three at KSC, which allows all four vehicles to be processed simultaneously. That means between 12 and 18 flights a year, if ET and SRB production and processing permits it. Atlantis between STS-51-J and and STS-61-B had demonstrated a 55 day turnaround between flights (45 days minus the days lost by ferrying Atlantis between Edwards and KSC), so ramping up to 7 flights for one orbiter was theoretically doable back then. Columbia probably would never be able to manage more than 4-5 flights a year given her history of being chronically stricken with technical issues compared to the other orbiters. a rate it would never hit again although it flew eight per year several times in the 1990s. Without losing Challenger, how many flights could NASA have expected to have flown a year? If Challenger had not been destroyed (say, the windshear did not cause the leak to reopen at altitude), and the severe damage of the o-rings was found after SRB recovery, this should have been sufficient for Thiokol's engineers to effectively force a moratorium on Shuttle launches until the joint heaters could be implemented, resuming flying say in 1987. During that time, the Shuttle program could well have caught its breath and built up a stockpile of spare parts that would have made meeting the flight rate somewhat easier (this was done after Challenger.) I think realistically the program would have topped out around 15-16 per year, 12 from KSC and 3 or 4 from SLC-6. Agreed, though SLC-6 would have likely put a huge damper on things for a while once the actual fueled testing of Columbia at that facility revealed the flaws there. *I understand it was contemplating perhaps two dozen a year with the four shuttles; was such a pace feasible? No. External Tank production would probably have peaked around 18 per year. Michoud could handle *a little more, but I doubt they would have really pushed that hard. They'd have reduced the flight rate to keep things under control. They'd have had no choice, looking back on it. There were other technical issues that would have forced delays or flight rate reduction or caused a catastrophic loss. *If not that many, a dozen? 15? Probably, if they funded a third OPF at KSC (without sacrificing SLC-6.) Would the agency order a fifth shuttle with such demand? No, they would have backed out of the commercial market anyway, relieving pressure on the 24-per-year goal. Arianespace would have taken more commercial payloads regardless of Challenger. Why? STS had huge cargo capacity for most of the then existing satellite classes. Just load up a bunch of satellites into one mission as was done for STS-41-D. -Mike |
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