You by far are one of the most reasonable Shuttle defender around but where were you in 2004? I do not agree we should keep Shuttle. It is not a safe vehicle and costs way too much despite being a magnificent vehicle. A little like Concorde but for space. Well actually Concorde was providing an income towards the end but anyway. It is too late to get Shuttle going again. There will be a 2 year gap per John Shannon at a cost of at least $4.8B. For the same cost we can develop a new vehicle, not a Shuttle mind you but something that can loft people to orbit. Or we can develop 2 such vehicles. So I am afraid Shuttle’s time has passed now. The real question is how to minimize the effects of the transition. How do we keep the people we need to do the job? How do we know who are the people we need? And what do we want to do in the future? Do we need a reentry vehicle with good down/cross range? What for? Does it have to land on a runway? Why? In essence we need to look way into the future, accommodate with the political realities of our government and go forward. In the mean time we need to alleviate the pain of those being laid off, whose dreams are being shattered and make sure we use them effectively in the transition. It’ll be long and painful but we have to do it.

If ISS is valuable, then the more capability it has, the more it can accomplish. The original plan was to use Shuttle to continue adding modules, science, spacecraft servicing, etc. Shuttle provides a combination of cargo, people, and equipment to do the job which is unexceled. If ISS is just an unprofitable waste that we are supporting just to meet an arbitrary obligation, then we should abandon it immediately.

“If we truly wanted a backup to Soyuz, and we wanted it ASAP, then we have three non-Shuttle systems that could be online by 2015 or so.”

The Shuttle is operating right now, not in five years plus potential delays. It can hardly be considered a backup to Soyuz, since its capabilities are far greater and Shuttle is currently our primary access to ISS. The Soyuz is a backup to Shuttle, but as such it is far from ideal, having had two near misses due to the still unresolved failure of the service module separation bolts. SpaceX would provide a better backup to Shuttle than Soyuz or Orion. SpaceX requires little additional funds and no facilities other than Complex 40, so it can easily operate in parallel with the Shuttle.

Although ULA has many excellent engineers, the company is not cost-competitive and the Orion capsule, designed for the lunar mission, is substantially inferior to the Dragon in the logistic role, carrying far less cargo and fewer crew despite its greater weight. The Lockheed capsule for the Atlas does not yet exist but even if feasible it will still leave the US dependent on Russian engines.

“The reliability of the Shuttle has increased with every mission, since the problems that caused the two losses and several near-misses were each corrected. The number of problems has decreased consistently in the last five years. Consequently assertions that its reliability is 1/66 are incorrect. That is its historical loss rate, but its current loss rate is less than 1/132. It is currently the most reliable launch vehicle available in the US.”

Reliability is one thing, but survivability is another. The marked difference in survivability with old-fashioned capsule launchers comes from the ability of a capsule to also be the escape system when leaving the failed launcher. For the Shuttle, unless you can land it, you have to bail out from it. This is the inherent problem with all-in-one vehicles, which also includes modern airliners.

For cargo, reliability is paramount, since we do not incorporate escape systems for the payload. For crew, the question is not necessarily whether something is the most reliable, but whether it’s the most survivable. However, there is risk in everything we do, so it’s more a matter of acceptable risk, however each of us defines that.

“SpaceX and Shuttle use different pads and are complementary. Constellation and SpaceX require the same resources and cannot coexist, financially of physically.”

Huh? I think you have that backward, if anything. Other than range support, SpaceX is completely separate from everything NASA, Shuttle or Constellation. Ares V, I believe, was going to use the Shuttle launch pads.

“Constellation was a huge and inexplicable step backward, and we should cancel all remaining Constellation activity immediately. If this were done we could easily afford to keep flying Shuttle at full flight rate until 2020, while developing a new fully reusable system to replace it and operating SpaceX in parallel as a backup cargo and ultimately human access to space.”

Cancel Constellation – agreed.

“easily afford to keep flying the Shuttle” – yes, but at the expense of what? You have a fixed budget, and the $6B increase over 5 years has not been approved. The Shuttle Program Manager has stated that it costs $200M/month to run the Shuttle program, regardless if you launch anything. $200M gives you almost 4 full Falcon 9 launches, for a total of 92,200 lbs of mass to LEO. Do you see trade-off here?

“flying Shuttle at full flight rate until 2020″ – to do what? The ISS already has contracted services to keep it supplied with crew and cargo through 2015, and after that the prices should go down as Orbital and SpaceX mature, and new capsule systems come online. What is the economic need for the Shuttle?

If we truly wanted a backup to Soyuz, and we wanted it ASAP, then we have three non-Shuttle systems that could be online by 2015 or so. Delta IV Heavy with an Orion ($300M/launcher only), Atlas V with a commercial capsule ($130M/launcher only), and Falcon 9/Dragon for $20M/seat. All of these are far less expensive than the Shuttle, and they are all common with their cargo versions, which means they will only get more reliable/survivable.

So many tiles were lost in the initial missions including the even where gasses entered the wheel wells that if they understood the risks, you’d expect someone would have spoken up. But no one did. They were so nonchalant about it that to this day, even after Columbia failed in a near carbon copy event, people don’t even know what went on in the early days. If you read the post-flight reports, it reads more like a maintenance checklist than any red lights going off. The risks may have been known, but they were far from well-understood. The estimates on the magnitude of the problem were way off.

“This one in one-hundred is the probability risk assessment number given,” NASA space operations spokesman Allard Beutel tells PM. “It’s the chance of the possibility of loosing the space shuttle and crew.” It’s not, however, the odds of losing the crew on any given mission.

The general nature of all these reports is that “we know what we’re doing, it might be too complex for you to understand. In hundreds of assessments in print and in actual meetings, I have almost never seen any attempt to test actual subsytems and components for failure rates and modes. Instead these are simply guesses, but they are made with such authority (rhetoric element ethos; believe me because I am authoritative) rather than scientific tests to establish component reliability (rhetoric element logos, believe me because I am logical) that no one questions them. Really they are just meaningless wags. I have personally sat through meetings where design decisions were made on this basis. For reasons unknown to me NASA engineers never admit that a component reliability parameter is unknown and would cost some time and work to measure. I’ve seen them take estimates of completely different devices from other industries, or just estimate based on the “order of magnitutde” method, i.e. writing down risks of .1, .01, and .001 and then choosing which ever seems right. I have actually seen NASA engineers generate a risk assessment by looking at the specified availability in the RFP and stating that “the contractor will be required to meet this level of reliability”. In fact, this seems to be the origin of the famous 1 in 100,000 estimate of risk early in the Shuttle program. Similarly the current PRAN is obviously too low because if it were correct, given that the flaws that caused the two losses have been corrected, we would have seen at least two more losses in the past 132 missions. No one questions how NASA can be credible today when they make such widely varying estimates. Here’s a pretty good intro to the field. Note that the most consistent predictor of launch vehicle reliability is the number of launches that have been made with the system:
http://www.aero.org/publications/crosslink/winter2001/03.html
Another bit of foolishness is the the faith NASA has in redundancy. Challenger had redundant O-rings. Both failed almost simultaneously. Redundancy only increases reliability when failures are random and failure modes are anticipated, while most launch failures are deterministic (the short launch period provides little opportunity for wear and similar random processes) and due to unanticipated failure modes.

The basic problem is that any NASA engineer, asked a question, will never say “I don’t know.” They will provide an answer, and will never express doubt. I would like to see just one authoritative text on reliability engineering that supports this approach. Practically everything I have seen published on the PRAN fails to make any mention of the parameters that were estimated.

The USA engineers, for the most part, have considerable hardware experience with the systems and don’t bother with such foolishness, concentrating instead on how failures really occurred and can be prevented.

Systems engineering is a useful tool when experience or testing of a system is adequate to establish the actual modes and rates of failure. In the absence of this data no level of complexity in a paper analysis produces accurate results.

A new vehicle should of course learn from and improve upon Shuttle. Constellation instead preserved the SRB, which was responsible for one of the two Shuttle losses, while claiming that it was now 100% safe since only the RSRM was considered. The Shuttle carries almost twice the crew and ten times the cargo and flies more than twice as often as Orion, all for the same price. Constellation was a huge and inexplicable step backward, and we should cancel all remaining Constellation activity immediately. If this were done we could easily afford to keep flying Shuttle at full flight rate until 2020, while developing a new fully reusable system to replace it and operating SpaceX in parallel as a backup cargo and ultimately human access to space.

SpaceX and Shuttle use different pads and are complementary. Constellation and SpaceX require the same resources and cannot coexist, financially of physically. SpaceX serves no meaningful strategic goal and should be canceled immediately.

‘Surprise’ is your term. It’s evident the vehicles and crews were ultimately lost because of poor management, not sloppy engineering. The engineering strengths and weaknesses were seen -or revealed- through flight experience to the engineering teams– and often ignored, or deemed acceptable flight risks, by management. Schedule and budget pressures; cost considerations. Bad habit thinking. Putting Challenger aside, the steadfast disbelief of shuttle managers to initially dismiss- or to avoid accepting the possiblity that foam could damage tiles on Columbia at those velocities – something similiarly familiar to HS physics students– was stunning to witness on national television. [Even woodpeckers and raindrops were an endless problem.] Those managers should have been fired – not transferred. The performance envelope of the spacecraft is what it is. This writer places blame on loss of vehicles & crews firmly with management– not the engineering community. But the crews knew the risks and weighed that risk against the rewards. We probably agree shuttle management is mediocre at best; deadly at worst.

Uh, actually, ‘most’ did, particularly the ‘most’ who were trained and culled from the ranks of military test pilots. Good grief….

I know a “few” astronauts and have flown with “a few” of them…and I know a few of the “managers” in the program (particularly from the 90’s) and…. Rand is correct on this.

what surprised a lot of them was “how” the orbiters were lost….and the near misses that almost lost vehicles.

none of these events have been “Surprises”. Everything that got them or almost got them has been well understood as a problem until the moment something went bang, or there almost (or wasnt) wasnt enough hydrogen to get to orbit because of an H leak or well even the foam flying off and “denting’ the tiles.

that is the problem with the shuttle in specific and NASA management in general. They dont have a cluehow to safely operate any human vehicle these days.

Robert G. Oler