How fast could the Space Shuttle be made operational again, in an emergency?

Well for one thing my WAG is that they wouldn’t bother with the shuttle in an emergency where they had to get people into Orbit (and back). My guess is the quickest way to get people into orbit would be putting a Gemini like capsule on a Delta IV Heavy or a Falcon X.

Anyone got an educated guess on that scenario?

Yes fair point, I was thinking mainly about a moon mission. But I guess this amounts to a thread hijack.

The point is, “safety measures” are necessary to insure a successful mission. What good is it to get a Shuttle off the launch pad quickly if it doesn’t successfully get to orbit and do its job?

“pogo problems” :confused:

Pogo oscillation: fluctuations in fuel pressure (and, thus, thrust). The first stage of the Saturn V, in particular, suffered from it.

This isn’t a problem like building pyramids or making cheese sandwiches. Large scale technical problems such as this have a complex schedule of activities that must be conducted in a certain order, and technical hurdles that have to be overcome before the effort can advance to the next phase. Fred Brooks summed this up best in his seminal The Mythical Man-Month with the oft-quoted phrase, “Nine women can’t make a baby in one month.”

This doesn’t mean that some work cannot be done in parallel; for instance, in a hypothetical manned Lunar mission, you can design the space launch vehicle, TLI stage, command and service module, and the lander all in parallel. However, because the design goals of each of these affects the others, i.e. the booster has to be able to lift all of the elements, the TLI has to be able to provide sufficient impulse to boost the CSM and lander, the lander and CSM have to function together, et cetera, none of these can be done in a vacuum. Despite what some people believe, this isn’t like making a Shake’N’Bake dinner; you can’t just throw a bunch of smart people into a room with a computing cluster and a wheelbarrow full of cash and expect the result to be good.

This is where systems engineering and large scale program management comes into play. System requirements analysis is performed to understand the interrelations between the different subsystems and how to even define the trade studies that let you hone in on an optimum design. Another aspect of this is test planning analysis, in which the necessary testing and coordination is defined so that tests are done in the appropriate order. Risk assessment and management is performed to highlight existing risks and predict future risks so that they can be “burned down” by mitigation activities (testing, inspection, analysis, redundant design, et cetera) to prevent having any nasty surprises near the end that cause you to go back to the drawing board. All of this work that is done up front ultimately gets folded back into a milestone schedule, which then defines your critical path, i.e. the tasks and hardware that will most influence your schedule, especially if you underestimate their time. When you slip a milestone, everything else past it also slips out. Systems engineering, originally applied on the Polarius and Minuteman developments, was basically perfected on the Apollo program, and particularly the Saturn family of boosters.

The one value of throwing more resources at a problem is that you can work design solutions in parallel, and thus, if one line gets stuck, another can (hopefully) keep going. This was done, sort of, on the Apollo/Gemini program. After President Kennedy announced the intention to put a man on the Moon, the Apollo program was started to deveop the necessary technology to do so. However, it was appreciated that we had relatively little experience in working in freefall and vacuum conditions (as the Mercury missions were pretty much ballistic up-and-down trajectories in which the astronauts were basically helpless meat puppets). In order to study human physiology in freefall, understand practical workload capability, and otherwise develop the techniques that would be needed for Apollo, the Gemini program was launched. Gemini used far less sophisticated hardware that was essentially a development of existing systems. The Gemini Launch Vehicle, for instance, was essentially a Titan II ICBM with additional features for man-rating. The Gemini capsule was, to some extent, an enlarged and somewhat more sophisticated Mercury capsule, and the service module was a very simple system with analog controls and solid propellant retromotors based on early satellite position and spin motors. The Agena restartable post-boost stage was originally developed for surveillance purposes.

Gemini got astronauts up into space quickly (and with generally good success) so that the problems of working in space could be better defined. Apollo was designed–perhaps overdesigned–to be a more capable system that corrected and built upon those lessons. That being said, up until 1968 when it was pretty clear that the Saturn-Apollo would be successful at getting people to the Moon, there were numerous studies by both NASA and the Glenn L. Martin company about using modified versions of Gemini for Lunar landings and other missions (serarch on “Big Gemini”) as well as a high availability manned launcher for Air Force applications such as the Manned Orbiting Laboratory. Although the two efforts had very different goals, they both reinforced and complemented one another in providing both unique and overlapping capabilities.

The development of the Saturn V booster and the Apollo CSM are probably about as fast as it is practical to develop a new launch and manned space system from a blank sheet, even with computer simulation tools, existing knowledge, et cetera. The longest single amount of effort is the testing, and during Apollo NASA engaged in what is called “full up testing”; testing a full launch vehicle in complete form rather than performing a lot of intermediate testing first. This is a risky strategy; if it succeeds then you save a lot of time and have genuine “flight like” test conditions and data to boot; but if it fails, you may be set back considerably. However, if you can start with significant subsystems that are already well-characterized, such as engines, tankage structures, avionics, et cetera, you can save considerable time and effort. But resorting to off-the-shelf solutions doesn’t always save as much time as one might expect, and sometimes introduces novel problems when an existing system is put to a use that exceeds previous experience.

In short, hard problems don’t get easier by throwing a lot of resources at them any more than five loggers can fell a single tree faster than one or two. These problems only get solved by hacking away at them in a logical, ordered sequence so that the tree falls in the desired direction.

Stranger

So did the S-II (to a lesser extent), and the Titan main stage. In fact, most pump-fed liquid systems will suffer from feed line oscillations that can only be mitigated by the use of accumulators and other anti-resonance features. One of the advantage of purely pressure-fed systems (depsite lower performance) is that they are generally far less subject to pogo oscillations.

Solid propellant motors aren’t immune, either; they can also suffer destructive resonance (“sine vibe”) albeit for very different reasons. In extreme cases, the sine vibe can cause propellant grain structural failure or debonding and catastrophic pressure spiking, but it is more typically the case that it will just create unacceptably harsh environments. This is especially true in the case of acoustically-reinforced longitudinal low frequency vibrations that affect the payload directly. For this reason along, the Ares I CLV was probably doomed to failure.

Stranger

What was the typical cycle time of the pogo oscillations in the Saturn rockets? Did the astronauts experience vibrations at jackhammer frequency, kangaroo-hopping-in-a-car frequency or something slower?

Pogo generally occurs somewhere between 5-20 Hz. NASA had a limit on the Saturn V of 0.25 g, but astronauts experienced pogo on the Titan GLV of up to 4 g at ~10 Hz. Current knowledge of human physiology suggests that this is about the limit a human being can endure and remain functional, so Gemini was running right on the edge. Pogo typically occurs late in burn when the propellant mass is low and the rocket is generally more “lively”, and therefore harder to predict dynamics, and it generally only lasts 5-10 seconds.

Stranger

You’re forgetting Footfall.

If my basis for a space program is responding to the threat of alien pachyderms from Alpha Centauri…let’s just say I find that to be a fairly remote possibility.

A more likely thread is collision with a large potentially hazardous object (PHO), in which case the best response is to launch a series of directed nuclear impulse devices; think Project Orion but instead of the pusher and two stage piston, using a consumable polymer ‘puck’ to absorb radiation, converting it to a energetic cloud of high momentum plasma to deflect the PHO out of Earth’s pass.

Stranger

I have a buddy who works in the aerospace industry and he’s constantly complaining to me that he’s amazed we get anything working in orbit anymore (let alone man-rated stuff to the fricken Moon), quite frequently half-baked platforms get launched into space because of the almighty schedule (or budget dollars) in the hopes that it’ll either be “good enough” or it’ll at least be tweak-able from the ground to meet the specs. Most of what he’s involved in is SECRET stuff so he can only complain in general terms. :slight_smile: But it seems to me that the engineers who built Apollo were probably either “The Greatest Engineers” or also, quite possibly, the “Luckiest Engineers”. :slight_smile: And if no one has said that before, Copyright fiddlesticks, 2011.

Faster, cheaper, better…pick any two. When you hold all three as simultaneous goals, you generally end up with a big pile of snot.

Stranger

What about cobbling together a capsule and throwing it on top of existing rockets that are currently used to throw military and commercial stuff into orbit? Those rockets are reasonably reliable and produced both currently and at a decent rate. Sure a quickly thrown together capsule, particularly without much testing and/or engineering analysis would be heavier than an optimized one but I think one could be produced pretty darn quick and is certainly easier than designing a whole rocket from scratch and/or throwing something as complex as the shuttle back together and hoping the billion parts all still work.

See [POST=14505697]post #11[/POST].

Stranger

Unless I missed something in that post (though it was a good one!) doesnt say anything directly about what I just asked. Currently existing Commercial/military launcher, design/throw a capsule together, get into EARTH orbit with a person/persons in it to do whatever important “must be done now” thingy that created this time crisis. Bonus points for actually having a heat shield/ return plan.

Going to the moon/designing most of it from scratch wasn’t was I was proposing or asking about. Okay, there is one sentence in there about it I guess but it doesnt expand upon it anymore than I just did :slight_smile:

What **Stranger **said was that Gemini was exactly that sort of cobble-it-together program. With, by the last 20 years standards, pretty much an unlimited budget. So Gemini gives you a pretty good idea of what could be done today with unlimited money if you threw out most of the safety concerns & just went for it.

An often re-learned law of contracts/proposals/projects. You can be pretty certain that as soon as all three variables are specified, the effort is doomed. It is an easy way to know what will succeed and what won’t. In fact, I can’t think of a project I have ever been involved in this rule failed to work.