I agree. However, if I were the shuttle program manager, I’d be more worried about the destruction of a third shuttle. I wouldn’t want after a third group of astronauts screwed the pooch be quoted in the press having in the past saying “Problem? What problem?”
Stranger on a Train’s summary of the state of the space program is one of the best I’ve ever read.
No, quite the opposite. NASA’s shuttle manager today said his team would work toward a solution no matter how long it takes. “It might take weeks or even a few months,” to paraphrase him. :rolleyes:
I’m basing my arbitrary 30-month value on the previous Columbia post-mortem, but the delay may be longer. As Hyperelastic notes, NASA opted to tweak when a fundamental redesign might be warranted. If so–if they have to go back to the drawing board, reconceptualize and fundamentally reengineer, then test, test, test–the delay could extend for several years. And as Kunilou implies, NASA can’t screw up again–especially via the foam scenario.
NASA long ago placed all its eggs in one basket and now finds itself in a tough spot. Which to choose: re-engineer the shuttle or pull the stakes and accelerate development of its successor? My bet is on Plan A, but the ongoing foam problem might be the wooden stake in the heart that the US space program really needs. The shuttle is yesterday. We need a fresh start. NASA knows all this, but political constraints prevent them from acting boldly.
Such a design change should certainly require requalification of the fuel tank for manned flight.
I agree wholeheartedly. NASA should replace all of the foam insulation on the Space Shuttle with live kittens. That will surely get the press off their backs!
Wait a minute. Have you seen what a cat can do to sofa? Imagine the kind of damage hundreds of live kittens could do to the Shuttle!
Then there’s the whole hairball problem: “Houston, we…we can’t seem to fire the front port RCS. There appears to be something blocking the nozzle. We can’t exactly see what it is, but it’s kind of…fuzzy.”
Now, flying monkeys…there’s a solution for you. Plus, they’re very fast.
Stranger
Couldn’t have said it better myself. I agree completely with your commentary on the space program.
The real shame about this is NASA and its contractors might now spend even more time and resources on the shuttle, instead of on alternatives. And the ISS gets delayed anyways.
The basic problem with the shuttle is that it was designed with very loose requirements. Successful engineering programs tend to be those with very specific requirements and hard thresholds for success.
Successful spaceship: “We need a spaceship that will lift 2000 kilos into LEO at $1000/kg, carrying three astronauts, with the capability to dock with a docking ring of specification xxxy”.
Unsuccessful Spaceship: “We need a spaceship that is reusable, that can do all the jobs we can think of doing in the next 30 years, which meets all the needs of the military, which keeps all the people at these three centers employed, which…”
The latter set of requirements is how you build a white elephant. Take reusability: It was treated as goal, because once the decision was made to go with reusable craft, it became a political requirement. Instead, the requirement should be stated in terms of cost to LEO. If reusable does the job, great. If it doesn’t, try something else. But treating ‘reusable is best’ as an axiom was simply destructive. It turned out that the amount of labor to make the tiles, inspect them after each flight, repair them, refurbish other systems, and transport the shuttle back to the launch facility made the thing hideously expensive - probably much more so than an equivalent disposable rocket.
I have hopes for the new space initiative, because their requirements make much more sense, and are very focused on the specific mission rather than being all things to all people. And for the scope creep that inevitably happens, the system is designed to be modular so capability can be added later, rather than having to engineer for every possible use right from the start.
Well said, Sam.
Whoops. This excerpt better syncs with your closing statement re: white elephants.
I don’t think it would have taken any longer than 30 months to completely redesign and requal the tank. They had the money. That was why, when I was musing on why they didn’t do a complete redesign, I had to look for sociopolitical reasons.
But after thinking about it, I’m changing my mind about why they didn’t do a redesign. They didn’t because they couldn’t. NASA lost the ability to run a human spaceflight development program decades ago. They used to design space vehicles like General Motors designs cars, but now they’re just like your local mechanic; if your brakes keep wearing out, they don’t design a new brake pad with a longer life, they just keep replacing the old ones. Look at the Challenger aftermath - in that case, some people said, let’s get rid of the o-rings altogether. Develop a liquid booster, or invent a new kind of segmented solid booster, anything to get rid of the o-rings. That is what they would have done in 1968. But instead they made some pretty minor tweaks to the existing design, and paid a lot more attention to launch temperature limits. And after Columbia, instead of eliminating external foam, they chose to make very minor upgrades to a few obvious trouble spots, and cross their fingers about the rest. You could almost see the determination to do just barely enough redesign to get the various oversight bodies to let them fly again, and no more.
There’s a story in the LA Times today quoting a couple of outside engineers who tried to sell their ideas for strengthening the foam to NASA, but NASA said, “We don’t have the ability or resources to evaluate your ideas.” That is the smoking gun.
So the answer is to go back to what worked in the past - bring the systems engineering talent back into NASA. Griffin has already hinted that this is what he’s going to do. That’s the only way they are going to be able to do the Moon-Mars thing. Maybe the STS-114 foam loss was a blessing in disguise - it was just scary enough, coming so soon after NASA was supposed to have solved the problem, to finally focus people’s attention on NASA’s eroded capabilities.
The U.S. Air Force tried what you are suggesting, “managing by requirements,” with disastrous results - they lost several billion dollars worth of satellites in a short time frame. You can also see this in the commercial space launch business, where the failure rates are significantly higher than for traditional cost-plus government contracting. (In the commercial business they compensate for lax oversight by buying launch insurance. That doesn’t work for manned flight.) It is very difficult to write requirements for a space launch system. To write good requirements, NASA would have to hire enough engineering talent that they might as well just design the damn system themselves. Then you don’t need a contractor to do your systems engineering and integration. If you don’t contract out your SE&I, the way NASA has effectively done with USA (NASA has an SE&I organization, but it is pathetically weak), then you don’t need to spend so many resources on writing requirements.
This is a great summary of NASAs philosophy toward the Shuttle. During Gemini and Apollo the craft went through numerous upgrades that were integrated into the design and production as problems were discovered or improvements were devleoped. By the time the Gemini program was completed, the capsule and service module were virtually redesigned. Of course, the whole point of Gemini was that it was a test and development program, intended to encounter problems and failures. When a system broke or didn’t work, it wasn’t a problem to be rationalized into nonexistance but a learning experience, and given the crash timeschedule and experimental nature of the entire program its surprising that not one casualty occured, the nearest being Gemini VIII’s emergency landing due to a stuck RCS thruster.
I take exception to the comment that “They used to design space vehicles like General Motors designs cars,” though. If GM were designing spacecraft, they’d have all kinds of extra foam stuck in the most ridiculous places, and knobs and dials falling off all over the place. 
That is, in a nutshell, the problem with “managing by requirements”; you’re just creating another layer of bureaucracy through which to communicate. I hate getting a sub-sub-sub-subcontractor’s technical requirements and then trying to follow it back up through the line until I get to the contract TRD, only to find out that, like a joke translated through five different languages, it no longer bears any but the slightest resemblence to the original requirement. NASA either needs to hand off complete program management and responsibility to a subcontractor (as it does with the semi-autonomous JPL’s unmanned missions) or they need to maintain inspection and design control throughout development. There exists no requirements document that cannot be outlawyered by some clever contractor in order to deliver a vehicle that is not what the mission calls for.
In the case of the Shuttle, though, it’s clear that even NASA didn’t really know what they were going to do with it.
Stranger
I wasn’t suggesting a specific management philosophy, but stating a general principle that vehicles that are designed to be focused on a tightly defined mission will be more successful than a vehicle that is designed to be everything to everyone.
But that was the whole purpose of the space shuttle – to be an all-purpose “truck” for lifting astronauts and various kinds of payload-cargo into orbit. Don’t we need that?
And look how well that turned out…
Why do we need that? Might it not have been better to have a number of specialized vehicles for specialized purposes? After all, the Russians have done wonders with a Soyuz for people, Progress rockets for cargo, etc.
Maybe we would have been better off with a large heavy unmanned lifter for large payloads and a smaller craft for people.
While I agree with the sentiment that NASA would rather replace the brake pads than redesign the brake system, I disagree that the shuttle has been a failure. I think the idea of a re-usable space truck is great, I just think the whole thing needs to be redesigned (or designed anew) to incorporate the advances in technologies that have been made in the last 30 years.
I wouldn’t drive a 30 year old rig on the interstate highways to deliver goods; I’d get a new truck.
I wouldn’t buy a 30 year old “portable” to cruise the internet; I’d get a new computer.
I wouldn’t make a list with only two items; I’d say “Hi, Opal”.*
- I know that had nothing to do with the whole discussion, but I’ve wanted to include that in a post since I read about it in Beginner’s Guide to Glossary of Terms on Straight Dope Message Boards
I’m sure that it has been said many times before - that the attempt to combine heavy lifting with several humans was stupid. So true. It has been said that NASA is a highly innefficient organisation, which I think is so true.
Combine all this with thousands of bits of porcelain stuck with glue to a spacecraft and what do you get?
The problem with a “one size fits all” transport is this: when you want to exchange crews on the ISS, you end up spending a half billion dollar flight ticket for one launch (and trying to shove in enough work to make the trip worthwhile). If you want to send up cargo, you end up pushing a lot of extra weight (the “reusable” orbiter) to shove a payload into space. There were complaints about the cost per launch of the Saturns, but in terms of dollars per pound to orbit the Saturn V had the Shuttle beat hands down.
There are other issues as well; the Shuttle Main Engines (SME) are still the most powerful engine per size in the world, but the stresses in them are such that they have to be inspected and refurbished every flight, and replaced every other flight. Despite advances in materials science (some of which have made their way into the SMEs) these machines are operating at safety margins that are close to 1. For an unmanned booster, this is acceptible, espeically given that we’ve yet to experience a catastrophic failure of the engines (though there have been a couple of “Gulp!” moments) but undesirable for a manned flight. An SSTO or aerospace plane designed primarily for transporting people and minimal cargo, with a much less stressed engine (like the Aerospike) and that can be turned around in a matter of days instead of months makes much more sense economically and logistically. We can build a stockpile of boosters for heavy lift and use them as needed; a habitable, reusable spacecraft is a different story.
I think the only time that we’ve actually needed both cargo and crew at the same place is during repair and recovery missions, such as the Westar-6 or Hubble. These occur rarely enough, and for a mission in which the repair can be performed in situ, it’s a straightforward matter to launch the cargo and the crew seperately and have them rendevous. We’ve been doing this since Gemini.
Stranger
I totally understand, Stranger.
I also still think the idea of a re-usable vehicle is the way to go, just not the one we have now. As you’ve pointed out, it’s too expensive, too dangerous, and too much time is spent refurbing for the next mission.
I think an aerospace plane is prolly the way to go, but until we have a truly viable facility in place in orbit to house people and things, the idea won’t be worth the time and effort.
We need a moon base or an L5; someplace we can operate from on a regular basis that won’t be cramped with more than 5 people on board. Then I agree that it would be waaaay easy to send the people up to base, and simply lob cargo into an orbit that could be picked up or intercepted.
What I like about the shuttle is that, for it’s time, despite all the political machinations, it was a truly forward-thinking idea. With years of effort and dedication it became a reality. The research done to bring the idea into existence yielded info that was useful in other areas, and the research the shuttle enabled once we had it has been useful, too. I think the same would be true for a new design, but I just don’t see that it’s really happening right now (at least not within NASA).
It frustrates me a bit that so much of the science fiction that I grew up reading about is now a part of my reality, but the greatest adventure is stagnating. Imagination, perseverance and ability can be the cornerstone for terrific accomplishments. I know we have all of those things in abundance in America, and I’d like to see some of my tax dollars support them (in a way that doesn’t necessarily mean killing lots of people, I mean).
Exactly. Luckily, this is the strategy NASA has now adopted. A heavy unmanned lifter, and a modular, flexible crew vehicle.