Should the Space Shuttle Fleet be retired?

[lyghtningbyrd]

Speaking of NASA and spaceflight, could anyone explain to me why we don't send space craft into orbit/space with a ground horizontal takeoff like we do with planes. Its seems like a much simpler method. I've never understood why it just takes off from a stationary straight up position. If anyone could explain, I'd app. it Thanks

 

[davefoc]

I agree with everything that daver said plus a few of the other posters.

I wouldn't abandon the thing because of international commitments but the space shuttle should be used at the dead minimum to satisfy that and nothing else. I don't believe that whatever NASA does will appreciably reduce the odds against a catastrophic failure to much below the historical 2%, the thing is horrendously expensive to fly and doesn't seem to be contributing to much of anything (oh, I guess it's nice when they fly up and fix the Hubble, but I think there's only one more flight scheduled for this).

The engineer in me would like us to continue to pursue manned space flight, but with a more realistic approach and with realistic goals. I think a new space shuttle, should be designed that is based largely on existing technologies. It would be smaller, cheaper, and more reliable than the current one. It would have almost no cargo capacity. Remotely controlled rockets seem to work just fine for cargo.

The libertarian in me thinks that this is all a giant waste of money, especially the money of people who have no interest in it and derive no benefit at all from it and the government should just cancel the whole thing, period.

 

[LucyR]

RichardR,

The scientific reasons put forward in favour of the exploration and colonisation of space may be less than compelling. However, the amount of money spent on this endevour is surely insignificant when compared with that spent on the design and production of weapons.

Put another way, a colony on the moon is no less likely to increase the sum total of human happiness than a planet bristling with tens of thousands of nuclear warheads.

Unfortunately, it is, as we know, much easier to sell things to people if you appeal to their fears.

Personally, I find the idea of space exploration very exciting, although I would find it difficult to convince a skeptic of its value on the basis of a purely rational argument (much like my disapproval of vivisection).

Lucy.

 

[davefoc]

lyghtningbyrd said:

Speaking of NASA and spaceflight, could anyone explain to me why we don't send space craft into orbit/space with a ground horizontal takeoff like we do with planes. Its seems like a much simpler method. I've never understood why it just takes off from a stationary straight up position. If anyone could explain, I'd app. it Thanks

lyghtningbyrd,
I'd like to take a shot at an answer, but I'm no expert so take what I say with a grain of salt.

The big problem with getting into space is something called the rocket equation and the fact that you need to be going more than 15,000 miles an hour even for a low earth orbit. The concept is that you have to lift the fuel, to lift the fuel, to lift the fuel,......., to accelerate you to the final speed. So if you accelerate too slowly you have to carry too much extra fuel to support the flying rather than the accelerating.

There is some advantages to something like you talk about if you could use air breathing engines for the first part of the trip so you didn't need to lift all the oxygen you needed. NASA and others have been theorizing around ideas like this for years. All of which seemed to have been abandoned for now. The scramjet engine was conceived to do just this.

The really cool idea to me, has been mass launchers. Just fling the stuff towards space getting a big chunk of the acceleration on the ground where you can accelerate the stuff with energy on the ground so you don't need to accelerate a lot of the fuel so you get around at least some of the consequences of the rocket equation. Alas, I haven't seen any articles suggesting this idea is going anyplace either.

 

[RichardR]

The scientific reasons put forward in favour of the exploration and colonisation of space may be less than compelling. However, the amount of money spent on this endevour is surely insignificant when compared with that spent on the design and production of weapons.

Put another way, a colony on the moon is no less likely to increase the sum total of human happiness than a planet bristling with tens of thousands of nuclear warheads.

Agreed. But surely that’s not the comparison that should be made.

I would compare the costs and benefits of colonization with the costs and benefits of more robot probes. The majority of the cost of a manned mission to (say) Mars would be in ensuring the survival of the humans. If a fraction of this cost were devoted to developing robot systems I believe the benefits would be much greater, because we would be able to do much more.

 

[daver]

lyghtningbyrd said:


lyghtningbyrd,
I'd like to take a shot at an answer, but I'm no expert so take what I say with a grain of salt.

The big problem with getting into space is something called the rocket equation and the fact that you need to be going more than 15,000 miles an hour even for a low earth orbit. The concept is that you have to lift the fuel, to lift the fuel, to lift the fuel,......., to accelerate you to the final speed. So if you accelerate too slowly you have to carry too much extra fuel to support the flying rather than the accelerating.

I'm no expert either, but if i talk real fast maybe nobody will notice.

Wings and jet engines are useful to maybe 2,000 mph. For the remaining 16,000 mph they're dead weight. And for every pound that you've wasted on wings and jet engines, you need to carry ten pounds of fuel. That adds up real fast.

There is some advantages to something like you talk about if you could use air breathing engines for the first part of the trip so you didn't need to lift all the oxygen you needed. NASA and others have been theorizing around ideas like this for years. All of which seemed to have been abandoned for now. The scramjet engine was conceived to do just this.

So far as i know, we still don't have a practical scramjet engine. I saw a post claiming that scramjets wouldn't be practical much past Mach 11, which is only about 40% of the way to orbital velocity. However, that might be good enough for a first stage. My guess is that we're at least 30 years away from something like this.

There are other air-breathing proposals--LACE (liquid air cycle engine, i think) was a proposal to use the hydrogen rocket fuel with oxygen from the air. There was a British horizontal take-off horizontal landing proposal based around this. Unfortunately, they couldn't get funding.

The really cool idea to me, has been mass launchers. Just fling the stuff towards space getting a big chunk of the acceleration on the ground where you can accelerate the stuff with energy on the ground so you don't need to accelerate a lot of the fuel so you get around at least some of the consequences of the rocket equation. Alas, I haven't seen any articles suggesting this idea is going anyplace either.

There are a couple of proposals to keep most of the hardware on the ground. The mass launcher mechanism is going to submit the load to enormous accelerations--a 100 g launcher is still going to be 20 miles long. You'd want most of that in vacuum.

Another proposal was a launch laser--you put reaction mass on the bottom of your capsule and zap it with a whopping big laser beam. The energy from the laser gets depositied into the bottom layer of the reaction mass, which essentially explodes, but with more energy than any chemical reaction. Jerry Pournelle used this in some of his SF.

 

[arcticpenguin]

Here's the solution: Worms from experiment found in shuttle debris

Nematodes can survive a shuttle break up at 60000 meters altitude and Mach 18. Humans can't. All we have to do is teach the nematodes to fly the shuttle and carry out the missions.

 

[daver]

Here's the solution: Worms from experiment found in shuttle debris

Nematodes can survive a shuttle break up at 60000 meters altitude and Mach 18. Humans can't. All we have to do is teach the nematodes to fly the shuttle and carry out the missions.

We could then make the shuttles much smaller--say about the size of a tennis ball can. The cost savings would be enormous.

 

[Larspeart]

Should they be retired? Yes. Soon? Not possible.

Until the ISS is done, and we have a WORKING REPLACEMENT, retiring the fleet will effectively end any manned space work, including maintenence and repairs of existing sats 100%.

Privatize the whole damn thing, and you'll see a TON of new accomplishments. Federal redtape adn other assorted ◊◊◊◊◊◊◊◊ has been hampering space exploration since it all began with the military.

If we had a privatized space 'program' 20 years ago, we'd be going to Mars soon, if not already. As it stands now, it could be decades or a century before man sets foot on it.

Still, we have to use them for now. Retiring them out of safety fears is crap. The world is too damn concerned with safety. My attitude is that if you volunteer for space duty, you should sign/accept the same risks as the military. There should be a big line in bold letters that says 'Space travel is risky, and you could die. Please sign below if you fully accept this risk.' (i'm sure it is in there somewhere).

 

[FutileJester]

Actually I'd say it's largely a question of who funds it. I'm in favor of manned spaceflight in the same way that I'm in favor of music and art; they're wonderful, essentially human things that uplift the spirit. But I don't want the government funding art, and I don't want it funding manned spaceflight. To the extent that people are moved by music, art, and manned spaceflight, they will ultimately create it without the government.

 

[repairman]

IIRC The cost to send up a team to repair the Hubble exceded the original cost of building and launching it in the first place. So if your only justification for manned space flight is repairing and replenishing satilites and the ISS then I don't see a point to continuing manned space flight. I would still love to go!

 

[ceo_esq]

Here's the solution: Worms from experiment found in shuttle debris

Nematodes can survive a shuttle break up at 60000 meters altitude and Mach 18. Humans can't. All we have to do is teach the nematodes to fly the shuttle and carry out the missions.

And, just for good measure, build the entire shuttle out of the material those intact worm-canisters were made from.

 

[shecky]

If we had a privatized space 'program' 20 years ago, we'd be going to Mars soon, if not already. As it stands now, it could be decades or a century before man sets foot on it.

I don't know about this. There was nothing really holding back the private sector from going into space twenty years ago. If there was a compelling commercial reason for the private sector to go to mars, they'd probably be going for it now. That's the biggest problem with human space travel. There just isn't much reason to do it.

 

[DogB]

Speaking of NASA and spaceflight, could anyone explain to me why we don't send space craft into orbit/space with a ground horizontal takeoff like we do with planes. Its seems like a much simpler method. I've never understood why it just takes off from a stationary straight up position. If anyone could explain, I'd app. it Thanks

Some good answers already but I'm gonna stick my 2c worth in anyway. (2c Australian.....about 1.2c US)

As other posters have noted the most important requirement for orbit is horizontal speed.

Accelerating to high mach numbers at low altitude where the air is thick really isn't a good idea. So the ideal initial flight path is straight up to where the air is thinner. Then the rocket transitions to horizontal flight to gain horizontal speed. In reality rockets climb so fast that the transition begins almost immediately.

As far as propulsion is concerned we really don't have anything which gives us the same power a a rocket engine. Unlike air breathing engines (Conventional jets, Scram and Ram jets) rockets work more efficiently the less air there is so once again the ideal flightpath is a quick climb to altitude.

I think it's also easier and lighter to engineer rockets with only one thrust axis.

Dog

ps If you really want more details JayUtah at the BadAstonomy forum is an ex-spacecraft engineer, he'll probably give you much more accurate info than I can.

 

[daver]

I don't know about this. There was nothing really holding back the private sector from going into space twenty years ago. If there was a compelling commercial reason for the private sector to go to mars, they'd probably be going for it now. That's the biggest problem with human space travel. There just isn't much reason to do it.

There are problems getting money. The investors aren't going to be too interested if (1) the government is subsidizing the competition and (2) the experts (who just happen to be the government copetition) say it can't be done that way. And then, there's (3) the current market, based on the current price, won't allow your company to make enough profit to offer the investors a good return.

There are also some legal problems. Ths US is responsible for any and all damages caused by anything launched by a US company. The US has the responsibility of making sure that anything launched by a US company is safe; if you're paranoid, you might figure that the US would be a bit more stringent about a competing launcher than it would be a shuttle, particularly if it's a manned launcher.

 

[daver]

As far as propulsion is concerned we really don't have anything which gives us the same power a a rocket engine. Unlike air breathing engines (Conventional jets, Scram and Ram jets) rockets work more efficiently the less air there is so once again the ideal flightpath is a quick climb to altitude.

I'll put in another bit--rocket engines typically have much more thrust to weight than jet engines. It's not that hard to make a rocket engine that can lift 100x its weight; it's much more difficult to make a jet engine that can do that. An air-breathing flyback first stage would likely end up being quite a bit heavier and more complicated than a big dumb LOX/kerosene rocket.