YARN
Fleet Captain
The space elevator is old news. The space escalator - now that is exciting. Better yet, the space ski lift offers the prospect of a scenic view into to space and hot cocoa once you get to the ski lodge...
Will it be ever possible to have long term space travel?
- Thread starter ReadyAndWilling
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The space elevator is old news. The space escalator - now that is exciting. Better yet, the space ski lift offers the prospect of a scenic view into to space and hot cocoa once you get to the ski lodge...
Space elevators are an engineering pipe dream that's unlikely to work properly even if you're stupid enough to build one. It's a cool idea and all, but not very practical.
All this article proves is that it's really NOT feasible. The currently used methods of getting into orbit are a alot cheaper and more economical when you consider thousands of shuttle flights just to get the thing built. And the 24,000 mile number mentioned is 2,000 mile longer than what I mentioned.
After seeing the new Dragon spacecraft lift off today, I'd reaaly like to see a new shuttle designed and put in service. We will always need a shuttle-like spacecraft as long as we have a presence in space.
I think eventually the developers will go back to a modified aircraft. For heavy traffic, something that can re-enter the atmosphere and land is sure to be preferable to a one-way trip transport with a simple pod return system. I think the only difference is that the engines will be reusable too in a future design.
ProtoAvatar
Fleet Captain
First - you won't need thousands of shuttle flights to lift a hundred km worth of carbon nanotube ribbon into orbt.
Second - who says you will lift these carbon nanotubes and not manufacture them in orbit.
The current recommended length is 100.000 km, 62.000 ml AKA 100 km or 62 miles.
Watch the comma, Captain Rob.
You mean like the dissapointing soon-to-be-retired shuttle?
A shuttle designed today won't have large improvements over that - the essential propulsion technology hasn't changed.
YARN
Fleet Captain
So true.
At any rate, I am not sure why so many are whining about the difficulty.
The trick is to actually build infrastructure in space. The ISS is not infrastructure but the equivalent of a modular trailer park floating in low Earth orbit.
How could we possibly build a true interplanetary spaceship?
Easy.
You put up a few pieces at a time using something like a Saturn V rocket. You assemble the thing in space. Voila.
With patience you can build an arbitrarily large space craft.
This ain't rocket science. You just need old-school rocket science to pull it off.
There are alot of uses for a shuttle-like system, but we don't really NEED one, and we haven't needed it for decades. Actually the shuttle's capabilities won't be all that useful to anyone until we have something valuable to transport back to Earth from space. At the end of the day, the only way to justify the cost and complexity of a shuttle-type system is if you're manufacturing something big and having the shuttle bring it home for you at regular intervals. It's way over-powered and over-engineered for the relatively simple task of putting things INTO orbit when a conventional rocket can do the same job for one tenth the price.
To add: as far as launch costs are concerned, I've run the numbers myself based on possible scenarios using SpaceX's Falcon 9 and ULA's Delta and Atlas rockets. The main obstacle behind those costs is, interestingly enough, the huge amount of idle time between launches. Development costs of a new launch system amortize over its operational span, and the cost of a new rocket is slightly less every time you build one (that reduction is EXTREMELY rapid if you get into something that resembles mass production). Based on these scenarios and some historical precedent, I figured out that a payload rate of $200/kg could be achievable IF you could achieve a flight schedule of not less than 700 launches over a ten-year period. Thanks to savings from mass production, it drops down to about $170/kg if you can do this over a five year period. Compare with the current Falcon-9 system, which projects a rate of about $5000/kg with a flight schedule of not more than 20 launches over the next five years.
Refitting the ISS for that task would be relatively simple. Replace the solar arrays with nuclear reactors, strap a VASIMR package on the end of Zarya and send it on its way. You could conduct a three-month science mission to the moon, with ISS as a refueling/resupply base to landers visiting multiple landing sites and then return the whole thing to Earth to be resupplied and refueled, crew replaced, new landers sent up, etc.
As far as I can tell, ISS is already an interplanetary space ship, all it needs is a drive section and a better power plant.
Everything except for that big orange tank was reusable. And it was that tank (the simplest part of the system) that's been such a big problem. I'd like to know why they never tried to imbed some sort of fiber mesh into the foam. So if it fractured that it would stay in place. They could have sprayed in a fiberglass layer into the foam during the application process.
As for the disappointing shuttle. The disappointing part was the decisionmakers at NASA not following their own rules.
And the above posters are correct. The Space Shuttle needed someplace to go and stuff to carry back and forth. I was thinking a new smaller shuttle that can carry at least 12 people, and have a smaller cargo bay (or an internal section) to carry supplies and smaller payloads. We need to put up more stations using bigger sections put up with heavy-lifters and get the job done alot faster. ISS is just about finished and they're already talking about decommisioning it. We could build a modular spaceship the same way in orbit. Then take it to the Moon for a few months at a time. Perhaps leaving part of it behind in orbit as a lunar station. Then add more sections to it and fly it to the asteroid belt or to Mars. Or anywhere you want to go. We need to get moving.
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SpaceX is working on converting the Falcon-9's first stage to be reusable. That's considered the holy grail of liquid-fueled launch systems.
Same answer for both cases: WEIGHT. Just that layer of white paint on the first couple of launches cost a few dozen tons of payload capacity. Fiber mesh or any other strengthening system in the foam would have been even worse.
Anyway, I'm still personally dubious to what extent the external tank really WAS a problem in the first place. NASA blames Columbia's loss on a foam strike on the heat shield, but after all these years I still don't buy it. I believe the ship was either hit by some sort of space debris before reentry, or it just succumbed to the law of averages at a really unfortunate time.
Actually, the disappointing part was the cost. The shuttle was supposed to provide cheap access to space for everyone who wanted it just by virtue of its reusability; NASA was promising launch costs between $200 and $500 a pound, claiming that since the tank was the only thing destroyed, their operating costs would be minimal. Not only was this completely wrong (the shuttle is second only to the Saturn-V as the most expensive launch system in American history) but the shuttle's turnaround time is way too slow to compete with even the next most expensive disposable launchers. It doesn't do what it was supposed to do, and after Challenger they even stopped using it for THAT. That left the STS with a dramatically reduced mission role that it failed to properly fill even when NASA's funding wasn't being cut.
I see that in all this talk about potential reusables, no-one has mentioned the British Skylon. It will have a very quick turnaround time on the ground and reduces the cost of putting payload into space by a fifth.
http://www.reactionengines.co.uk/skylon.html
http://www.reactionengines.co.uk/skylon.html
It doesn't mention that it's even in development yet, let alone having a prototype for trials.
Do you know what the word "discussion" means? I was commenting that nobody's made a prototype yet.
Well, your right it says its not in development yet.
It says 'proof-of-concept phase'.
It will take 10 years to develop and will pay for itself in the long run.
I think its a good idea, I would like to see the Un-manned part changed.
looks real sci-fi. But hopefully they take it to production.
Actually it looks like SR-71 blackbird.
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