RapierFugue
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Joined: 3/16/2006
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quote:
ORIGINAL: Aneirin
But what to replace the space shuttle with, surely not wasteful chemical rockets to attain orbit, for surely given the HOTOL idea, a space plane that takes off from earth as a plane is the way forward, attain altitude by normal aerodynamics then allow thrust to take over when the correct altitude is attained. So here we have Skylon developed from HOTOL, and a project many believe could be the space shuttle replacement.
The problem as I understand it (and I'll cheerfully admit that I'm not an expert, though I do have an interest in the subject) is that, having reached the moon, the next viable (in any sense of the word) goal becomes Mars (since there's little point in merely repeating a previous achievement). The problem with this is that a manned Mars mission is several orders of magnitude more difficult than a moon landing, therefore the amount of hardware that has to be shifted across vast (by the standards of what we've previously moved across) cross-solar system distances becomes almost unfeasibly large. Put simply, the moon's just a pop to the shops in a comfy SUV, whereas getting to Mars is like trying to cross the Sahara unaided, and without water supplies.
So the challenge becomes one not so much of putting tonnage into space reliably, via a suitable launch vehicle, but of finding a more energy efficient way of achieving reasonable speeds in post-orbital spaceflight after you've got it out of earth's orbit, understanding of course that, in the case of a manned mission, one also has to bring the buggers home again afterwards.
Therefore the launch mechanism, as important as it is (and please understand I'm not dissing your point) is much less important than developing a new technology or technologies to allow much larger distances to be travelled at speeds consistent with being able to sustain human life - i.e. it's no good putting them on a slow boat to China/Mars, because they'll have munched through their rations before they're a tenth of the way there.
Historically, the most expensive endeavours are always the ones where a genuinely new technology is required - i.e. the costs of putting a man into space, then of putting him on the moon, were at the time centred around finding reliable, high-yield rocket engines (as just one example), whereas now what we need is something that can whoosh us across the big black with minimal (or at least substantially reduced) energy consumption. Since that need for an energy-efficient power source and delivery system is also a major requirement of sustaining human life in significant numbers beyond the 21st century (i.e. when the oil runs out), I'd venture to suggest that manned space flight is not something the human race "should think about doing as a “nice to have” if it feels like it", but is something it either does, and does successfully, or risks either dying out in vast numbers (as food transportation becomes impractical, as just one example) or having its numbers reduced to such an extent, with such a low energy availability, that we're effectively reduced back to a modern Stone Age. Sustainable energy production, even allowing nuclear into the mix (and that has its own issues) simply isn't enough, or anywhere near enough, at present, to allow continued survival.
So we have to reach for the stars – to do otherwise is to sign our own death warrants, as a species of course – I’ll be long gone by the time the energy crisis comes to a head.
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Atlantis (STS-136) Final Shuttle Launch - 
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