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Joined: May 2000
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addict
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addict
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Not quite sure about this, etaoin. A technology exists but not the technology.
It's too easy to say that the technology exists to get us to Mars when we are still stuggling with sub-orbital space stations. It's not just a case of building a spaceship and launching it. That's been proved to work. It's maintaining a workable life-support system and a healthy crew for ten years in space which are the problems. The technology does not exist for this.
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Joined: Aug 2001
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Carpal Tunnel
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Carpal Tunnel
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It's maintaining a workable life-support system and a healthy crew for ten years in space which are the problems. The technology does not exist for this.
And that, of course, is the crux of the matter. We don't really know whether what we have available works or not without the testing we're doing now. I suspect it does, _if_ it can be made reliable enough. (Which, clearly, is a big "if.")
A word about the foam and tiles - it's the relative speeds that count. The 1200-2000 mph speed of the foam isn't that much different from the speed of the shuttle, so that even if it's hardened foam (not soft and squishy at all, the way we tend to picture "foam") the difference in speed may not be enough to make it a damaging projectile. A little slower to be sure, but enough to cause that kind of impact and damage? That's what the experts are trying to determine, as best thay can.
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Joined: Jul 2002
Posts: 742
old hand
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old hand
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Rubrick, where do you get the ten years? The unmanned missions to Mars have only taken around 18-21 months to get there, so a manned trip should involve no more than 5 years in space (2.5 there, 2.5 back). Mars ain't that far away, after all. Cassini will reach Saturn less than ten years after launch, so ten years to Mars must be taking the scenic route.
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Joined: Sep 2001
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Carpal Tunnel
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Carpal Tunnel
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In reply to:
A word about the foam and tiles - it's the relative speeds that count.
What you wrote makes sense.
But there's still the commentary made on Sunday that a piece of foam hit the exterior rocket engine in a lift-off over a year ago and made a dent in the steel.
This foam issue isn't minor. From what I've been reading, experts have warned about the foam problem for years. Modifications have been been, but I haven't inferred in reading anything that there was ever consensus that foam was now a non-issue.
So back to the fine point you made about relative speed. If what you wrote is abolutely true, then how did a piece of falling foam insulation put a dent into an exterior steel rocket engine? I'm curious about how the relative speed factor didn't come into play there.
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Joined: Aug 2001
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Carpal Tunnel
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Carpal Tunnel
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Perhaps the relative speeds _are_ different enough to cause damage. As I said, that's what the experts have to figure out.
The same issue arises in consideration of the airplane that supposedly shoots itself down by firing its guns, then diving under the bullet trajectory and picking up speed, then overtaking and getting hit by its own bullets. Is it a true story, or apocryphal? Anyone know the status of that phenomenon? I'd almost sooner believe it inhaled it's own (relatively slowly-moving) bullets and fouled its turbines.
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Carpal Tunnel
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Carpal Tunnel
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Pretty good article here with a video clip of the foam falling: http://www.msnbc.com/news/867336.asp?vts=2720031323#BODYOne thing the video clip impressed upon me was the foam was falling in one direction, but the shuttle was moving upward in the opposite direction, so the force of impact would have been far greater than had the foam and shuttle been moving in the same direction. You're in a race with someone; you're moving in the same direction; he catches up with, slaps your hand forward; not too much pain. Completely different scenario if you're running toward each other and he slaps your hand--you're going to feel that impact more. In other words, had the shuttle been heading toward the earth and had hit a piece of foam heading the same direction, the impact wouldn't have been as great as in the case as it was. But the vulnerable part of the left wing--that leading edge--from this video clip it doesn't appear that the foam hit the leading edge where the problems have been assumed to have begun. Could just be the lack of clarity in the clip. Has anyone read any confirmation that the insulating foam hit the leading edge of the left wing?
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Joined: Aug 2001
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Carpal Tunnel
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Carpal Tunnel
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One thing the video clip impressed upon me was the foam was falling in one direction, but the shuttle was moving upward in the opposite direction, so the force of impact would have been far greater than had the foam and shuttle been moving in the same direction.
Still the same problem: the foam probably wasn't falling yet, just no longer rising as fast as the shuttle was. It looks like falling because the camera is following the shuttle up, at say 2,000mph, while the debris had slowed because it was no longer attached to the pushing-up rockets and because of air resistance.
How much did it slow in that less-that-one-second? to -- what? 1999 mph? 1950 mph? 1900 mph? 1500 mph? That's what determines the severity of the impact.
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Joined: Sep 2001
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Carpal Tunnel
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Carpal Tunnel
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Well, for sake of argument, say the foam was immobile in space and the shuttle hit it at 2000 mph--hmmm. That's still quite a whack. And then let's say, again for sake of argument, that the glue on the tile on that leading edge hadn't been applied as precisely as it should have been, the tile itself could have been vulnerable.
That said, I really don't expect the gluing to have been a problem--though it certainly has been a past problem--especially with the leading edges on the wings, which were critical points. I would expect the crew that glued to have taken special care with the gluing of tiles onto those leading edges.
I hope the portion of the wing that was recovered today was the left wing...
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Joined: Mar 2001
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Carpal Tunnel
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Carpal Tunnel
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I see no reason not to continue with both programs in conjunction with the other. I'm all for the ISS, and was highly disappointed when they cut the size back so that habitation can only accommodate three astronauts/scientists rather than the intended twelve. That would have been a real little community working together in space, and would have greatly enhanced the amount of experimentation which could be conducted on an ongoing basis. But why couldn't we, for instance, have continued with the Apollo program at the same time we were developing the shuttles and space stations? I know it's largely due to budgetary concerns...so increase the budget! What we spend on space is a paltry sum compared to other areas of exorbitant expense. Both programs are important and should be pursued together, complimentary to one another...not as an either/or proposition. And I certainly don't see where "flag waving" is any longer a factor in all this...the Cold War "Space Race" had it's place, and that notion is now passé. I really don't think anybody's going to Mars to be the first one to plant a flag there. That trip will, and should be, an internationally supported journey to explore other worlds for the benefit of mankind...and maybe for proof of other life.
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Carpal Tunnel
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Carpal Tunnel
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wofa:
Do NOT do this, but think about what happens:
Driving along at 60 miles an hour, throw a styrofoam cup out of the window at the same time you throw out, oh, a marble.
Which one is going to continue moving at close to 60 MPH and which one is going to slow down immediately. That piece of foam would go to zero air speed pretty quickly. And when your tail fin hits it. . . .
TEd
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