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Author Topic: Is this a good time to make a change in NASA spacecraft?  (Read 1517 times)

Offline Eric A. Taylor

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I'm very worried about the end of the Shuttle program. Here we have a vehicle that works, and still has several flights left. Each shuttle was built to fly 100 missions. NASA currently has 3 shuttles Discovery (37 Flights plus 2 more on the books for 2010) Atlantis (30 Flights plus 1 for 2010) and Endeavor (23 flights). After Discovery's last flight in September 2010 NASA plans to develop it's next gen space craft to fly in 2014. I wonder if NASA is going to have the money to do this. With health care such a high priority and extremely high cost I imagine Congress is probably going to gut NASA for funds. Then NASA will be stuck with no space craft to fly humans and no money to develop a new space craft.

I know that they have had problems with the shuttle. Challenger and Columbia have been lost with 14 lives altogether. That is two fatal events in 129 flights. The Soyuz program has also suffered 2 fatal events (Soyuz 1 and 11) in 103 flights with the loss of 4. So by stats the Shuttle is safer. Maybe you can discount the Challenger accident because it's loss can be attributed to stupidity (NASA engineers had begged the managers not to launch in cold weather) but then maybe you have to do the same for Soyuz 11, which lost pressure when a valve broke and the crew was unable to close the valve in time (they wore only shirtsleeves, not pressure suits). They would have been saved by a 1/4 turn valve that costs $3.50 in any hardware store.

Maybe NASA should hold onto the shuttle a little longer.


 

Offline LeeE

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Is this a good time to make a change in NASA spacecraft?
« Reply #1 on: 26/11/2009 11:15:15 »
The Shuttle is actually a rather fragile and dangerous design.  As a launch vehicle it is more complex than necessary, as it integrates the life support module into the design and requires a human crew.  As a human transport system it it incorporates an unnecessarily large payload bay.

The Soyuz launch vehicle, in it's various guises has made more than 1700 flights and can be used to get either payload or humans into space.  As it doesn't incorporate the life support and re-entry module, and require a crew to fly it, it is a lot simpler, with less to go wrong, requires less energy for a given payload and is cheaper to build.
 

Offline LeeE

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Is this a good time to make a change in NASA spacecraft?
« Reply #2 on: 01/12/2009 17:24:06 »
I think the idea of a reusable space-plane was, and still is, attractive in many ways, but I don't think anyone expected that the shuttle would have to undergo a major rebuild after every flight.  I also suspect that another factor in switching to a space plane was the strong desire on the part of the majority of astronauts of the time to have something that could be maneuvered and actually 'flown', as opposed to a simple 'can' - there were early comments from many of the astronaut aviator candidates about the first astronauts just being 'spam in a can'.

Perhaps it was partly a case of trying to do too much too soon when a smaller and less ambitious vehicle, with a much reduced payload might have been more successful; having to only lift a smaller payload would have allowed for a both more robust and yet simpler design (with less to go wrong).  As it was though, I think the shuttle tried to achieve too much for the technology of the time.

The Apollo capsules had escape systems but there was no certainty that they'd work.  Any explosion front would be much faster than the velocity achievable by the escape system, so even if the escape system triggered before the explosion occurred, or before the explosion front reached the capsule, it's likely that the capsule would still be enveloped by the explosion.  If the explosion started behind the capsule, as is the most likely scenario, then the re-entry shield may have offered some protection against the blast and heat but even then the explosion overpressure may have been enough to collapse the front of the capsule as they were really designed for under-pressure.
 

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Is this a good time to make a change in NASA spacecraft?
« Reply #2 on: 01/12/2009 17:24:06 »

 

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