uaaerospace wrote:
Sure, it would be nice to stick a P4 in the shuttle, but what of extreme temerature consequences? Humidity? Moisture?
Radiation as well - all the components on the shuttle/ISS are "radiation hardened" so they won't be taken out by a stray cosmic ray or solar flare.
I agree that an alternative to the Shuttle is necessary - but let's not forget what we're losing. The Shuttle was designed as a multipurpose vehicle. Its flexibility accounts for some of its inefficiency as a transport-only vehicle. In losing the Shuttle we also lose an alternative to the space station for research projects up to 15 days duration, and a platform for in-space construction and maintenance (e.g. of the Hubble) Thousands of fine scientific experiments have been conducted onboard the Shuttle in the last 20-odd years. It also played a major role in assembly of the ISS. The CEV, an Apollo capsule on steroids, is a crew transport vehicle plain and simple. Yes it will get our crews into space more efficiently, and will be able to leave low earth orbit, but will be vastly LESS effective as a place for doing any kind of useful work in space.
Another drawback of the CEV is that unlike the Shuttle and ISS, its life support system is designed for short trips only and uses Apollo-era life support technology. No water recycling; no oxygen generation from CO2; no stabilization of solid wastes. And NASA has lifesupport technology just about ready for ISS installation (urine and graywater recovery) and ISS testing (advanced air revitalization schemes) which may simply be discarded as all available funds are funneled into CEV. Nearly all advanced life support projects at NASA are being mothballed. A flight ready water recovery system was to go up to ISS 1 or 2 shuttle flights after Columbia. It's still waiting, and may never fly.
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When work begins on the lunar outpost in 2015, where will the technology be to support people cost- and mass-effectively in a closed system for periods of 30-90 days? Where will they get the technology to support a Mars mission in which crew will remain in transit for half a year in each direction, and stay on the Martian surface for 600 days or more, using Martian atmosphere and ground ice as raw materials for manufacturing return propellant, air and water? The Shuttle and ISS can provide excellent testbeds for life support development but no, the Shuttle is to be abandoned and the ISS program further downsized. NASA's whole knowledge base in life support is being trashed, along with much of its scientific program, in order to support development of the CEV. When NASA picks up life support development in 10 years, who will do the work? All of today's life support development experts will have moved on or retired and there will be no one in the pipeline.
So yes, we need to develop the CEV and replace the Shuttle, but don't forget the inevitable losses as you're counting up the anticipated gains.