Do We Need An Orbital Spaceplane?
In spite of the fact that the Columbia Accident Investigation Board has labeled the Space Shuttle as still being a developmental vehicle, NASA is nevertheless rushing to bring the 3 remaining orbiters and their associated systems back into service as quickly as possible. Since each future flight is now essentially considered to be a test flight, some question this haste on the part of NASA. However, NASA has good reason to get the Shuttle program back on its feet as quickly as possible. The Shuttle is the only means of completing construction of the International Space Station and the only method of delivering sufficient cargo, mainly water, to the crew in order to make the station operational. All of this brings us to the next question. It is clear that we need a replacement for the aging Shuttle fleet. But what should that replacement be?
NASA has sought to accelerate the development of the Orbital Space Plane to have it available at the ISS as a crew rescue 
vehicle by 2008 and as a crew transfer vehicle by 2012. 3 industry teams are competing for the contract. In the meantime, we must still rely on the Shuttle to construct and supply the station. It goes without saying that, based on past experience, whatever cost NASA estimates for such an endeavor will be woefully low, and that the Orbital Space Plan will still suffer from many of the Shuttle's problems and essentially be a test vehicle for years to come. I am not advocating that the Orbital Space Plan be abandoned. By no means. I do believe it should be developed but it should not be depended upon for so important a role as replacing the Shuttle. Indeed, we have a much more prudent course to follow if we are really intent on developing the ISS into a legitimate outpost in space.
Two components for ground support are necessary for the ISS: crew transfer and cargo delivery. These must be simple, safe and less expensive than the Shuttle.
I do not want to depend on the Russian Soyuz to ferry astronauts to and from the station. The last wild ride home should be enough to convince us of that. The Russian spaceflight infrastructure is crumbling and the Soyuz is old outdated technology. A better course of action exists and it does not require any new cutting edge science, but depends on tried and true technology. Develop an Apollo command module derived orbital transfer vehicle capable of carrying up to 6 passengers. Such a vehicle would require a smaller
man-rated booster than the envisioned Space Plane and would be capable of carrying a larger crew to and from the ISS. Furthermore, it relies on tried and true reentry techniques which require far less risk and far less cost than the current Shuttle. In all probability these Apollo derived ferries could be refurbished for several additional flights, further lowering the cost. According to one study the CM's which never left Earth orbit probably still have at least half of their ablative material left on their heat shields after their single reentry. The use of such a ferry also has the advantage of a proven abort after launch system which would eliminate the necessity of crew "bail-outs" at hypersonic speeds. Such a vehicle is a proven system and was used by NASA to ferry astronauts to and from Skylab in the 1970's. NASA even developed a rescue version of the Apollo CM which could carry as many as 5 astronauts back to Earth from Skylab.
There is no reason why humans lives should be at risk when you are simply launching cargo or additional ISS modules into space. NASA should develop a throw away cargo canister with an attached remote controlled maneuvering unit that can be launched atop one of our newly developed and very capable EELV's, the Delta 4 and the Atlas 5. Since these rockets come in a number of configurations depending on the mass of the payload, and since this module would essentially be nothing more than a container (much like the Shuttle's external tank), it should be a simple matter to build cargo modules of different sizes to fit the requirements of different missions. The maneuvering unit would be the same for each and could either be expendable, or perhaps even recoverable. Russian Progress supply ships rely upon automated maneuvering systems and the ability to dock with the ISS while being unmanned. If the Russians can do this why can't we?
The use of both of these systems would be far cheaper than the Shuttle or the Space Plane as they rely on proven technology. They would be safer for those instances when humans must fly into space. They would also not involve the loss of one-quarter of our spacefaring ability should a need to abort a launch arise. These proposals would make the ISS less of a monetary drain on our space program, free up more money for the development of a future, true single-stage-to-orbit spaceplane and our other unmanned exploration programs.
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