Interesting discussion of alternative Lunar exploration architectures

The problem with the proposed Constellation Program is that, while based on proven technology, that technology is itself, at its basis, half a century old. We are again reverting to ballistic missiles to launch payloads into space. It works- certainly. But it is also the most inefficient means of doing so.

With ballistic tech, you are essentially lifting mass against gravity by brute force alone. In so doing, you must also lift a huge amount of fuel and engines, which must be discarded by stages in the process of flight. Thus, the vast bulk of the launch vehicle is destroyed before even achieving orbit. The space shuttle ameliorated this somewhat. But note that it was still launched vertically and threw away much of itself.

This is why space travel has not proceeded beyond Earth orbit for so long. Economic flight to orbit is the great bottleneck that's defeated space exploration all this time. Until it's resolved, manned ventures to the planets will remain just that- brief, dangerous and expensive ventures. No staying power.

Constellation does not resolve this and can't. The logical alternative would seem to lie in the developing "scram-jet" technology, whereby vehicles can be launched from a conventional airfield, proceed efficiently through atmosphere at hypersonic speeds and translate into rocket power for the final ascent into orbit. From there, deep space vehicles- built in orbit and utilizing the VASIMR high thrust plasma drive- can travel at high speeds to planetary destinations; also efficiently.

If we're to have any future in space, something along these lines must be pursued and established.