This is an historic moment, one of great opportunity. NASA can either rise to the challenge and scrap the shuttle, or just muddle along. An intermediate path would use the shuttles on a reduced schedule, while developing a big booster capable of hauling up the big loads needed to build more onto the station. This would be cost-effective and smart.
A Mars expedition would be the grandest exploit open to the 21st century. It would take about 2.5 years, every day closely monitored by a huge Earthside audience and fraught with peril.
This is what we should be doing. Such an adventure would resonate with a world beset by wars and woes. It has a grandeur appropriate to the advanced nations, who should do it together.
We have to stop pissing around in earth orbit, figure out what our long term goals are, and go for them. And the obvious goal is Mars. The status quo in the long term just means a retreat back to earth. In the short term, I think Benford is right. A reduced shuttle schedule until we get something better is exactly right. It signifies that we are not giving up. The thing that scares me about the idea of abandoning the suttle and saying that we will build something else is that getting the something else started might then be hard. Having the shuttle still operating, and its presence acting as a reminder that the somthing else is needed, might well speed up the development of the something else.
Of course, there are two working launch systems for manned spaceflight in the world. One is the shuttle, and the other is the Russian Soyuz launcher. This carries a smaller payload, and can only take three people into orbit at once, but it is a proven, reliable vehicle. (It was developed in the late 1950s, but age is not necassarily an obstacle if something was got right in the first place. The B-52 bombers that are the mainstay of the USAF's bomber fleet were built in the mid 1950s, and the Boeing 747 was developed in the late 1960s. The trouble with the shuttle is that it is unreliable and too complex for its task, not that it is old). In the worst case, the Americans could pay the Russians to increase the present Soyuz production from 2 to 3 per year to a larger number, and then as a temporary measure use the Solyuz for American space activities as well as Russian ones. This will not happen, because it would be too great an admission of failure on the part of NASA, but it seems perfectly practical. Having to rely on a foreign designed and built vehicle would be an even stronger encouragement for America to build something new, however.