When Dr. Mike Griffin, the new NASA Administrator, took charge of NASA, he accelerated the schedule for the shuttle replacement to reduce the time between the retirement of the Shuttle and the launch of its replacement. He ordered this study as part of the plan to select the design earlier than the previous schedule.

The New York Times (free registration required) has a good overview article and Spaceref has a more detailed article. NASA Watch has some commentary.

In summary, the designs use SRBs and SSMEs from the shuttle with the payload, a new Crew Exploration Vehicle (CEV), in an Apollo-like configuration. They also call for two similar but different systems, one for crewed missions and one for cargo.

For the last several years, I have worked on projects that looked at technology choices for the Shuttle replacement: Second Generation RLV, Third Generation RLV, Spaceliner 100, etc. I know some people who did work for this current study. However, since my job has been to write software for the people who did the studies, I don’t know much about it first hand. However, I learn quite a bit from the system engineers and Subject Matter Experts I work with.

What strikes me most about these new designs is there simplicity. We had studied technologies such as Hall Thrusters, Nuclear Thermal, Pulsed Denotation, TBCC airbreather, RBCC, etc. Some of these were near-term options, some were for later, I’m not sure which. (Like I said, I’m not a rocket scientist, just a software engineer.) However, the new designs don’t use any of new technologies. They use current engines.

NASA has also learned some lessons from the Shuttle. A RLV (reusable Launch Vehicle) sounds good, but unless you get the flight rates up high enough, it is actually more expensive. Also, these new designs put the payloads on top, similar to Apollo. We have seen that there is a risk of damage to the payload by debris when it is not on top.

Also, separating the cargo launches to a different vehicle seems to be an excellent idea. It should reduce the cost of launching cargo significantly. There is no need to have a human-rated system to launch cargo.

From what I know, I think these are good designs. They reduce development cost and increase reliability by using existing technology where they can (engines) and new technology where needed (the CEV). Also, they reduce the “space gap” that will be left by the Shuttle’s retirement.