Misc. Ramblings

There is more than one way to get to the moon and planets, which way is the best is now beginning to be debated.

Even as the space shuttle is set to return tomorrow, NASA understands that it needs a replacement for the aging shuttle fleet. The questions is: replace it with what? What is the mission? What criteria should be used to determine what the next manned spacecraft should be able to do?

This Popular Mechanics article says it may look something like the illustration on the left. According to the article, the "primary requirement is to 'ensure crew safety through all mission phases.'" One would think that is a given, but perhaps I am mistaken. The other stated goal is to have a vehicle able to go beyond Earth orbit.

The article is kind of fuzzy on the details but it appears the Lockheed Martin shuttle would be made up of three parts (crew module, mission module, and propulsion stage), each launching separately. The modules would then dock in low earth orbit (LEO) and continue on to its destination, whether the space station or the moon and beyond. While this certainly makes for mission flexibility, I think it increases the complexity and the number of things that could cause mission failure.

For example, it could take six to nine or more launches, depending on the mission, to assemble the required modules in LEO. As we should have learned from our experience in building the International Space Station, a lot of things can and will go wrong while trying to assemble a multi-module space craft in LEO.

I could be wrong, but I seem to remember a debate, during the early part of the race to moon, whether to go directly there or use multiple launches and assemble in LEO and then go on to the moon. The decision was to go directly to the moon because, it was determined, it was simpler (and simpler is more reliable and usually safer).

Nonetheless, I guess the closest analogy is one of a train and its modular design. When bigger payloads are needed, you add more engines and then more cars to carry more cargo. Don't need to carry more but want to go farther? Add more propulsion and fuel. In other words, you configure the craft to meet the mission.

Another big change, but perhaps a retrograde one when returning, is the shuttle would not glide back to Earth but rather, would use parachutes. Much like the spam-in-a-can capsules of the 1960's and 70's. Thus, the dream of a shuttle that could fly into space and fly back, much like the commercial aircraft of today, would end.

Whether this is the winning design is too early to determine, but I wonder if the design criteria shouldn't be made clearer, first.

Aloha!