The 30 July public meeting of the Augustine Commission on The Review of Human Space Flight Plans was fascinating from several points of view.
First, to see some really bright folks working on a really hard problem. Second, to see how individual views had changed since the first public meeting on 17 June.
The session was devoted primarily to the subgroup “Exploration Beyond Low Earth Orbit” (see the previous NSSPhoenix post here). The chairman of this subgroup is Dr Ed Crawley, first on the left, above. He introduced the topic. The charter of the subgroup is to present options for Why we explore, Where and How. There were a lot of surprises during the two and a half hour presentation. Of major interest was Crawley’s observation that President Kennedy had changed the American space program from Pay as you Go, to Pay this Decade. It was to have profound impact on the future of Space Exploration.
Dr Wanda Austin, second from the left above, discussed the Evaluation and Assessment methodology the subgroup would propose for evaluating the options for exploration. Bo Bejmuk (first from the right) discussed Science at various destinations. Then things got really interesting.
Jeff Greason (CEO XCOR Aerospace, and second from the right above)) was committed to Evolved Expendable Launch Vehicles (EELV) at the first meeting on 17 June. At the 30 July session, he spoke on access to Low Earth Orbit (LEO) and beyond. To get beyond LEO, you need a large Earth Departure Stage (EDS) and a lot of propellant. Then we got his first surprise. The next few minutes were devoted to the concept of Propellant Depots (PD). As Greason noted, this would allow launch and exploration to be decoupled. This is similar to the “tanker mode” advocated by Werner von Braun before he consented to the Apollo Luner Orbit Rendezvous (LOR) architecture. Greason noted that had von Braun been successful in his position, Apollo would not have landed on the Moon in 1969, but we likely would have been on Mars by the 1990’s. The reason is that you can launch a large empty EDS with payload, and fuel it in orbit. This Earth Orbit Rendezvous (EOR) architecture requires two launches of smaller and less expensive rockets. The Apollo program was effectively canceled with the elimination of funding for the Saturn V before Apollo 11 landed on the Moon. It was too expensive.
And now, Greason brought forth his second surprise. He suggested there were three classes of launch vehicles in sight: 25 mt (metric tons), 75 mt and 120 mt. The first, 25 mt, is represented by the Delta and Atlas EELV rockets. These he concluded, are “too small”. The 120 mt class, represented by NASA’s Ares V rocket, is a repetition of the Saturn V problem: it is “too big” and too expensive. The 75 mt class, however, is “just right”. With propellant depots, you could launch an empty EDS with payload weighing 75 mt. Then you would add 375 mt of fuel from the depot. You now have a 450 mt EDS, which would allow you to explore a wide range of destinations in the Solar System. Such a rocket is represented by the Direct Team’s Jupiter Rocket, which was presented to the Augustine Commission at it’s 17 June 2009 meeting.
In future posts, we will discuss the options presented by the subgroup and the summation by Chris Chyba (third from the right): “Destinations are not Goals”.