May I ask here what the stance of the Direct team is on the (potential) use of EELVs (D4 and A5) in NASA's human space exploration efforts? In a short paragraph.
Thank you.
DIRECT intends to use Delta-IV Heavy starting in 2014/15 for lifting routine crew rotation missions to ISS. (Note: We chose DIVH for a number of reasons, but one of which is because its upper stage is larger than the current Centaur and thus has a greater potential "throw" capability -- and we want to use that on top of Jupiter-130 for some very specific missions).
We are designing the Jupiter-130 to be able to do crew+cargo missions to ISS, but we expect to really only need those for a handful of missions around 2012-2015. The key intention of using these early flights is as a "stepping stone" to enable us to transition the Shuttle workforce smoothly across the "gap" and into the Exploration Program more effectively.
Because the human-rated EELV schedule doesn't affect many jobs, the priority for us is to expedite the SDLV system as much as possible.
We ultimately intend that the primary focus of the Jupiter systems will move to 'beyond LEO' missions after 2015/16 though, although the capabilities in LEO will still prove useful from time to time (Hubble Servicing Mission #6, anyone?).
We wish to phase most ISS duties over to EELV/COTS systems around 2015 or so, with only the odd Jupiter delivering any required "big stuff" to ISS only once every few years after that.
In addition to ISS duties, we intend to provide a lot of work to the EELV-class systems around 2018/19/20 to begin delivering some pretty serious quantities of propellant to an orbiting Depot in LEO, in support of 'advanced' HSF Exploration missions.
I'm talking about somewhere around 400-600 metric tons of LH2/LOX being delivered to LEO every year, so that would require a *lot* of EELV-class flights. There's a great opportunity there to get all the commercial operators to really compete for those contracts -- and that sort of competition is good for everyone.
The same Depot arrangement opens the door for foreign partners to also 'buy' seats and payload mass on missions heading to the Moon, Mars or Beyond too. And all nations who don't have their own space programs would need to contract for Propellant Deliveries on the world launch services market -- and US companies can compete for that business as well!
We believe this is a pretty good model which combines all the strengths of SDLV, EELV and COTS systems into one unified program and "spreads the wealth" quite fairly to everyone.
Ross.
