As the struggle between NASA and Congress over the future of a shuttle derived super heavy lift launch, affectionately known as the Senate Launch System, wears on, I think it's clear that we need to balance the will of Congress with engineering and architectural needs, because a perfectly designed, unfunded rocket will fly just as well as one that only has money going for it.
The announcement of the Falcon Heavy has changed the BEO landscape dramatically, particularly with its ~$100 million price tag. We can do an awful lot with 53 metric tons. LEO, NEO's, Lunar Return, Venus orbit, even Martian moons are all within reach. With that in mind, it's very easy to think that we should just run with that for a while.
However, everyone knows that sooner or later we will need something more, even Elon Musk admitted it when announcing the Falcon Heavy. The BA-2100 requires a 100 tons and an 8m faring, a Hubble replacement will, ect. More over, Congress, specifically Congresscritters from Florida, Alabama, Texas, and Utah, are demanding it, and that it use legacy hardware from the shuttle era. Their constituents demand it, and one can hardly blame them, it's their livelihood. The problem is the infrastructure and manpower is expensive, whether it flies or not, whether we have a payload for it or not. In any conceivable architecture, the needed flight rate will be low. It also crowds out the fledgling commercial launch market.
So, how do we reconcile the competing interests of new and legacy space and forge a robust, sustainable exploration program in an era of tight budgets?
I think we need to revive an old idea, the wet workshop.
New Space can put payloads up quickly and cheaply. Logistics, fuel, people. But the rockets are relatively small. Faring volume is limited, pressurized volume even more so, even with inflatables. Real interplanetary volumes, particularly surface installations, like the BA-2100 would provide, are at this time out of reach. Musk might have ideas about that, time will tell.
Legacy space does have its infrastructure issues, but it's also simple, reliable, and massive. Whatever you want to call it, SLS, DIRECT, Jupiter, ect, its expandable and provides all the capability we would need. I really don't think, even with the labor costs involved, that if stop wringing our hands and get to work, it can be relatively affordable keeping in mind that unlike the Falcon Heavy, it would be more capability than the commercial market needs, and NASA would be the sole customer. Therefore it not only needs a mission, but a regular flight rate.
I propose pressing foreword at a low development rate, with the Jupiter (SLS) rocket, the aim being to leave plenty of room in the HSF budget to fully utilize commercial space capabilities to perform ISS missions, NEO missions, Venus orbit missions, and lunar return sorties before the decade is out. This will delay Jupiter a couple of years to around 2018 for a purpose, to make the necessary modifications to deliver the core tankage to a standard LEO orbit and be capable of maneuvering and maintaining orbit. This will be its primary function, to deliver on a regular basis, 2000m^3 of pressurized volume to orbit for future use. These modifications will include at least two, possibly 3 sets of AJ-10 rockets inset aft, just above the core engines, which will be jettisoned, and either at the intertank, and/or just above the LOX tank to maintain orbit, as well as systems to provide power and access to the interior.
This will provide affordable volume for a variety of operations, orbital, interplanetary, atmospheric, and surface, for a fixed annual cost. These modules work hand in hand with New Space, providing destinations for furnishing and servicing. And it maintains a super heavy lift capability for when payloads need to be launched.