Keith's note: The House wants to cancel James Webb Space Telescope (JWST) outright. We haven't heard anything specific from the Senate - yet. Every time NASA mentions a cost for JWST it is higher than the previous cost. Now NASA wants to take human spaceflight funds to help pay for JWST which means less money available to build the Space Launch System (SLS). NASA's internal SLS report casts significant doubt on NASA's internal budget numbers and cost projections - which almost always means that NASA will need more money than it thinks it will need in order to build the SLS.
But NASA does not really want to build the SLS (nor does the White House) since it is simply a re-imagined variant of Ares V - a rocket that NASA already halted. The Senate is forcing the SLS down NASA's throat. Yet Congress has given no indication what level of funding it will guarantee for NASA so as to build and fly the SLS and has given no hint whatsoever of funding for the payloads that such a hugh rocket will be designed to carry. And, oh yes, OMB is telling agencies to come up with budgets for FY 2013 that include cuts of up to 10%.
So, we have one giant money sponge (JWST) already sucking up dollars with yet another money sponge (SLS) on the drawing board. Since the money simply is not there to do either project to begin with, trying to do both of them together will devour funds from smaller NASA programs. It will also pit these money sponges' ever-growing chronic need for dollars against the other's similar insatiable appetite. And all of this will happen while the Federal budget is almost certainly going to be constrained - regardless of who wins the 2012 election.
So, will someone explain to me how NASA is going to build and launch both JWST and SLS and have money left over to do all of the other things that it is both chartered to do - and directed to do - by Congress?