For only $18Billion….and I’m not kidding about the ‘only.’ This is a big budget program on a pitiful credit line. All the technology development is to happen in the first couple of years of development, before inflation robs the fixed and thus effectively decreasing NASA budget, of its buying power. The choice of technologies was based on reusing the shuttle solid booster technology, shuttle main engine derivatives and the canceled Constellation’s upper stage engine because they are hydrogen fueled and thus use shuttle Infrastructure. It will launch either cargo or cargo and the Orion exploration capsule/system into low orbit.
It’s an impressive beast, it will start with the ability to loft 70 tons into orbit and end with something like 130 tons, significantly more than the Saturn V of Apollo fame. But the plan is to launch maybe 1 a year, and that will make it terrifically uneconomical. The intent is to have a booster capable of lifting exploratory craft for Luna and Lagrange Point exploration, with multiple launches it could do a Mars mission.
In the meantime we are supposedly going to fund the Entrepreneurial Space companies to compete for ISS supply including crew launch and recovery…..
But if we have the ESpace why do we need SLS. If SLS is going to need to do multi craft build to go further than Luna or the Lpoints why not focus on building up our space infrastructure and refueling capability to support a common set of commercially viable launchers lofting the parts for assembly of the earlier and simpler systems in orbit. It may seem more expensive at first but in the long run it will become cheaper because the launchers are cheap on a per use basis.
OK I’m sure they’re promising that SLS will be real cheap per lb to launch because it uses proven technology and it has the advantage of being bigger (bigger is generally more efficient in this game.) But its a Gov’t program w/infrequent launches, using technology that has been chosen to save money up front. Not a promising Start.
And it’s quite possible that one of the driving factors in choosing solid booster over pure liquids was to keep the manufacturer in business (I believe there is only one US supplier at this point) Solid fuel rockets are brute simple, on the surface, but brutally complex in detail, and the only other significant market for the stuff is weapons. With the wind down of the cold war and the use of solids for various boosters the solid rocket industry has hovered on the brink of bankruptcy. That means the supplier will have the ability to hold NASA over the barrel for providing the boosters.
So the SLS remains the Senatorial Launch System and a yoke around the neck of our future in space…..Its a pity we didn’t build this system twenty years ago, when it would have had a positive impact….