It looks as though someone at NASA neglected to inform GAO that the answer to that question is zero. NASA plans to spend zero on 105- and 130-tonne SLS variants because they’ve cancelled development of all the parts needed to build them. No more advanced liquid-fueled boosters. No more high-energy upper stage with J-2X engines. Hell, no RS-25E’s for the core stage for that matter.

This article a week ago on Nasaspaceflight.com mentions a “possible” intermediate unmanned SLS mission between the unmanned EM-1 mission and the manned EM-2. It would supposedly occur in 2019 for the purpose of testing the Exploration Upper Stage with four RL-10’s as powerplants. This test would be needed if the Exploration Upper Stage was to be used on the EM-2 manned mission as NASA has lately been suggesting it would. NASA rules prohibit using an untested stage for a manned mission. This in-between mission doesn’t seem to have a designation yet. Mr. Earl goofed in calling it AA-2. You are correct, it’s not AA-2.

Personally, I think it ought to be designated UG-1, the UG standing for Underpants Gnome. I have no idea where anyone at NASA thinks the parts for this thing are going to come from.

Orbital-ATK’s contract for 5-segment boosters and Boeing’s recent contract for SLS core stages only provide for two sets of flight hardware each. Oh yeah, ESA is only on the hook for two Orion service modules too.

So, if EM-1 launches with the Interim Upper Stage (single-engine Centaur) a service module and an Orion capsule – as planned – then the putative UG-1 had better not fly with either a service module or an Orion or NASA will have insufficient parts to put together EM-2, the first manned Orion mission. Even so, it would mean burning up four more currently irreplaceable RS-25’s just to test fly a “Centaur on steroids” upper stage and boost a big boilerplate chunk of inert mass to – where? Then all NASA has to do is come up with two or three billion extra dollars they don’t – and won’t – have to buy a third SLS core stage and an extra flight set of 5-segment boosters for EM-2.

I think DEA is missing a good bet if they don’t raid MSFC right away. They’re smoking some damn fine crack down in Huntsville.

By that time Falcon Heavy might have been operational for a year or more. Maybe even returning cores for re-use.

What are SLS supporters going to say to justify the costs? “We need the SLS because the payloads we want to design are too large.” “The payloads we want to design are too large because they are needed to justify a large SLS type rocket.”

To everyone who is involved in designing future large payloads: Be smart. If you actually really care if your payload flies then design for a launch system that looks like it will actually be operational and available long-term. If something wonderful happens and a SLS sized lifter is suddenly available and affordable then your payloads will still fit and may even be bundled. But if a SLS type rocket never really works out as the affordable and available launcher your payload won’t automatically be disenfranchised simply because of its size.

Be smart.

Game Changing Technologies

— Donald

Solar Power for Deep Space Exploration

“I believe nom de plume answered this question earlier in this thread.”

No, all he did was reference a couple year old listing of technologies, systems, vehicles (it is really a hodge podge of different kinds of things) that might be priorities.

I am asking is anyone really working on these things?