When you look at the BAH-prepared Executive [Cost] Summary of the NASA way-ahead for the Space Launch System (SLS), Multi-Purpose Crew Vehicle (MPCV), and 21st Century Ground System (21CGS) Programs, here’s what to remember:
All three Program estimates assume large, unsubstantiated, future cost efficiencies leading to the impression that they are optimistic. A scenario-based risk assessment, which excludes cost estimating uncertainty and unknown-unknown risks (historically major sources of cost and schedule growth), reveals all three Programs’ reserves are insufficient.
Decoded, this means once the programs get past today’s three to five years budget horizon, they are likely to cost much more than is being publicly discussed (and actual numbers aren’t even being discussed at all). More succinctly, these are all success-assumed programs.
So what to do? How about giving new space a chance? Otherwise, it’s a simple case of keep doing what you’re doing, keeping what you got. Still, a new space “solution” presumes that manned spaceflight adds value-added to Americans’ lives, so consider this from the comments at Space Politics:
The problem with SLS and with MPCV is more fundamental than the cost overruns. It is unclear that they provide any benefits that the taxpayers, or other customers, would consider worth even the original cost.