“Why would they man rate the Delta IV?”

There are a lot of “what-ifs” that would have to happen to get to that point, but I would imagine the only way it would come about is if there were an agreement to cancel the SLS and fall back on using the “proven MPCV launcher”, which would be the Delta IV Heavy (used for the 2014 MPCV test).

Totally made up reason, of course, since in a fair competition the Falcon Heavy would provide more mass margin and cost less, but hey, if that’s what it took to cancel the SLS, I’d vote for it.

As to human-rating Delta IV Heavy, ULA stated back in 2009 that it would cost $1.3B.

“I do remind you that Lori Garver resigned her position as deputy administrator of NASA. Abruptly.”

Just because you weren’t made aware of her decision until it was made public does not mean it was done “Abruptly”. Since she was one of the longest serving NASA Deputy Administrators, I’d say it would have been more surprising if she would have stayed on longer.

“…and again and again, until I see progress towards cancellation.”

Oh, now you’re back on the cancellation effort again? It’s hard to keep up with you since first you wanted Congress to spend more on the SLS to make it reusable (amongst other things).

But hey, you want to help us cancel Constellation? Great. Just don’t act like a wacko and cause a distraction.

If what I am doing this month doesn’t work, I’ll try something else next month, and again and again, until I see progress towards cancellation.

I agree with Matt that the “SLS is needed for backup” argument was always a poor one, since it would cost far less to fund a second Commercial Crew provider.

NASA has stated many times that Orion/MPCV is not compatible with the ISS docking ports. The “backup” argument is a figment of Congress.

“The SLS is a backup for Commercial Crew to the ISS. With 2+ manned craft a government supplied back up is no longer needed.”

I agree with Matt that the “SLS is needed for backup” argument was always a poor one, since it would cost far less to fund a second Commercial Crew provider.

And unlike the few in Congress that are obvious SLS supporters, I have no doubt that the private sector can provide safe crew transportation to the ISS – likely far safer than what the government-run SLS/MPCV will be able to provide.

Ignoring the SLS/MPCV, the Soyuz continues to be the backup for NASA’s Commercial Crew if they only are able to contract with one provider. I hope that doesn’t end up happening, since demand for transporting people to LEO will appear much quicker if there are at least two providers. Two providers tells the potential market that they have options and redundancy, both of which make it more likely that new entrants will want to test out new space-related business ideas.

That being said, even if we do end up with just one commercial crew provider, SLS as an ISS crew backup was never an idea to be taken seriously. It’s not like there will be SLS cores sitting around in inventory, available to swap in if/when a commercial crew or Soyuz isn’t available. NASA would need to know years in advance of such a flight that an SLS needed to be built. And of course the cost for an SLS launch to ISS would make Soyuz per-seat costs look like a bargain.