Also, if we had spare resources, I’d agree with you. We don’t. _Anything_ that is not absolutely, unavoidably in the critical path to a minimum Lunar Base needs to be delayed until after the base is deployed. Even then, this is going to be almost impossible in the budget we have. . . .

— Donald

Yes the EELV’s are available, but they are not ready to launch a CEV. There has only been one launch of an EELV that would have the capacity to lift even a “small” CEV; that is hardly a proven vehicle. So I don’t see the development gulf between SRB launcher and EELV launcher for CEV being as great as you believe it would be.

Also, you and Karen both keep ignoring one key aspect of my argument. I am not saying that we should stick with EELVs forever, or even for very long. Even if we continued to use medium-class vehicles, I would only advocate using the EELVs until the SpaceX crowd come up with something better.

What I am advocating is using EELVs to get a start, either while (or more realistically before) developing the optomised transportation system and all the other stuff that engineers want to develop. Send a hand-full of crews there with the inefficient method, but get them there soon. They can use a small lab to develop the knowledge and equipment that Karen needs to do her mining, and get a lot of science done in the process. Then, you’ve got something to show for the VSE that justifies further investment.

I am not against your HLV, only against making it the first step of what will, in either case, be a long and drawn-out project lasting decades to thousands of years. But only if it gets started. Every journey starts with a single step; if you take ten at once you only trip and fall.

— Donald

And you are ignoring the costs of building enough EELV pads to support a launch rate that would enable us to build a Moon base in a reasonable period of time at 20 tons per launch. There would need to be 4-6 EELV launch pads to enable that number of EELVs to launch on the same day (in theory) to loft the same mass that one HLV could lift on that same one day. And then you still have the task of assembling those 4-6 “modules” while the HLV lofted payload is already on its way to the Moon. The supplier base for Shuttle derive vehicles is already in place (and with considerable political backing as I’ve stated before) and there is no reason to believe that the task of launching numerous EELV’s to get a require tonnage in orbit will require less of a standing army that one HLV would require. As for additional complexities are you saying a Delta IV is less complex than an SRB? Somehow I doubt that. Launching 20 tons at a time and assembling in orbit, even assuming no launch delays, is certainly more complex than launching everything on one HLV.

David: “What if neither if the two assertions above re SRB’s is true? Would that be a problem?”

The SRB designs thus far proposed do have greater lift capacity than any current EELV, that is a simple fact. As for being cheaper, that’s my guess. Do you have anything to refute my belief that an SRB is cheaper than a comparable (capacity wise) EELV?

David: “By the way, a five segment Solid Rocket Booster would be the first stage of the smaller of the two of Dr. Griffin’s proposed missiles. This missile would have an L2/O2 second stage. This newest NASA vision does not call for an all-SRB launch missile.”

An EELV based CEV launcher would in all likelihood require a second stage as well. Your point is…?

David: “Since you have not seen any “real” dollar figures, how can we be confident about your bet?”

Show me some real figures and we’ll see.

David: “Show us some data that backs up that alleged 50%.”

Delta IV Heavy 20-25 (depending on source) tons to LEO, 5-Segment SRB with SSME upper stage 29 tons to LEO. Do the math yourself; it comes to approximately 25-45% more capacity.

Donald: “Also, Cecil, your back-of-the-envelope figures assume no benefits from economies of scale.”

The more we buy the cheaper they become, but how much cheaper? To be truly affordable there would need to be at least a 50% reduction in the current $250 price tag on a Delta IVH. I just have very serious doubts of that ever happening.

I’ve still not seen any “real” dollar figures on DIVH vs SRB, but I think it is a real good bet that an SRB costs less than the DIVH $250 million.

Since you have not seen any “real” dollar figures, how can we be confident about your bet?

Given the SRB’s nearly 50% lift capacity advantage

— Donald

Of course we’ve been over all this before……

My real problem is with the Suttle-derived HLV, as you know. Again, this is something NASA gets to pay for by themselves, it adds to the number of launch vehicles we have to maintain, and under no conditions is it likely to have a high launch rate. Worst of all, the costs have to come before the Lunar Base, not after.

The key innovation of Mr. O’Keef’s idea, which has now been effectively abandoned, is to spend money on exploration, not launch vehicles, and to keep the whole thing within current budgets.

If you can develop Shuttle-derived HLV, medium-class SRB-derived, the CEV itself, lunar transfer vehicle, lunar lander, and lunar surface infrastructure all at once and keep the peak spending below $8 billion, more power to you. I am _extremely_ dubious.

— Donald

But if an SRB launcher is cheaper, and can lift more, what is the problem?

I’ve still not seen any “real” dollar figures on DIVH vs SRB, but I think it is a real good bet that an SRB costs less than the DIVH $250 million.

And even if NASA started using a dozen CBC’s a year, I doubt that would bring the piece price of the EELV down by more than 10-20 percent. It would never get down to the orginal estimate of $170 million.