Jon Berndt has an article in the current issue of the Houston AIAA newsletter on the subject of heavy lift, citing yours truly, among others. (Warning, it's a three meg PDF). My only quibble is that he misses one of the other problems with a heavy lifter--lack of resiliency. If we develop an exploration architecture that's dependent on heavy lift, then we should have multiple means of providing it, which means two development programs with inadequate flight rate to amortize the costs.

Along similar lines, Bob Zubrin has a long essay on space policy in The New Atlantis that's now available on line, with a harsh critique of NASA, including the Bush-era NASA and Sean O'Keefe. Surprisingly, I agree with much of the early part of it (though as always, the tone is a little problematic). I don't agree with this:

The ESMD plan requires a plethora of additional recurring costs and mission risks for the sole purpose of avoiding the development cost of a big new rocket—a heavy lift vehicle (HLV). Yet, since one goal of the Vision for Space Exploration is to get humans to Mars, an HLV will need to be developed anyway.

He states the latter (the necessity of heavy lift for Mars) as though it's established fact, rather than Bob Zubrin's opinion. He doesn't seem to support it in any way, except for his ongoing complaints about the "complexity" of multiple launches. He also repeats the flawed argument for heavy lift that I critiqued a few weeks ago.

He concludes, of course, with his proposal to go to Mars, go directly to Mars, do not pass go, do not collect 200 dollars. Except, in the tenor of the times, he's saluted the Moon by pointing out that his plan allows us to go there, too. He's explicitly calling for a revival of the Apollo mentality, not understanding why Apollo ultimately failed in terms of opening up space to humanity.

There is no question that his plan is technically feasible. But I don't think that it's either affordable, or sustainable (nor are ESMD's current plans, which have their own problems). In either case, we are spending far too much for far too little, because we don't recognize the real problem--the cost of access to orbit itself. Until we address that, and creatively, we will be doomed to continue spending (and wasting) vast amounts of money for little return on our space dreams.

Even at $2,000-$3,000/lb to LEO, $15 billion can afford 5,000,000 to 7,500,000 pounds to orbit (100-150 50,000 lb payload launches). If NASA got into the space access subsidy business instead of whatever business it's in now, private enterprise would find a way to put the pounds to sustainable and profitable use (albeit at first only with the subsidy).

We do not have a crisis of physics. Merely economics and politics.

Zubrin has a habit of stating opinion as fact without qualification. He is an interesting writer, but I have been frequently annoyed by some of his "statements of fact" in "The Case for Mars" and other writings. Given the number of problems I have found, I wonder how many more I have missed. He is thought provoking, but I don't trust him, even a little.

Bob's a nut. (Oops, did I say that?)

I do enjoy his enthusiasm. And I applaud his creative mission design and more importantly the vim he uses to get it out into the public consciousness.

The idea of using in situ resources is now conventional wisdom. The idea of surface rendevzous is a serious contender. Multi ship redundant designs are acknowledged for their benefits. These ideas may have existed before, but they are given credibility when packaged and promoted in a viable scenario.

On the other hand, others have argued along economic lines that multiple independent launchers will prove cheaper, more robust, easier to test than HLV. These arguements are compelling, and will win the day eventually.

I find it ironic that Bob argues against BattleStar Galactica ships to Mars but he misses essentially the same point about getting to LEO.

--Fred

Note that Sam's 100-150 launches might maybe get you to the point where you get some economy of scale, not to mention some measure of improved reliability. OTOH, for simply lobbing bulk material into orbit (e.g., 100 metric tons of water), you might not need much in the way of development costs. In fact, that might make a good experiment (i.e. a prize competition) for seeing just how cheap one can be - after all, even a 50% failure rate might be tolerable for this application.

The point is that if there's a new booster (or boosters) to be built, then it ought to be sized for the actual applications. Things like the costs (both $$ and mass/volume) of docking mechanisms vs. # of launches need to be considered. Doing heavy lift for stupid reasons (or simply for some more Freudian reason) is wrong, but so to may be doing a gazillion smaller launches, if it involves too much parasitic mass or in-space complications. This is actually one of the more interesting system engineering problems (IMHO), particularly given the existence of boosters whose development costs are already sunk.

- Eric.

A 5 segment RSRM with a cluster of RL-10s for an upper stage - - if ordered in quantity - - might well achieve $1000 per pound for bulk delivery of crewless cargo without ANY new technology.

"Zubrin has a habit of stating opinion as fact without qualification."

Do you intend to qualify that opinion ;) Ha!

"I find it ironic that Bob argues against BattleStar Galactica ships to Mars but he misses essentially the same point about getting to LEO."

Does he? His point is that HL is a practical (direct) way to Mars without the added risk of orbital assembly. He's argued against the space shuttle as essentially an RV (=Battlestar?) So I don't believe he missed the point.

You may argue that it's the wrong thing to do, but you can not argue with the fact that HL is a useful capability.

Agree with him or not, Zubrin has vision. I wish more people did.

The problem is not the "pounds" to orbit, its the number of pounds in one go and the configuration of those pounds. This is not just about the physics, politics or economics; it's also about the logisitics. For certain components there will be a volume as well as mass constraint.

FOr bulk launches which are not critical path nor volatile you could use the "lots of smaller launchers" model. But there will be bits that will be in the critical path - potentially, if you are limited in launcher volume you may end up needing to have several time critical and critical path components needing to be launched in relatively short periods of time where you can't afford a launcher loss. This doesn't get any better with large launchers either - but the problem has to be worked around.