You just won my yuk yuk of the day award…..

Paul is right on all of this of course. I went to some of these confabs like this and I was completely amazed that a core part of the Bush speech was rejected (ISRU) because it was not a mature technology.

Good figging lord!

the trick to moving forward would be a clear explanation on how we go from a permanently crewed Lunar ISRU station to a permanently crewed Mars base

I contend that part of the problem we have is the obsession with Mars. I consider it A destination, not THE destination. Our real goal is to become “space faring” — this is, the ability to go where we want, when we want and with whatever we need to do any job we can imagine. That requires a space transportation infrastructure.

I am proposing the development of cislunar space based around the harvesting and use of lunar propellant. If we have that, we can access all the “pay zones” of cislunar (MEO, GEO, HEO, the L-points and the lunar surface), for whatever activities people want to do there. Such a capability permits real return on investment (e.g., large (ISS-sized) communications complexes at GEO assembled by people and robots.) in the near-term and provides independent revenue streams. Moreover, the development of such a transportation infrastructure enables human missions to the planets.

The inevitable focus on Mars as some kind of “ultimate destination” for our civil space program over the last 30 years has done more to hold us back than any lack of funding has. The Mars obsession is a classic example of the adage, “The Better is the Enemy of the Good.”

Thus, the first step is an order of magnitude estimate of propellant production requirements:

10 mT —> enough to lift an ascender module or two;

100 mT —> enough to start making a significant dent in the cost of a Lunar base;

1000 mT —> enough to render an aggressive Lunar base essentially self-sufficient in propellant;

10,000 mT —> enough to enable an abundant chemical Mars architecture.

10,000 mT sounds like a lot: if we go with 5:1 mass ratio, that would require cracking 15,000 m^3 of H20; but at 10% water content with a 2-meter deep pit, about 9 acres per year would have to be exacavated: basically the size of your local mom ‘n’ pop gravel pit. Since the base would be self-sufficient in propellant, the annual overhead for the base could reasonably be expected to be on the order of $2B/year; thus propellant would cost ~$200/kg.

To get to this point, I’ve estimated the total downmass to be on the order of 400 to 600 mT. With beefy landers of the DTAL sort that ULA proposed and landing at the rate of 2 or 3 cargo flights per year, all the parts could be emplaced within 10 years of 1st landing.

The showstopper is going to power requirements: to crack and liquify that amount of propellant is going to run into multiple 10’s of megawatts.

Of the 10,000 mT of propellant produced at Lunar surface, up to 3,000 mT/year could be made available at an L2 depot. This is huge: for NASA to replace that capability at current launch prices of $10K/kg, it would cost taxpayers an astounding $72B/year! This is the sort of leverage Lunar propellant can provide!

The propellant would be lifted to L2 using a small fleet of DC-X-like VTVL SSTO tanker-landers with a capacity of
120 mT of LH2/LO2.

If the SLS ever gets built, I would recommend turning it into a 1-trick pony where its only job is to lift 120-mT tankers. This way, they could possibly get the launch rate up to the best Shuttle levels–say 6 flights per year. The Block II could lift these fully fueled at a cost of about $3K/kg; Block I LV’s could be topped off at a LEO depot.

Rather than disposing of these modules at L2, they should be stockpiled and used to construct the MTV’s. The ULA MTV consists of 6 120-mT propellant modules surrounding a central habitat module. And they propose sending 2 at a time. That’s 1440 mT per Mars mission just for the MTV’s. Note single stage MTV’s would have a delta v capability of 11 km/sec–more than enough for round-trip, fully-propulsive Hohman transfers. If refueled in Mars orbit, they could get the 1-way trip to Mars down to perhaps 90 to 100 days.

Flying depots composed of clusters of 7 modules would have 840 mT capacities. We probably want to send 2 of those depots. These could double as giant L2-departure stages for deliver of cargo and landers to Mars.

Since launch windows open every 2 years, but round-trip Mars missions last longer than 2 years, thus in order to be able to launch missions every window, we would have to double the number of all spacecraft. That would take 52 120-mT tanker modules, but with 60 120-mT tankers sent to the Moon over the course of 10 years, there would be enough to make a spare MTV or flying depot.

As Marcel points out, a lot of the Mars development costs would have been paid for by the Lunar program. But it’s better than that: the beauty of the abundant chemical architecture is that if there is a design problem, it is solved by throwing propellant at it. Rather than being mass starved, the abd-chem architecture has more cheap propellant than it knows what to do with. No need for aerocapture. Landers and all interplanetary spacecraft would be fully propulsive. Martian ISRU can be taken off the critical path–no more need for CO2 sniffers–there is a reason we don’t do this on Earth….

In sum, there is no need for an exclusionary Moon or Mars, soup or salad choice: we can have the cream and we can have the sugar if we want! The path from A to Z merely has to be spelled out all the way.

Thank you for the comments. Note that I am NOT a “non-fan” of commercial space, but rather, have pointed out in past writings that true commercial entities use their own capital to develop and market their products or services and are not dependent on government grants and loans.