People need to land, on the Moon. More than one geologist needs to walk there, dig there in more than one place. Someone needs to go see the frozen water and sift it through their gloved fingers.
- Ed Kyle
Historically NASA has been dominated by the fixed launch cost of their vehicles. Like the guy in charge of the shuttle program said it cost 200 million dollars per month just for the shuttle to operate. That is about 2.4 billion a year. It really does not change much if there are 4 flights or 12 flights.
However using commercial launchers negates the need for these incredibly expensive launchers that NASA builds so that more money can be spent on actual exploration. If the cost to get to the lunar surface we can conceivably build a moon base that is sustainable like the ISS, but probably at first a great deal smaller.
Those "commercial" outfits will have their own fixed program costs. ULA, for example, gets something like $1-ish billion per year just to keep its launch pads and rocket factories open, whether it launches or not. (The Air Force said this week, BTW, that those fixed costs are going to increase significantly in the wake of the Constellation Cancellation.) The Shuttle program fixed costs are not just for the launch, but also for the astronauts, etc., something that ULA doesn't have to worry about (yet).
In broad, general terms, it costs X dollars to put a kilogram into orbit, regardless of who does the launching. NASA's real problem is that each Shuttle launch sends a lot of kilograms (more than 100,000 of them) into orbit, and thus costs a lot of dollars. The real reason that "commercial" crew launch would, or should, cost less is that ISS crew spacecraft are going to weigh one-tenth as much as a Shuttle orbiter. They should therefore cost one-tenth as much to launch, but that remains to be seen. NASA does not, for example, have to build a brand new Shuttle orbiter for each flight.
Going to the Moon is another matter. Although there are some clever ways to minimize the orbited mass needed for each lunar landing mission, the unavoidable truth is that a lot of mass, roughly the weight of 1.3 to 1.5 Shuttle-orbiters, is needed for each landing. Three-fourths of that mass is propellant. Another unavoidable truth is that more than one costly expendable spacecraft is needed for each lunar mission. Complex spacecraft, manned or unmanned, tend to cost on the order of a large fraction of a billion dollars per mission, each. In order to get to the Moon within existing budget limits, NASA will need to do the following.
1. Leverage the fixed costs of existing, or soon to exist, launch systems by using them for crewed missions.
2. Reduce annual budgets by reducing the total mass orbited each year compared to STS or Constellation.
3. Design slow-rate missions to efficiently use that mass.
One way to meet these requirements would be to use a storable LEO propellant depot that could gradually be filled over the course of many months, if not years. The depot could support a lunar landing mission once every 18 to 24 months, for example. Another way would be to launch lunar mission elements in pieces using existing cryogenic stages directly to L1, allowing the storable propellant elements to gradually assemble there, from where a lunar landing could periodically be staged.
Using these methods could allow an Apollo-class lunar mission to be staged with only five or six Delta 4 Heavy-class launches. If those launches could be spread over a couple of years (think about needing only one launch every four months), NASA could afford the mission - and the launch pad and crews would be able to support non-NASA missions during the launch campaign "gaps".
- Ed Kyle