The command module will need full life support, docking port, air lock for Moon walks, limited cooking cleaning & hygiene facilities. storage space, sleeping area, internal cargo area, external cargo space and controls. The XEUS will provide the propulsion and possibly the navigation.

Right! So we keep it and learn new ways to use it.

The International Space Station can be extensively modified, enlarged, and improved.

Old modules can be de-orbited.

Keeping the ISS permanently for research, testing of new space technologies, training of international Lunar crews, storing supplies and propellant, Earth and space monitoring, building and maintaining spacecraft, and the stacking or staging of missions to the Moon, asteroids, and Mars in the nearby and relatively safe harbor and significantly radiation reduced environment of LEO is a wise choice.

The ISS was built in large measure because of the real opportunities it offered to teach a diversity of humans and nations how to peacefully and productively work and live together in LEO and on the Home Planet while learning, testing, and evolving the many skills and technologies needed to explore space.

The political, diplomatic, economic development, and modernizing cultural usefulness and influence of the ISS are far from being fully exploited.

Many commercial modules could eventually be attached to the evolved and much larger ISS.

The SLS and other large launchers can be used to launch the needed new and much larger modules and other structures.

The ISS in LEO is useful, will remain useful, and has evolving and potential capabilities that should not be thrown away.

Solid rocket motors power our nuclear delivery systems.

Solid rocket motors power our anti-missile systems.

Solid rocket motors power our air to air missiles.

Solid rocket motors power our air to ground missiles.

Solid rocket motors may eventually power our anti-NEO missiles.

The only real way to carefully maintain that large capability to produce solid rocket motors, test, and significantly improve its technological base is to actually be using that capability to routinely evolve, build, and fly various types and sizes of solid rocket motors.

The evolving SLS and its evolving, powerful, and efficient solid rocket motors also peacefully and yet effectively and consistently demonstrate the diverse and high technology military and space capabilities of America and thus serve as a useful deterrent to large wars.

The military folks like to keep a sharp edge on their swords and other weapons because they know a dull edge won’t cut much of anything in a war and won’t do much to help deter a potential large war or win a small war.

Evolving and maintaining a sharp edge to our extensive solid rocket production capability through actively using it for peaceful and trust building international space missions while it also directly makes an extremely valuable contribution to deterring large wars and winning small wars also means it should not be thrown away or diminished with a narrow and dangerous ‘penny wise and dollar foolish’ mentality.

If managed properly the DSG habitat module will be the flight test prototype for the life support systems of the lunar base.

In my view that lander with devices to render ice into water and propellant are the critical enablers that need to be talked about. In this respect the Orion is indeed a turkey right now. Until we have shielded habitats out there for people it is not necessary.

NASA can take on new missions and discard others like any agency. And their budget can go up. And they can be pointed at colonization. Saying that is not going to happen and then in the same comment saying “someone” is going to live on Mars is bizarre and makes little sense.

There is no reason to go to Mars. It is a scam.

The Moon is the place where the resources are close and in a shallow gravity well. The Moon is where colonization can begin as a public works project- as Gerard K. O’Neill envisioned.

Mars, like LEO, is a dead end.

It’s harder to see the argument for anything human beings need to use. Unless you want a lifeboat option. All that’s really needed is a simple insulated fuel tank you can transfer LOX to and from. And possibly some modest power and maneuvering bus (esp. if you stick it in LLO where mascons must be dealt with). Any crew capsule will have adequate life support to wait for any orbital phasing anyway.

Eventually, someone *is* going to live on Mars.

I tend to agree Mars is not as promising for human colonization as some think (even with full terraforming that we are not capable of, we still don’t know how humans can live and reproduce in .38G – maybe it’s doable, but we simply do not know yet). But the interest *is* clearly there. Some hardy souls are going to try it; if not Elon Musk, someone else will try it by the next century.

And if that certain someone is willing to pay for it – let ’em try. Something will be learned in the process even if it doesn’t succeed very well.

But NASA is not going to colonize anything, on Mars, on the Moon, or in orbit, or deep space. That’s not in their statutory mission. Nor their budget. Tech research and radar mapping the surface of Europa is the sort of thing that’s really their forte. Colonization will require some other yet-to-exist entity, public, private, or a combination of both.

At most, you need only a power module and perhaps just a simple universal hab adapter for transfer to a lander (or use as emergency lifeboat). Anything beyond that should be offered to commercial operators if they want to add on to it through spare ports, to be launched on commercial launchers.

I think NASA can afford a lunar surface station, or a DSG – but not both. A simple depot might be a possibility in combination with the (presumably ISRU capable) lunar surface base. But that’s it. The money is just not there otherwise. And if I can only have one or the other, I would rather have the surface base.

2. Regarding SLS’s costs: “A faster pace of a lunar surface return could bring these costs down, although they would still be in the range of multi-hundreds of millions of dollars per flight.”

But that raises the question of how you pay for it.

Simply splashing or turning over ISS alone won’t cut it.

SLS right now is planned for a flight every other year, then rising to once a year or so by the mid-2020’s. If you want to increase the rate of fabrication of cores at Michoud, it will require (according to Charles Bolden) just about doubling the workforce, and other plant modifications. So there’ s a major capital investment up front, and that is going to offset a certain amount of economy of scale advantage.

And then, well, you need to come up with the money to pay for actual payloads for all these flights. Right now, SLS doesn’t have any payloads even for the few flights it *can* manage. And now we learn that NASA might be forced to build a new launch tower, since the cost of modifying what they have to accommodate the EUS may well be more trouble than it’s worth.

The concern about SLS is that it’s not affordable at *any* tempo.

That 8.4m fairing is nice. But it shouldn’t be a non-negotiable for payloads. ULA offers a 7.2m fairing for Atlas V; Blue Origin has just announced a 7m fairing for New Glenn; and SpaceX is apparently open to wider fairings for Falcon Heavy (now rated at 64mT to LEO in expendable profile). Given the vast differential in cost for these launchers versus SLS, it’s hard to say the modest increase SLS offers can justify using it over the alternatives now or soon to be available domestically.

There’s only so much money available for a lunar program (which I think we all want). So it’s a question of how to get the most out of what limited funds are going to be made available by Washington.