This thread is certainly interesting and entertaining! It is
good that someone at NASA at least is paying some attention to this type
of ISRU-based architecture, although i believe that there are many
optimistic assumptions in here that will not pan out should this be
pursued further. The study is short on the technical details,
unfortunately, as that is where the meat of the concept ultimately
resides. Nonetheless, here are my comments.

1. Two basic elements that make this work (Phase 3) are the RLM and
the in-space transfer. On both of these, i question the assumptions.
The mass fraction for the lander is just too optimistic, and i believe
cannot be built. The Isp for the RL10 would need a very large engine
bell for gas expansion, but there is no room on a lander to get it under
there unless there are huge landing legs. this vehicle would be very
large in mass, but no discussion was made on how to get it built in
space. A single stage reusable lander needs even more structural margin
due to fatigue loading, and they don’t mention it. The same comments
hold for the mass fraction and design assumptions for an aero-braking
in-space reusable transfer stage. This is a very difficult problem to
design for reusability while giving grossly optimistic numbers for
performance. Aero-braking will generate a LOT of heat, yet the H2 tank
will want to stay really COLD, and so that challenge will cost mass.
Air density unknowns will result in large error bars on exit velocity
which will be compensated by extra fuel, a factor not taken into
account. On the plus side, i note that Phase 1 and 2 landers use Direct
Trajectory profiles. Good deal, as long as one doesn’t have to
rendezvous with anything first.

2. I see no technical reason for human sorties to the equator. Maybe
the authors assume that politics requires some human presence to keep
such an architecture alive. I don’t believe that any technology
development is needed on key GN&C systems, nor on landing systems enough
to have a specific mission for equatorial human sorties.

3. I question some of the power requirements in the report, especially
regarding the power requirements for ISRU capabilities. Are the rovers
nuclear-powered? If not, you would need to charge them every time you
exited the cold trap, and that may require a traverse of a few
kilometers. A valid operational concept with timelines and power
profiles would show that they are too optimistic. Similarly, in Phase
3, electrolizing that much water is power-intensive. I see they bring a
nuclear reactor. How big is it and what can it do? No details usually
means that they have not thought in detail about the operation.

4. The concept of an International Lunar Authority is interesting,
although in practice i would see this more as an international
government body because of the initial participants being all
governments as opposed to commercial entities. The cost is just too
high to make this a commercial based endeavor (If it was possible, would
not some commercial entities already have developed one?) Much like the
lack of progress on the grand lunar X-Prize, the commercial costs are
too high for a questionable ROI, and even if so, positive ROI is far in
the future on general financial timescales. As well, because the costs
are so high, i believe that initial customers will all be governments.
If so, there is no major benefit for PPP, since the government would
have to pick up all the cost (no price-sharing with other customers).

5. Following the above comment, PPP is not a panacea; it has
applications where it is good, and others were it is not. For launch
vehicles, there are others in the industry that have been building
launch vehicles for a long time so that the basic functionality is
well-known and systems are generally well understood. That is not the
case with reusable landers and in-space reusable transports. If the
government is the sole customer, they (the government(s)) will drive the
requirements. If they drive the requirements, requirements will drive
the costs, much like the COTS ISS cost that has been much debated in
this blog thread. It doesn’t matter what the generic quoted price is,
the true cost will be only known when all the requirements are in, and
if history is any guide, it will be factors higher than the quoted
generic prices.

6. I think the idea of non-government ownership of assets which will be
solely used by government entities is non-viable for the basic
infrastructure blocks. If the government is going to generate the
requirements, operate the hardware, and repair it when it brakes, then
it is hard to imagine why this would be a good deal. These systems will
break down and will need to be fixed. Unless there are other commercial
crew on-site to fix hardware, this doesn’t seem to be a good idea to
me. Note that SpaceHab was at most a 2-week mission and would be
returned every mission for refurbishment. Yes there were some basic
standard contingency procedures, but there are just too many unknowns
for NASA to allow for ownership of a critical element requiring in-situ
and unknown repair capabilities.

In summary, good idea to keep In-Situ human space architectures in the
national discussion (which by inspection would point to the Moon as the
proving ground), but this one to me needs some more polish.

Nothing else comes close.

As well as limiting the production of cores at Michoud and giving away one of the launch pads, the present administration is now faced with justifying billions wasted on the amazing exploding falcon and a deteriorating space station which will have a Boeing taxi ready just in time to be decommissioned.

All the while sticking with Mars as the “horizon goal.” Mars has too much gravity to land on easily, not enough to keep humans healthy, not enough solar energy to sustain a human presence, and no reason to really go there at such incredible cost. And in reality there is no way to go anywhere Beyond Earth and Lunar Orbit (BELO) without a nuclear propelled and massively shielded spaceship which can only be shielded with water from the Moon, assembled, tested, and launched from lunar orbit outside the Earth’s magnetosphere.

LEO is a non-nuclear dead end and Mars is too far away for chemical propulsion. The best destination was always the Moon and the best ride is the SLS and the best reason to go the ice deposits at the poles- yet billions continue to be poured into the space station to nowhere and not one but two taxis- and yes, we continue to pay for rides from the Russians.

With about a quarter century of lifespan left my only hope of ever seeing human beings leave Earth again is the next administration abandoning LEO and Mars and making the Moon the “horizon goal.” This would entail cutting off the corporate welfare to the worthless NewSpace companies and expanding the tooling and workforce at Michoud very soon.

The “Vulcan”? It is not a Moon rocket any more than the funky falcon faux heavy is.

I’m more excited about the development of Vulcan and ACES.
From what ULA is saying, Vulcan can outperform the Delta IV.
And I think it comes close to beating what Falcon Heavy is claimed to be able to do.

This seems to be referring to my observation that the study appeared to have taken the SpaceX assertion that the Falcon Heavy could launch 53 Metric Tons to LEO for $90 M and to have additionally assumed that the 53 Tons was all pure payload.

He seems to be saying that the study assumed a sort of Falcon Heavy Plus with “stretched barrel sections of the LOX and RP tanks” . This more capable version of the Falcon Heavy would have the additional capacity to take on the mass penalties for “the additional mass of fuel transfer and RCS propellant minus the mass of the 2t payload fairing” (not to mention the mass of rendezvous/docking hardware etc.) and still arrive at the original SpaceX claimed 53 matric Tons as pure payload delivered.

How very coincidental.

Throwing the B.S. flag on that one. The hobby rocket IS the poster child the child and the other “data points” are things like the Glory satellite fiasco and the Virgin Galactic fatalities. NewSpace is a scam and needs to end.
There is no cheap.

Not yet. The only reusable rocket engines to date were used on the shuttle and soon to be reused as expendables on the SLS. There will be no cost savings reusing that cluster of crummy little kerosene burners- it is cheaper to drop them in the ocean- it is a scam. Try again.

“That “hobby rocket” to which he refers so smugly just finished driving the venerable Delta rocket out of business.”

The hobby rocket just blew up- something the Delta has not done in it’s entire launch history. Since this puts the future of the funky falcon faux heavy on hold the Delta will be launching spy satellites for years to come. So says the Air Force the foreign born founder of SpaceX sued.

Stop making stuff up. Calling me a NewSpace hater is the only thing you got right. NewSpace is the worst thing that has ever happened to the U.S. space program.

Marcel