Great article, Doug.

It would be a dream come true to see government support of ULA ACES hardware, SpaceX, Blue Origin, and other players in an effort to establish infrastructure on the moon. I believe it is doable if NASA wisely allocates its resources to the best performing providers. RPM PPPs are definitely the way to go, in my opinion.

NASA administrator nominee Bridenstine seems committed to RPM PPPs. However Bridenstine's confirmation seems iffey. I am hoping lunar advocates both liberal and conservative will write their representatives and senators. I hear Bill Nye of the Planetary Society may endorse Bridenstine. Endorsement from Nye and a few other widely accepted science advocates might be sufficient to get enough Democrat votes for Bridenstine's confirmation. Getting a toe in the door towards opening the solar system as a new frontier should be a bipartisan goal.

Without Bridenstine I am pessimistic Trump's administration could make much headway towards establishing lunar infrastructure.

"I bet it would be cheaper to launch water from Mars and send it all the way to Earth orbit than get it from the moon!"

More than double the delta V budget as well as launch windows only every 2+ years as well as 8 month trip time. That is a clueless bet.

With delta V budgets greater than 9 km/s it is very difficult (if not impossible) to build economic, reusable spacecraft. You have dry mass fractions of 5% or less. And that fraction must include payload as well as structure and thermal protection (if you're doing re-entry).

With an extra-terrestrial propellent source, space craft could move about the earth moon neighborhood with delta V budgets of around 4 km/s. Not only could they have a much higher dry mass fraction, but these spacecraft would never have to endure an 8 km/s re-entry.

So a lunar propellent source would make it much easier to move about our local neighborhood where all our important commercial and military orbital assets dwell.

The moon is about 2.5 km/s from EML2. And EML2 is about 1 km/s from Trans Mars Insertion. If an interplanetary vehicle could stock up on propellent and life support consumables at EML2, it would cut gross lift off weight from earth's surface more than four fold. It would also make it much less difficult to re-use the interplanetary vehicle.

Okay, give me a hillbilly accent if it makes you feel better. Still doesn't defend Tom Murphy's math. Just as I said - Murphy's do the math crowd doesn't do any math. If you choose to support your stance with obviously wrong arguments you are indeed "agin" any reasonable person.

But maybe you aren't defending Murphy's bad math. You're merely stating with absolute certainty that the need for robot maintenance is a show stopper.

There are robotic probes that have been functioning well for decades sans maintenance, thank you very much. Yes, a robot capable of building infrastructure is on a different level than the Curiosity Rover. But making something like B.P.'s ROVs more durable isn't an insurmountable goal.

Much of the routine maintenance such as cleaning optics or tightening mounting bolts can be done by other robots.

And early mining endeavors needn't be beyond the reach of earth's supply line. A rock parked in lunar orbit is about 4 days and 3.5 km/s from Low Earth Orbit. Launch windows open constantly. Light lag latency is 3 seconds. Same is true of a mine at the lunar poles except a lunar facility would be 6 km/s from LEO.

With 4 day trip times It would even be possible to occasionally send a human to help with maintenance. An intermittently occupied Bigelow Hab needn't be the same size and complexity as the I.S.S.

"You really shouldn't take others for task for getting things wrong, , when your own plans rely on capabilities that not only don't exist, they aren't even in the pipeline."

Presenting your questionable opinions as indisputable fact doesn't persuade me.

By "facing reality" you mean meekly accepting the arguments of nay sayers like Tom Murphy or Charlie Stross?

Murphy's arguments are wrong. The way he patches conics would get him an F in orbital mechanics 101. And Murphy's asteroid retrieval scenario described in "Stranded Resources? His numbers are off by 3 orders of magnitude.

Stross' argues it's too hard to lift canned meat out of an 11.2 km/s gravity well. (Canned meat is his term for humans and the massive habs needed to keep them alive).

Stross may not have noticed but robots are becoming more able. British Petroleum uses R.O.V.'s to build sophisticated infrastructure on the sea floor. Robots are becoming semi-autonomous. Light lag latency can be largely mitigated with features like collision avoidance.

Can P.R., D.S.I. or a similar entity use robotic avatars to build infrastructure on other bodies? I'm betting they can. Humans need not be present to build shelters, extract ISRU propellent and life support consumables. Once these things are accomplished, it's no longer necessary to lift canned meat out of an 11.2 km/s gravity well.

Space meow boys like Stross and Murphy enjoy snickering at "space cadets". They (correctly) note many space cadets are long on wishful thinking and short on math skills. However the space meow boys are just as innumerate as the most clueless space cadets. And not all space enthusiasts are innumerate.

Is it doable to open a new frontier? That is still an open question. The addled arguments of Stross and Murphy not withstanding.

Yeah, space enthusiasts are out to trash the planet. That's why Elon Musk is aggressively pursuing solar energy and electric cars.

Most space advocates I know of are well aware that our planet is a finite, fragile place. They are more likely to insulate their homes, drive cars with good mileage, etc.

It's disappointing to see this horribly stupid straw man come from the head of Google X Labs.

I agree that a LEO centrifuge is desirable. But I'm disappointed with this article. No mention of Valeri Polyakov. No mention of Dizio's research.

An exciting report!

Successful government-private partnerships have built U.S. transportation and communication infrastructure. I believe such partnerships are needed for space infrastructure.

Besides helping with deep space missions, lunar propellent could make cislunar ferries possible. Easier access to geosynchronous and other important earth orbits would have huge commercial and military benefits.

But we still don't know if the volatile deposits are rich enough to make a propellent mine worthwhile. Prospector rovers to the cold traps should precede humans flights.

Besides water and continuous sunlight at the poles, temperature swings are relatively mild. The constantly illuminated plateaus are thought to be -50º C plus or minus 10º. The mild temperature swings mean less wear and tear on the infrastructure.

Great article. If we start using tethers, dead sats might have vaule from their orbital momentum alone. The issues you mention might be an obstacle to such salvage. So I linked to this article from my blog post Orbital Momentum as Commodity