Remember the Bob Zubrin who cast scorn on the idea of propellant depots?
Well, now he has a new proposal:
Zubrin’s concept is, at its core, a space access subsidy program. Rather than spend billions on new launch vehicles, he envisions NASA instead spending a modest amount of money—he suggested $1.2 billion a year, about six percent of its current $18.5-billion annual budget—buying the most “cost-effective” launch vehicles available. That cost effectiveness would be some function of its price and payload capacity; Zubrin has a particular preference for SpaceX’s proposed Falcon Heavy, which could launch up to 53 metric tons into low Earth orbit (LEO) for as little as $80 million a launch.
NASA would then, in turn, resell that launch capacity to itself, other government agencies, and the private sector, at the artificially low price of $50 per kilogram, or about $2.65 million per fully-loaded Falcon Heavy. Those launches, he said, would take place on a regular schedule, regardless if the capacity on each vehicle is fully subscribed. “You don’t hold the train in the station until it fills up,” he explained. Any excess capacity would be filled with consumables like water, oxygen, and propellant, which could be stored on orbit for use by any interested parties.
Emphasis mine.
In what does he propose to store the propellants, if not depots?
I should note, though, to be fair, that he wrote the PJM stuff a few weeks ago, so it’s possible he’s changed his mind.
Just thinking about Brayson Cycle devices. The real goal isn’t the temperature so much as the radiative heat flux at a given temperature.
A one meter pit on Earth is basically a completely pointless method of dumping heat.
Yeah launching to LEO or L-1 could better in terms of lowering launch costs. But having rocket fuel at the Moon would make a NASA lunar manned mission cheaper, so it’s better for NASA.
I don’t understand what you mean. Why would it be cheaper for NASA to have propellant on the lunar surface than at L1/2? Of course, eventually you would want NASA to buy propellant on the moon. The market could then decide the right time to stop flying in propellant and to start producing it locally.
“I don’t understand what you mean. Why would it be cheaper for NASA to have propellant on the lunar surface than at L1/2? Of course, eventually you would want NASA to buy propellant on the moon. The market could then decide the right time to stop flying in propellant and to start producing it locally.”
“Of course, eventually you would want NASA to buy propellant on the moon. ”
I don’t want NASA to wait. It is slow enough already.
I want NASA to explore the Moon to determine if there is minable water.
I don’t want NASA to mine lunar water.
I don’t want NASA to wait for lunar water to be mined.
After NASA have finished exploring the Moon- and it’s finished as far as I am concerned once it’s determined if there is or is not minable water.
Though NASA can do other things also. It can characteristic various different locations on the Moon where there is water and other information which could useful for any companies thinking of mining lunar water. NASA can also explore the Moon for other minable resources- and characterize these areas.
NASA could also choose to demonstrate how a mining operation could function- so something on a very small scale-total cost of doing this well below say 1 billions dollars.
So once NASA is finished exploring the Moon, it ends Lunar exploration as a major program and start either Asteroid mission OR manned Mars.
I think if NASA doesn’t find there is minable water on the Moon, it should consider exploring asteroids, rather than starting a Manned Mars.
Or said differently, I don’t see much purpose in doing a Manned Mars without the being “space markets” or the potential of space markets.
And what I mean by space markets would things like fuel depots, lunar water mining, space tourism to LEO and beyond, etc
So, if there wasn’t minable lunar water, but there was significant space markets, then perhaps then NASA should do a Manned Mars program.
So if there is a possibility of Mars colonies occurring, within say 3 decades after NASA lands crew on mars, then Manned Mars makes some sense. If it’s 4 decades or later, it makes far less sense.
“I don’t understand what you mean. Why would it be cheaper for NASA to have propellant on the lunar surface than at L1/2? ”
The simple answer is NASA needs 1/3 of the rocket for the crew to get to the Moon.
Or with any hvy booster available now, with single launch NASA could put crew on the Moon, and by refueling it on the moon, leave the moon. And it would also need another launch to put a Earth return vehicle in lunar orbit or L-1.
Now if private sector wants to put space station in L-1, the NASA earth return vehicle could dock with it, and lunar ascent vehicle could dock with it. And NASA could pay the private sector space station owner by giving them the the lunar lander. If no space station, then NASA would need to dock the earth return and lunar lander, and then throw away the lunar lander.
So for NASA it would be less expensive to make as many lunar landers as it has lunar manned missions. Having many lunar landers means lunar mission doesn’t grind to halt if “the One Lander” fails in some way. And any delay months or years in lunar program costs far more than the cost of lunar landers.
So, as far as NASA buying rocket fuel, all it really needs is to buy rocket fuel on lunar surface. For Manned Mars, NASA should buy lots of rocket fuel in L-1. But NASA should not wait for lunar rocket fuel to made on the Moon for the Manned Mars- obviously it would buy it if it was competitive to rocket fuel shipped from Earth. And it should stage for Manned Mars with this possibility in mind- and for other reasons.
@gbaikie:
I still don’t understand your point, since I’m in agreement with most of your goals. Are you perhaps thinking the propellant would have to come from ISRU? In that case it wouldn’t help establish a propellant launch market and it wouldn’t contribute to lowering launch costs. Once we have cheap lift we’ll definitely want ISRU too, and since it will take time to set up we could build up the ISRU infrastructure using mission fueled with propellant launched from Earth.
I don’t want NASA to wait. It is slow enough already.
Absolutely, that’s why I’m arguing for buying propellant at L1/L2, not in LEO let alone at the lunar surface. It’s also why I’m advocating use of storable propellant (specifically MMH/NTO) and existing spacecraft engines (AJ-10).
As for water, although it would be the easiest source of oxygen (and hydrogen too), it’s not the only source of oxygen. Oxygen can also be extracted from regolith. It would require even more energy than electrolysing water, but it would be feasible. I would want to make sure we don’t make commercial propellant launches dependent on there being lunar water.
The simple answer is NASA needs 1/3 of the rocket for the crew to get to the Moon.
If you only provide propellant at the lunar surface then you’ll need a larger launch vehicle than when you can refuel earlier, at L1/L2. Once you can refuel even earlier, in LEO, you can use an even smaller launch vehicle. But L1/L2 is good enough for now, as we could preposition the lander and transport crew capsules with existing launchers.
So, as far as NASA buying rocket fuel, all it really needs is to buy rocket fuel on lunar surface.
It needs much less than that. As far as I can tell L1/L2 is the easiest option.
Or with any hvy booster available now, with single launch NASA could put crew on the Moon, and by refueling it on the moon, leave the moon.
Not with a single launch. You could use existing launchers though if you launched the lander and capsule separately. You could do this with a repeated 2 launch scenario. For each payload (lander, capsule, propellant, cargo) you would use LEO rendez-vous of the payload with a cryogenic upper stage, then dock and go on to L1/L2. To make this work you would have to launch the lander dry to reduce its mass sufficiently, unless it is very small. If launched dry you would then have to refuel it at L1/L2.
Once the lander was in place at L1/L2 fully fueled, you could launch a crew and capsule to the ISS. Inside the ISS they could await their launch window and a separately launched cryogenic upper stage which would take them to L1/L2. Once there, they would dock with the lander, transfer to it, undock and do their missions. At the end of their mission they would ascend to L1/L2, dock with the capsule, transfer to it, undock and return to Earth.
then throw away the lunar lander
Or refuel it at L1/L2.
There’s a far better method for truly breaking the chicken-and-egg problem:
Have the government guarantee, say, a $20 billion prize (2000x the historical X-Prize) to any domestic private entity that is the first to develop and deploy a launch system which in operation and with independent auditing decreases the cost to orbit to $300/kg or below within 15 years, launching thousands of tons.
If nobody does so, it costs the government nothing. If someone does do so, the cost of the prize was relatively a small price to pay compared to the future benefits from 1-2+ order of magnitude launch cost reduction, to current $200 billion/decade NASA spending, etc.
Win/Win or more precisely No-Loss/Win.
There are ways to do that. Wikipedia articles on StarTram, Maglifter (rocket sled launch article), Sea Dragon, etc. give a decent intro with references.
Some legal details could be worked out for some possible complicated scenarios like if multiple entrants were more or less meeting the criteria. But it’d solve the current problem of being unable to guarantee near-term payback to investors, as today’s world launch market is nearly zero tonnage by the standards of other transportation (200 tons/year, which would be < $0.6 billion a year if it was < $300/kg instead of currently shipping anything to space costing around its mass in gold).
That’s only a better plan provided NASA gets out of the manned spaceflight business in the mean time. As a proponent of limited government I’d be in favour of that while as a space enthusiast I’d be somewhat disappointed.