Jeff Foust has a post on what the panel is considering. As some of my long-time readers might guess, my choice would be Option 5 — Flexible Path. We don’t need a destination — we need a vision, and infrastructure. Once we have the capability to get into the vicinity of various locations, and developed depoting capabilities, we can then figure out the best way to get in and out of the wells. And the easiest resources aren’t in deep gravity wells — they’re in shallow dimples.
[Update a few minutes later]
I would note this paragraph, having now read the full document:
The transportation infrastructure decisions (decisions 4 and 5) will be examined as a comprehensive trade space of launcher vehicles, depoting and destinations. That is, we will examine the possible in-space transportation infrastructure to all likely destinations for each of the launch vehicle classes, with each of the depoting concepts.
That is, they have accepted depots as interesting options to consider as a fundamental part of an infrastructure (which one must to have any truly promising options).
NASA Watch reports Buzz Aldrin is promoting depots as part of a Mars plan.
It’s worth noting that Jeff Greason is on the “Exploration Beyond LEO” subcommittee that released the document:
http://www.nasa.gov/pdf/365046main_HSF_Subgroups.pdf
At first I thought it was a little strange that he was on the beyond-LEO subcommittee instead of the “LEO Access” one, but I’m now pretty excited about it. The “Flexible Path” option and propellant depot analysis seem to have his fingerprints. đ
If you have a choice of producing a vehicle designed to go to one specific location or one that can go to any location… it’s a no brainer. It makes no economic sense to build a ship for a specific use when a general design may work even better.
Flex wins.
That said, I’d still like to hear that someone is working on a Mars lander đ
I still think for what the government plans to spend on getting to the moon a private company could sell passenger tickets and make a bundle.
Martinijn,
Yes, you need a market for the Lunar LOX and fuel depots for Mars missions will be one market.
How would one get the Lunar-derived LOX to where it’s needed?
(I assume the depots would be in Lunar orbit and/or one or more Lagrange points and/or LEO.)
With a reusable surface-orbit transport that used lunar LOX and either lunar fuel or imported fuel (for LOX/hydrogen, most of the weight is the oxidizer).
LEO tethers to catch in-bound lunar LOX tanks allow you to import to LEO both lunar LOX and delta v.
The same tether(s) used to catch in-bound LOX can later transfer some of that captured momentum to outbound cargo shipments, thereby saving fuel, thereby saving money.
Mine lunar momentum as well as lunar LOX.
Dr. Forward (now deceased) and Hoyt have done a lot of theoretical work in this area.
I find this passage to be excellent news:
That is, we will examine the possible in-space transportation infrastructure to all likely destinations for each of the launch vehicle classes, with each of the depoting concepts.
Depots should be considered in the context of every possible launch vehicle – such as EELV and Jupiter (Direct).
Depots are a leveraging technology that can enable and augment ANY chosen launcher system and if the Russian figure that out — with kerosene depots being easier that LH2 depots – we may have another space race on our hands.
Regarding space propulsion using in situ materials, the LOX/Al monopropellant slurry looks awfully interesting. I suppose solar thermal and nuclear thermal are also options.
Oh yeah, there is also LOX/LCH4 (if you can get the volatiles from somewhere like Mars). IIRC Nuclear thermal (and I guess solar?) can use other things than LH2 as reaction mass. I seem to remember a CO2 reaction mass nuclear rocket somewhere…
Frank,
At the start I assume some type of reusable lander, perhaps using some local fuel with the LOX for propulsion.
Eventually a mass driver or similar ground based launcher would be nice.
That actually is one of the advantages of the Moon. No atmosphere and the EML1 is always in the same position relative to the surface. Two great features for a mass driver system (or similar system) for delivering fuel into orbit once the volume demand justifies the cost for its development.
> Frank Glover Says:
>
> How would one get the Lunar-derived LOX to where itâs needed?
>
> (I assume the depots would be in Lunar orbit and/or one or more Lagrange points and/or LEO.)
> Rand Simberg Says:
>
> With a reusable surface-orbit transport that used lunar LOX and either
> lunar fuel or imported fuel (for LOX/hydrogen, most of the weight is the oxidizer).
I really find it hard to see how that could be cost competative with fuel shiped from Earth via a RLV – and the RLVs more useful and cheaper to operate then a Lunar surface to orbit craft could be. The launch costs from the Moon to most interesting Earth-Moon orbits would be less then from Earth, and your not buying a lot of extra lunar infastructure. For space high capital cost and low utilization drives costs. So a system with extra expensive infastructure is almost always at a disadvantage.
I really find it hard to see how that could be cost competative with fuel shiped from Earth via a RLV – and the RLVs more useful and cheaper to operate then a Lunar surface to orbit craft could be. The launch costs from the Moon to most interesting Earth-Moon orbits would be less then from Earth, and your not buying a lot of extra lunar infastructure. For space high capital cost and low utilization drives costs. So a system with extra expensive infastructure is almost always at a disadvantage.‘
I’m sorry, but none of this makes any sense at all to me. Are you really saying that it would be cheaper to deliver propellant to L1 from the earth than from the lunar surface?
> Iâm sorry, but none of this makes any sense at all to me.
> Are you really saying that it would be cheaper to deliver
> propellant to L1 from the earth than from the lunar surface?
Yeah all things being equal. Certainly its historicaly been that way given the high costs of operating a lunar to L1 launcher vrs Earth to L1 launcher. (ok historically is a extrapolation given the few lunar launchers ever operated. đ )
I hope you realize the old “its 20 times cheaper to launch from the moon due to the lower gravity well” saw is a myth? The ENERGY cost is 20 times less, but the energy cost from Earth to LEO is about a $0.5 a LB out of the $1,000 – $10,000 actual costs, so its not real helpfull.
A lunar shuttle can be simpler – but its also a extra cost system you don’t need to pay for if you launch from Earth, and servicing and operating it (not to mention the ISRU) on the moon is expensive with all the overhead adn support costs.
A lunar shuttle can be simpler – but its also a extra cost system you donât need to pay for if you launch from Earth, and servicing and operating it (not to mention the ISRU) on the moon is expensive with all the overhead adn support costs.
Assuming that you are visiting the moon anyway, a “lunar shuttle” is going to exist. I’m simply pointing out that it can deliver propellant as well as other cargo, and if the propellant is being manufactured on the moon, it makes sense to get it from there, and not from earth. And “historical” examples are utterly mindless, since there is no “history” from which to draw.
The question of how to get supply to a depot will be answered by the market assuming open competition.
> Assuming that you are visiting the moon anyway, a âlunar shuttleâ is going to exist.
That wasn’t my assumption in the ISRU issue.
>Iâm simply pointing out that it can deliver propellant as well as other cargo,
> and if the propellant is being manufactured on the moon, it makes sense
> to get it from there, and not from earth.
Makes sence in what way?
But the question was would it be cheaper to get it to LEO/L1/LLO from Earth or the Moon. That opens up a lot of system cost issues.
> And âhistoricalâ examples are utterly mindless, since there is no âhistoryâ from which to draw.
There was Apollo, and the LEMs cost a lot more to boost things to orbit.
Also there were the studies of Lunar sources of material or Earth based for SSPS programs, which showed it was cheaper to launch from Earth, especially to build something out of it.
> ken anthony Says:
>
> The question of how to get supply to a depot will be answered by the market assuming open competition.
One would hope – though certainly for NASA that’s unlikely.
I think Kelly Starks has a good point.
If you include the cost of the lunar-specific infrastructure, delivering LOX from Earth (via RLVs plus reusable OTVs) to L1 will be much cheaper.
Now, at the moment that we decide to “settle” the Moon, and thus decide to develop a reusable lunar lander, we will start supplying LOX to the L1 depot from the Moon.
Reading Rand’s quotes of Worden, it sounded like Worden was advocating avoiding gravity wells for awhile. I think this makes sense. Build in-space infrastructure like depots (LEO and L1) and reusable OTVs, as well as on-orbit assembly plus RLVs, and we get a pretty darned good set of capabilities.
At that point, it will be much easier to develop and settle the Moon.
FWIW,
TANSTAAFL
That wasnât my assumption in the ISRU issue.
It was mine.
There was Apollo, and the LEMs cost a lot more to boost things to orbit.
I have no idea what this means. Cost a lot more than what? And of course they did — they were thrown away each flight.
Also there were the studies of Lunar sources of material or Earth based for SSPS programs, which showed it was cheaper to launch from Earth, especially to build something out of it.
That was for manufacturing satellites, not delivering LOX. And they were in GEO. And not all the studies showed that. Some showed the opposite. It depends.
If you are manufacturing LOX on the moon, it will be much cheaper to ship it to L1 or L2 from there than to deliver it from earth.
>> The question of how to get supply to a depot will be answered by the market assuming open competition.
> One would hope – though certainly for NASA thatâs unlikely.
Thankfully there are other potential suppliers and customers than NASA.
>> There was Apollo, and the LEMs cost a lot more to boost things to orbit.
> I have no idea what this means. Cost a lot more than what? ==
The cost to boost things off the moon per pound with the LEM was higher then the cost to lift a pound from the Earth on a Sat V.
> Also there were the studies of Lunar sources of material or Earth
> based for SSPS programs, which showed it was cheaper to launch
> from Earth, especially to build something out of it.
> That was for manufacturing satellites, not delivering LOX.==
Its cost per pound to orbit regardless of it being a rock, a tank of LOx, or manufactured parts.
Though yes, a big fact also is the cost of the stuf. To launch ore from the moon, you need to launch a hell of a lot more to process into the finished part, then the mass of the finished part. And the finished part, processes ore, LOx will cost more to make in a remote isolated site with new equipment designed just for that — then to buy the same stuff on Earth, out of the huge market here. These costs also need to be considered in the total cost to get apound of – whatever – at your desired orbit.
> And they were in GEO. And not all the studies showed that. Some
> showed the opposite. It depends.
> If you are manufacturing LOX on the moon, it will be much cheaper to
> ship it to L1 or L2 from there than to deliver it from earth.
How could it possibly be cheaper to ship it to L1 from the Moon then to ship it to L1 from the Earth?
Or more basically why would you think it would be cheaper? Ar there special conditions that would allow a lunar launch to be cost competative with a Earth Launch?
>>> The question of how to get supply to a depot will be answered by the market assuming open competition.
>> One would hope – though certainly for NASA thatâs unlikely.
> Thankfully there are other potential suppliers and customers than NASA.
Right now there are no customers or supliers – nor a obvious other customer in the near term for depot suplied fuel/LOx.
The cost to boost things off the moon per pound with the LEM was higher then the cost to lift a pound from the Earth on a Sat V.
Which is completely irrelevant to the topic under discussion.
How could it possibly be cheaper to ship it to L1 from the Moon then to ship it to L1 from the Earth?
How could it not?
The cost of getting it to L1 from the moon is a small delta vee of a vehicle that doesn’t have to go through the atmosphere.
Right now there are no customers or suppliers
I said potential, which would include anyone with a vehicle that can reach the orbit of the depot. Potential suppliers are all potential customers as well because a vehicle that can supply the depot could also have it’s range extended for other missions (assuming fuel transfer can go both ways.)
>> How could it possibly be cheaper to ship it to L1 from the Moon then to ship it to L1 from the Earth?
> How could it not?
>
> The cost of getting it to L1 from the moon is a small delta vee of a vehicle that doesnât have to go through the atmosphere.
??
Yeah and the energy cost to fly from Chicaho to Cedar rapids is much less then Chicago to London â but the ticket prices are the same or less to London. Its cheaper to fly food in from the states then grow it in a Antarctic base. You can get oil from wells in Illinious, but generally the fuel for Chicago comes from the gulf coast. etc.
Ok, this deserves a more detailed answer. Sorry, it will be long.
The delta V (to quote Musk) is free. Fuel and LOx costs are under to well under 1/1000th the cost per launch â so we can ignore that.
Given the ships are likely close enough in weight and complexity, that they cost roughly as much to develop. Just like Concord and the Orbiter both cost about as much to develop given their similar weight and comparable complexity.
To lift a given amount of tonnage, assuming the Earth and Lunar craft are RLVs, similar tech, etc (no ion thrusters in orbit etc); youâd expect a similar weight craft. Lunar needing less delta-V, so it can SSTO from Luna to L-1 or whatever. Then boost back to a soft landing. Roughly ?? 200 times cargo weight in fuel and LOx? from Luna to L1 and back per flight?
Earth based RLV:
– could be a SSTO or stage + whatever.
-It needs 20 times as much power to get from Earth to L-1, then back to LEO, though return to surface it aero brakes.
-It needs about 20 other Earth to LEO flights to refuel a ship to carry the cargo to L-1.
Course currently the costs are pretty much dominated by fixed costs per year, and capital costs to develop the craft â with hardly any cost per flight, so one flight or 20 doesnât mater to the âprogramâ. However, at some point we hope the flight rate is higher so direct costs start to become more of a factor.
What are the flight rates from Earth to Leo vrs Luna to space? Obviously with the Depot refueling trick there is a lot more flights to LEO for the Earth craft â but ignoring that theirs still likely more traffic from the Earth to service tourists, industries, sats, your lunar base, etc. So more ships (lower cost per ship given economies of scale), more flights (lower overhead fraction per flight ).
And now â what does it cost to service and support you Lunar craft? Cost per flight to ship it spare parts? Cost per labor hour to service it between flights? Facilities cost on the moon to support the flights.
I mean on Earth everything from Fuel to Pumps, to CPUs is a phone call and UPS truck away. All would be much more expensive to make on the moon in smaller batches, in a remote location. Or in most cases it would be impossible to make on the moon with base facilities â so its shipped from Earth.
Cost to support your base would be far higher then to support the community near a launch facility (airport?) on earth. Higher cost to construct everything (and on the moon you would need to build it all) Labor hours involve a lot more supply issues, medical issues, more complex and expensive tools, other costs, etc.
So the moon, like every other isolated operation has dramatically larger operating costs, and a much smaller market to spread them over. And to recover and use that lunar fuel, you need to develop a lot of new technology and systems no one else is going to need. Certainly fewer folks will need them then will need the Earth launcher and its tools, hangers, and community support infrastructure.. So even if it takes 20 times as many flights. The total cost of the programs, vrs mass to L1, youâld expect the launch cost from Luna to L1 to be much higher then from Earth to L-1.
Oh, in case you want to consider future tech. With things like electro magnetic launchers from the Moon, you could comparably have laser launchers on Earth. Both still needing some rockets to get into a orbit or insertion trajectory, etc. Lasers adn electro-meg accelerators could be a similar pain to build, but the Lasers are built and serviced in a shirt sleevish outdoors, and power is a power line away (and still virtually free per flight).
Given the ships are likely close enough in weight and complexity, that they cost roughly as much to develop.
If by “ships” you mean a LEO space transport and a lunar lander, this statement is so nonsensical that I quit reading after this point.
Don’t be a jerk Rand. Your the one jumping on unsupported assumptions here.
Your Luna to L1 to Luna landing RLV would need similar structural and fuel ratios as a Earth Surface to LEO RLV. Similar dry masses and complexity. Wings or reentry shields are not going to drive you up orders of magnitude in dry weight.
Your Luna to L1 to Luna landing RLV would need similar structural and fuel ratios as a Earth Surface to LEO RLV. Similar dry masses and complexity.
I’m sorry, but this is complete and utter nonsense. Are you not aware that mass ratios are a function of delta vee?
Yes (gee after most of 20 years on NASA projects your expect that), and the delta V from Moon to L1 and back is about 5 Kkm/s. LEo to L-1 about 7. Your lunar to L-1 to return craft would need a fuel mass ratio of about 4.34. The Earth shuttle would need to be 7.6 Pretty close to a decent 1+ RLV (say a biamese).
Fuel tanks and main engines would need to be a couple take of mass, so say 10-15% unfueled weight. Pretty much the same for a non SSTO Earth RLV. As to structure, other systems, hull. I doubt you’ld get cargo weight to be 60% of unfuled weight. For a Earth RLV 25-35% seems about right.
Given the above, the dry weight of the Lunar shuttle would be at best half the cargo weight (and I’m dubious) Using the orbiter with extra weight for tanks as the RLV mass, you’ld get 3 to 1 ship to cargo. A SSTO would be over 5.
So assuming a non SSTo from earth your at maybe a 6 to 1 mass ratio for the two craft. Given 100 to one weight shifts in similar range aircraft etc only get you a 10 to 1 cost magnification. I’m not expecting a huge dev dif between the two. They both need rockets, controls avionics, nav, etc. The Earth craft needs better aerodynamics – and the weight of wings – but those arn’t big drivers.
For examples. The Apollo CM/SM cost a little more to develop then the Shuttle orbiter. Even though its nearly 10 times lighter, and less complicated, and obviously not reusable or winged.
opps that was not clear
Lunar shuttle dry weight 50% + of cargo weight
Earth shuttle dry weight 300% of cargo weight
I.E. for same cargo capacity the craft are maybe 6 fold dif in dry weight. So similar dev costs – as the SM/CM adn Orbiter are near 10 times dif in weight, but the orbiter cost less to develop.
Ah!!
I forgot the L-1 to Earth shuttle doesn’t need to slow down to LEO speeds! It just needs to rework its trag so it hits the air adn areo brakes. Apollo his the air at about 2.7 KM/sec above orbital velocity. So the fuel mass ration for the L-1 to Earth shuttle would be 4-5km/sec not 7!
Arg.
This pretty much eleminates any LEO->L-1->Earth vs. Luna->L-1->luna deltaV differnce. So the ships would have the same fuel to dry mass ration.