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The most interesting talk at Space Access was a fill-in that was not blogged by Rand, but was by Clark Lindsey:
a CEV concept [was presented] that Boeing is investigating that involves commercial delivery of fuel to orbiting depots. This so-called "dry launch" approach would mean that vehicles for in-space and lunar transport could be launched without fuel and so, being lighter, they would not need new heavy lifters. This would open a great opportunity for the new launch companies to provide fuel to the depots.
It involves an alternative concept (see page 32) from Boeing. The idea is to launch the lunar transfer vehicle dry and provide commercial propellant delivery. This could result in thousands of metric tons of fuel needing to be delivered to LEO. This might bootstrap the commercial launch industry. There are also opportunities for "the last mile" because some launcher companies will not want to have to figure out how to dock with a fuel depot.
1000 metric tons of fuel would be a cool $3 billion unless someone can undercut Elon Musk. 9000 metric tons through 2030 would be $27 billion at current prices, but would likely spur a tech drive and a bidding war to compete prices down to $1000/kg or less.
A big part of the cost of fuel will be how big the "chunks" of fuel need to be to be practical when delivered.
If we deliver it 10 tons at a time, thats obviously practical but takes a big launcher.
What if we deliever it 1 ton at a time? 100 kgs at a time? 1kg at a time (laser launch?)
What's the point at which more launches imposes more overhead so that you lose the possible advantages of smaller/cheaper vehicles?Posted by Joe Pistritto at May 3, 2005 08:33 PM
Whilst watching a Titan launch the other night, oohing and awing at separation, a thought occurred. That's not very high up - took a whole first stage to get there. Some space vehicles are launched from aircraft to to take advantage of aerodynamic lift but are limited by the lifting capabilities of the mother ship. How about a rocket with wings? Not pretty and an aerodynamic abomination (ever see a C-124?) but with a 25,000 foot takeoff roll and all day to get to altitude you might find some economies.
Division of payloads to LEO
I've thought for some time that dividing all payloads to orbit into three categories, crew, equipment and propellent, and then mating them by orbital rendevous made the most logistcal sense. This Boeing orbital fuel depot idea fits right in with that.
Since the propellent at the depot may have to sit and accumulate for some time between tappings, changes from the coventional fuel choices might be in order. Since LH2 is such tricky stuff, maybe methane would be a superior fuel (or even ammonia and xenon used for a bimodal NTR/electric propulsion system).
I suppose the depot could use water for long term storage and then crack it into hydrogen and oxygen when needed using solar electric power. But that would add complications of its own.Posted by Brad at May 4, 2005 01:25 AM
I'm giving a talk on an orbiting supply depot concept at ISDC. I looked at electrolysis, but the power requirements were prohibitive. Here's an article describing the old electrolysis approach:
The paper at ISDC will include some new insights.Posted by Tom Hill at May 4, 2005 04:30 AM
Mike Griffin has indicated that he is not interested in introducing commercial solutions in to the critical path of the VSE.
I cannot put public money at risk depending on a commercial provider to be in my critical path. source: space politics
Does that position preclude private fuel supply to LEO? Boeing suggests that the key difference between the baseline and its 'Case 2 Dry Launch w/LEO Depot' is that 'Existing ELVs capable of launching dry elements'.
But that wouldn't be fun for Marshall! Griffin really wants them to develop a heavy-lifter at NASA and that would stick to the baseline - no LEO fuel depot.
Furthermore, the Planetary Society's 'Extending Human Presence into the Solar System' (guided and cited by Griffin) favors a heavy-lifter:
With Orbiter retired after U.S. Core complete and with international agreement to proceed, any remaining assembly tasks can be completed by the heavy-lift launch vehicle (HLLV) that must be developed to support later stages of the Exploration vehicles (EELVs)
Posted by John Kavanagh at May 4, 2005 06:41 AM
Joe, you asked:
There are asymmetric penalties. If you build a big launcher you have more R&D and interest costs and lower flight rates. If you build a little launcher you have more fixed costs per pound capacity, but lower R&D, interest and operating costs. Small launchers can also rack up high flight rates so their insurance costs can fall.
It's like cell phone plans. A big launcher is like buying 10,000 minutes on a cell phone plan. Less per minute, but you probably won't use all the minutes. A little launcher is like having a cell phone plan with a high per minute fee with only 100 minutes bought in advance. Right sizing the launch capacity will be a trick.
Hopefully, the market will be able to come up with the answer to that question.
Should NASA buy fuel delivered by Zenit-USA, an American company (NYSE perhaps) that contracts to purchase Zenit boosters?Posted by Bill White at May 4, 2005 07:24 AM
I have a question maybe one of you can answer. Why don't rockets in the lower atmosphere (i.e. first stage) use air (intakes like a jet) instead of onboard LOX to burn with their fuel? Wouldn't this either save or reduce on the amount of LOX the rocket would have to carrry for upper/atmosphere space? I know it takes 8lbs of LOX to burn with every 1lb of Hydrogen, so I would think this would be significant.Posted by T. Williams at May 4, 2005 07:52 AM
T.: the reasons we don't see airbreathing first stages is that liquid oxygen is very cheap, rocket engines have much better thrust/mass than airbreathing engines, airbreathing engines don't work well over broad ranges of speed and air density, and because the specific impulse of the first stage doesn't matter very much (since it is dropped at a fairly low value of cumulative delta-V).
I'm not sure a fuel depot makes sense at this time (although in the future, it is without a doubt.)
Before we start putting reaction mass in orbit we need to get over the nuclear issue. If we store water, we need power to get hydrogen and oxygen; but if we have the power, why bother? Steam itself may be good enough for reaction mass.
We can't let idiots continue to dictate energy issues. Nuclear energy is less dangerous than the alternatives and provides magnitudes better performance.Posted by ken anthony at May 4, 2005 09:44 AM
Reading my comment above, I realize I seem too negative on the dry launch issue. Actually, I do think separating people, cargo and fuel is a good idea. But I also think we do need HL capability. I'm not sure how to deal with the problem of HL taking away business from the private sector, but I think a free market would favor whatever is the most economical.Posted by ken anthony at May 4, 2005 09:52 AM
So where is Beale Aerospace now that we need them?
"So where is Beale Aerospace now that we need them?"
Beal made some lousy technological and commercial choices. For instance, using a nasty fuel and picking a segment of the market that was already crowded. When those bad choices caught up with him, he blamed his failure on NASA and bugged out. It was an embarrassment on several levels.Posted by Jurgen Pellikov at May 5, 2005 08:55 AM
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