NewSpace 2009 Propellant Depot Panel
Jul 11th, 2009 by Jonathan Goff
I just wanted to mention that I’ll be chairing a propellant depot panel at the NewSpace 2009 conference this next week. This year, due to time constraints, I’m going to go for a slightly different format than I did last time. Basically my plan is to give a short 10 minute intro to the topic and the panel, and then spend the bulk of the rest of the time asking some prepared questions to the panelits, and then soliciting questions from the audience. If any of you have questions you’d like to get their take on, let me know in comments. Hope to see many of you there.
Here’s my question:
Since depots are one way to mitigate the need for very heavy lift, how does the industry advocate for depots and the architecture depots represent without picking fights with Senators looking to employ vast armies of people hell bent on building new hardware?
Here’s a question:
Spacecraft cost thousands of dollars per pound. If at all, how does a propellant depot change spacecraft design, manufacture, test, and launch in order to reduce the cost of the actual spacecraft?
I’ll be in Mountain View for a couple different reasons, including the conference. I’ll see y’all next week, and look forward to the panel.
Here’s a question:
The satellite the US military shot down in february 2008 points out a possibility of fuel depots of a type not normally considered; masses of propellant frozen solid in space. A mass of several tons of frozen hydrazine was given a good chance of surviving reentry with enough of it intact on landing to be a toxic chemical hazard.
What does the panel think of the possibility of depots consisting of blocks of oxidizer and fuel, frozen at a low enough temperature to minimize evaporation in vacuum?
Hints: Jonathan Post at Rockwell studied hydrogen snowballs in vacuum in 1990, Hydrogen Peroxide freezes at 273K, LOX at 90K.
A question from a different angle: what is the minimum fuel payload that makes sense from the perspective of the propellant depot (_not_ the launch vehicle). For example could something as small as a payload of 1 kg or 2 pounds of fuel or oxidizer be of interest for the depot? I’m sure there’s a lower limit somewhere but where is it likely to be?
Are they aware that an upper stage becomes a Lunar or Mars capable vehicle if refueled in LEO? Are they aware that that same upper stage refueled in Lunar orbit becomes capable of reaching the outer solar system with the same propulsion system?
@Habitat Hermit
The proposed propellant depots are being designed to refuel spaceships so they will be optimised to handle tons of propellant at a time. Automated systems will find handling 1 kg loads difficult unless this was built into their planning. For instance the RCS on the space tug used to collect the 1 kg of LOX may use more than 1 kg of fuel.
1 kg may be too small but 1 kg a minute may be different. 1 kg/mins is 1 * 60 * 24 = 1,440 kg a day.
A machine to collect 1.44 tonnes a day could be worth launching. An electromagnetic method of accelerating payloads such as coilguns and railguns may be able to repeatable place 1 kg in orbit.
The 200 kg – 300 kg payloads launchable by Falcon 1 and Pegasus LV would need more consideration.
@jsuros
Most rocket engines use liquid fuels so the oxidiser and propellant would need melting before it could be used. This melting would use a lot of energy, possibly from the sun.
Andrew,
The main point I was trying to make is that rocket fuels can be stored in space in solid form indefinitely. Fuel processing for vehicles would consist of putting the solid fuel in a tank or bag, sealing same, and shining sunlight on or into same.
Since depots are one way to mitigate the need for very heavy lift, how does the industry advocate for depots and the architecture depots represent without picking fights with Senators looking to employ vast armies of people hell bent on building new hardware?
Boeing’s approach has been to sell them as a way to leverage heavy lift for more capability to the lunar surface.
What is the reasonably largest amount of propellant that could be depoted using the ISS as the depot? GIven the power margins, radiator margins, GNC/Attitude control margins, Structural margins. I realize this isn’t a complete engineering study, but, try and estimate what load could be transmitted through a docking port, or an external berthing station on the truss. Also, a quick thermal sketch on how much power and cooling would be needed to maintain LOX or LH at ISS.
What is the reasonably largest amount of propellant that could be depoted using the ISS as the depot?
That would require a complete redesign of the ISS, and prevent it from doing microgravity science. It would be much cheaper to develop a new one (or more than one, for redundancy) from scratch, at a lower inclination that was cheaper to get to.
Beyond immediate mission execution, I’m interested in manned spaceraft reusability once they are back in Low Earth Orbit. Given an effective propellant depot, what is the suitability of current man-rated architectures (Dragon, Orion, Soyuz, etc.) to be left untended in orbit if they were equipped with propulsive modules that were refuealable? Let’s break it down three ways–what is the suitability with MIR/ISS-like constant Mission Control monitoring (assumed high), what is the suitability without monitoring (lower cost mission execution), and finally–how many years could such craft be left in orbit before they would need to be “drydocked” for refurbishment (assuming other expendables could be replenshied at the depot also)? For example–how could the Soyuz lifeboat lifespan be extended beyond its current six months? What are the risk factors into moving into a less robust monitoring/Mission Control paradigm? How close right now is ISS monitoring to SATCOM monitoring paradigms? How can the ground element costs be reduced, and what would the concerns/pushback be from the manned spaceflight community?
1) How does one ensure multiple commercial propellant depots perhaps in different orbits with competition between them?
2) If one is going to have propellant depots, which somewhat presume reusability, then slower higher ISP solar powered tug hybrids become more attractive in some scenarios – provision for keeping this development path open with respect to the propellant depot?
3) Robotic arm or separate tug docking systems so as to unconstrain vehicle design from the outset?
4) Ensuring a flexible modular propellant depot that can change and evolve along with the vehicles, customers and suppliers that wish to work with it?
5) How to prevent old space market and design capture?
How do satellites fuel on the ground now? I realize this isn’t a deep, ground-shaking question, but I can’t find the answer.
Which propellants? Which licensing scheme? Which usage policy?
Godzilla,
Not clear what you’re asking.
Rand,
Thanks for answering the question about using ISS for a depot. It’s a common question, but most people haven’t thought out the implications.
~Jon
Would propellant depots (reasonably) allow a lunar architecture that doesn’t require sending a reentry vehicle to the moon and back, by using propulsive braking to return to a LEO station where they can be ferried back home in a small capsule. I would love to see a distinction made between in space hardware and reentry hardware, and this cant happen without prop depots. The requirements are so vastly different between a craft that gets people to and from space and a craft that takes people to the moon and operates in space that it seems terribly wasteful and inefficient to try to cram them all into one vehicle.
Could a propellant depot be built from flexible walled pressure vessels, akin to Bigelow’s habitats?
Advantages: Depot volume exceeds payload volume of launching rocket.
Disadvantages: ??
Aaron,
Regarding propulsive breaking. Yeah, you can do it, but it really is painful unless propellant is *very* cheap, both in LEO and on the Lx side of things. For most of my analyses, I’ve only assumed the transfer stage did propulsive breaking (since it weighs so little it can manage that). You really want to use some sort of aerobraking if you want to reuse the crew transfer part of the vehicle.
~Jon
MG,
I’m actually a bit of a fan of inflatable propellant tankage. Easy to do for storables, but a bit harder to do for cryogens. There are some materials that can work down to LH2 temps, and they’ve actually tested such stuff (mostly for use in positive displacement bladders), but they don’t tend to hold up very well. If you can actually keep it mildly pressurized the whole time (so it isn’t actually pressure cycling more than once), it might work better….
The potential’s there, but there are issues that would need to be overcome.
~Jon
Jon,
Three thing spurred my question:
1. Your post some time ago about “black aluminum”, and the thought that an anisotropic-capable material assembly might be create structural shapes that differ from aluminum.
2. The early conceptual studies of balloons for Titan and Venus, which suggests that material choices might be available that could work for a propellant-holding pressure vessel.
3. Super-pressure balloon structural proposals.
4. America’s Cup competition-spurred developments in sail technology.
Okay, that’s four things. So sue me.
[i]Aaron Williams said
Would propellant depots (reasonably) allow a lunar architecture that doesn’t require sending a reentry vehicle to the moon and back, by using propulsive braking to return to a LEO station where they can be ferried back home in a small capsule. {snip} [/i]
By refuelling at LEO, L1 and L1 (return) a reusable lander can meet a small re-entry vehicle in Earth orbit. Use a solar electric tug to take the propellant to L1. An alternative is for the astronauts to change spacecraft at L1.
Each of the questions, so far have dealt with propellant delivered from the Earth. NSS-in-Second Life has built on the NSS Island, a model of a Mass Driver that would be used to deliver a capsule with about a metric ton of frozen LOX to a Highly eccentric Earth Orbit. I believe it is possible to also produce an acceptable heat shield from Lunar Glass. The heat shield could allow aerobraking of the capsule of frozen LOX till the HEO apogee was reduced to that of a fuel depot, and a medium-sized laser could then be projected from the depot to the capsule, vaporizing some Oxygen through a nozzle, to raise the perigee. This matching of orbits seems to make depoted propellant from the Moon and possibly asteroids a good thing to do.
Will the depots spoken of by the panel include the ability to accept such deliveries of propellant from off Earth with little or no change to their structure? Will systems that make it easier to lift and match orbits with payloads from Earth in the basic designs make it harder, or impossible, to bring in propellant from outside? I see no reason that this need be, but I have not placed much attention on the depot end of such systems. Please bring this up in the panel, Jon, OK?
Regards,
Tom Billings
Sorry, I did forget to state that the models we are making on NSS Island in Second Life are part of a Lunar Development that would include the Mass Driver in the end of Phase 2 or the start of Phase 3.
Mars sample return has been the holy grail of robotic martian exploration.
Show the mars science community how propellant depot ( storable propellant ) anywhere ( LEO, lunar L2, martian orbit ? ) will help accomplish MSR mission cheaper and/or more capable than current baseline ?
( http://www.esa.int/esaMI/Aurora/SEM1PM808BE_0.html )
Done that, you gain a huge supporter base.
Direct link to report:
http://esamultimedia.esa.int/docs/Auror/iMARS_Report_July2008.pdf
This calls for Atlas 551 and Ariane 5 ECA dual launch right now ( see page 23 for launch architecture )
Rand Simberg’s description of the Boeing argument (at #9 above) is the right road forward, IMHO.
If you argue that depots render heavy lift obsolete, then hoards of US Senators will ally to block your plans, including Senator Shelby. Therefore, ANY depot plan that does not include a realistic political plan to win Congressional support is merely fantasy.
On the other hand, if you argue that depots leverage heavy lift to allow truly massive amounts of infrastructure to be sent to the lunar surface then maybe those same Senators will support you.
Then, once depots are funded developed and deployed choosing the right sized lift for various missions becomes far easier.
To advocate for depots as a reason to terminate the STS workforce is more like going through the Maginot Line rather than around it.
Bill,
There are big problems with this line of thinking–the argument that PDs should only be pitched as augmenting HLVs and not as possibly making them redundant. The problem is that as soon as you pitch them only as helping HLVs, and that HLVs are still required, you’ve put yourself in a position where NASA will say “see HLVs are still the critical path–we’ll fund PDs once we have the HLVs working”…which is functionally identical with saying that they’ll never fund PDs. I really don’t see how underselling PDs in this way gets you *anything* if you actually care about PDs. For the past 40 years it’s always been “well we need HLVs. PDs are nice, but we have to have HLVs” so we always end up blowing money on HLVs that never get built, and PDs only get the scraps.
The only way that it gets you anything is if you have an architecture where both HLVs and PDs are on the critical path, but I doubt anyone is going to choose such an architecture, just because it has two big tech developments that have to work.
I have no problem pointing out that if they insist on doing HLVs, that PDs are still useful. But I’m not going to leave out the fact that PDs can allow for a non-HLV architecture that is more capable and more affordable. If the politicians want to screw around in the engineering for political reasons–let *them* make that call. Don’t water-down the engineering and give them political cover to make dumb decisions.
~Jon
Of course you should not omit the fact that depots can (from a technical perspective) permit all EELV architectures (something the Northern Alabama Space Agency surely knows already since Boeing proposed exactly that approach in the pre-Griffin era back in 2004/2005) but if that approach is dead-on-arrival politically what do you gain by choosing this hill to die on?
There is a saying in politics – don’t call for a vote until you’ve already counted the votes, in advance.
Going all Don Quixote won’t get you propellant depots, either.
Bill,
That’s the thing though. Why compromise if it doesn’t give you anything? What do you gain by giving them yet another piece of excuse to punt on depots? If I thought that compromising and saying “yeah we still need heavy lift, but depots would be nice” would actually get us anywhere, I might be more willing to. But as far as I can tell, that’s a great way to waste a huge amount of time and effort for no gain. Why even promote depots at all if we do it in a way that has no chance of getting depots implemented?
I know that Shelby and Nelson are politically powerful. But a lot of the reason why they’re politically powerful when it comes to NASA issues is that most of the senate doesn’t really care that much, and more importantly doesn’t know there are better alternatives. No Senator or Congressman is going to second-guess NASA or a presidentially appointed blue ribbon panel technically (they may disagree with goals, or decide to cut back on scope if the price is too high). But if the panel comes back with some options that are a lot cheaper and more innovative, and say that they look technically realistic, and look like they could benefit congress people in other districts (some in California, Colorado, Virginia, etc), there is a lot higher of a chance for actual change. But so long as all the “non-biased government experts” are telling them that there’s no real alternative to Shuttle Derived Heavy Lift if they want to go back to the Moon, it’s a lot easier for Shelby and Nelson to hold everyone hostage to their parochial interests. If they come back with at least one or two of their options being depot-centric, non-HLV architectures that they say are technically legit, then there may actually be some real discussion about why a center with such a nearly unblemished record of failure should continue to get massive subsidies when there are better options out there.
~Jon
Heavy lift PLUS depots allow the deployment of considerable amounts of lunar surface infrastructure. Why would Shelby and Nelson oppose that if they can still preserve their jobs base in AL and FL.
Heavy lift without depots merely allows for flags and footprints missions which is why that route should not be chosen, either.
Yes, much of NASA is a “self licking ice cream cone” but so is the F-22 program (well scattered across Congressional districts to avoid cancellation) and various national ballistic missile defense programs. DDX to involve the Navy. That mobile artillery piece.
The Osprey? Although that might be more anti-Marine sentiment.
Having “real” discussions about whether to cancel those programs is darn near impossible and therefore to demand such for NASA certainly seems Don Quixote-esque – especially since you face a steep learning curve in Congress with respect to an EELV only + depots architecture.
And of course, I believe Jupiters PLUS depots truly would allow us to move tremendous amounts of mass onto the lunar surface and actually do the things Paul Spudis and Dennis Wingo want us to do.
Bill,
Think about economics for a second. You’re telling them that without depots you can still do a lunar program, just not as nice, but without HLVs you can’t do a lunar program at all. When the money gets tight (which it will with a massive HLV program run by MSFC), do you really think they’re going to fight as hard to keep depots funded as they will to keep HLVs funded? Every time in the past that NASA has said “we’ll build a launch vehicle and some infrastructure to go with it that will make it better”, what has happened? The infrastructure gets caught when the LV starts suffering its inevitable cost overruns.
That’s the problem. If you have HLVs, depots are only “nice to have”, and “nice to have” always loses to “have to have” when you have limited resources. Sure, HLVs plus depots wouldn’t be a total waste even if it is less efficient. But I don’t think that “HLVs plus Depots” will really end up as “HLVs plus Depots”.
I’m not saying that Shelby and Nelson would “oppose” depots per se if they were part of the HLV+depot combo. But if forced to pick supporting one or the other when the money gets tight, they’re not going to support depots over HLVs. Which is effecitively the same thing.
~Jon
I’d tell them that there is a difference of opinion about whether we can do any lunar program without heavy lift. Which also happens to be true. Recall that even Mike Griffin agreed we could do a lunar program with medium lift, he merely said he thought it would be “silly” to do that.
Yes, depots might get cut before heavy lift but on the other hand I also believe that if the workforce is terminated now, Obama will only fund NASA sufficiently to reach ISS. No depots, no lunar program but merely a light crew taxi not capable of going beyond LEO. If that.
IMHO, nothing less than “we cannot afford the Moon” will be a sufficient political argument to overcome Nelson and Shelby’s support of the STS infrastructure. In addition, out placement funding and alternative jobs programs will be charged to NASA’s budget further reducing money for depots and landers and ISRU.
Be careful for what you pray for, for your prayers may be answered with a hidden catch you did not foresee or desire.
So… what DoD champions are there for a propellant depot? Maybe trying to sell the idea through NASA isn’t gonna work because it works against the institutionalized interests of the NASA tree stumps.
Surely the USAF, with its aerospace superiority mission, might be interested in advancing the idea a bit further?
And while we are at it, can I have my purple unicorn now?
Maybe trying to sell the idea through NASA isn’t gonna work because it works against the institutionalized interests of the NASA tree stumps.
Yep. Those tree stumps were rather aggressive in trying to swat down DIRECT which is scarcely a revolutionary proposal. IMHO, any political hope for EELV only plus depots evaporated when Admiral Steidle left NASA. As I recall ending the STS standing army was Job #1 pre-Griffin and those guys have all been driven out if NASA.
Going forward, Team DIRECT is depot advocates best hope, IMHO.
That said, perhaps depots would allow a foreign country to beat NASA back to the Moon. Remember, Chris Columbus wasn’t a Spainard.
Depots and/or refuelling can increase the size of unmanned probes sent to the Moon and Mars. A 1.5 or 2.0 launch programme. No need to wait for the Ares V to fly.
Once again, i asked about MSR, and there is no reply. PDs are supposed to be this great flexibility bringer and way to lower cost.
MSR is an immediate problem in need of a solution, and doing MSR affordably will garner a huge support base in planetary science crowd, and hence also some political support.
As stated, current MSR reference desing is baselined for Atlas + Ariane, mission budget anywhere from $4B to $8B ( see the links above ).
Certainly too big for ESA to undertake.
Exactly how are PDs going to help with MSR ?
I agree with Jon here on the political approach.
NASA is in the driver’s seat no matter how powerful Congress is. Somebody needs to fight for feasible, economical development and exploration of space. Congress doesn’t know enough or have this interest at heart. If NASA doesn’t do it, then the task falls to space advocacy groups and space blogs, neither which has anything like the credibility or endurance of NASA.
Personally, I think it’s a poor negotiation tactic to compromise on your greatest needs right from the start. NASA needs the space infrastructure, they don’t need the shiny new HLV. Keep in mind that NASA has held hostage in the recent past it’s shiniest programs (like the alpha magnetic spectrometer module for the ISS or the Hubble telescope) before. That is some viable leverage on Congress. So at the least, they should be able to say “We can’t do Lunar missions without propellant depots” and muscle some funding in that way.
I think Jon is right that HLV + depots will likely end up as HLV only or at best as depots 15-20 years from now, with much reduced traffic. ISS only, on EELV, would be the best outcome if there isn’t the money for an exploration program. At least it would kill the Shuttle stack, forever ending the HLV discussion.
There is another point though: the risk (both perceived and real) of propellant depots. If Congress believes depots are riskier than HLVs, then they may not want to go down that road. Of course recent NASA attempts at building even a small launcher have proved to be incredibly risky, so the balance may have shifted.
@Jon, Karl, Martijn
Who at NASA is willing to stick out their necks in support of putting depots on the critical path? Can you name a name of anyone within NASA willing to take such a stance?
Today, Jeff Greason of XCOR could be your only near term hope for putting depots on the critical path back to the Moon. If he stands firm in the manner Karl proposes and makes it clear he will openly dissent from the Augustine Commission report IF depots are not on the critical part then your strategy might work.
But unless someone within NASA (or Greason) is willing to take a strong public stand, those of us out here in blogger-land will merely be ignored. Negotiating strategy is irrelevant if no one will take you seriously in the first place.
I’m hoping for budget cuts. The Shuttle stack has to go before there will be progress. I’m pessimistic.
Kert,
Sorry for no reply. I actually thought your question was a good one. I’ve just been buried by trying to get this panel prepared, while trying to finish writing my PD white paper, while trying to get stuff at work setup so that I can leave for vacation for a week. Don’t worry, lack of comment doesn’t mean lack of interest in this case.
~Jon
How about that propellant depots are a necessity to fill the HLV gap – which is indeterminately large
.
Is SpaceX likely to pursue a propellant depot approach? Is this a better angle? What could SpaceX reasonably accomplish with a propellant depot?
Explicitly on the point of questions for the panel, a question:
“Has anyone spoken with Jeff Greason of XCOR on whether the Augustine Commission has considered placing propellant depots on the critical path for lunar return and what are the odds that Greason (or someone else) will fight vigorously for including language within the Augustine Commission report that declares
propellant depots to be an essential technology for lunar return.”
A follow up:
“Other than Jeff Greason, who else on the Augustine Commission can be seen as an ally of the propellant depot approach?”
If Jim Muncy attends the Space Frontier event, I would also seek his opinion / advice concerning how to best persuade Congress about propellant depots and ask his opinion what the odds are of having NASA and Congress place propellant depots on the critical path in the near future.
Who at NASA is willing to stick out their necks in support of putting depots on the critical path? Can you name a name of anyone within NASA willing to take such a stance?
Not a soul as far as I know. But then again, I don’t see anyone in a position of leadership at NASA promoting a viable space program for NASA whether it be propellant depots or some other approach. So the absence of someone boosting my favorite isn’t particularly disheartening. I figure either NASA will continue to be weakly relevant to space development or real leaders with real direction from above will some day be appointed. In the latter case, the propellant depot will have its say and will stand or fall on its merits.