The summary somewhat misrepresents what Worden said. From the article, here's Worden's actual statement, which seems quite sensible to me: "Governments can develop new technology and do some of the exciting early exploration but in the long run it's the private sector that finds ways to make profit, finds ways to expand humanity.... Most of private individuals I've talked to about interest in settling on Mars, including Elon Musk, talk about in the next few decades they think the private sector will fund settlement missions - whether to the Moon, Mars, or asteroids. As a government laboratory our job is to develop to enable those kinds of things by developing technology and early exploration, and we hope the private sector will find a way to do something like that."
SO...a rational person at NASA, if the organization was not at the mercy of Congress for every project, would dedicate ALL of their budget to getting that $10k/kilogram cost down to something affordable.
Quick correction: It's actually down to a price of ~$2k/kilogram with the SpaceX Falcon Heavy. That's still a fair bit of cash, but somewhat reasonable compared to the cost of developing a payload.
I've often wondered why Space-X doesn't open an office in Huntsville. There's got to be more than a few different-thinking unemployed "rocket scientists" there.
Currently, though, the notion that "private sector will solve all!" seems like more of an ideological excuse than an honest assessment of what the U.S. is capable of in space.
Not a lot of people realize this, but -all- DOD launches and all non-Shuttle NASA launches, plus of course all commercial satellite launches, have been on privately-built rockets for quite a few years now. This includes multi-billion dollar satellites critical to national security. It's somewhat nonsensical to have a separate government-designed/operated launcher just for manned US launches, especially when NASA hasn't successfully developed a launch vehicle in the past 30 years (plenty of failures, though).
If there's someone Lou Friedman should be complaining about, it's Senators Nelson and Shelby and their fixation on providing pork to large aerospace contractors in return for bribes, I mean campaign donations.
I would have hoped that someone in his position would be better informed, frankly.
Actually, while the summary doesn't mention this, this is pretty much exactly what Friedman says in his piece:
Having caved in to Congressional special interests on the Space Launch System (SLS), the administration is now prepared to sacrifice science and exploration programs in order to prematurely start its development, with requirements that will neither be met nor needed for more than a decade.
It's worthnoting that the bulk of the mass and cost is in the first stage and its engines. For example, the Falcon 9 first stage has 9 Merlin engines and the upper stage only has one. This is even more extreme with the Falcon Heavy's 27:1 ratio. Reusing just the first stage might not get them a 100x cost reduction, but it should get them most of the way there.
My personal suspicion is that they'd prefer landing on a platform at sea. Blue Origin has a patent on this, though, so I can see why they wouldn't want to put this in their videos.
This requires separate landing systems for each stage of the rocket. This is a lot more added mass. And the worst thing to add to a rocket is more mass.... At this point, it doesn't seem that chemical rockets will become that more efficient barring major breakthroughs, like much lighter alloys, or totally new chemical reactions for the fuel. Neither of these seem very likely right now, and the second seems to be much less likely.
Actually, the Merlin engines SpaceX has been using have been getting more efficient, with the new engines providing 50% more thrust and a slightly higher ISP than their earlier engines. This extra capability is presumably what allows them to "spend" mass on things like VTVL landing systems and the required excess propellant.
Actually, I'd argue that SpaceX has benefitted much more from NASA's efforts in unmanned exploration and low-cost space technology than it has from the much higher-funded Space Shuttle program. For example, SpaceX has used and improved on technology like the PICA heat shield material (now the PICA-X used on Dragon) and the principles from the Fastrac experimental low-cost engine were used in the first version of SpaceX's Merlin engine. I can't think of a single thing from the Shuttle program that has benefited SpaceX, unless you count it as an example of how -not- to design a reusable spacecraft.
IMO the goal of our space programs isn't just to put humans into space. It also serves to dump piles of money into US science an tech development. Our space program is an investment in the US that allows us to maintain a technological edge. We've lost hope of outproducing developing countries like China, out best chance now is to keep ourselves ahead of them technologically. We can't do that unless we are keeping our scientists and engineers working and advancing our sci/tech industry.
Not a lot of people realize this, but spending in technological research has actually been a fairly small portion of NASA's budget for quite some time, with far more money going towards things like paying for the standing army of maintenance personnel for the Space Shuttle.
In the past few years NASA asked for permission to spend $1 billion/year to revive technological research in NASA and invest in technologies needed to perform new types of exploration missions and perform existing missions more cost-effectively. Unfortunately, Congress wasn't a fan of the idea, IMHO because they weren't sure if the money would end up in the districts of Congresspeople who typically support the NASA budet. Instead, Congress diverted almost all the space technology money to building the SLS, an in-house rocket based on Shuttle-legacy technology. The two main features which have been politically touted for the SLS have been that it employees a large number of former Shuttle contractors and minimizes development of new technology.
The solution is for Congress to allow NASA to invest in research in space technology again, but it'll probably be a while before that happens.
Oh if only some other nation had something spaceworthy... Like a shuttle or so...
Funny joke, but Shuttle wasn't able to serve as an emergency Crew Return Vehicle due to limitations in in-orbit idle time. The Space Shuttle could only stay in orbit for a few weeks at a time, while the CRV requirement was for a half-year or longer.
Since the start of the ISS the only functioning CRV has been Soyuz. NASA had some attempts at building their own CRV, like the X-38 and Orbital Space Plane, but they were canceled back in the early 2000s. Commercial vehicles with CRV capabilities like Boeing's CST-100 and SpaceX's Dragon are under development, but it'll be a few more years before NASA allows their astronauts on them.
There's also NASA's Orion/MPCV, but its launcher, the Space Launch System, isn't due to be ready until 2017 or so.
I hope they were in a state where wagering is legal. Otherwise, a public bet like that should be for token gifts and/or bragging rights.
I'm pretty sure these terms are legal in just about any state:
(1) Series production models of the Tesla Model S have to be delivered to paying customers before the end of 2012. (It was originally 2011, but Neil concedes that Tesla said it wouldn't make that date fairly early, and has since stuck to its 2012 date.)
(2) The Model S has to have seven passenger seats, certified as such by the National Highway Traffic Safety Administration, and earn a 4- or 5-star safety rating from the NHTSA.
(3) It has to have a battery pack that allows en-route swapping at a highway roadside station, similar to the Better Place battery swapping scheme.
(4) Model S prices must remain at the levels Tesla and Musk announced: $57,400 for the version with 160 miles of range, $67,400 for the 230-mile version, and $87,400 for the top-of-the-line 300-mile version (which will comprise the bulk of early production). All prices are before any Federal or other incentives.
But if Tesla does what it said it will, Neil loses, and--being a journalist, not a multimillionaire entrepreneur--he will donate $1,000 to the same group.
Did I complain yet about the sound in space? Yes? Well, it is a pretty big fucking issue. Everything you need to know about the US can be summarized as a NASA science video having sound in space...
Sound doesn't get transmitted through space, but a microphone mounted on the rover would have easily picked up all the sounds in the video.
The answer for why this needs to be attached to the space station is because it's making use of Dextre, the very large/expensive/awesome robotic arm attached to the ISS. The initial experiments may also likely need a human finely controlling the robotic arm or conducting extra-vehicular activities to set things up. There's some more details in this article.
It also wasn't mentioned in the summary, but a big part of why this is so challenging is that the tech is ultimately intended for satellites which weren't immediately designed to be refueled. There's a -lot- of old satellites out there with their fuel supplies winding down, and this could be potentially useful for quite a few of them.
You don't even need to look outside NASA to see ridiculous spending to compare to. The same House appropriations bill with the $431M JWST cut includes $2B for the Space Launch System (SLS) and $1B for the Orion/MPCV capsule. The SLS is basically Congress's mandate to NASA to build a heavy-lift rocket out of Shuttle-legacy components capable of competing with SpaceX's Falcon Heavy rocket. The $2B is only for the first year of SLS funding, for a rocket which isn't expected to have its first launch until 2017 or later. Mind that this is for a rocket that NASA didn't even want in the first place.
The amount being spent here seems to be a whole lot, until you consider how much is going to be poured down the "back-up insurance plan" with the SLS program just in case the commercial spaceflight approach doesn't work. I've heard estimates of about $3-4 billion being spent just on that one program, something that still has yet to even be figured out in terms of who is even going to build it in the first place.
It's kind of terrifying when one realizes that the combined budget for SLS and the MPCV capsule is $2.5B/year, and it's expected to be at least 6 years before it's ready for first launch. You could buy quite a few SpaceX's for that much money.
If you want to launch station segments by themselves like the Russians do the segments become more expensive, smaller, and less capable because each segment has to be its own spaceship complete with guidance, altitude and attitude control, and docking capability. The shuttle allowed for the segments to be large, cheep, and uncomplicated.
The actual cost numbers don't match your assertion: Mir cost about $4.3B to build, while the ISS cost around $100B. (ISS's pressurized volume is only about twice Mir's)
If a self-driven car is able to pass a normal driver's test (perhaps even including natural-language processing of the DMV employee's requests), do you think it should be allowed to drive? What's if it's able to pass several driver's tests, with a success rate significantly higher than the average current driver?
As a bit of trivia, Caltech alum Bill Gross actually ended up founding GNP Audio based on an engineering project he did as a student. He later went on to co-found, like, a gajillion other companies.
But what's the point of L2? You need a depot in Earth orbit to fuel up for the trans-lunar burn, and one in Lunar orbit to fuel up for the trans-earth burn. Why put the lunar depot at L2 as opposed to a lunar orbit?
I'm by no means an expert, but my understanding is that there's a few different advantages L2 has over LLO:
* Lower delta-V to reach it from LEO (3.43 km/s vs. 4.04 km/s), and -much- lower delta-V to go from there to Earth escape orbit (0.14 km/s vs. 1.4 km/s). This makes it much more practical for sending missions/probes to Mars, the outer planets, or just about anywhere else in the solar system. * In that likely case that you're using hydrogen/oxygen propellant, boil-off is going to be your primary long-time storage concern. In LEO (and presumably lower orbit) you not only have to worry about shielding a depot from the Sun, but also have to worry about shielding the thermal emissions from a nearby constantly-moving terrestrial body. If you're in EML2, all you need is a sun shield to keep the temperature down. * I suspect it's much more difficult to dock with a constantly-moving target in lunar orbit than with a more stationary target at a Lagrange point, both in terms of actual maneuvers and mission scheduling. * There's substantial gravitational anomalies in the Moon, adding stationkeeping costs for maintaining a consistent lunar orbit.
I don't think I quite get how this is more economical. Is it actually cheaper to send up a bunch of smaller rockets with fuel as payload than it is to simply send a bigger rocket with enough fuel on it? Can somebody walk us through the math?
Absolutely. Remember that development costs tend to be very important when it comes to rockets. For example, the recently-cancelled heavy-lift Ares V rocket NASA was building was projected to cost at least $32B to develop (ignoring operations costs). This was for a rocket with 188mt capacity. By comparison, SpaceX recently announced a smaller rocket (53mt capacity) which will launch at $100M/flight starting in 2013. Instead of spending $32B to develop a bigger 188mt rocket, NASA could instead spend that money to launch fuel and payloads on 320 Falcon Heavies (16,960mt total payload). This of course ignores the greater economics of scale that could be obtained if you were launching a rocket that many times.
In an optimistic scenario, the Ares V would launch once or twice per year. If you assumed that the Ares V launched twice per year and was completely free to operate (which is false, as it actually would've cost billions more to operate), it would take 45 years before the Ares V would have launched more payload than you could've launched spending the same money on Falcon Heavies.
L1, L2, and L3 (the ones in line with the primary and secondary bodies) are dynamically unstable. It's not like you can park there. L4 and L5 points are much better because they are dynamically stable points, however nobody talks of placing a fuel depot there.
Actually, assuming you're talking about a hydrogen/oxygen fuel depot, you'll have a few pounds of propellant boil-off every day (out of several tons total). You can redirect the boil-off for station-keeping, and it pretty much meets the requirements for station-keeping at L2. There's more details in this ULA publication on depot architectures:
Actually, not only is it not politically sexy, but it's outright politically dangerous. Having fuel depots allows you to use existing rockets for exploration beyond low-Earth orbit, alleviating the need to develop heavy-lift rockets. A number of politically-powerful congressional districts (and congressmen) are heavily banked on NASA building a heavy-lift rocket from Shuttle-legacy components, while that isn't the case for fuel depots. I predict it won't be long before this particular effort is squashed by Congress, perhaps even outright banning it like they did with the TransHab inflatable modules.
Slashdot Mirror
The summary somewhat misrepresents what Worden said. From the article, here's Worden's actual statement, which seems quite sensible to me: "Governments can develop new technology and do some of the exciting early exploration but in the long run it's the private sector that finds ways to make profit, finds ways to expand humanity. ... Most of private individuals I've talked to about interest in settling on Mars, including Elon Musk, talk about in the next few decades they think the private sector will fund settlement missions - whether to the Moon, Mars, or asteroids. As a government laboratory our job is to develop to enable those kinds of things by developing technology and early exploration, and we hope the private sector will find a way to do something like that."
To me the site just seems like a blatant promoter of cronyism, promoting the hiring of friends or aquaintences over those who may be more qualified.
It's not who you know, it's who knows you don't suck as an employee or coworker.
SO...a rational person at NASA, if the organization was not at the mercy of Congress for every project, would dedicate ALL of their budget to getting that $10k/kilogram cost down to something affordable.
Quick correction: It's actually down to a price of ~$2k/kilogram with the SpaceX Falcon Heavy. That's still a fair bit of cash, but somewhat reasonable compared to the cost of developing a payload.
I've often wondered why Space-X doesn't open an office in Huntsville. There's got to be more than a few different-thinking unemployed "rocket scientists" there.
Like this one?
Currently, though, the notion that "private sector will solve all!" seems like more of an ideological excuse than an honest assessment of what the U.S. is capable of in space.
Not a lot of people realize this, but -all- DOD launches and all non-Shuttle NASA launches, plus of course all commercial satellite launches, have been on privately-built rockets for quite a few years now. This includes multi-billion dollar satellites critical to national security. It's somewhat nonsensical to have a separate government-designed/operated launcher just for manned US launches, especially when NASA hasn't successfully developed a launch vehicle in the past 30 years (plenty of failures, though).
If there's someone Lou Friedman should be complaining about, it's Senators Nelson and Shelby and their fixation on providing pork to large aerospace contractors in return for bribes, I mean campaign donations.
I would have hoped that someone in his position would be better informed, frankly.
Actually, while the summary doesn't mention this, this is pretty much exactly what Friedman says in his piece:
http://thespacereview.com/article/1947/1
Having caved in to Congressional special interests on the Space Launch System (SLS), the administration is now prepared to sacrifice science and exploration programs in order to prematurely start its development, with requirements that will neither be met nor needed for more than a decade.
It's worthnoting that the bulk of the mass and cost is in the first stage and its engines. For example, the Falcon 9 first stage has 9 Merlin engines and the upper stage only has one. This is even more extreme with the Falcon Heavy's 27:1 ratio. Reusing just the first stage might not get them a 100x cost reduction, but it should get them most of the way there.
My personal suspicion is that they'd prefer landing on a platform at sea. Blue Origin has a patent on this, though, so I can see why they wouldn't want to put this in their videos.
This requires separate landing systems for each stage of the rocket. This is a lot more added mass. And the worst thing to add to a rocket is more mass. ... At this point, it doesn't seem that chemical rockets will become that more efficient barring major breakthroughs, like much lighter alloys, or totally new chemical reactions for the fuel. Neither of these seem very likely right now, and the second seems to be much less likely.
Actually, the Merlin engines SpaceX has been using have been getting more efficient, with the new engines providing 50% more thrust and a slightly higher ISP than their earlier engines. This extra capability is presumably what allows them to "spend" mass on things like VTVL landing systems and the required excess propellant.
Actually, I'd argue that SpaceX has benefitted much more from NASA's efforts in unmanned exploration and low-cost space technology than it has from the much higher-funded Space Shuttle program. For example, SpaceX has used and improved on technology like the PICA heat shield material (now the PICA-X used on Dragon) and the principles from the Fastrac experimental low-cost engine were used in the first version of SpaceX's Merlin engine. I can't think of a single thing from the Shuttle program that has benefited SpaceX, unless you count it as an example of how -not- to design a reusable spacecraft.
IMO the goal of our space programs isn't just to put humans into space. It also serves to dump piles of money into US science an tech development. Our space program is an investment in the US that allows us to maintain a technological edge. We've lost hope of outproducing developing countries like China, out best chance now is to keep ourselves ahead of them technologically. We can't do that unless we are keeping our scientists and engineers working and advancing our sci/tech industry.
Not a lot of people realize this, but spending in technological research has actually been a fairly small portion of NASA's budget for quite some time, with far more money going towards things like paying for the standing army of maintenance personnel for the Space Shuttle.
In the past few years NASA asked for permission to spend $1 billion/year to revive technological research in NASA and invest in technologies needed to perform new types of exploration missions and perform existing missions more cost-effectively. Unfortunately, Congress wasn't a fan of the idea, IMHO because they weren't sure if the money would end up in the districts of Congresspeople who typically support the NASA budet. Instead, Congress diverted almost all the space technology money to building the SLS, an in-house rocket based on Shuttle-legacy technology. The two main features which have been politically touted for the SLS have been that it employees a large number of former Shuttle contractors and minimizes development of new technology.
The solution is for Congress to allow NASA to invest in research in space technology again, but it'll probably be a while before that happens.
Oh if only some other nation had something spaceworthy... Like a shuttle or so...
Funny joke, but Shuttle wasn't able to serve as an emergency Crew Return Vehicle due to limitations in in-orbit idle time. The Space Shuttle could only stay in orbit for a few weeks at a time, while the CRV requirement was for a half-year or longer.
Since the start of the ISS the only functioning CRV has been Soyuz. NASA had some attempts at building their own CRV, like the X-38 and Orbital Space Plane, but they were canceled back in the early 2000s. Commercial vehicles with CRV capabilities like Boeing's CST-100 and SpaceX's Dragon are under development, but it'll be a few more years before NASA allows their astronauts on them.
There's also NASA's Orion/MPCV, but its launcher, the Space Launch System, isn't due to be ready until 2017 or so.
I hope they were in a state where wagering is legal. Otherwise, a public bet like that should be for token gifts and/or bragging rights.
I'm pretty sure these terms are legal in just about any state:
(1) Series production models of the Tesla Model S have to be delivered to paying customers before the end of 2012. (It was originally 2011, but Neil concedes that Tesla said it wouldn't make that date fairly early, and has since stuck to its 2012 date.)
(2) The Model S has to have seven passenger seats, certified as such by the National Highway Traffic Safety Administration, and earn a 4- or 5-star safety rating from the NHTSA.
(3) It has to have a battery pack that allows en-route swapping at a highway roadside station, similar to the Better Place battery swapping scheme.
(4) Model S prices must remain at the levels Tesla and Musk announced: $57,400 for the version with 160 miles of range, $67,400 for the 230-mile version, and $87,400 for the top-of-the-line 300-mile version (which will comprise the bulk of early production). All prices are before any Federal or other incentives.
If Tesla misses any one of those targets, Neil says, he wins the bet and Musk must donate $1 million to Médecins Sans FrontiÃres (Doctors Without Borders).
But if Tesla does what it said it will, Neil loses, and--being a journalist, not a multimillionaire entrepreneur--he will donate $1,000 to the same group.
Let's send the Boeing CEO in to space, and let him pay back the company the cost of the trip out of his own paycheck!
FYI, the Boeing exec in charge of the CST-100 program has already been to space a few times:
http://en.wikipedia.org/wiki/Brewster_H._Shaw
Did I complain yet about the sound in space? Yes? Well, it is a pretty big fucking issue. Everything you need to know about the US can be summarized as a NASA science video having sound in space...
Sound doesn't get transmitted through space, but a microphone mounted on the rover would have easily picked up all the sounds in the video.
The answer for why this needs to be attached to the space station is because it's making use of Dextre, the very large/expensive/awesome robotic arm attached to the ISS. The initial experiments may also likely need a human finely controlling the robotic arm or conducting extra-vehicular activities to set things up. There's some more details in this article.
It also wasn't mentioned in the summary, but a big part of why this is so challenging is that the tech is ultimately intended for satellites which weren't immediately designed to be refueled. There's a -lot- of old satellites out there with their fuel supplies winding down, and this could be potentially useful for quite a few of them.
You don't even need to look outside NASA to see ridiculous spending to compare to. The same House appropriations bill with the $431M JWST cut includes $2B for the Space Launch System (SLS) and $1B for the Orion/MPCV capsule. The SLS is basically Congress's mandate to NASA to build a heavy-lift rocket out of Shuttle-legacy components capable of competing with SpaceX's Falcon Heavy rocket. The $2B is only for the first year of SLS funding, for a rocket which isn't expected to have its first launch until 2017 or later. Mind that this is for a rocket that NASA didn't even want in the first place.
The amount being spent here seems to be a whole lot, until you consider how much is going to be poured down the "back-up insurance plan" with the SLS program just in case the commercial spaceflight approach doesn't work. I've heard estimates of about $3-4 billion being spent just on that one program, something that still has yet to even be figured out in terms of who is even going to build it in the first place.
It's kind of terrifying when one realizes that the combined budget for SLS and the MPCV capsule is $2.5B/year, and it's expected to be at least 6 years before it's ready for first launch. You could buy quite a few SpaceX's for that much money.
If you want to launch station segments by themselves like the Russians do the segments become more expensive, smaller, and less capable because each segment has to be its own spaceship complete with guidance, altitude and attitude control, and docking capability. The shuttle allowed for the segments to be large, cheep, and uncomplicated.
The actual cost numbers don't match your assertion: Mir cost about $4.3B to build, while the ISS cost around $100B. (ISS's pressurized volume is only about twice Mir's)
If a self-driven car is able to pass a normal driver's test (perhaps even including natural-language processing of the DMV employee's requests), do you think it should be allowed to drive? What's if it's able to pass several driver's tests, with a success rate significantly higher than the average current driver?
No one at Caltech has to use Bose, they can build their own that are better.
Curiously enough, there used to be a Caltech project class based on pretty much exactly that, although it's unfortunately no longer offered:
http://www.its.caltech.edu/~musiclab/
As a bit of trivia, Caltech alum Bill Gross actually ended up founding GNP Audio based on an engineering project he did as a student. He later went on to co-found, like, a gajillion other companies.
But what's the point of L2? You need a depot in Earth orbit to fuel up for the trans-lunar burn, and one in Lunar orbit to fuel up for the trans-earth burn. Why put the lunar depot at L2 as opposed to a lunar orbit?
I'm by no means an expert, but my understanding is that there's a few different advantages L2 has over LLO:
* Lower delta-V to reach it from LEO (3.43 km/s vs. 4.04 km/s), and -much- lower delta-V to go from there to Earth escape orbit (0.14 km/s vs. 1.4 km/s). This makes it much more practical for sending missions/probes to Mars, the outer planets, or just about anywhere else in the solar system.
* In that likely case that you're using hydrogen/oxygen propellant, boil-off is going to be your primary long-time storage concern. In LEO (and presumably lower orbit) you not only have to worry about shielding a depot from the Sun, but also have to worry about shielding the thermal emissions from a nearby constantly-moving terrestrial body. If you're in EML2, all you need is a sun shield to keep the temperature down.
* I suspect it's much more difficult to dock with a constantly-moving target in lunar orbit than with a more stationary target at a Lagrange point, both in terms of actual maneuvers and mission scheduling.
* There's substantial gravitational anomalies in the Moon, adding stationkeeping costs for maintaining a consistent lunar orbit.
I don't think I quite get how this is more economical. Is it actually cheaper to send up a bunch of smaller rockets with fuel as payload than it is to simply send a bigger rocket with enough fuel on it? Can somebody walk us through the math?
Absolutely. Remember that development costs tend to be very important when it comes to rockets. For example, the recently-cancelled heavy-lift Ares V rocket NASA was building was projected to cost at least $32B to develop (ignoring operations costs). This was for a rocket with 188mt capacity. By comparison, SpaceX recently announced a smaller rocket (53mt capacity) which will launch at $100M/flight starting in 2013. Instead of spending $32B to develop a bigger 188mt rocket, NASA could instead spend that money to launch fuel and payloads on 320 Falcon Heavies (16,960mt total payload). This of course ignores the greater economics of scale that could be obtained if you were launching a rocket that many times.
In an optimistic scenario, the Ares V would launch once or twice per year. If you assumed that the Ares V launched twice per year and was completely free to operate (which is false, as it actually would've cost billions more to operate), it would take 45 years before the Ares V would have launched more payload than you could've launched spending the same money on Falcon Heavies.
L1, L2, and L3 (the ones in line with the primary and secondary bodies) are dynamically unstable. It's not like you can park there. L4 and L5 points are much better because they are dynamically stable points, however nobody talks of placing a fuel depot there.
Actually, assuming you're talking about a hydrogen/oxygen fuel depot, you'll have a few pounds of propellant boil-off every day (out of several tons total). You can redirect the boil-off for station-keeping, and it pretty much meets the requirements for station-keeping at L2. There's more details in this ULA publication on depot architectures:
http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf
Actually, not only is it not politically sexy, but it's outright politically dangerous. Having fuel depots allows you to use existing rockets for exploration beyond low-Earth orbit, alleviating the need to develop heavy-lift rockets. A number of politically-powerful congressional districts (and congressmen) are heavily banked on NASA building a heavy-lift rocket from Shuttle-legacy components, while that isn't the case for fuel depots. I predict it won't be long before this particular effort is squashed by Congress, perhaps even outright banning it like they did with the TransHab inflatable modules.