AirSpaceMag.com

As long as everyone agrees that HLVs are not needed/detrimental to actual space development, and existing launch vehicle stable is just fine ( even if expensive ) its all good.

prototyping ISRU on moon – yes
depots/refuelling architectures on LEO/GEO/ lagrange points – yes

Now, if Senate Launch System funds could be reallocated to do even tiny bits of the above …

Comment by kert — March 31, 2011 @ 3:19 pm

The HLV requirement is not going to go away. The only effective way to put any payloads down of any size at the lunar poles is an HLV. There will be no water machines on the moon without heavy lift. There are no self assembling machines- it will remain science fiction for many decades to come. The rovers and industrial equipment to set up for a system of launching fuel (or far more likely, just plain water) into lunar orbit will be multi-ton payloads and the smaller they are the more difficult, time consuming, and failure prone the operation will probably be.

There is no flexible path. The only vehicle that will succeed in setting up for resource utilization on the moon is a heavy lift vehicle with hydrogen upper stages. And the only vehicle that can be had in the foreseeable future is a Shuttle Derived Sidemount Cargo Vehicle with a hydrogen earth departure stage. If we do not get this architecture in place very soon we will be trapped on earth for many more decades than is necessary. In my humble opinion, of course.

Comment by VirgilSamms — March 31, 2011 @ 4:00 pm

The only effective way to put any payloads down of any size at the lunar poles is an HLV

I can soft land 2 metric tons right now with a Delta-IV Heavy; about 1.5 mT with an Atlas 551. You can do a lot with such capability.

If we get an HLV, it will be very useful in lunar return. But if we don’t, it doesn’t make lunar return impossible.

Comment by Paul D. Spudis — March 31, 2011 @ 4:02 pm

I agree with Kert regarding the consensus that is growing concerning a current lack of real need for an HLV.

Certainly one of the first roadblocks to current exploration plans is that they require an HLV, and don’t design their needs to existing launcher capabilities. Though we have budget limitations, there is no reason we can’t start exploration efforts using current launchers. The 1 million lb ISS certainly shows what we’re capable of building with 50,000 lb payload limitations.

Regarding depots, I see them as not only an early enabler, but as we know from our terrestrial existence, depots will always be with us as we expand further into space.

The question Paul Spudis seems to be debating is where the supplies will come from. For now, I think it makes sense to lift up supplies from Earth, since that requires the least amount of infrastructure and leadtime.

However at some point in our expansion the volume of supplies needed will require an assessment of the cost, and that’s where I see supplies from the Moon becoming more viable. But if we mandate that we “build the store before we settle the town”, then that may slow down our overall space exploration, and lead to spending money on creating lunar infrastructure before we really needed it.

Just like with the lack of market demand for the HLV, there is not yet a market demand for lunar supplies, and applying too much capital in addressing a non-critical issue is not a good idea. Exploration is good of course, since we know it will be needed at some point, and who knows, the market demand for lunar supplies may not be that far in the future. Time will tell.

Comment by C. Adelphia — March 31, 2011 @ 5:23 pm

The question Paul Spudis seems to be debating is where the supplies will come from

No, that’s not the “question I am debating.” I am saying that here we have two proposed programs, spending roughly the same amount of money over roughly the same period of time. At the end of each program, I am suggesting that lunar return under our architecture leaves you with more “bang for the buck” — both a reusable transportation system for all of cislunar space and an operational lunar outpost capable of producing 150 metric tons of water per year. With the GT/NIA architecture, you get one human mission to an asteroid. I am suggesting that our plan offers more value for money.

But if we mandate that we “build the store before we settle the town”, then that may slow down our overall space exploration, and lead to spending money on creating lunar infrastructure before we really needed it.

We’re not doing that. We are creating a system that permits freedom of movement throughout cislunar space. That volume of space is where all of our national security, economic and most scientific assets reside. Freedom to access these space assets is more valuable than a one-off stunt mission to some distant destination.

Comment by Paul D. Spudis — March 31, 2011 @ 6:21 pm

I think the question here is what would a manned expedition to an asteroid accomlish, that robots could not, that would be worth even a tenth of their projected costs. Sample return? We already have tens, if not hundreds, of tons of asteroid samples on Earth today. They’re called meteorites. We already know in great detail what asteroids are made of. Some of them are probably just rubble piles made of a great variety of things, and they are probably almost all covered with a layer of regolith which would make sampling the body of the asteroid difficult.

One of these days we are going to need to deflect an asteroid on a collision course with Earth. Exploding a series of nuclear bombs at the surface of the asteroid is probably the most practical way of doing that, and we don’t need to know what the asteroid is made of to do it.

Indeed, you are quite right in calling an asteroid mission a “stunt”. It is almost as worthless as going to a Lagrange point. Give me that much money, or even a quarter of that amount, upfront, let me decide how to invest it, and I can go to Mars within 10 to 12 years.

Comment by Dick Morris — March 31, 2011 @ 7:36 pm

Adelphia:

Initially, of course, everything will have to come up from Earth. But I agree with Dr. Spudis that the first order of business for any sustainable program of lunar exploration and development is to set up a propellant production plant. It is not an “advanced” capability that will be established only when the traffic builds up enough to “justify” it. The ability to refuel spacecraft on the Moon with all, or a large fraction, of their Earth-return propellants will make a major reduction in the total cost of the program.

Comment by Dick Morris — March 31, 2011 @ 7:50 pm

Paul:

Over the long term, the cost of HLV development will become insignificant, provided that we continue to use it, over and over again for the next several decades, just as we should have for the Saturn V.

“New Space” needs to abandon their futile and counterporductive attempts to canabilize NASA and focus instead on practical, affordable, reusable technologies for dramatically lowering launch costs enough to grow new markets such as space tourism. Most NASA missions are too infrequent, demanding, capital-intensive, and specialized to be a good fit for the likes of Blue Origin, Armadillo Aerospace, and XCOR.

Unlike the phantom selling points of commercial space dogma, simple economics dictate that ISRU technologies will be vital for exploration and development of the Moon and Mars.

Comment by Nelson Bridwell — April 1, 2011 @ 3:26 am

Obviously the debate is not so much heavy lift vs. fuel depots, but rather Moon vs. anywhere but the Moon. The Georgia Tech study is interesting, though it tends to wave away certain problems. In any case, it does not get us to a proper destination, which is its primary flaw.

Comment by Mark Whittington — April 1, 2011 @ 7:15 am

Mark,

the debate is not so much heavy lift vs. fuel depots, but rather Moon vs. anywhere but the Moon.

Quite true, but it’s also about more than that. It’s about creating lasting capability in space vs. conducting one-off PR stunt missions to nowhere. It’s about having a viable, exciting space program vs. doling out corporate welfare checks to widget shops. It’s about having achievable, realistic goals with near-term milestones vs. vague promises of trips to somewhere, sometime — 20 years down the road.

The current debate is real and about fundamental issues. “Moon vs. no Moon” is symptomatic of the dichotomy.

Comment by Paul D. Spudis — April 1, 2011 @ 8:07 am

“I agree with Kert regarding the consensus that is growing concerning a current lack of real need for an HLV.”

A few words about the “consensus that is growing” rationale:

“The 1 million lb ISS certainly shows what we’re capable of building with 50,000 lb payload limitations.”

Actually (for the Shuttle) the payload increments were more like 35,000 lb to the ISS Orbit. The ISS assembly required many launches over a number of years and a great degree of Human led EVA operations (supported at first from the Shuttle then from the ISS itself). The Shuttle capability will soon be gone and while assembly at the ISS is surely possible it would require additions to the ISS capabilities that will not be free. Those costs (realistically assessed) need to be considered also.

“Regarding depots, I see them as not only an early enabler, but as we know from our terrestrial existence, depots will always be with us as we expand further into space.”

I also support the concept of in-space refueling (especially after ISRU comes on line), but all these discussions seem to start with the assumption that any HLV (even one as close to the current Shuttle configuration as the Side Mount) will be prohibitively expensive, while in-space refueling is an already existing technology (or at least one that will be fast, easy, cheap and low risk to produce) and there is no reason to believe that to be the case. If your only interest is eliminating Heavy Lift because in-space refueling is cheaper then realistic cost estimates for developing the in-space refueling capabilities must also be considered (by the way this comment is directed to C. Adelphia not Dr. Spudis who does not appear to be a proponent of the all one way or the other argument).

A final point is a kind of “Catch 22”. An HLV will allow bigger modules and thus require fewer assembly operations. That would reduce the amount of direct human support initially required. Smaller boosters mean smaller modules and more assembly, increasing the need for earlier human activity. But the availability of an HLV makes human missions easier. Anybody got a headache yet?

Dr. Spudis is certainly correct that the lack of an HLV “doesn’t make lunar return impossible”, but it will make it more difficult.

Comment by Joe — April 1, 2011 @ 10:29 am

Again, Cost is King.
But wait, if we changed the law, and removed the legal handcuffs from exploration funding by private corporations, then entrepreneurs could raise capital, make investments in vehicles/ architecture, and then go to mine resources on Luna, Mars, or asteroids. BTW, and I may be wrong on this, if NASA or someone plans to use in-situ fuels from Luna or Mars, then do certain international (UN)treaties need be revised to allow that use ? (This is one example of restrictions that may need to be changed).

We could become space-faring, following a time-proven model, i.e. Columbus/1492, Marco Polo, and the British East India Company, among others.

Future worlds await, we have but to allow risk-taking people the freedom to act.

Comment by Thomas White — April 1, 2011 @ 1:32 pm

Future worlds await, we have but to allow risk-taking people the freedom to act.

What specific law(s) or regulatory regime is stopping them?

In regard to extracting or using lunar resources, no law or treaty prevents this. One could read that from the 1979 U.N. Moon Treaty, but we (the USA) are not signatories to that treaty.

Comment by Paul D. Spudis — April 1, 2011 @ 1:51 pm

“It’s about creating lasting capability in space vs. conducting one-off PR stunt missions to nowhere.”

I have to agree. Though I would like to see some deep space missions the moon has to come first for several reasons (in my essay link on this thread).

The shielding to protect against just solar events, let alone GCR, would be pretty heavy and I do not think they will go anywhere without it. It is just a begging for a dead or irradiated crew. With that said, only several HLV missions would be able to put up the basic shielding and propulsion and life support required for a NEO mission. I do not see that happening since we do not even have an HLV project in progress yet. Building such a mission with inferior lift vehicles would require several dozen launches and cost close to what the ISS does. Not going to happen. And depending on how long the mission is for, there is the 800 pound gorilla called heavy nuclei GCR no one will talk about except to throw smokescreens deceiving the uninformed into thinking it is not a problem. It is THE problem. The moon and lunar orbit is the only place to launch deep space missions from because of the heavy nuclei radiation shielding- which requires nuclear propulsion- which is not going to happen in earth orbit. And then there is all that shielding which can only come from one place; lunar ice.

The whole infomercial scam concerning HSF-BEO missions is a sham. I do not know how it keeps being discussed and brought to the table in all these powerpoint advertisements that depict chemically propelled unshielded spacecraft in deep space.
That is science fiction.

Comment by GaryChurch — April 2, 2011 @ 7:20 pm

Hi Gary,

heavy nuclei GCR have their electrons stripped and so carry a charge. The following article argues that magnetic shielding should be able to provide sufficient protection. Those magnets are not so large and with modern, relatively high temp superconductors, I would think that they could be placed behind shades and be at low enough temps to not require liquid nitrogen. But please explain if I am wrong. If I am right then this could help colonization both during interplanetary travel and on the surface.

http://www.islandone.org/Settlements/MagShield.html

Comment by JohnHunt — April 3, 2011 @ 10:56 pm

Dr. Spudis, Did this study differ from that of you and Lavoie in regards to the use of commercial launch services. If so, why?

I do not at all support any asteroid-first approach. Indeed, I advocate a Moon-first, development of lunar ice to provide LOX/LH in LEO. However, I feel that comments against an asteroid-first plan are being made without any fair defence. So I’m going to suggest what their replies might be.

It is true that they routinely make the arguments for sample return and as a practice run for nuking an incoming asteroid. And I’m not going to even try to defend those arguments because I think that they are bogus based upon the point that both are probably not necessary and that both could be easily and for far less expense done by robots.

However, ever distant steps get us closer to Mars which (whether stated explicitly or not) truly is the destination. IF the Flexible Plan actually were to lead to humans landing on Mars, I think that most citizens would consider that a “proper destination”.

The whole point of a trip to an asteroid is to have the first time venturing beyond the Earth-Moon system and for months at a time. Can long-term radiation be mitigated and survived? Can supplies and equipment last for that length of time in deep space? If so, then the next trip to Deimos would be justified. Did the first lunar lander launched to LEO go nowhere? Sort of. But the point was to test its docking and manevering before a later mission headed to the Moon. A trip to an asteroid is a similar concept. So, it’t not entirely fair to call it a “one-off stunt”. They would argue that it is a stepping stone for yet deeper missions.

I think that there’s a bit of value here it’s just that I don’t think that it is anywhere as valuable as what we get from developing lunar ice. Plans to go to an asteroid do nothing to reduce costs and so blow open space.

Now, the other main reason given is to engage the public and to inspire a new generation of young people to pursue the sciences. I personally think that this is a weak argument. Many Internet entrepreneurs (including Elon Musk) weren’t even alive at the time of the first lunar landing. And yet they went into sciences none-the-less and launched companies.

Further, in a gynmasium, stick an astronaut and “Robbie the tele-operated talking lunar Robonaut” and then let in a bunch of 3rd graders. Who do you think they’ll run to? Development of lunar resources can be both productive and inspiring.

Comment by JohnHunt — April 3, 2011 @ 11:25 pm

I was under the impression that Galactic Cosmic Rays reach even into the deepest mines on Earth. A little shielding will not impede their progress. Just one of those hazards of becoming a space fairing society.

Comment by Rhyshaelkan — April 4, 2011 @ 3:50 am

My mistake. After some research, I was thinking of neutrinos.

Comment by Rhyshaelkan — April 4, 2011 @ 3:58 am

JohnHunt,

Did this study differ from that of you and Lavoie in regards to the use of commercial launch services.

They costed their architecture using both EELV and Falcon 9 options, both separately. We conducted our cost estimates using EELV (Atlas 551) plus a 70 metric ton (medium) HLV. The GT/NIA EELV baseline cost estimate ($86 B and 20 years) is nearly identical to our EELV/MHLV cost estimate ($87 B and 16 years).

I am in complete agreement with you on your other points.

Comment by Paul D. Spudis — April 4, 2011 @ 5:59 am

In getting a large payload out of LEO I can see some resemblance to the first B-29s operating out of China, in that the effort to create a fuel depot over the Himalayas was disproportional to the real mission, which was to fly to Japan. My question is whether the added complexity of multiple launches is itself a factor in deciding the launch vehicle to be used.

Comment by Phil Thomas — April 4, 2011 @ 9:54 am

Comment by JohnHunt — April 3, 2011 @ 11:25 pm
First a little ‘truth in packaging’. My first exposure to taking space activities seriously (after growing up watching the original Star Trek) was doing a book report on Islands in Space by Cole/Cox. The vision of use of NEO’s in that book is what pushed me to want to be an engineer. So I am an Asteroid First guy at heart.

That being said there is an additional point in the Moons favor. When I worked on the ISRU research for President George H.W. Bush’s SEI, I discovered that the basic engineering required for mining and processing would need to bring in ‘outsiders’ (people from mining and other industries not usually associated with aerospace). In talking to these folks I learned they were enthusiastic about the idea but were very reluctant to try and work with the ‘weightless’ (actually mili-gravity) environment that asteroid ISRU would require. They were however comfortable that their methods could be adapted to the Moons 1/6 G Gravity. It was at that point that I became what I guess you could call a ‘Moon First’ Guy, even though the conventional wisdom at that time was that the Moon was lacking in Hydrogen, Carbon and Nitrogen. The recent revelation of large amounts of water on the Moon only increases the case for Moon First.

Questions for Dr. Spudis (while we are on the subject). I have recently seen reports implying the existence of amounts of Carbon and Nitrogen on the Moon also in excess of what had been believed. Is that true? If it is true, are these concentrations of Carbon and Nitrogen sufficiently large to be practically useful?

Comment by Joe — April 4, 2011 @ 10:32 am

Phil,

My question is whether the added complexity of multiple launches is itself a factor in deciding the launch vehicle to be used.

There are several consideration in regard to depot or not to depot, including the complexity of coordinating multiple launches, rendezvous and transfer of propellant payload, boil off of cryogens, and the goals of your chosen architecture. These considerations must be weighed against the costs of the alternative development and operation of a new heavy lift launch vehicle. Also, there is the “new widget” factor — we’ve done heavy lift, we have not yet done propellant depots. As to which issue is of most concern, I suspect that the answer would vary by who answers the question.

Comment by Paul D. Spudis — April 4, 2011 @ 10:33 am

Joe,

I have recently seen reports implying the existence of amounts of Carbon and Nitrogen on the Moon also in excess of what had been believed. Is that true? If it is true, are these concentrations of Carbon and Nitrogen sufficiently large to be practically useful?

Yes to both questions. The initial analysis of results from the LCROSS impact suggest that polar volatiles are present in (more or less) cometary proportions. Carbon is found as methane and simple organic molecules. Nitrogen appears to be in the form of ammonia. Both are present, although their concentrations are still being derived.

One point in regard to the concentration of compounds and elements estimated from the LCROSS data. The fractional amount of water present in the target site depends on the mass of water ejecta vs. the mass of particulate ejecta. Although we can directly measure the mass of water, the particulate material is dark and not well quantified. The presumption that there is 5-10 wt.% water in the Cabaeus floor is dependent on the LCROSS crater behaving “normally”, i.e., ejecting the amount of material predicted by theory. But theory is incomplete for unusual impact conditions like LCROSS (i.e., an extremely low density projectile impacting at relatively low velocity (~2 km/s). So if the total amount of ejecta is much lower than we might expect, the corresponding concentration of water in the dark area could be much higher than presumed. Data from the Mini-RF radar experiments show craters will large amounts of radar bright material scattered around the poles; these feature may contain as nearly pure water ice. So the total amounts of water and other volatiles such as carbon and nitrogen may be much greater than currently thought.

Comment by Paul D. Spudis — April 4, 2011 @ 10:41 am

Comment by Paul D. Spudis — April 4, 2011 @ 10:41 am
“Yes to both questions.”

Better and better. At least in the practical sense. Now if a way could just be found to make the politics sync up with practicality.

Comment by Joe — April 4, 2011 @ 4:21 pm

SpaceX’s announcement today about a Falcon Heavy might be good news for the Moon. Being able to put 53,000 kg in LEO, gives a lot to work with in terms of payload on the Moon and for a Martian sample return but it sounds like it might be insufficient for a manned Martian mission.

So, with this capability in a few years, it puts pressure on Congress to kill the Senate Launch System and consider what could be done on the Moon first. If the Moon could provide LOX/LH fuel, then the Moon could be seen as a stepping stone to Mars.

Comment by JohnHunt — April 5, 2011 @ 3:13 pm

“But please explain if I am wrong.”

The only practical shielding against Heavy Nuclei is hydrogen rich mass and distance on the order of 500 tons and 14 feet for a small capsule. The magnetic field sham is constantly pushed as a solution when there is NO SUCH TECHNOLOGY. The super powerful magnetic fields required to stop GCR are science fiction. The megawatts of power and supercooled superconducting coils required to even see if it would provide partial protection without scrambling the brains of the crew are a non-starter. It is the same old smokescreen that keeps getting thrown out into cyberspace- and it is B.S. There is not one even small scale demonstration of any active shield scheme that will stop the heavy nuclei component of galactic cosmic rays. Not one. And there will not be. It is the cold fusion myth of deep space travel.

Comment by GaryChurch — April 5, 2011 @ 3:14 pm

Comment by JohnHunt — April 5, 2011 @ 3:13 pm
Interestingly the last paragraph of the Space X press release for that announcement says the following:

“Please note that Falcon Heavy should not be confused with the super heavy lift rocket program being debated by the U.S. Congress. That vehicle is authorized to carry between 70-130 metric tons to orbit. SpaceX agrees with the need to develop a vehicle of that class as the best way to conduct a large number of human missions to Mars.”

I know they are talking Mars and I am sure they want the “70-130 metric tons to orbit” HLV to be of their design but it is interesting that Space X is indorsing a 70-130 metric tons to orbit HLV regardless of orbital refueling capabilities.

Comment by Joe — April 5, 2011 @ 4:45 pm

That vehicle is authorized to carry between 70-130 metric tons to orbit. SpaceX agrees with the need to develop a vehicle of that class as the best way to conduct a large number of human missions to Mars.”

I don’t agree that it’s the best way to conduct a “large number of human missions to Mars.” They are presupposing that we do Mars missions in the “Apollo mode” of launching everything from the Earth. Instead, Mars missions should be fueled with propellant made on the Moon, as the VSE adumbrated.

Anyway, what’s this nonsense about “a large number of missions” to Mars? Hasn’t Elon heard that once you’ve visited a destination, “we’ve been there”?

Comment by Paul D. Spudis — April 5, 2011 @ 6:58 pm

Phil wrote:

“My question is whether the added complexity of multiple launches is itself a factor in deciding the launch vehicle to be used.”

A propellant depot would add some complexity, but nothing like the complexity of landing hundreds of flights, refueling them, then sending them on their way again, as happens every day at any large airport. It is certainly nothing we can’t handle. A propellant depot in LEO would allow us to use a smaller launch vehicle for lunar and Mars logistics, which we could afford to make fully reusable.

Refuel the orbiter stage of a 2-stage, VTOL RLV in LEO, and it can fly out to the Moon or Mars, unload it’s payload, refuel with propellants manufactured from indigenous resources, then fly back to Earth and aerobrake into LEO. It can do all that with a single stage and without expending any hardware. That would certainly be much cheaper than using an expendable, super heavy lift launch vehicle.

Comment by Dick Morris — April 5, 2011 @ 7:06 pm

Comment by Paul D. Spudis — April 5, 2011 @ 6:58 pm
“I don’t agree that it’s the best way to conduct a “large number of human missions to Mars.” They are presupposing that we do Mars missions in the “Apollo mode” of launching everything from the Earth. Instead, Mars missions should be fueled with propellant made on the Moon, as the VSE adumbrated.”

I agree with you. I did not say it was admirable, only interesting in the sense that they are supporting HLV (of some design) when many of their supporters are so adamantly opposed to HLV.

For what it is worth my own “seat of the pants” opinion is that a 70 to 100 ton lift capability is needed, but should be enough for the kind of lunar based program you are proposing and I adamantly support.

Comment by Joe — April 5, 2011 @ 7:29 pm

“Propellant depots are a necessary but insufficient element in a long-term space faring strategy. To truly change the rules of spaceflight, we need to learn how to access and use what we find in space to create new capabilities in space. This involves learning how to use extraterrestrial resources of material and energy.”

We need learn how to cheaply “use extraterrestrial resources of material and energy”.

The major aspect of fuel depots is they could be a market for rocket fuel in space, and could the start a market for water in space.
NASA highest priority should be to start new markets in space- the main reason it should be exploring space is to assist in the possible development of new markets in space.

If the only market in space which ever developed is the satellite business, NASA decades of effort will only be a waste of time and money. It won’t inspire future generations, all it will have done is mislead them.

Comment by gbaikie — April 5, 2011 @ 8:33 pm

NASA highest priority should be to start new markets in space- the main reason it should be exploring space is to assist in the possible development of new markets in space.

That is only one of the many “missions” of NASA as defined in the Space Act. Anyway, learning how to use lunar resources is starting a “new market” in space.

Comment by Paul D. Spudis — April 6, 2011 @ 12:40 am

“That is only one of the many “missions” of NASA as defined in the Space Act. Anyway, learning how to use lunar resources is starting a “new market” in space.”

Perhaps it is one of many missions, but I think it should have the highest priority.
I would like to hear someone argue that something else has higher priority. I no idea what could more important and urgent.
And yes, I certainty see NASA exploration of the Moon as linked with starting new markets.

Comment by gbaikie — April 6, 2011 @ 3:40 am

Oh, and once say a dozen of more markets are started in space, NASA’s priority could be changed. And the Dept of Commerce could assume this priority.
If any of them had any brains, the Commerce dept would already be involved with establishing markets in space.
Though it might hard “know”, what does anyone think NASA’s high priority should be once there already are many markets in space?

One idea would be more focus of the exploration of the stars- which may involve making massive telescopes in space. And/or the search for alien life, in this solar system and beyond this system.

Comment by gbaikie — April 6, 2011 @ 4:17 pm

“-it is interesting that Space X is indorsing a 70-130 metric tons to orbit HLV regardless of orbital refueling capabilities.”

Don’t say that anywhere the musk worshipers hang out- they will go into attack mode. The want nothing to do with any heavy lift that might stop funding for their space station vacation with elon on the ISS. They defend anything Musk does to the death with idiotic zeal. They will tell you any number of things that are just plain wrong. Like kerosene is a better propellant than hydrogen (because musk cannot afford hydrogen upper stage technology) and that 27 engines on the falcon “heavy” is a great idea (because musk cannot afford to build bigger engines) and that using a human rated capsule to haul cargo is wonderful (again, because musk cannot afford anything else). And it goes on and on. Unfortunately the private space sycophants are not stating the truth; that losing our HLV infrastructure will imprison human space flight missions in low earth orbit for decades to come or longer.

The whole refueling depot scheme is science fiction. Fueling up an HLV in a silo on the moon is perfectly doable but doing it in space is an order of magnitude more difficult. It will take decades to develop if it is practical at all (which it almost certainly is not with liquid hydrogen). Performing maintenance on a reusable spacecraft in an underground lunar hangar is perfectly doable but doing it in space is a ridiculous idea.

Only governmental resources and a lunar base are going to allow any kind of Beyond Earth Orbit Missions. Sorry Muskovites, but your dreams of zero G vacations are just childish fantasy. Endless circles at high altitude in low earth orbit are a joke.

Comment by GaryChurch — April 7, 2011 @ 8:29 pm

“They will tell you any number of things that are just plain wrong. Like kerosene is a better propellant than hydrogen”

In fact I just had such a conversation at Stross’ blog on SpaceX Falcon Heavy.
http://www.antipope.org/charlie/blog-static/2011/04/you-probably-already-saw-this-.html#comment-107503

I tried to explain that different circumstances call for different propellants. But this fell on deaf ears.

Some factions of the kerosene cult wrongly conclude that water isn’t worth much. I’m disappointed this erroneous meme enjoys a home at Stross’ forum.

Comment by Hop David — April 9, 2011 @ 10:20 am

“learning how to use lunar resources is starting a “new market” in space.”

I am pretty leery of the whole for-profit game in space. I of course get accused of being a communist for it. In my opinion the profit motive is toxic to space exploration. This idea of opening up the solar station with obscenely expensive tourist rides for the ultra-rich makes me nauseous. My angle is planetary protection and getting access to DOD dollars that way. I wrote an essay about it but it is not going viral that’s for sure. No one seems to be able to wrap their head around the idea of atomic bomb propulsion. And talking about massive radiation shields just makes people roll their eyes at the seemingly impossible number of tons required. But maybe someday I will be recognized as a visionary, who knows? I think I am. But then everybody does.

I wonder why Dr. Spudis gets so few comments on this blog? Other space sites get hundreds. Maybe he just put’s up too much hard science and not enough bubble gum B.S. to attract all the surf bums like me. At least he let’s me post; the other sites do not seem to like my pro-nasa anti-new space position. That falcon heavy reminds me of the Russian N-1 moon rocket with all those engines. I am not buying any of it. SpaceX is going to hit a wall with their cheap and nasty is better philosophy. I suspect there is alot of smoke and mirrors going on, especially with the payloads they are quoting.

Comment by GaryChurch — April 9, 2011 @ 8:46 pm

I am pretty leery of the whole for-profit game in space.

By that statement, you’ve just consigned Direct TV, Sirius, and most telecommunications companies into bankruptcy. The comm sat originally was simply a tech demo; it was ultimately turned into a source of revenue. Markets in space exist now and more will exist in the future. NASA’s job is (or should be) to lead the way by demonstrating new technologies and capabilities for later commercialization.

I wonder why Dr. Spudis gets so few comments on this blog? Other space sites get hundreds.

And most of them are totally worthless. I get all the comments I need, thank you. Quality is more important than quantity.

Comment by Paul D. Spudis — April 10, 2011 @ 4:04 am

Dr. Spudis,

I have read your article above and listened to your interview on ‘The Space Show’ with Dr. David Livingston. I could not agree with you more regarding the current direction of NASA under President Obama’s administration and the need to focus on a lunar-based space infrastructure. Flying to an NEO at this point is little more than a stunt with little to show for the effort.

However, without HLV, I suspect that the limited capacity offered current launch systems will be the critical factor in driving costs even with the development of a fuel depot system. This limited capacity was what drove ISS construction costs to beyond $100 billion mark and took 12 years to complete, STS issues aside.

One subject that seems to be missing in many of these discussions is the impact of population dynamics on the development of transportation systems. Our current transportation systems based here on Earth were driven by markets established by large populations. The relative paucity of human presence in space is the defining problem for space transportation development.

The ISS, while expensive to build, was a milestone because it established a small population of humans in LEO. This milestone helped to generate commercial development over the last decade with companies like Space X, Bigelow, Masten, XCOR, Blue Origins, and many others.

Thus, an architecture that emphasizes increasing human population in space- LEO, cislunar, and lunar -by building more destinations like space stations and lunar bases. This increased population results in a greater logisitical demand for cargo and human space transport providing more commercial opportunities and spurring greater economic from both the government and the private sector. Such an architecture requires HLV in order to succeed.

Gary Miles

Comment by Gary Miles — April 10, 2011 @ 11:43 am

Comment by Paul D. Spudis — April 10, 2011 @ 4:04 am
“I wonder why Dr. Spudis gets so few comments on this blog? Other space sites get hundreds.
And most of them are totally worthless. I get all the comments I need, thank you. Quality is more important than quantity.”

Beat me to it. Most of those “hundreds” of posts are made by the same handful of people arguing the same point over and over again. If they made their point and (had the sense) to stop there would be far fewer post on those sites.

Comment by Joe — April 10, 2011 @ 1:19 pm

Gary,

Such an architecture requires HLV in order to succeed.

Unless one can change the rules of spaceflight so that we don’t have to launch everything we need from Earth’s surface. That’s why I advocate early experimentation with lunar ISRU — to learn how to cut the logistics cord with the Earth as quickly as possible. We can begin processing resources on the Moon now, without an HLV. If one becomes available later, we can use it. But we don’t need one in hand to get started.

Comment by Paul D. Spudis — April 11, 2011 @ 4:14 am

Paul,

But you miss my point. ISRU technology and fuel depots are only likely going to come about when there is a market demand for them. Since market demand is derived from an existing population in specific locales and space is absent a sizable population, the chances of anyone building an space-based transportation infrastructure even with current launch systems are very slim. Not only that, but since we don’t know what the destinations will be, any infrastructure that is built may not be optimal to serving the market.

So the focus of any space program should be the development of destinations like a space station for artificial gravity research, a space hotel, an industrial research and manufacturing facility, or a lunar base. By building all of these destinations in space, the human population can be increased to a point that the is a greater market demand for ISRU development and fuel depots.

This is why when people state that US should reduce cost of space access first I disagree. In the absence of any significant population, such approach is unlikely to succeed. And such approach does not follow historical patterns of transportation development.

Comment by Gary Miles — April 11, 2011 @ 8:37 am

Gary,

But you miss my point. ISRU technology and fuel depots are only likely going to come about when there is a market demand for them.

No, I got your point — I just don’t agree with it.

I am suggesting that we should make lunar return and learning how to do ISRU the centerpiece of the civil space program, as it had been up until the change in policy last year. Because we do not know at this time the difficulty and the break points in this processing, it is an engineering R&D effort and an appropriate activity for the federal government to undertake. Markets follow technology development; once we know that this can be done, commercial markets will emerge naturally.

Comment by Paul D. Spudis — April 11, 2011 @ 9:15 am

Comment by Paul D. Spudis — April 11, 2011 @ 4:14 am
“Unless one can change the rules of spaceflight so that we don’t have to launch everything we need from Earth’s surface. That’s why I advocate early experimentation with lunar ISRU — to learn how to cut the logistics cord with the Earth as quickly as possible. We can begin processing resources on the Moon now, without an HLV. If one becomes available later, we can use it. But we don’t need one in hand to get started.”

I do not know if I should get involved in this or not, but here goes. Part of this HLV is needed or not derives from the definition of HLV. If you are talking about 130 tons then at least in my opinion you are absolutely correct, if you mean 70 – 100 tons then I have reservations. I believe you are going to end up needing direct Human Intervention in the assembly of the Lunar Processing Equipment sooner than is currently allowed in the plan. I am not talking about a permanent base for scores of people, more of an outpost for 2 – 4 people to inhabit for weeks at a time during crucial parts of the assembly sequence. The Side Mount SDHLV can meet those requirements (thus greatly increasing the projects chances of success), while at the same time maintaining critical skills for future development.

Comment by Paul D. Spudis — April 11, 2011 @ 9:15 am
“I am suggesting that we should make lunar return and learning how to do ISRU the centerpiece of the civil space program, as it had been up until the change in policy last year. Because we do not know at this time the difficulty and the break points in this processing, it is an engineering R&D effort and an appropriate activity for the federal government to undertake. Markets follow technology development; once we know that this can be done, commercial markets will emerge naturally.”

Agree 100% on this point.

Comment by Joe — April 11, 2011 @ 9:44 am

Joe,

The Side Mount SDHLV can meet those requirements (thus greatly increasing the projects chances of success), while at the same time maintaining critical skills for future development.

Agreed. If we must build a SDHLV, then side-mount is the way to go — cheapest, fastest and least new development amnd infrastruicture creation required. 70 metric tons is a lot of capability, certainly enough for human missions to the Moon.

Comment by Paul D. Spudis — April 11, 2011 @ 10:22 am

Paul,

Markets follow technology development

This is our fundamental disagreement then. In terms of transportation systems, the technology follows the market which is driven by population dynamics. The train tracks were laid long before the advent of the steam locomotive or diesel engine because the first “trains” were pulled by teams of horses or mules. It is no coincidence that the first tracks were laid between major cities and not small towns. Highways existed long before the advent of the automobile and the roads between big cities tended to be wider and better maintained. The first commercial transcontinental airplane service took almost a dozen stops and several days to make. Why? Because the planes first used for service did not have the range to make direct flights. That came later with the development of pressurized cabins and better engines. Companies were willing to invest in these technologies because there was a proven market for their use. Even today, such technology as hybrid electric vehicles are first marketed to states like California, New York, and Florida which have among the highest population density in the nation. Also, there is a great deal of technology that has been develop that has never found any market use or very limited market use like the supersonic jet.

This principle is true even for other areas like communications. Communication technology development and implementation generally occurred faster in major cities with high population densities. Population dynamics is very much a factor in development and implementation of technology. Which is why in human spaceflight we have been going around in circles, there is simply not a significantly large enough human population in space to provide a market and drive technology development.

Comment by Gary Miles — April 11, 2011 @ 10:27 am

In regards to supersonic jets, I should say that while it has military applications, the technology has little commercial use.

Comment by Gary Miles — April 11, 2011 @ 10:56 am

Gary C.:

An in-space refueling depot is not nearly as hard as you seem to think it is. NASA has been handling LH2 for about 50 years, so the technology is well developed. Hydrogen has a notorious tendency to leak, but in a vacuum any leaks would dissipate very quickly and there would be no possibility of a fire or explosion. Centrifugal force would be an effective substitute for gravity: Spacecraft would dock to the propellant depot tank set and the entire assembly would be slowly rotated about its common center-line to settle the propellants in their tanks, and the propellants would be transferred from one to the other by gas pressure. No zero-g propellant acquisition devices would be required.

The propellant depot would consist of some tanks, plumbing, a cryostat to re-liquify propellant boiloff, and a solar power supply. It might also contain an electrolysis unit to generate LO2 and LH2 from water (from Earth or the Moon). There is no reason to believe that that would require billions of dollars and decades to develop.

I am also mystified by your claim that LEO tourism is a “childish” notion. Tourism is over a $500 billion industry on Earth, and polls have shown that a substantial fraction of the population would like to take a vacation in space. At prices attainable with fully-reusable launchers, that could eventually generate a market for millions of passengers – thousands of flights – per year.

We have had the technology for fully-reusable, 2-stage, VTOL launchers for at least 40 years, so there is nothing stopping us. Unfortunately, NASA developed the mind-set that everything they do has to be done the hard way – simply “because they are hard” – in order to “push the technology”. Thus the horizontal landing designs for Shuttle, NASP, and X-33. NASP and X-33 suffered the further crippling handicap of being single-stage designs. NASA selected those designs for no other reason than that they were the most difficult ways to develop a launch vehicle that they could imagine, and, therefore, promised to “justify” massive amounts of technology development work for their research centers. The VTHL design selected for X-33 was also the most wildly impractical design that has ever been selected for anything.

Low cost space transportation requires a large market, in order to spread fixed costs over a large number of flights. A large market, on the other hand, requires low cost transportation. It is a classic “chicken or the egg” problem. LEO tourism is the only foreseeable market that is big enough to make an RLV development pay off in launch cost savings, and it is the cost of Earth-to-orbit launch which has kept us in LEO for the last 30 years, not an inability to launch large payloads.

As I have outlined elsewhere, the orbiter stage of a 2-stage, VTOL RLV can be refueled in LEO, carry a substantial payload to the Moon or Mars, be refueled with propellants made from indigenous resources, then fly directly back to Earth (that can be done with a single stage) and aerobrake back into LEO. LEO refueling allows us to do manned lunar and Mars exploration without an HLV, and the RLV would be small enough that we could afford to make it fully-reusable.

Comment by Dick Morris — April 11, 2011 @ 8:14 pm

Comment by Dick Morris — April 11, 2011 @ 8:14 pm

A couple of comments.
“NASA has been handling LH2 for about 50 years, so the technology is well developed.”

For use on the ground, not in orbit where weight is at a premium. Properly insulating the storage tanks (to avoid excessive boil off) while not making the structure to massive will be a challenge

“Hydrogen has a notorious tendency to leak, but in a vacuum any leaks would dissipate very quickly and there would be no possibility of a fire or explosion.”

True, but not the point. The problem is not to lose too much Hydrogen during extended storage.

“Centrifugal force would be an effective substitute for gravity: Spacecraft would dock to the propellant depot tank set and the entire assembly would be slowly rotated about its common center-line to settle the propellants in their tanks, and the propellants would be transferred from one to the other by gas pressure. No zero-g propellant acquisition devices would be required.”

This would require an RCS system that could control such a docked structure while its center of mass was changing constantly and considerably (as fuel was moved from the depot to the vehicle). Again a considerable challenge.

“The propellant depot would consist of some tanks, plumbing, a cryostat to re-liquify propellant boiloff, and a solar power supply. It might also contain an electrolysis unit to generate LO2 and LH2 from water (from Earth or the Moon). There is no reason to believe that that would require billions of dollars and decades to develop.”

As stated above the challenge is considerably more than you think. I am actually a proponent of Orbital Refueling (once extraterrestrial propellants become available), but trying to understate the work that will be required to make them a reality is not doing the cause any favors (at least in the long run).

“Thus the horizontal landing designs for Shuttle, NASP, and X-33. NASP and X-33 suffered the further crippling handicap of being single-stage designs. NASA selected those designs for no other reason than that they were the most difficult ways to develop a launch vehicle that they could imagine, and, therefore, promised to “justify” massive amounts of technology development work for their research centers.”

Actually NASA inherited the SSTO part from the Strategic Defense Initiative Organization (SDIO). The late Max Hunter was a big supporter of SSTO and sold it to them.

Comment by Joe — April 12, 2011 @ 1:24 pm

“For use on the ground, not in orbit where weight is at a premium. Properly insulating the storage tanks (to avoid excessive boil off) while not making the structure too massive will be a challenge…..The problem is not to lose too much Hydrogen during extended storage.”

That is why I assume that the depot will have propellant re-liquefaction capability. The tanks will also need to be thoroughly insulated, but insulation blankets are not that heavy, and we only need to put them up there once. Weight is an important consideration for a launch vehicle, which repeatedly accelerates through a delta-V of 9 km/sec, but not so much for a facility which remains in orbit, and only because Earth-to-orbit transportation is currently so expensive. Give us an RLV and payload weight will no longer matter very much.

“This would require an RCS system that could control such a docked structure while its center of mass was changing constantly and considerably (as fuel was moved from the depot to the vehicle). Again a considerable challenge.”

The mass will move from a tanker to the depot, or from the depot to a spacecraft essentially along the spin axis. That should not be much of a problem, and gyroscopic forces will tend to stabilize the system. I also envision the depot consisting of two separate tank sets, in a common framework, which would be counter-rotated so they could be spun up with electric motors rather than by burning RCS propellant. Stability and control will be an important design challenge, and I don’t rule out an RCS system, but it’s nowhere near a “show stopper”.

“As stated above the challenge is considerably more than you think. I am actually a proponent of Orbital Refueling (once extraterrestrial propellants become available), but trying to understate the work that will be required to make them a reality is not doing the cause any favors (at least in the long run).”

NASA has an unfortunate tendency to not only OVERstate the difficulty of their programs, but to deliberately MAKE them more difficult than they need to be in order to “push the technology”. I try to counteract that tendency by emphasizing the KISS principle (Keep It Simple, Stupid), though I don’t deliberately understate the difficulty of anything I propose. Maybe it only seems like it by contrast with NASA’s “business as usual” approach.

“Actually NASA inherited the SSTO part from the Strategic Defense Initiative Organization (SDIO). The late Max Hunter was a big supporter of SSTO and sold it to them.”

As I recall, Max Hunter was a supporter of a VTOL SSTO concept, the SSX, which was similar to the DC-X. NASA took over the DC-X and then started the X-33 program, for which the DC-X was one competitor. But they actually selected the “Venturestar” VTHL concept for the X-33. VTHL combines the worst of both worlds: heavy engines for vertical takeoff with heavy wings for horizontal landing. VTHL also virtually precludes the largest potential market for an RLV: tourism. (Imagine the fun you would have getting the passengers in their seats if a 747 took off vertically, standing on it’s tail.) There are no transportation systems anywhere on Earth in which the vehicles rotate 90 degrees between departure and arrival, and nobody in their right mind would design such a thing.

Comment by Dick Morris — April 13, 2011 @ 8:31 pm

“By that statement, you’ve just consigned Direct TV, Sirius, and most telecommunications companies into bankruptcy.”

Sorry Doc, I should have clarified; I was talking about human space flight specifically.

Comment by GaryChurch — April 13, 2011 @ 8:32 pm

“An in-space refueling depot is not nearly as hard as you seem to think it is. NASA has been handling LH2 for about 50 years, so the technology is well developed.”

Not nearly as easy as you think; NASA handles LH2 on the ground- not in space.

Comment by GaryChurch — April 13, 2011 @ 8:33 pm

Comment by Dick Morris — April 13, 2011 @ 8:31 pm

“That is why I assume that the depot will have propellant re-liquefaction capability.”

An interesting assumption and one that further complicates the design.
“The tanks will also need to be thoroughly insulated, but insulation blankets are not that heavy, and we only need to put them up there once. Weight is an important consideration for a launch vehicle, which repeatedly accelerates through a delta-V of 9 km/sec, but not so much for a facility which remains in orbit, and only because Earth-to-orbit transportation is currently so expensive”

True about the difference between a vehicle that is going someplace different and one that is only station keeping, but weight will still be at a premium as compared to on the ground.

“Give us an RLV and payload weight will no longer matter very much.”

Yeah give me an RLV and I will be very happy. Unfortunately no one I know of is handing them out.

“The mass will move from a tanker to the depot, or from the depot to a spacecraft essentially along the spin axis. That should not be much of a problem, and gyroscopic forces will tend to stabilize the system.”

Even as the CM moves from one end of the spin axis to the other?

“I also envision the depot consisting of two separate tank sets, in a common framework, which would be counter-rotated so they could be spun up with electric motors rather than by burning RCS propellant. Stability and control will be an important design challenge, and I don’t rule out an RCS system, but it’s nowhere near a “show stopper”.”

You are talking about substituting gyroscopic forces for RCS propellant. Not a bad (or new) idea, but now you have added counter rotating segments (complete with bearings – I assume) to your notional design, again another complication.

“NASA has an unfortunate tendency to not only OVERstate the difficulty of their programs, but to deliberately MAKE them more difficult than they need to be in order to “push the technology”. I try to counteract that tendency by emphasizing the KISS principle (Keep It Simple, Stupid), though I don’t deliberately understate the difficulty of anything I propose. Maybe it only seems like it by contrast with NASA’s “business as usual” approach.”

I am going to skip responding to the NASA bashing, I know it is popular in some quarters; but it is simply politics and there are plenty of other venues for that.

“As I recall, Max Hunter was a supporter of a VTOL SSTO concept, the SSX, which was similar to the DC-X. NASA took over the DC-X and then started the X-33 program, for which the DC-X was one competitor.”

True, but even though the Delta Clipper design was not selected NASA inherited the SSTO requirement (which you criticized as opposed to TSTO) which was my point.

This has all the earmarks of one of those unending threads playing by the “he who post last wins” rules. I do not agree with those rules, so I will sign off of this as of this post.

As I said I am a supporter of In Space refueling (with ISRU propellant) but you are trying to make development of the operational technology sound way to easy and simply asserting that NASA intentionally makes things harder than they have to be does not change that fact.

Comment by Joe — April 14, 2011 @ 9:53 am

I am puzzled by this continuing reference to an “RLV.” For any long term use a space vehicle would have to be brought into a pressurized environment for extensive maintenance. The people who talk about a spacecraft merrily bouncing around for months on end do not seem to understand that a human rated spacecraft will not only have more sensitive systems than a satellite or probe, but a heavier payload. Rocket motors would have to be torn apart regularly if they are to work reliably and that cannot be done in a space suit. A large inflatable space dock of some kind- which would be zero G and that makes work more difficult- not easier, would be the only practical solution outside of a moonbase. The point is this would take a workforce and an infrastructure to support them that would be far beyond anything you RLV guys are contemplating. Underground on the moon would be doable with great expense but establishing a base in space to support working reusable spacecraft is 2001 stuff. Fantastically expensive. There is no cheap.

Comment by GaryChurch — April 15, 2011 @ 5:53 pm

Comment by GaryChurch:

“Not nearly as easy as you think; NASA handles LH2 on the ground- not in space.”

Where did I say it was “easy”? Nothing we do in space is going to be “easy” – certainly nothing involving LH2. I have not seen any reason to believe that handling LH2 in space is going to be greatly more difficult than handling it on Earth.

Comment by Dick Morris — April 15, 2011 @ 7:13 pm

“I have not seen any reason to believe that handling LH2 in space is going to be greatly more difficult than handling it on Earth.”

You have got to be kidding.

Comment by GaryChurch — April 16, 2011 @ 6:05 pm

“You have got to be kidding.”

You have got to be kidding. You keep saying things like in-space refueling “almost certainly” cannot be done, but have provided not a shred of evidence to back it up.

The RLV would be serviced on the ground at it’s launch base. It would be designed for reliability, with sufficient redundancy to enable it to return there regardless of any plausible failure. Rocket engines in particular can be made reliable if reliability is an important design requirement.

Comment by Dick Morris — April 19, 2011 @ 10:29 pm

You haven’t even presented any reasons why you believe that. Your position seems to be that anything and everything we do in space is super, super difficult, and if something hasn’t been done, that proves that it cannot be done. In fact, we have transferred propellants in space. Not a great deal, but enough to show that it can be done.

Comment by Dick Morris — April 20, 2011 @ 2:42 pm

“True about the difference between a vehicle that is going someplace different and one that is only station keeping, but weight will still be at a premium as compared to on the ground.”

Not really. The principal reason that space hardware costs so much more than similar terrestrial hardware is the obsession for mass minimization. NASA will spend billions on engineering and technology development designed to minimize mass and thereby save millions in propellant costs. I call it NASA’s First Commandment: “Thou shalt minimize the mass of everything which thou launcheth into the heavens. The greater and the lesser masses shalt thou minimize”. Propellants are CHEAP.

About 20 years ago I worked on a 747 freighter which Air France planned to use to carry car parts to an assembly plant in Africa. They didn’t redesign those car parts for minimum mass, since that would have been much more expensive than the air freight charges.

“Yeah give me an RLV and I will be very happy. Unfortunately no one I know of is handing them out.”

NASA was handed 3 golden opportunities to develop an RLV and blew all of them. Now they seem to have given up. I don’t recall seeing or hearing anybody in NASA even talking about CATS in years. Maybe they expect somebody to just hand it to them, but I suspect that they don’t really want it after all, since that would tend to reduce their budget. It would certainly blow their “justification” for a lot of technology development work.

“I am going to skip responding to the NASA bashing, I know it is popular in some quarters; but it is simply politics and there are plenty of other venues for that.”

As “give ‘em hell Harry” used to say, “I just tell the truth, and they think it’s hell.” If we’re going to fix NASA, we have to face the fact that it is seriously broken, and many of those who criticize NASA are actually it’s best friends.

“True, but even though the Delta Clipper design was not selected NASA inherited the SSTO requirement (which you criticized as opposed to TSTO) which was my point.”

I don’t recall that NASA has ever been bound by SDIO requirements. X-33 was a NASA program and NASA could establish their own requirements for it. I don’t even recall that single-stage was an official NASA requirement, or if the competitors simply saw the handwriting on the wall and gave NASA what they thought they wanted.

“As I said I am a supporter of In Space refueling (with ISRU propellant) but you are trying to make development of the operational technology sound way to easy and simply asserting that NASA intentionally makes things harder than they have to be does not change that fact.”

I never said it was “easy”, or simple, just that it can be done, and outlined a practical way of doing it.

Comment by Dick Morris — April 20, 2011 @ 4:07 pm

“You keep saying things like in-space refueling “almost certainly” cannot be done, but have provided not a shred of evidence to back it up.”

You keep getting it backwards Dick.

We have already gone beyond earth orbit with HLV’s. That concept is completely proven beyond doubt.

Your “RLV refueling depots” have not a shred of evidence to back them up. You have no idea of the reality of keeping an operation going for months and years at a time, going through hundreds of tons of propellants and dozens of missions. One crack in a fuel- and that happens alot working with a substance a couple degrees above absolute zero- and everything comes to a halt. Turning wrenches in a space suit is a major operation- like deep sea diving. Except there are no multi-thousand ton support ships in space.

Comment by GaryChurch — April 21, 2011 @ 1:03 am

We have considerable experience sending large quantities of LH2, sometimes at very high pressures, through fuel lines subject to the g-forces and vibrations generated by large liquid rocket engines such as the J2 and the SSME, and aerodynamic forces. NASA has decades of experience storing large quantities of LH2 for considerable periods of time at Launch Complex 39. Building ISS and servicing Hubble has required much more complex operations than hooking up lines at a propellant depot, including turning wrenches in a space suit. Hooking up propellant lines need not necessarily involve EVA at all.

I’m not necessarily opposed to HLVs either. In fact I support an early new-start for Zubrin’s classic Mars Direct. I think we should all contact the President and advocate exactly that as a way to commemorate the 50th aniversary of Kennedy’s “before this decade is out” speech, comming up on May 25, which launched the Apollo Program. (See my letter in the Feb. 14 Space News.)

I consider HLVs to be a temporary measure to get the ball rolling until we can transition to RLVs. That’s the way to build a long term program and keep manned lunar and planetary exploration from being shut down again, perhaps for decades as happened with Apollo, by shutting down the HLV production line.

Comment by Dick Morris — April 21, 2011 @ 8:57 pm

“I consider HLVs to be a temporary measure to get the ball rolling until we can transition to RLVs”

There are people who understand the rocket equation and people who do not. There are people who understand material limitations and people who do not. And there are people who become mesmerized by ideas that violate the equation and other limitations. And there are people like me who do not.

Dick, you are obviously and enthusiast like me, so I do not want to insult you as is the popular pastime on some of these sites. But ISP’s really do matter and making something light enough to be used for a rocket kind of makes it useless after being subjected to the extremes of temperature and vibration of a launch. The same goes for engines. I hate analogies but it might help to visualize a jet engine or even a car engine that goes for thousands of hours and travels thousands of miles. Now compress that wear and tear into a couple minutes and you have a rocket engine. You still get the thousands of miles because you are in orbit but you do not get to use the engine or structure again because it is worn out.

There are techniques to reuse parts of a launch vehicle- like the extremely expensive SSME’s or using an empty fuel tank in a “wet workshop”- kind of like Skylab (Skylab was a “dry workshop”). But many engineers, for good reason, consider re-use a myth. The steel casings on SRB’s are so far the only really practical item for reuse- and that is only because it allows for constant inspection and improvement, not because it is cheaper.

The fuel depot advocates like to paint themselves as conservatives by presenting fuel transfer as a way to get away from all the expense of HLV’s by using smaller launch vehicles. The reality is this concept is radical and very risky- we have no experience doing it except for limited amounts of storable propellant on the space station. Cryogenic fuels are a whole new game. The people who want to concentrate on what will work for sure want nothing to do with it.

Comment by GaryChurch — April 23, 2011 @ 5:16 pm

“There are people who understand the rocket equation and people who do not.”

I have done hundreds of hand calculations based on the rocket equation, and my LEO/Lunar/Mars logistics spreadsheet has done thousands more. I am an engineer with 38 years experience in aerospace. I did a
Google search, but didn’t find a “Gary Church” who had any relevant experience. Do you?

Comment by Dick Morris — April 25, 2011 @ 6:04 pm

“Now compress that wear and tear into a couple minutes and you have a rocket engine. You still get the thousands of miles because you are in orbit but you do not get to use the engine or structure again because it is worn out”

I have read that the Russians have fired some of their rocket engines for up to 14 hours without maintenance, and when they were disassembled, they showed no visible wear.

I have also done qualification testing on aerospace hardware which involved extremes of temperature and vibration, so I know something about that. Designing for reusability is mainly a matter of establishing proper design requirements, with generous safety factors to ensure reliability.

Comment by Dick Morris — April 25, 2011 @ 6:14 pm

“The steel casings on SRB’s are so far the only really practical item for reuse- and that is only because it allows for constant inspection and improvement, not because it is cheaper.”

The reason that rocket engines have had such short lives in the past is because they were designed to be used on ICBMs, which could only be used once – they were ammunition. Neither engines, nor the rockets they are used on HAVE to be made so fragile they can only be used once. Mass minimization is simply NASA’s quasi-religious dogma.

If you design a launch vehicle for a given payload, and you increase the dry mass fraction, you make the vehicle bigger, but it can still be built. In fact, it will probably be cheaper to develop and operate, because you won’t have to run endless trade studies to shave off every possible ounce of weight, and the resulting vehicle will be much more durable and reliable, which will save a great deal of money in pre-launch processing.

The reasons the Shuttle orbiter takes so much effort to reprocess, are because, first, they designed it for absolute maximum performance with absolute minimum mass, and, second, because they designed it with a huge number of critical, single-point failure modes. (Commercial aircraft have zero – the FAA doesn’t allow them.) Third, they picked a design which placed the orbiter’s re-entry heat shield adjacent to the ET, which causes it to be damaged by foam coming off of the tank during launch.

The hundreds of hand calculations that I mentioned previously each involved the solution of systems of seven simultaneous equations, four of which were based on the rocket equation. I was introduced to the rocket equation, and the equation for calculating Isp, by my father about 55 years ago. I think I understand them.

Comment by Dick Morris — April 26, 2011 @ 5:44 pm

“Google search, but didn’t find a “Gary Church” who had any relevant experience. Do you?”

Cred boasting is not appropriate on an open forum Dick. There are no engineering degrees required by Dr. Spudis to post here. This is not a peer reviewed environment. I have absolutely nothing to prove to you. Why do you? I do not have and do not want access to your hand calculations.

Dick, you might be smart but you are not getting the message; it is about putting tons up. Reusing rockets,if it was practical for putting the most tons up would have been done by now. Von Braun’s 1950′s calculations for rockets have low payloads not because of his ISP’s or structure numbers- it was because of the parachutes and other equipment needed to recover the stages. I do not know what numbers you are using but his are still probably pretty good today. You can google search Von Braun and you will find him. Tell me something I don’t know and you may change my mind. This is my personal unqualified opinion. Take it or leave it but do not rub my nose in your college degree. Thanks.

Comment by GaryChurch — April 26, 2011 @ 8:33 pm

All right, lads. You’ve both had your say and now, I’m pulling the plug on this exchange. Take your discussion elsewhere.

Comment by Paul D. Spudis — April 27, 2011 @ 2:55 am