On Orbital Fuel Stations 152
dylanduck writes "Being able to fill up your spacecraft from a fuel depot in orbit round the Earth or Moon is key to the long-term prospects of astronauts exploring the solar system, according to NASA engineers. Trouble is NASA doesn't want to build it themselves. So there's $5 million for any enterprising groups who can develop a simple version themselves."
It's doable (Score:4, Insightful)
In outer space the asteroid captures YOU! (Score:3)
Re:In outer space the asteroid captures YOU! (Score:3, Interesting)
"Icy Asteroid" (Score:2)
I would suggest fuel might be more likely to come from either: the moon, or a rocky asteroid, by chemically breaking down rock matrices. Of course, to do that efficiently might require something a bit more energetic than sunlight, one might want to go whole hog for nuclear fission (fusion) reactors.
Hmmm (Score:5, Insightful)
So sure, once you get liquid hydrogen from the moon / some other energy source it'd be usefull.. which pretty much means we need a moonbase first.
Re:Hmmm (Score:5, Funny)
Re:Hmmm (Score:4, Insightful)
Fuel depots make sense for aircraft on Earth because you can use cheap surface transport to deliver the fuel, store it, and then load it into your aircraft when needed.
This might work in space if you have ion powered slow boats to ship the heavy stuff, and fast human carrying vehicles to load up on fuel. But we are not that advanced yet. If we go to mars any time soon it might make sense to launch the cruise stage unmanned and then hook it to the command module in earth orbit. That would be a kind of fuel dump.
Re:Hmmm (Score:4, Informative)
Effectively that's what's being planned with the earth departure stage for the proposed lunar missions. That stage would be launched on the Cargo Launch Vehicle into earth orbit, where a CEV launch would rendezvous with it for a trip to the moon. See the Project Constellation [wikipedia.org] article here.
Re:Hmmm (Score:4, Interesting)
There might be methods whereby you wouldn't need to carry the fuel with you, for example with a space elevator. However, just what advantages would a space elevator offer over a tower launch? (I've used parts of this post before, but I have since refined my ideas). I contacted a man responsible for a similar idea a while back, the skyramp [skyramp.org] (warning: hideous javascript menu may break firefox), Carlton Meyer, and had a dialogue in which he pointed me to a tower launch archive [yarchive.net].
The ideas I see bandied about there are similar to what I had in mind, which would be essentially an 11km tall tower (think pylons rather than skyscrapers, based at sea), with evacuated airless launch tubes, using nuclear reactors to power a maglev or pulley system to accelerate vessels to escape velocity. These would then emerge above the end of the troposphere [gatech.edu], with it's associated weather and air pressure, and have little to no fuel needed to match the earth's gravity, meaning you could do a lot more while you were up there. At a reasonable acceleration (5 to 7 g's) you would be in geostationary orbit. From there you could build a fully system wide ship or ships, as its much easier to escape the planet's gravity from GEO than from the surface.
Not only would this enable multiple launches daily, it is, unlike the space elevator, readily achievable with today's technology, and financially viable as well. Given NASA had an annual budget of $16.2 billion for 2005 [space.com], and a nuclear power plant costs a cool billion to build, give or take, we could have this up and running in a few years.
Re:Hmmm (Score:3, Insightful)
Re:Hmmm (Score:2)
I am not sure, myself. However even if it cost ten times more, it would still be less than NASA's 2005 budget. There ain't much you can't do with 15 billion.
Re:Hmmm (Score:2, Insightful)
Re:Hmmm (Score:2)
You're talking about building a structure 33 times as tall, tight enough to hold a reasonable vacuum, associated power plant, etc...
Re:Hmmm (Score:2)
And the big dig in Boston cost 10 odd billion. Kindly read all the links before responding, thanks.
Re:Hmmm (Score:2)
For a three and a half mile tunnel.
That is over $800,000 per FOOT of tunnel. Holy crap.
Talk about corruption and blatant theft
Easy to be critical, but lets consider some things (Score:2)
2. The tunnel has to go through reclaimed swamp silt. For a significant part of it, they had to drill holes and fit pipes into the ground in an area, then pump a supercooled solution (not sure if they used saltwater or glycol) through the pipes and freeze the ground hard enough to dig through as they placed the tunnel.
3. The tunnel has to go through the center of a major city which is the economic engine fo
Re:Hmmm (Score:2)
I suggest you stop spouting 'read all links' all the time, unless it's just up a post or so. At least specify the correct link.
For that matter, a carbon fiber tower is likely going to end up in the trillions for cost, once you factor in the cost of mounting the launching system.
Re:Hmmm (Score:2)
Nope, materials cost for a carbon fibre tower 1800km tall would be 80 billion, so you aren't talking costing the earth. Then you have construction costs, insurance fees, permits and labour, but I mean, who said we should build it in America? Hell build it in international waters you could declare it your own nation. In any case the initial costs, however steep, are always going to be dwarfed by the ROI. This is space, baby, space.
Re:Hmmm (Score:2)
Re:Hmmm (Score:2)
One single asteroid up there contains about 5 tons of high quality steel for every man, woman, and child on earth. How many more asteroids do you think there are? Algae pods (nutrients, sunlight, and ice are abundant, albeit spread out a bit) to grow biodiesel or refine metals, clone banks to hold replacement organs (eternal life anyone?). Manufactories to process the ores retrieved and shape them into useful products. Biodomes where crops and vat-grown meat can be cultivated. The ultimate removal of all m
Re:Hmmm (Score:2)
One single asteroid up there contains about 5 tons of high quality steel for every man, woman, and child on earth.
Which does very little good for me as I'm right now down here and not up there. Bringing down such things is not easy (can't build your reentry vehicles in space for quite a while) and simply dropping them down would incur even more costs. You can't easily process it in space either. In a
Re:Hmmm (Score:2)
The question then becomes where do you get the raw materials from and where do they stuff the garbage. Unless they send al
Re:Hmmm (Score:2)
Ah yes, the hard headed realist who advocates a magical space elevator.
Which does very little good for me as I'm right now down here and not up there. Bringing down such things is not easy (can't build your reentry vehicles in space for quite a while) and simply dropping them down would incur even more costs. You can't easily process it in space either. In addition you'd need to overcome the political and technological hurdles of getting a rock that close to earth. Keep in mind that bringing things up wo
Re:Hmmm (Score:2)
No I simply said that theoretically it has various advantages over your plan. I always find it funny how zealots can never understand that some people aren't like them.
I feel like I am talking to myself here. The cost of bringing things up would be much lower with a tower launch, thats the entire point. The whole. Entire. Point.
Well you apparently can't read or don't know how much sending things up costs now. In either case I wonder why
Re:Hmmm (Score:2)
That sound you may have heard, that grinding squishy sound, was your pwnage in the last post I made. Your entire post has degenerated into a tantrum of some sort, lacking facts, real responses, any manner of thought, or originality. There are so many holes in what you are saying it would take me the best part of an hour to go through it all, and my time is far more valuable than that. You even mentioned turrursts, and that took some doing. In fact, its boring the shit out of me listening to your ass-gas fl
Re:Hmmm (Score:2)
Re:Hmmm (Score:3, Interesting)
I very very very much doubt it. Even at 31km you still have 1% of the sea-level air-pressure, and at 9km healthy people can still breathe unaided. (as witnessed by the fact that people have climbed Mt. Everest without oxygen)
I don't know the air-pressure at 11km, but I'd guess around 15% of that at sea-level.
Re:Hmmm (Score:2)
Right, I have discussed it with people who actually have done the math, and what you think diverges wildly from reality. Sorry about that. Escape velocity is waaaay higher than what you need for GEO orbit. And unless you have some actual facts to back up your hypothesising, I'll file it under "s" for speculation. Or maybe "u" for uninformed speculation. And do read the links like a good man.
Re:Hmmm (Score:2)
Listen, its fairly trivial math. Here, let me help you. I'll do it rigth here in this post.
First, earth has a radius of about 6375 km (eqautorial), geosynch orbit is about 35700 km above sea-level, which means a circular geosynchronous orbit has a radius of about 42100 km or so.
Now, to be geosynchronous you need to circle once a day, so you'll have to go 42100*2*3.14 km every 24 hours. This works out to 30
Re:Hmmm (Score:2)
Just google it in slashdot, I already discussed this with a variety of people and I'm not going over the same ground again.
Re:Hmmm (Score:2)
I think it is between 20% and 25%, depending upon weather and latitude, based on the heights of the 200hPa and 250hPa pressure surfaces.
Re:Hmmm (Score:2)
This is totally beside the point anyway, my entire point was that 11km up is not anywhere remotely close to a vacuum, thus a spaceship being released there at 10km/s or whatever would experience significant air-friction. Likely enough to burn it up, or if not, atleast enough to significantly slow it down, requiring an even higher release-velocity to make geosynch possible.
Re:Hmmm (Score:2)
Sure you do this in your big particle accelerators, but there are precious few maglev trains 11km long, never mind running them vertically inside a particle accelerator style environment!
Maybe this is a case of scaling up current technology, and maybe apollo was just a case of scaling up the v2 rocket, I'm still somewhat sceptical though since we've never built a building 1km tall, never mind 11!
Re:Hmmm (Score:2)
Transatlantic vac train tunnel, the research has alredy been done. Google it yourself, I'm too damn sunburned right now. And read the links for gods sake. Buildings 1 mile high were 1950s technology.
Re:Hmmm (Score:3)
Sure you do this in your big particle accelerators, but there are precious few maglev trains 11km long, never mind running them vertically inside a particle accelerator style environment!
Translation: It'd be expensive.
From the proposals I've seen, it's a decent idea. Every pound of fuel you can drop from the vehicle makes it that much cheaper. Not having to deal with atmosphere for the first part, or maybe only the 11km pressure is of great assistance.
One problem I see is how
Re:Hmmm (Score:2)
If the top end of the tube was high enough, ie "in space" for whatever values of "in space" are appropriate (ie maybe a lot more than 11km!), maybe the end could just be open, as it is in "space" and therefore actually in a vacuum. You'd need some sort of air-lock (er, vacuum-lock?) at the base to load your next container, but otherwise, the open top would take care of itself!
er ... maybe?
Re:Hmmm (Score:2)
Since gravity is the reason for the pressure increase, if you leave the top open and attempt to evacuate the tupe, you'll have a constant inpour of gas from the top to repressurize the tube. So you'd have to cap it off, somehow designing the cap to not interfere with the launching ship. Don't forget turbulance from
Re:Hmmm (Score:2)
Yup, already been over that, an iris airlock covers it nicely. Thats two irises near the top of the tower. One opens to let the ship through, then closes immediately after, the other does the same, but you just evacuate the airlock between launches.
Re:Hmmm (Score:2)
Re:Hmmm (Score:2)
Well the idea of evacuating the tower is twofold; one is to remove friction drag, the other is to stop shock wave effects weakening the tower structure. This ain't the barrel of a gun here. :D It would also be a lot more difficult to pump air out of the entire tower, as opposed to a small area on the top. As to the speed of the irises, if we can design processors of over 4 gigs commercially, a couple of irises shouldn't stretch our engineering abilities.
Re:Hmmm (Score:2)
Re:Hmmm (Score:2)
Wow. Sometimes it helps to read past the first few words of a post. Not often, but on occasion.
Re:Hmmm (Score:2)
Simply put, we have materials which survive tension+torsion much better than the materials which survive compression+torsion. We might be able to build an 11km high structure with current materials, but the structure would be VAST at th
Re:Hmmm (Score:2)
20:1 height to base ratio. Read the links.
Re:Hmmm (Score:2)
A truly reasonable acceleration (read: basically none) although this means a very long ride up (week to GEO). Much safer travel, no massive acceleration or high speeds on either the way up or down. On that note going down doesn't require being a few feet from fiery death. The structure has nicer failure conditions and less mass that can impact if it fails, and is basically impossible to take out. The construction is simpler in ma
Re:Hmmm (Score:2)
Much safer travel, no massive acceleration or high speeds on either the way up or down. On that note going down doesn't require being a few feet from fiery death. The structure has nicer failure conditions and less mass that can impact if it fails, and is basically impossible to take out. The construction is simpler in many ways if the correct material is found, both in the elevator itself and the actual "construction".
But your shortfall there is that we have not and may never have the neccessary materi
Re:Hmmm (Score:2)
Such a venture is not realistic or profitable for at least another 30 to 40 years so we can wait. Theoretically such a material is possible using carbon nanotubes and we'll probably know in 40 years if it is actually possible.
Well we may as well shelve the whole space program then, in case "shit happens".
The space program is a very limited, government owned, highly selective and highly unprofitable venture. This is ver
Re:Hmmm (Score:2)
Such a venture is not realistic or profitable for at least another 30 to 40 years so we can wait. Theoretically such a material is possible using carbon nanotubes and we'll probably know in 40 years if it is actually possible.
Or possibly 300 to 400 years. Or never. Magical imaginary materials are all well and good, but honestly, I wouldn't trust my weight to them.
If you lose 1% of your launches you're not going to get many engineers to go up there and build your space based infrastructure.
They al
Re:Hmmm (Score:2)
If you are in the mood for unpleasant surprises, try reading the links. That you have to ask what it would be made of means that you shouldn't be contributing to this discussion. Have a nice one.
Re:Hmmm (Score:2)
Very gracious of you sir, and I apologise for being so snappy. I got something of a case of sunburn yesterday and everything is a bit red tinged.
More than proportional (Score:2)
I think it's more than proportional, acually. For every piece of luggage you want to put up there, you need some amount of energy. That energy comes from fuel, which in itself adds to the total mass, thus requiring even more fuel. The fuel can quickly become the largest part of your spacecraft. Look for example at a NASA shuttle at the launch pad [wikipedia.org]. As you probably know, the orange thing just contains fuel, and the two sol
Re:More than proportional (Score:2)
On the other hand, air-resistance grows less than proportionally with weight, although I guess that's less by several factors...
.. damn I wish I had done more actual physics calculations. I don't have any sense of proportion :/
Re:Hmmm (Score:2)
True, it doesn't save money in the short run. But even if all that fuel still comes from Earth, it lowers the minimum mass per launch. So you can use many light boosters to supply the fuel depot instead of a few heavy ones. Some people believe that the current high cost of launches is due to a low launch rate (maybe only 10-20 a year, worldwide), and increasin
Not necessarily. (Score:3, Interesting)
Re:Not necessarily. (Score:2)
Re:Not necessarily. (Score:2)
Re:Hmmm (Score:2)
Only for loose values of "reasonably". Other important factors include:
Required reliability - if an expendable launcher is 50% as expensive but only 95% as reliable, then it's worthless for launching humans, undesirable for precious cargo, but fantastic for fuel.
Flexibility with existing launch vehicles - if your mass budget for a mission creeps up to 10% more than yo
Re:Hmmm (Score:2)
The nice thing about fuel is that unlike people or equipment you don't really care how it gets there: lots of small launches or a few bigger launches, high Gs or a gentle ride, expendable or reusable, winged or VTVL, high or low reliability. Whatever.
Some people claim launch costs can be reduced by somewhere between one and two orders of magnitude using only existing t
Refuelling (Score:2)
Not being an engineer, or even a particularly practical mathematician (but ask me about finite automata!
Have we learnt nothing. (Score:4, Funny)
Refuelling in orbit is dangerous!
Next they'll be suggesting we man these orbital filling stations with drunken Russians. I only hope Ben and Bruce are there to sort things out when matters go awry.
Re:Have we learnt nothing. (Score:2)
I, for one, welcome our oxygen yielding overlords! (Score:3, Insightful)
Space One proved that a competition with a good incentive can produce results faster than state sponsored research. I hope the trend will continue.
Re:I, for one, welcome our oxygen yielding overlor (Score:3, Informative)
NASA's role has always been vision, specification, oversight, and operations. Design and construction have always been contracted out to the public sector, and to the universities.
Classic examples of this method are the Gemini and Apollo projects. NASA's document, Chariots for Apollo [nasa.gov] gives a fascinating account of how this process works.
Zero Gee problems? (Score:4, Insightful)
A short list includes:
Human health (bones, muscles, fluid accumulation etc)
Environment (air flow, hygeine)
Fluids in general (measuring, pumping)
Going to the toilet (or john)
And lots of others.
I have a question: Why aren't we putting some effort into artificial gravity? I mean centrifuge effects - not Star Trek. After all, we're expending all this effort into individual engineering solutions for each problem. If we had AG of some sort, wouldn't that remove the need for that?
Just my 2 pennies worth.
Re:Zero Gee problems? (Score:2)
Re:Zero Gee problems? (Score:4, Insightful)
If and when our technology has matured enough so we can start designing RAMA-style spaceships [wikipedia.org] or large spacestations with permanent crews of dozens or hundreds, then this or another kind of AG will certainly be included.
Re:Zero Gee problems? (Score:2)
No one is taking long-term human space exploration seroiusly yet. The Americans haven't even been to the Moon since 1972, and no one else has ever been.
It will either take commercial space exploration or another cold war type space race between superpowers before anything actually gets done.
At the moment, there is no commercial incentive to "explore" anything other than communication satellites.
If China were to decide to establish a permanently manned lunar colony, I could imagine that the Americans woul
Re:Zero Gee problems? (Score:2)
Except, of course, for the fact that the moon, and all other celestial bodies, are DMZs. Surely permanent bases would cause some diplomatic problems.
"I have in my hand a piece of paper." Neville Chamberlain, 1939.
How can you enforce a law if you can't get there to enforce it?
Re:Zero Gee problems? (Score:3, Insightful)
To dock, you pull up to the middle and grab old of the rotating cable. You then lower yourself down to the station, and ent
Johns? (Score:2)
Geez, there are already Johns and Hos in space even before the first space hotel is launched???
Oh Gee (Score:2)
Wait, don't say it! I'm one orbit ahead of you... Illegal aliens: Doing the jobs our astronauts (and filling station attendants) won't do.
Re:Zero Gee problems? (Score:2)
I think building a spacedock at La Grange point L1 is the best idea, and a moonbase to get most of the materials for the spacedock, and intrastellar craft.
Also satellites built and launched from the spacedock/moonbase would have a lower cost to put in high earth geosynch orbit.
Although Stratallites are probably and even cheaper and easier to maintain scenario vs. satellites. http://www.21stcenturyairships.com/AirshipFAQ [21stcenturyairships.com]
Easy (Score:2)
So my winning design is a huge ice bucket attached to a big set of solar panels, some electrodes, and some cryo-pumps (ok don't actually know what cryo-pumps are, but they sound like the cool)
Re:Easy (Score:2)
Delivering Fuel (Score:5, Interesting)
The method we looked at was a BFG to launch the fuel into orbit.
The big gun used hydrogen gas that is quickly heated in a heat
exchanger, then pushes a 600 kg projectile to 2/3 of orbital
speed. The projectile uses some onboard fuel to go the rest
of the way to orbit, then delivers the remaining 100 kg of fuel
to the orbital gas station. The projectile de-orbits and is
recovered to be reused. The projectile is rugged enough that
it can land on anything without damage.
The big gun is very cheap ($100M) compared to electromagnetic
launchers, because it is basically a length of pipe, compared
to a series of coils, switches, and big power supplies. On the
other hand, it is more expensive to operate.
The velocity split between the gun and the projectile depends
on the size of the projectile and how much traffic there is to
orbit. For the case we were studying, delivering fuel to
carry comsats to GEO, we were launching 100 kg a day, or 30 tons/yr
(allowing for downtime).
DRN
Re:Delivering Fuel (Score:2)
Without damage to WHAT? But, ok, there are lots of sparsely populated places, in addition to open sea, but it's not like you can just ignore the damage at return, even if it's not your projectile that is damaged.
Re:Delivering Fuel (Score:5, Interesting)
http://www.astronautix.com/articles/abroject.htm [astronautix.com]
Re:Delivering Fuel (Score:2, Interesting)
The density is obviously lower than liquid water - but theres no throw away / reuse of the casing required.
Making the projectiles would require freezing water into the projectile form. It may be cost effective to make a larger solid ice proj
Trouble figuring out how much you have? (Score:2)
Re:Trouble figuring out how much you have? (Score:2)
chemical reaction propulsion (Score:2, Insightful)
We won't become much of a space faring race until we have *advanced physics drives of some sort that work with gravitrons or something along those lines.
*note:said "advanced". We need to be able to understand and manipulate gravity i
Re:chemical reaction propulsion (Score:2)
Re:chemical reaction propulsion (Score:2)
It already has been thought of - infact it's been known since the 60's. But there is no economical incentive to implement it - because their aren't enough payloads to make it work. (And of course, without a launcher, there's no reason to create payloads that will use it.)
This cruel chicken-and-egg dilemma is what is holding us back.
Orbital Mechanics (Score:2)
Re:Orbital Mechanics (Score:2, Informative)
Problems solved (Score:2)
I'm sure spacecraft can measure fuel levels in zero g - would seem odd not to be able to. And you have to suck fuel out in just the same was regardless of if it's going to an engine or another fuel tank.
hard to lift it from earth economically (Score:2)
This fact means that unless rocket technology and materials building became absurdly cheap it will never provide the basis for a massive launch capacity needed for ideas like colonization or even large scale outposts on other planets at anything approaching economicaly viable costs.
True reuseablity is about the only thing that could make this piti
Water? (Score:2)
Where's the actual rocket fuel here? Last I recall, oxygen makes a great fire enabler, but pure oxygen itself doesn't really burn - it makes fire possible, makes fires better - but there needs to be some sort of fuel to burn in the first place. And as for H2 - if memory serves me correctly hydrogen + oxygen + spark does
Re:Water? (Score:3, Informative)
Anyway, one of the reasons why to use hydrogen is that the hydrogen/oxygen reaction has an extremely high specific impulse for a chemical rocket. Here [wikipedia.org] is a Wikiped
Re:Water? (Score:2)
One technical point about Hydrogen. It doesn't explode. It burns, certainly. Very hot, and with a dangerous, invisible flame. However, when hydrogen burns, it combines with oxygen to form water. You would combine 2 moles of H2 and 1 mole of O2 (6 moles of individual atoms) to get 2 moles of H2O - water vapor. Going from 3 moles to 1 mole of volume means that burning hydrogen IMplodes, not explodes.
It was
already proposed - next problem (Score:2)
http://www.transformspace.com/ [transformspace.com]
big city gang method (Score:2)
Re:Interesting (Score:2)
Sure just design your out-pipes with a gauge, like a speedometer. Measure the speed of fuel coming out and factor in the width of the pipes (and fuel density?). Its then just a case of keeping track of how much fuel you have used. I mean how is this a major problem? You could even build a fit-all for hand held containers with vernier calipers inside to measure pipe width, enter your fuel type and let it keep track for you. Or if you encounter the odd situation of an ungauged fuel tank of some kind, design
Re:Interesting (Score:2)
Or even just measure the internal pressure of the tank. Less pressure, less fuel. Can someone write me a cheque now please?
Re:Interesting (Score:2)
My guess is they are trying to cut down on all unneccesary weight, so the mechanisms I mention here would not perhaps be optimal. What would be optimal would be their dipstick. This has the sad drawback of not actually working, so they might have to bite the bullet. On the other hand, maybe some visionary will solve their problems for them at 2% of the budgetary requirements it would otherwise take. Sigh. What about keeping the fuel in a collapsable skin inside its hard shell, and put a pressure gauge blee
Re:Interesting (Score:2)
Re:Interesting (Score:2)
Re:artificial gravity (Score:2)
Re:Fuel Problems Solved (Score:2)
Re:If it's done by private industry... (Score:2)
That seems way worse to me than losing a sa