On Orbital Fuel Stations

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."

Comments

It's doable

[PatrickThomson]

Obviously you need atoms up there, which have to come from somewhere, but splitting them into fuel is easy, you're floating in space with all this sunlight. The problem is that if you carry a kilo of water from the surface and then swap it for a kilo of hydrogen/oxygen when you get to space, the benefits are minimal (easier storage?). This would work well coupled with a captured icy asteroid, even a small one.

Hmmm

[hyfe]

Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?

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

[Funkcikle]

"$9 a gallon? Let's just orbit a bit longer till we find a cheaper one."

Re:Hmmm

[MichaelSmith]

Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?

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

[Darkman, Walkin Dude]

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 (warning: hideous javascript menu may break firefox), Carlton Meyer, and had a dialogue in which he pointed me to a tower launch archive.

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, 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, 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

[cnettel]

I somehow imagine that the pylon construction could be far more expensive than the power plant part.

Re:Hmmm

[Darkman, Walkin Dude]

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

[adam1234]

Most of NASA's budget inevitably goes to people (ie, payroll) and bureaucratic oversight, not operations.

Re:Hmmm

[Eivind]

Is 11km really enough that you don't need to worry about air-friction emerging from the tube at escape-velocity ? (well almost, you said geosynch orbit. But that is like 90% escape-velocity anyway)

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. Are you suggesting that punching trough 15% of sea-level air at speeds around 40.000km/h causes negligble frictional losses ?

I haven't done the math, but I think it's more likely the resulting friction would make re-entry look gentle, thus you'd need to start out going *even* faster to compensate the frictional losses.

In short, I think releasing a spacecraft at 11km with sufficient speed to reach geosynch is impossible, you would have to release it with such a speed that it'd immediately burn up.

Re:Hmmm

[Soft]

Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?

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 increasing that rate would help lower this cost. See e.g. a rocket a day.

Re:Hmmm

[rufty_tufty]

a tube 11km kept as a vaccum?
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

[Maset]

OK, being completely asinine:

"I veery 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)"

Show me anyone that can do ANYTHING without oxygen.

Asking a less stupid question:

Almost anyone can climb Everest without oxygen aids.

The real question:

Who got to the top of Mount Everest without oxygen aids?

Re:Hmmm

[GreyKnight]

I think you've underestimated the logistics and costs involved in building a 11 km tall structure.

Kansai International Airport was built on a man-made island. The island was constructed by laying 30 m of earth on the sea floor; the airport has cost $15 billion so far. Creating an 11 km tall structure is many orders of magnitude more difficult. (If we assume cost increases linearly with height, 11km/30m*$15 billion=~$5.5 trillion. I think that number is a bit conservative).

What would you make the tower of? Simply allocating that much material (regardless of whether you used earth, steel, or concrete) would be an task of astronomical proportions in itself. I am not a civil engineer, but I would imagine that lack of engineering knowledge at that scale, and at that altitude, would make constructing such a tower very expensive (and risky) simply from a design standpoint.

Get a civil engineer to estimate the costs of such a project, and I think you would be unpleasantly surprised. Personally, I think research into better jet engines/rocket engines is the way to go.

Re:Hmmm

[AndyAndyAndyAndy]

I'm seeing... a pipeline... a HUGE pipeline... pumping......... methane. And natural gas.

Direct from Neptune.

Yeah, real easy.

Re:Hmmm

[Darkman, Walkin Dude]

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

[Darkman, Walkin Dude]

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

[Darkman, Walkin Dude]

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

[GreyKnight]

Sorry, I only followed the first link.

If I read the second link correctly, the cost is estimated at $80 billion for carbon fiber to build a 1800km tower, which would likely put basic materials cost well within reach for a 11km tower. I think I'll avoid further speculation; you've obviously researched this more than I gave you credit for.

I apologize, and stand corrected.

Re:Hmmm

[grozzie2]

If you want to go on and on about a space elevator, then you need to start talking about how you will use it to put snake oil for sale in orbit. Space elevator, snake oil, all the same stuff.

Re:Hmmm

[Firethorn]

You'd be suprised how fast 15 billion can go when you're talking massive amounts of construction. For example, This article puts a 1,000 foot tower at 1-1.5 Billion.

You're talking about building a structure 33 times as tall, tight enough to hold a reasonable vacuum, associated power plant, etc...

Re:Hmmm

[Firethorn]

a tube 11km kept as a vaccum?
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 do you keep the tube evacuated while leaving a clear path for the ship?

Re:Hmmm

[AGMW]

One problem I see is how do you keep the tube evacuated while leaving a clear path for the ship?

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

[Firethorn]

Problem is that it's not actually high enough to be out of all the atmosphere. At 11 miles high(a good deal higher than 11km), around 10% of pressure of sealevel(11 miles is ~58k feet) remains.

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 the sudden movement as well!.

Now, make it 20 miles high and we'd be around the 1% pressure point. You'd still have to pump the thing out, just not as quickly.

Re:Hmmm

[NOLAChief]

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.

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 article here.

Re:Hmmm

[roystgnr]

Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?

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 your biggest launcher can lift, you can either spend millions of dollars lifting more fuel separately or billions creating a new rocket.

Flexibility with new launch vehicles - there are a lot of cheap space access ideas that won't work with "one launcher, one mission" plans. Electromagnetic "catapults" require too much acceleration for people and most cargo. Reusable vehicles may be cheaper per-pound but have smaller payloads per launch. Orbital assembly and orbital refueling can allow you to get the benefits of new spaceflight ideas without all the problems.

Competition! - Some of the biggest obstacles to cheap spaceflight aren't technological, they're economic. The more suppliers you can choose between, the better deals you can get. But is NASA going to trust their astronauts to a half dozen different rockets? Hell no - some people even think they deliberately increased the CEV mass to ensure that it would need a new NASA launcher instead of a commercial launcher. Even for probes and satellites, if you've spent a decade building a hundred million dollar science experiment, you're going to be very cautious about what you launch it on. But fuel? Fuel is cheap and fungible, many kinds are easily transferrable and storable, and any serious exploration of the solar system will require a lot of it in Low Earth Orbit. It's the perfect market for NASA to use to encourage and experiment with new commercial launch service suppliers. And once some of those suppliers have proven themselves by carrying commodity cargo, NASA will have more options for precious cargo, then eventually for human passengers.

Re:Hmmm

[Darkman, Walkin Dude]

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

[Darkman, Walkin Dude]

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.

Re:Hmmm

[Darkman, Walkin Dude]

Wow. Sometimes it helps to read past the first few words of a post. Not often, but on occasion.

Re:Hmmm

[Darkman, Walkin Dude]

And the big dig in Boston cost 10 odd billion. Kindly read all the links before responding, thanks.

Re:Hmmm

[wasted]

I don't know the air-pressure at 11km, but I'd guess around 15% of that at sea-level.

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

[Glonoinha]

Big Dig cost an estimated ~$15B, if you want to get closer to reality.
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 ... Boston - the best government money can buy.

Re:Hmmm

[XNormal]

Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?

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 technology, a bit of clever engineering and streamlined operations. I don't know if that's true but a good way to find out is for NASA to announce that it will be buying fuel in orbit and let entrepreneurs fight it out on who can do it at the lowest cost.

One of the problems with the current way NASA is doing "business" in space is that it dictates the technology and architecture. This way we'll never know if alternative approaches can work better.

Re:Hmmm

[Firethorn]

Have to be awfully fast irises. You wouldn't need two of them, though, you're not going to get a significant amount of air if the iris is only open for a few seconds. Heck, open it up when the ship pushes enough residual atmosphere up to equalize the pressure.

Re:Hmmm

[Firethorn]

Which links? I looked at three of the ones you posted way earlier, one was bad, two didn't mention the big dig. I did read about the carbon fiber tower, and the other was about a ground rail launch, not going up 11km or whatever.

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. Making it a vacuum is even better but again adds cost.

Re:Hmmm

[arkhan_jg]

I think it's the 11km tall tower that's the problem part! The difference is between a ladder planted on the ground, and a rope hanging from a high point. If you can reach the high point by another route and suspend the rope from it, you can have a much higher climbing method.

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 the base to withstand torsion - i.e. wind. The cost to build it would be staggering, and I think you're looking at more in the trillions range than the billions.

Re:Hmmm

[Darkman, Walkin Dude]

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

[Darkman, Walkin Dude]

20:1 height to base ratio. Read the links.

Re:Hmmm

[Rakishi]

ROI from what? I do expect concrete answers.

Re:Hmmm

[Rakishi]

However, just what advantages would a space elevator offer over a tower launch?

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 many ways if the correct material is found, both in the elevator itself and the actual "construction".

Shit happens, having that shit mean a 5km/s object to ripping through an 11km structure is never a good idea.

At a reasonable acceleration (5 to 7 g's) you would be in geostationary orbit.

I wouldn't consider that reasonable myself, the shuttle and soyuz are 3 to 4 G for example.

Re:Hmmm

[Loconut1389]

could you just suck fuel through the tubes?

Re:Hmmm

[Darkman, Walkin Dude]

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 materials. Maybe they will be designed next week, maybe (and more probably) in four or five centuries. The space elevator as it stands is not a viable option; we literally can't do it. If it was a viable option, I would definetely favour it over tower launches. But its not, so I am aiming to get us there within my lifetime.

Shit happens, having that shit mean a 5km/s object to ripping through an 11km structure is never a good idea.

Well we may as well shelve the whole space program then, in case "shit happens". And just to belabour the point a little, would you consider it more or less risky than blasting into orbit strapped to many tons of blazing rocket fuel?

I wouldn't consider that reasonable myself, the shuttle and soyuz are 3 to 4 G for example.

The early manned-space flight program used to launch astronauts at 9 Gs, the Mercury, Gemini, and Apollo programs. Also the amount of acceleration you can take depends on how long it is applied for. As the linked article shows, you can take accelerations of a hundred Gs for a very short period. The period of launch here would be no more than a few seconds, so yes, I would call that reasonable.

Re:Hmmm

[Darkman, Walkin Dude]

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 manufacturing and food production from the earths surface. And thats just orbit. Would you like a few more?

Re:Hmmm

[Darkman, Walkin Dude]

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

[Eivind]

You have discussed it with people who have done the math ? How ridicolous do you want to become ?

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 3060 m/s. In addition to this you need to actually lift yourself up to geosynchronous orbit, adding a whole lot of potential energy, the total works out to about 10km/s.

I would contest that this is waaaay lower than 11.2 km/s but to each his own...

Re:Hmmm

[Eivind]

Atleast 3 differnt people on 4 different occasions. Look it up yourself.

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

[Rakishi]

Ah yes the "I'll be dead before any that is feasible" reasons, which are really worthless in the near future.

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 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 would cost around $100 to $200/lb not counting the cost of your investment.

How many more asteroids do you think there are?

Quite a few, all of them far away and we don't know that much about them. Many people would prefer if they stayed far away and those people have nukes with which to make sure you don't bring any too close.

Algae pods (nutrients, sunlight, and ice are abundant, albeit spread out a bit) to grow biodiesel or refine metals

Not near future and possible on earth as well. You'd need to bring all those materials close which is not feasible in the near future. Then you'd need to again bring the processed goods back down.

clone banks to hold replacement organs (eternal life anyone?).

Personally I wouldn't want a new brain and barring that I'll be dead anyway. We're losing cells up there in my noggin at a decent pace you know. This could also be more easily done on Earth.

Manufactories to process the ores retrieved and shape them into useful products.

Trillions in costs probably, you'd need to figure out new mining methods and manufacturing methods or build complex structures to use earth based ones. Not to mention the general costs of designing things for space.

The ultimate removal of all manufacturing and food production from the earths surface. And thats just orbit.

See above or something. Your investors would long shut down the project before this becomes feasible.

Would you like a few more?

Yeah, how about a few which aren't so far in the future as to be worthless due to unpredictability of scientific advance. Someone has been reading way too much sci-fi. In essence your idea is not profitable for at least the next 40 years, so you have no ROI right now.

Re:Hmmm

[Rakishi]

But your shortfall there is that we have not and may never have the neccessary materials.

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 very different from the expectations of a massive, heavily used, and publicly used launch system. 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.

And just to belabour the point a little, would you consider it more or less risky than blasting into orbit strapped to many tons of blazing rocket fuel?

Rockets can be aborted in case of failure, the capsule can be (and has been in one Russian launch) ejected away from the rocket. In your system I'm stuck in the tube, and in addition if something goes wrong there is even less time to go to plan B than in a rocket (a rocket goes of course you have time, your maglev breaks and I'm most likely already slamming into the tower at high velocity). In addition a rocket failure costs you one, currently expendable, rocket while a catastrophic failure in your tower costs you one very expensive tower or at least heavy damage to said tower.

The early manned-space flight program used to launch astronauts at 9 Gs, the Mercury, Gemini, and Apollo programs

Because for affordable manned space flight what we all want is to require extensive training and medical tests. Note how all of those just keep adding to the cost and lowering potential for such a system.

The period of launch here would be no more than a few seconds.

20s at 5g, 18s at 7g.

Re:Hmmm

[Rakishi]

Let me expand on the previous post a bit, given a person requires 300lbs of food a year (I assume this is a very conservative estimate) and 15 billion people on earth you need to bring down 4.5e12 pounds of food per year to feed the world. At 200k lbs per flight you'd need to use 22.5 million such flights per year to feed the world. Add in manufactured products and it becomes even worse.

The question then becomes where do you get the raw materials from and where do they stuff the garbage. Unless they send all their garbage back up into space (See previous numbers for how many flights you'd need per year) Earth would become one giant garbage dump very quickly.

Re:Hmmm

[Darkman, Walkin Dude]

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

[Darkman, Walkin Dude]

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 already did. And they still are. The point being that you have to take some risks to conquer space. It's not socialised or subsidised, it won't fall into your lap if you just wait long enough.

Rockets can be aborted in case of failure...In addition a rocket failure costs you one, currently expendable, rocket while a catastrophic failure in your tower costs you one very expensive tower or at least heavy damage to said tower.

Thats a reasonable consideration. Of course you are failing to account for a variety of different modes of failure, nor flexing your headspace to consider how things might be compensated for. Eight-way rails would be more than redundant enough for a failure of three and still maintain a successful launch. As for rockets being aborted, your philosophy rather falls down in the face of the challenger disaster, doesn't it?

Because for affordable manned space flight what we all want is to require extensive training and medical tests.

As I already pointed out, leading me to believe you are short sighted or possibly trolling, you can withstand massive g-forces for a short time. And who was talking about 9 Gs in this setup? No special training required. Not that I'd put grandma in it, mind you...

20s at 5g, 18s at 7g..

wut. Where are you going, mars?

Re:Hmmm

[Darkman, Walkin Dude]

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 would cost around $100 to $200/lb not counting the cost of your investment

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. Bringing them down would be the easiest part. Since you don't have to haul up massive engines and drop them again, you can be more flexible in your re-entry vehicle design. Gravity, meet glider. Or even a big balloon.

Quite a few, all of them far away and we don't know that much about them.

Now I know you're trolling. Educate yourself, young man. FTFA:
Another example of wealth can be found on an asteroid called Amun, the smallest metallic asteroid of several dozen known. According to Lewis, Amun contains roughly 30 times as much metal as the entire amount of metals mined and processed over the history of humanity... University of Arizonas Lewis adds that many of these asteroids are relatively inexpensive to reach because they have orbits that are remarkably accessible from Earth.

That would make that one asteroid worth several times the GDP of the US. Seeing any ROI yet?

Not near future and possible on earth as well. You'd need to bring all those materials close which is not feasible in the near future. Then you'd need to again bring the processed goods back down.

No, you wouldn't need to bring it close. You could just saw it up where it is, even process it on the spot and float ingots gently back to earth orbit. Where will you get power for all this? There's a large star right nearby there... As for not near future possible, its already being done.. Anything else you'd like to share with us?

Personally I wouldn't want a new brain and barring that I'll be dead anyway... This could also be more easily done on Earth.

Bleh. Who cares if it doesn't suit you. And I can see many advantages to keeping it in orbit, not least of which is fast deployment in medical emergencies.

Trillions in costs probably, you'd need to figure out new mining methods and manufacturing methods or build complex structures to use earth based ones. Not to mention the general costs of designing things for space.

More figures pulled out of your ass. The only thing stopping us getting into space and taking advantage of it is the cost to orbit. Thats it, nothing else.

Yeah, how about a few which aren't so far in the future as to be worthless due to unpredictability of scientific advance. Someone has been reading way too much sci-fi. In essence your idea is not profitable for at least the next 40 years, so you have no ROI right now.

Blah. If you want an ROI right now, go deal some heroin. This whole operation could be up and running in fifteen years, with a little elbow grease. In more serious business, long term investments with massive potential returns regularily draw companies to the trough. In fact any company without a fifteen year plan shouldn't be in business in the first place.

The question then becomes where do you get the raw materials from and where do they stuff the garbage. Unless they send all their garbage back up into space (See previous numbers for how many flights you'd need per year) Earth would become one giant garbage dump very quickly.

Remember that extremely low cost to orbit I was talking about? Good man.

Re:Hmmm

[Rakishi]

Ah yes, the hard headed realist who advocates a magical space elevator.

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 you're proposing ideas. The current costs are $1 to 2k/lb to LEO and probably twice that to GEO. Nonetheless even at $100 to 200/lb the costs are still very high, and that is an order of magnitude less than current costs. Energy costs alone would probably put you in that range, and if not than maintenance and so on.

Bringing them down would be the easiest part. Since you don't have to haul up massive engines and drop them again, you can be more flexible in your re-entry vehicle design.

Only the shuttle hauls it's engines back down, most designed involve a relatively simple capsule which is still complex and costly. You're talking about millions of tons of material being brought down, in other words you'd need to bring up millions of tons of reentry vehicles.

Gravity, meet glider.

Glider meet atmosphere at 11000km/s, enjoy your fiery meeting. Oh right you need to send up a heat shield as well and design it and test it and so on.

Or even a big balloon.

Which would burn off the excess velocity how again? There is no atmosphere in space you understand right and you'd need to bring things down from GEO probably.

That would make that one asteroid worth several times the GDP of the US. Seeing any ROI yet?

Nope, I've read about this and the cost of bringing the material down and processing it far outweighs the gains you get from it.

No, you wouldn't need to bring it close.

Much easier than bringing all the required machinery to it but okay.

You could just saw it up where it is, even process it on the spot and float ingots gently back to earth orbit.

Earth based processing methods don't always work well in space, and most likely would require billions upon billions of investment. Constructing the infrastructure on the asteroid would be expensive due to the distances and probably require a manned flight.

Where will you get power for all this? There's a large star right nearby there...

You need to build solar arrays, maintain them, bring them to the correct location, replace them as they fail and so on. Can do the same thing on Earth for much less.

As for not near future possible, its already being done. [energybulletin.net].

I never said that is not possible, I know quite well what is possible. I simply said the whole scheme of doing it in space is not possible. Your argument is like saying that because we can build a tank on earth it is trivial to build a tank on Jupiter right now. A downright stupid argument.

Bleh. Who cares if it doesn't suit you. And I can see many advantages to keeping it in orbit, not least of which is fast deployment in medical emergencies. ...fast deployment from GEO or LEO? You require time to load it, set u pa vehicle, landing at an appropriate area, making sure it's not damage during transfer, moving it to the correct hospital and so on. Even worse if you don't have multiple such stations in orbit as that incurs even more time, and if you do then you may as well have multiple such stations on earth. Much cheaper, faster and simpler to simply have a number of local supplies (in large hospitals probably) and fly them using helicopter or plane to the required locations. Not to mention that in medical emergency and given such technology you can dump a person onto artificial life support.

More figures pulled out of your ass. The only thing stopping us getting

Re:Hmmm

[Darkman, Walkin Dude]

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 flappery. And you can quote me on that.

Yuo f4il it. Troll.

Re:Hmmm

[Rakishi]

Well I expected that, it seems whenever a zealot meets reality he goes and finds an excuse to run away. Well enjoy your fantasy.

Re:Hmmm

[Darkman, Walkin Dude]

Its true what they say. Never argue with an idiot, they will just drag you down to their level and beat you there.

Re:Hmmm

[AGMW]

Now, make it 20 miles high and we'd be around the 1% pressure point. You'd still have to pump the thing out, just not as quickly.

So how high would it need to be to have the top end in a total vacuum and therefore not need any "cap" on it? Just assuming, for the sake of the question, that we could build something that high!

Is this more or less feasible than a space elevator?

I guess you are always going to have to pump some air out of it, so there's presumably a tradeoff between extra height and pumping effort. Even if it were sufficiently far out in space to not allow any air to fall in from the top, there's likely going to be some air getting in from the bottom as you load the next vehicle, etc.

In outer space the asteroid captures YOU!

[Xner]

Given the mass ratio between anything we can send up and the average icy space rock, it's more likely the icy asteroid's gravity will capture the craft than the other way around. Not that it's a bad thing, mind you.

Re:In outer space the asteroid captures YOU!

[FormOfActionBanana]

we could shoot chunks of ice into low orbit, or near enough orbit to catch them.

Re:In outer space the asteroid captures YOU!

[mwheeler01]

Given the mass of a space station or an asteriod, the attraction of gravity really wouldn't have any real noticeable pull on either object. The asteroid would have to be ginourmous, and therefore unmanageable to have any real pull and I think at that point they start calling them small planets.

Re:In outer space the asteroid captures YOU!

[edf825]

And then, of course, there's all that business about said ginormous asteroid hitting us...

Have we learnt nothing.

[Kaptain_Korolev]

Honestly, have we learnt nothing from Jerry Bruckheimer's excellent film Armageddon.

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.

[roman_mir]

who said he was drunk? He was in a normal working mode. I would like to see you after you spend 18 months in space by yourself :)

Sounds like some sort of xbox comp to me..

[oztiks]

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

So the question remains, How much money will you recieve if you can install linux on them?

I, for one, welcome our oxygen yielding overlords!

[holdenholden]

I say good for NASA. They are finally starting to realize that science can be done outside the government laboratories too. An (academic-type) researcher wastes plenty of time begging for money, writing grants and often balancing a teaching load. In industry, on the other hand, you worry less about budgets and more about what you are trying to achieve and how to achieve it. There is a flip side as well--in academia you are free to work on pretty much anything you like, while in industry you work on whatever your manager wants you to work. In the happy case when your interests and the company's interests coincide, you are only limited by your skills and your knowledge.

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:Interesting

[holdenholden]

In fact, that makes me wonder, how do they measure basic attributes like weight, volume, speed over there in space.

It is not a huge mystery. Weight you can measure using inertia or angular acceleration. Measuring volume doesn't require gravity--either calculate it from the dimensions (eg. measuring the volume of a fridge of a microwave) or if it is a tank, you can fill it up with water or a known volume of gas and measure the pressure. Speed is the hardest, because you need a frame of reference. In geostationary orbit you can calculate it based on your height above the surface. If you are travelling from the earth to the moon, you can use radio signal delay to measure linear velocity (same principle as a radar) or Doppler shifts.

Re:Interesting

[Darkman, Walkin Dude]

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 fuel tanks as a collapsing piston; the level of the fuel could be easily read then by just mechanics. This has the added advantage of pressurising the fuel as well.

Zero Gee problems?

[Cicero382]

Has anyone else noticed that zero G is a constant PITA for nearly all space applications?

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?

[cnettel]

I think a significant aspect here is the size needed to get a reasonably large volume/area with somewhat consistent perceived gravity (preferably close to 1 g, as well). We simply don't build things that large. When we do, I don't see any big technical problems, but of course one can start to consider proper docking protocols and so on at that point. (Problematic if anyone gets the crazy idea to try to dock the rotating parts of two art-grav vessels with a mismatch in angular velocity.)

Re:Zero Gee problems?

[GroeFaZ]

Obviously, the cost-benefit-analysis, at the current state of technology, does not speak in favor of simulated gravity or the engineers would've done it already. Rocket engineers must justify every pound of mass they want to put into space (which is, by the way, an argument against manned space flight), and, while needless to say, it's just a LOT easier and cheaper to let an astronaut pee into a plastic bag and toss it out the window than designing the rocket with 2 huge rotating discs tens of meters in diameter. Ditto for all other points you mentioned.

If and when our technology has matured enough so we can start designing RAMA-style spaceships 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?

[turgid]

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 would race them to it, to prevent Commies taking over the moon. Japan will be busy working on supersonic aeroplanes.

Meanwhile, Europe and India will send up more TV satellites.

Re:Zero Gee problems?

[smilindog2000]

It's not as bad as people think. You need a long cable, with a good tensile strength to weight ratio. A simple steel cable will do. On one end you attach the space station, which could be as small as a single module of the current space station. The other end needs a weight, supplies, another half of the space station, space junk... whatever. Then you spin the thing. No big deal.

To dock, you pull up to the middle and grab old of the rotating cable. You then lower yourself down to the station, and enter through a hatch on 'top'.

I think for long-term living in space, it's a win. For the short term, it adds complexity and cost that nobody wants to pay for.

It's not rocket science :-D

Re:Zero Gee problems?

[Ex-MislTech]

Yeah, Zero G can be a boon and a bane, it has positive and negative aspects.

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

I would consider putting most of the moonbase far underground as it would give it some defense against meteor/asteroid impact and most radiation.

o2 could be acquired from lunar soil as part of the helium-3 mining process, saving hauling it to orbit.

Storing the fuel would be best done in multiple cylinders/containers so if you have failure it does not compromise your entire fuel supply, ie. redundancy.

Meteorite impacts on a fuel cylinder would be very bad, and some kind or defense protection against this would be needed .

A deflection system or decceleration system, like armor or layered airbags or combination of both. Layered airbags to slow it some, armor to deal with remaining inertia.

Multiple fueling stations intead of one to avoid the single point of failure scenario.

Like 8 arms on a spider coming out from the central hub of the spacedock.

Integrate with the spacedock on the outer reaches of something similar to piers like ships dock with on earth. Long tunnels connecting to the main spacedock, and if there is an accident at worst the tunnel and fuel pod is lost vs. the entire station. Multiple airlocks in tunnel protect the spacedock from most explosions.

The fuel pods could be attached on the end of the tunnel offset from where it would connect to the door of the docking crafts.

Ships could be brought inside the spacedock as well, but it would be preferred they leave their explosive fuel outside the spacedock in the independent fuel pods.

Getting water up into space could be done by magnetic coil launcher mass drivers tossing canisters of it into low orbit, and then have some kind of craft ferry it from low orbit to the la grange points near the moon wear the spacedock would have a long term stable orbit .

Water could be split into hydrogen and oxygen via electrolysis or other methods such as the extreme heat method recently discovered.

http://en.wikipedia.org/wiki/Hydrogen_economy#High -temperature_electrolysis_.28HTC.29

A passive parabolic reflector on the moon or in space could achieve extreme heat at its focal point, and high temperature on the moon reaches over 120 celsius.

With a focused reflector temperatures much higher than achieved at the solar collector in france could be achieved.

http://www.madsci.org/posts/archives/2004-07/10908 57033.Ph.r.html

With power near 12 million watts per cu cm inside the earth's atmosphere, it would be impressive what could be achieved outside it.

The moon would most likely be the easier place to build the series of reflecting mirrors and the tracking control system could be mostly underground to shield it from surface impacts.

With virtually unlimited solar power to process lunar soil and water sent their via mass drivers from earth, it would be a safe underground compartmentalized and redundant facility if built that way.

Ex-MislTech

Re:Zero Gee problems?

[turgid]

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:Interesting

[Darkman, Walkin Dude]

Or even just measure the internal pressure of the tank. Less pressure, less fuel. Can someone write me a cheque now please?

Easy

[Tx]

Well, maybe not. But I have to wonder, why not just store the water, instead of separating it and storing liquid oxygen and hydrogen? You've got plenty of energy available up there from sunlight, so you should be able to split the stuff when it's needed, thus avoiding the problems of storing the liquid gases long term.

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). Can I have $5m please.

To all those that didn't read the article BTW, the assumption for the design is that the water comes from the moon, whether that pans out or not isn't the problem of people submitting designs.

Re:Easy

[BiggerIsBetter]

Well.... if we're thinking big... If a Space Elevator is "feasable" assuming carbon nanotubes happen properly, why not a geosychronous fuel station that pumps water up from the ocean? Think of a big pump in space, with a firehose all the way to Earth. OK, I'll admit that it's a large amount of liquid to lift vertically, tonnes and tonnes and tonnes, but possibly a nuclear generator could provide current for the pumping engines (or some kind of temperature difference pump...?) and/or solar power to split the water to hydrogen and oxygen.

Anyway

[skyfi]

Delivering so huge amount of fuel to space orbit will cost really much. And is there enough fules on the planet to bring a project like this to life&

Re:Interesting

[Ginger Unicorn]

its so obvious... i was about to post the same pressurised piston idea but you beat me to the $5million.

bah

what is with NASA? it must have occured to them - perhaps the article is just pointing out some obvious issues with the general problem.

Delivering Fuel

[DanielRavenNest]

When I worked at Boeing, I was in charge of a fuel-depot study.
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

[cnettel]

"The projectile is rugged enough that it can land on anything without damage."

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

[plams]

A BFG you say? I hope the design included the operator to be blindfolded. Otherwise he'd might destroy everything in his field of vision.

Re:Delivering Fuel

[rufty_tufty]

Attempt to use BFG to get into orbit - mostly successful, damn politics though.
http://www.astronautix.com/articles/abroject.htm

Re:Delivering Fuel

[tarpitcod]

I wonder if it is feasible to fire a solid block of ice (projectile shaped) into orbit. I wonder how much would ablate due to frictional heating. If you use a large enough electrical arc at the base you could use some of the ice of the projectile as the reaction mass.

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 projectile and accept the ablative loss.

If you really want to get serious about space exploration you have to consider the energy density of what your sending. The best use of the ice / water on orbit may be as reaction mass for a nuclear thermal rocket.

--Tarp

Done and done

[Avatar889]

Tie a gas can to a rope and just huck it up in to space. It might take a try or 2 to get it that high, but it'll eventually work. And the rope is so we can bring it back so we don't little space. See? Fast, simple, and environmentally friendly. Please send me my $5 million money dollars in small, non-sequential, unmarked bills.

artificial gravity

[plams]

In zero gravity, cryogenic fuels still have surface tension and therefore stick to the walls of their tanks. Acquisition devices would have to find a way to pick up the liquid, but not the gases in the centre of the tank.

How about generating aritifical gravity by putting the entire gas station into a spin? (Yes, Arthur C. Clarke taught me this :-) There'd probably be some problems with this however.

• It may be harder to build an orbital structure that's able to sustain constant gravity.
• The station itself might need to consume fuel in order to sustain the spin. Though other orbiters need to perform correctional maneuvers too.
• From playing Orbiter I know it's a lot harder to dock while spinning :) Additionally, the spin rate would change while loading/unloading fuel.

Re:artificial gravity

[NOLAChief]

You're right on most of your points for why inducing spin in this sort of depot would be a problem. (That's one of the many, many reasons that Armageddon is so painful to watch). Acquisition devices for cryogenic upper stages have been used on flights for years, so it's nothing we don't know how to do. Not sure why the guy in the article is making such a big deal out of it, unless he's making sure that's something that people chasing after the prize are considering.

More than proportional

[Bromskloss]

and the cost of putting something up there is still reasonably proportional to weight?

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. As you probably know, the orange thing just contains fuel, and the two solid rocket boosters mounted on it doesn't contain any useful cargo either. The shuttle itself is the smaller part of it all.

Re:More than proportional

[hyfe]

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.

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:Interesting

[Darkman, Walkin Dude]

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 bleeding (very thin) air into the area the collapsing skin has left behind. The thinner the air beside the fuel tank, the less fuel you have.

If it's done by private industry...

[DarthChris]

...then it's less likely to screw up.
Seriously, how many times have we heard of various satellites/probes that have screwed up due to tiny/stupid errors? I'm talking about the kind of errors that would never happen in private industry, like probes crashing because one group of people is using metric and the other imperial. Such errors would cost people their jobs in a private enterprise, but typically not for government-funded projects.

Re:If it's done by private industry...

[conspirator23]

While there is a perfectly valid argument in suggesting that the private sector should be more involved in space exploration and development, your particular example of public-sector stupidity holds no water.

The "standard/metric" foulup you refer to is specifically a reference to the Mars Climate Orbiter that was lost in 1999 due to Lockheed Martin sending data to NASA in standard units where the NASA team receiving the data was expecting metric units.

I was working for LM at the time this occured. Even though we were an entirely different division of LM that had nothing to do with space exploration, we all felt collectively embarassed over this error. In the final postmortem of the event, I don't know how much blame falls on NASA's side of the fence, and how much falls to Lockheed Martin, but it is clear that the private sector is at least partially responsible for this mishap, if not more.

Furthermore, the Mars Climate Orbiter mission was part of a long series of missions that NASA designed under their revised "fast and cheap" philosophy they embraced in the 90s. The whole reason for that strategic shift in project design was to get more science done with less money, as well as distributing the financial risks of failure more widely. If you look at the Mars exploration projects of the last decade as a whole, then this strategy has been wildly successful with MCO only representing a single failure in an otherwise exemplary record. This is especially true with the Spirit and Opporunity projects, which have dramatically outlasted their original operating goals and have produced a fantastic ROI in space exploration terms.

So yes, lets have more X prizes, and private investments, and so forth. But simply regurgitating the idea that public sector projects are inherently inefficient and wasteful is a canard, and nothing more.

Re:If it's done by private industry...

[Concerned Onlooker]

You might want to take a look at the latest Wired magazine, page 42: The Worst Stupid Engineering Mistakes. At least 6 out of the ten appear to have been perpetrated by the private sector including McDonnell Douglas' DC-10 in the 1970s. Wired blurb states that nearly 1000 people around the world lost their lives "while the kinks were being ironed out. Blown out cargo doors, shredded hydraulic lines and engines dropped mid-flight were just a few of the" problems.

That seems way worse to me than losing a satellite or a probe.

I have this crazy idea...

[Kong99]

why not build a huge super tall space elevator... naaa, nevermind...

Trouble figuring out how much you have?

[Pedrito]

The article says one of the problems is figuring out how much fuel you have in zero G because it's all floating around inside the tank. Call me crazy, but can't you just rotate your station and then check the pressure on the inside walls of the tank? Not like centrifugal force is some newfangled idea or anything. It's not like it would even have to rotate particularly fast. Sheesh, do I have to figure out everything for these guys?

Re:Trouble figuring out how much you have?

[mitymidget]

Or you could put some sort of plunger which just compacts all of the liquid leaving no air where the liquid is, then you could constantly see the volume of fuel left. As long as a vacume is kept in the liguid and the plunger side is outside pressure it would work, I guess you'd have to calculate for temp too, but computers can do this for us :)

Re:Trouble figuring out how much you have?

[Glonoinha]

Or store the fuel in a flexible bladder and as the fuel gets sucked out, the bladder shrinks - like those baby bottles that have a liner that collapses as the baby sucks out the milk. Just look at the bladder, see how full it is (use some sort of metrics and measurements, of course.)

Re:Trouble figuring out how much you have?

[Archimboldo]

You would need a bit of a tweak to make it work. In a zero pressure environment, you wouldn't see the bladder collapse, but you could conceivably pressurize the interior of the tank. Then I would see no reason, the bladder wouldn't collapse.

chemical reaction propulsion

[zogger]

I doubt there will ever be a cheap/easy/affordable way to do this with chemical reaction rockets. If there was it would have been thunked up by now, doncha think? What you see is what ya get, big ole rockets carrying a relatively small amount of stuff up at great cost.

  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 in some fashion, right now the best we can do is we sort of measure it AFAIK.

One chemical alternative: wildcard long shot: could we build rockets where the structure (parts of it anyway) of the rocket itself could be transferred to being fuel? A cannibalizing rocket in other words, save a lot of weight that way and get more fuel to orbit.

    This idea is a variation on the "caseless ammo" concept. I saw one of these rifles before that used this sort of ammo, made by Daisy the BB gun guys, it worked perfectly fine, no brass at all. The concept never caught on much, but it worked. So maybe there is a way there to get a lot more fuel into orbit for much less cost than currently. Don't ask me for a detailed chemical composition outline though, no idea, just the concept of cannibalizing rockets.

Fill'er up!

[AndroidCat]

I hope they'll properly tax those damned fuel-guzzling Space Urban Vehicles!

Re:Fill'er up!

[PoorCoder]

Urban? Naaa... Outer Space Utility Vehicles!

out-er space u-til-i-ty ve-hi-cle (abbr: OSUV)
noun
a high-performance spaceship.

Re:Fill'er up!

[AndroidCat]

They're not that high-performance, it's just the way those astro-soccer moms fly.

Orbital Mechanics

[Esion Modnar]

Wouldn't there be a problem with the fuel depot maintaining a stable orbit? As it offloads mass to another vehicle, it seems its orbit should change because of its changing mass. Something to do with conservation of momentum.

Re:Orbital Mechanics

[solitas]

By and large, a change in mass shouldn't affect an orbit - speed and altitude (orbital radius) are interdependent. It would affect drag (atmospheric & from the 'solar wind' - less mass = less momentum so drag would slow it down faster), but that's about all.

Not necessarily.

[WindBourne]

Assume it is water to be split. First it has easy requirements for storage. Compared to h2 and o2, it is positively trivial to store and work with (in liquid and solid form). 2'nd, this does not need to be shot up there. It could also be shot up an electronic railgun, or a maglev, to get the initial acceleration. It should be possible to get it going into top subsonic and then allow a much smaller rocket to take it up. Nice advantage of this, is that it could be used on a continutal basis for other cargo that is relatively inert to high Gs.

Re:Not necessarily.

[NOLAChief]

A lot of people are suggesting using water, either launched up or from icy body capture (comet, asteroid, whatever) and then separating the two via electrolysis. Great idea, since water is much easier to work with and store, but once you have separated it into H2 and O2, those gases must be liquefied to be usable by most rocket engines. Liquefaction is a very energy intensive process, particularly for hydrogen, so suddenly the depot's energy requirements have gone up, plus you have to have space for water handling equipment (including melters if it's being handled as ice), water storage, the liquefaction equipment, and storage tanks for enough fuel to service a customer's rocket stage. This could be a very large station.

The last thing I haven't seen considered is the orbit for this thing. In which orbit do we put it to maximize it's utility to exploration vehicles? Having to stop off at this station could severely limit mission profiles that require refueling to orbits within a few degrees of inclination to that of the depot itself, since orbital inclination changes require a lot of energy. We can get around that by placing multiple depots into orbit, but that's more money.

Re:Not necessarily.

[NOLAChief]

OK, point. I neglected to mention the solar array requirement. The ISS will get a total of 110 kW from four pairs of 112'x39' solar arrays when completed. Those are very large solar arrays. I'm guessing significantly more of these arrays will be needed to let the "gigantic ball of fire" meet this depot's energy needs. Then what do you do when the depot enters it's eclipse period and it can't see the sun? Do you shut down operations every hour or so until you can see the sun again or do you send up batteries (== even more mass!) to maintain constant power?

Of course sending up a nuke reactor to power the thing is always an option. Good luck convincing the quivering greenies of that though.

Old idea?

[CBob]

It was (at least) once proposed that NASA have the shuttle carry the "empty" fuel tank into orbit & have them assembled into a "station" at some later point.

A small semi-dumb "tug-bot" could do the dragging into similar orbits part. However, it might take a few humans with wrenches to do the rest.

The cost would have been a reduced payload capacity for the shuttle(xx percent??). However, how many times have they launched at "full" capacity?.

Cryo fuels would be interesting due to the long term effects of extremes heating & cooling, but a few "sun shades" might help there. Using bladders for other fuels would prob work for a "quick" fix.

Google can do it

[jense]

Google is taking over the world already, why not expand their market share to space? I can see it already: "Mars Orbiter Googled in Midflight." From it's web server cell phone, of course.

Problems solved

[Tango42]

Aren't all the problems the same as those that exist for fuel tanks in spacecraft? In which case, they've already been solved in existing craft, so just modify their fuel tanks.

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.

Possible $5 million winner

[Apollo Lee]

I wonder if the Bigelow folks could do this? They may have at least the components of a station ready to go. www.bigelowaerospace.com

Re:I, for one, welcome our oxygen yielding overlor

[susano_otter]

Actually, the article summary is a little misleading.

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 gives a fascinating account of how this process works.

Hey NASA

[lbmouse]

Just launch one of these into orbit. Can I have my $5 million bucks now?

Re:chemical reaction propulsion

[NOLAChief]

Interesting concept, but it would be very difficult to use on current rockets. The structure on most rockets is pretty bare bones to begin with, for example only about 10% of the gross liftoff weight of the Saturn I-B first stage is structure/engines. The rest is fuel. The structure is important because it is what transfers the thrust of the engines from the engines at the aft of the vehicle to the payload at the other end. Having the structure eat itself away as extra fuel would cut this thrust transfer, defeating the purpose of the vehicle. Even in a solid rocket booster, the structure is important as it provides containment for the reaction. Most people around in 1986 know the consequences of an SRB losing containment.

If it were possible, it would really only be useful for solid engines. Liquid-fueled engines would be severely damaged by even molten materials that had been structural.

hard to lift it from earth economically

[tmortn]

Earth's gravity well is at the edge of bichemical propulsion capacity. The best systems to date still only lift less than 10% payload weight of the launch vehicle.

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 pitiful payload capacity work at all. At least then vehicle construction costs could be amortized over the course of multiple launches which could drop payload costs dramatically. Supplying a fuel station with throw away rocket technology is like suggesting the gas station down the street get replenished by buying a new tanker truck to deliver its fuel every time.

Sure the truck can be made less reliable. But you still have to build a working vehicle each time. This will never work for anything but the most rarefied needs.
We need a true shuttle system. One which can sustain multiple missions with a simple re-fuling turn around process. The present 'shuttle' is anything but.

The other option as always is new technology. None have really shown up as far as a primary lift capacity. All new ideas other than perhap NERVA or Orion have all been different versions of the same idea of combining chimical propellants. Short of a new and as yet unknown fuel, chemical propulsion has reached its known limits in rocketry.

Re:Interesting

[HermanAB]

Actually, there are many ways to measure the contents of a tank in space. Here are a few I can think of: You can bump it to measure the change in velocity, you can spin it and measure the change in momentum, you can hit it with a hammer to make it ring, or you can just measure the inflow and outflow properly.

Johns?

[HermanAB]

...(or john)...

Geez, there are already Johns and Hos in space even before the first space hotel is launched???

Refuelling

[Mark_MF-WN]

Presumably you could just fire a reusable rocket at the station carrying nothing but fuel (ie: no astronauts, satellites, robots, space weapons, toxic/nuclear waste, orphans, or toupees for the hole in the ozone layer). Then that fuel is available to vehicles that are laden down with those things, allowing those craft to be slightly smaller because they initially only have to carry their launch fuel.

Not being an engineer, or even a particularly practical mathematician (but ask me about finite automata! ), I'm not sure about the logistics of this. But hey, why not?

Other Challenges

[Frightening]

Heres a clicky for other challenges in NASA's Centennial Challenges programme.

Notice the very doable (slashdotters?) robotics one. 250k.

Re:Fuel Problems Solved

[Concerned Onlooker]

Obviously this idea sucks.

Oh Gee

[NetSettler]

Even if you conquer Zero Gee with Artificial Gravity, you haven't entirely solved the Toilets in Space problem. Especially when it comes to filling stations in space. After all, filling stations on earth often don't have the cleanest toilets. How are we going to keep them cleaner in space?

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.

Water?

[Glonoinha]

Everybody keeps going back to using water, cracking it via solar electricity into oxygen (gas, or cooled/compressed into a liquid) and hydrogen (again, as a gas, or (unlikely) as a liquid.)

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 doesn't explode, it implodes. It is a neat trick for high-school chemistry students, but implosions aren't particularly useful for creating thrust.

Re:Water?

[jo7hs2]

Huh?

Re:Water?

[Larthallor]

No, hydrogen is explosive. I'm not sure what neat trick you saw, but I would guess it was likely a decrease in pressure after an explosion caused by two gases combining to become a much denser liquid. In other words the container (attached to a balloon?) contained the explosion and then the water vapor condensed lowering the overall pressure.

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 is a Wikipedia link that explains more, but basically it is generally one of the most efficient chemical rocket fuels available.

Also, of course, it (water) is super cheap, abundant and safe to lift.

Re:Water?

[Glonoinha]

I was going to explain it but I haven't had enough caffeine - so I will simply Google / cut & paste.

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 wasn't about the water vapor condensing into water (liquid) lowering the overall pressure - it was about going from three moles (volume) of gas (hydrogen and oxygen) to one mole of gas (water vapor).

That said - perhaps the heat generated by this reaction could somehow be harnessed to superheat a separate container of liquid water into steam, and that steam could be routed out the back of the rocket (as it expanded) as the propellent. Not sure that would be the best material to use, but it would be available.

It is times like this we have to ask ourselves - WWAD? (What would Asimov do?)

Re:Water?

[Larthallor]

Sorry for the delay responding, but I just realized you responded.

I don't know what site you picked out in your Google search, but the explanation you found was wrong.

The mole is NOT a unit of volume. The mole is simply a quantity of items, usually atoms or molecules. A mole of any element is simply an Avogadro's number of atoms (6.02 x 10^23 atoms). You can't determine the volume, even in relative terms, by simply comparing moles of different compounds.

Also, since moles are counts of objects, you can't add moles of one compound with moles of a different compound and get a meaningful answer. A mole of hydrogen is a different unit than a mole of oxygen, just as a mole of oranges (6.02x10^23 oranges) is different than a mole of apples (6.02x10^23 apples) and adding the two doesn't give you 2 moles of anything.

Saying that 2 moles of H2 + 1 mole of O2 -> 2 moles H2O is similar to saying that 1 mole of men + 1 mole of women -> 1 mole of couples. The number of people involved didn't change, we're just grouping them differently.

The burning of Hydrogen in Oxygen is an explosive chemical reaction because the chemical reaction isn't 2H2 + O2 -> 2H2O. It's 2H2 + O2 -> 2H2O + lots of heat. This heat expands the water vapor (gaseous water) greatly resulting in an explosion, as defined by Wikipedia, amongst others.

Besides these links, try googling the following: hydrogen explosion balloon experiment

Easy to be critical, but lets consider some things

[CFD339]

1. The dig had to have a minimal environmental impact -- enough to satisfy Cambridge and the Cape.

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 for an entire region -- basically everything north of Hartford -- that has only 1 major central highway in and out, and a terrible lack of bridge and tunnel paths already.

4. The tunnel has to replace an elevated highway which is aptly named the "Central Artery" and is the single major traffic corridor through the city, but it has to do so without stopping traffic on that existing route.

Hell, the TEMPORARY bypasses are more complex and expensive to build than most highways.

When its done, however, what has always been the biggest blight on the city from an appearance, safety, and noise perspective will be gone.

What was an elevated 6 lane roadway will be green space. You will be able to walk from the Charles river all the way to South Station and Chinatown, stopping in the North End for an Italian dinner, at the Aquarium, at Fanuel Hall, at Rowe's Wharf, and at the Haymarket. Doing so now would be a noisy, dangerous, ugly nightmare of a walk. Doing it in a few years will be literally a walk in the park.

already proposed - next problem

[delong]

The T-space consortium already proposed this in their bid for the CEV program. NASA should concentrate on ideas that haven't already been given to them.

http://www.transformspace.com/

Re:Interesting

[BiggerIsBetter]

OK, lets use an arrangement with a dipstick affixed to a non-compressed outer housing, reaching into an internal bladder. The internal bladder is held centralsed within the outerhousing, and gets smaller as the fuel is used. You can use the dipstick to measure the difference between the outer and the inner, so giving an indication of the amount of fuel used. Or just use one of those flexible electronic ruler thingies to measure the bladder circumference directly.

Re:chemical reaction propulsion

[DerekLyons]

I doubt there will ever be a cheap/easy/affordable way to do this with chemical reaction rockets. If there was it would have been thunked up by now, doncha think?

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.

Re:chemical reaction propulsion

[zogger]

which "it" from the 60s are you referring to? Ion propulsion or what?

big city gang method

[rubycodez]

we'll send punks with gasoline cans and syphons up there and "liberate" the russian and chinese orbital fuels. heck, with a coat hanger and wire cutters they could even jack spacecraft.

"Icy Asteroid"

[Cadallin]

Problem is, there's a word for those once they get about as close to the sun as Jupiter, they're called COMETS. That Presents Something of a difficulty, particularly with maneuverability.

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.

Depends on the pressure

[cbhacking]

2H2 + 02 results in 2 water molecules and a decent amount of energy. Hydrogen combustion cars (not fuel cell cars, which are actually electric) use this technique; it produces enough energy to drive the pistons. The reason you see an implosion when a match is inserted into an inverted test tube is because the ware vapor produced cools very quickly, and at atmospheric pressure, water is far denser than H2 or O2. Thus a given mass of the gasses produces a much lower volume of water. However, in space the water vapor produced by the combustion is EXTREMELY expansive. It still cools rapidly (much more so, in fact) but a great deal of thrust can be produced by forcing it (at pressure, within the reaction chamber) out a rocket nozzle. Once exhausted it can cool all it likes; by then the ship is blasting out more water vapor and the rapidly freezing water is far away.

Tower to orbit....

[Firethorn]

So how high would it need to be to have the top end in a total vacuum and therefore not need any "cap" on it?

GeoSync is 35K kilometers(22k miles) above the surface, yet there's still enough atmosphere there that satellites have to be boosted occasionally. Still, much above the 20 miles you'd probably be pushing the break-even point. It takes about a 150 km of height before earth's atmosphere is thin enough to be 'low drag' to earth's satellites. So you'd need to go 93 miles up, or nearly 5 times as high as the 20 mile tower, to eliminate that remaining 1%.

At some point it's easier to put a cap on the tower, even if you'd have to remove it before launch. It's likely that the tower would be at least somewhat leaky, requiring constant pumping no matter what.

At some point it'd be easier to drop a cable from orbit to mate with the tower.

Is this more or less feasible than a space elevator?

Well, theoretically speaking we could build at least a 'short' tower now, and experience at least moderate benefits from it, even if you're just winching the rocket up to the top for launch in thinner atmosphere. We still have a while to go on material strength to build a cable type elevator.

I'll note that these would be 'zero power maintenence' options. IE you could at least theoretically remove power from them without nasty crashing problems. There are some ideas that require much less in the way of structural materials, but require more or less constant power. Another thing to note would be that, while we could build a beanstalk for the moon/mars now, earth's gravity is slightly too high, so a combined approach will probably be the end solution. Something like a rail or powered cable(see link) approach to get into orbit, then a 'short' cable that doesn't go into the atmosphere(the most expensive part). In that case it'd be used more for launching vessels to other planets, though it'd still be usefull for satellite placement and you'd likely have a huge base in the middle.