NASA Looking To Build 'Gas' Stations In Space

coondoggie writes "Fuel is a major issue when it comes to long-duration spaceflights — its weight is a problem for launch and once a spacecraft runs out of fuel there's no place to get more. That's where in-space 'gas' stations located at strategic spots along a route would be a boon to spaceflight. Which is exactly what NASA is looking to do by beginning to solicit proposals for what it calls an In-Space Cryogenic Propellant Storage and Transfer Demonstration that will lay the groundwork for humans to safely reach multiple destinations, including the Moon, asteroids, Lagrange points and Mars."

Comments

bathrooms in spppaaaaacccceeeee....

[splatter]

Aww man I'd hate to smell the mens room in that place.

Re:bathrooms in spppaaaaacccceeeee....

[Kagura]

Space. Space space. I wanna go to space. Dad, I'm in space! I'm proud of you, son. Dad, are you space? Yes, now we are a family again. Space space. Yes, please, space. Space. Space. Good space. Here come the space cops. Space cops help. Help. Putting the system on trial. In Space. On Trial. Guilty. Of being in space. Atmosphere, black holes, nebulas, astronauts, the big dipper. THE BIG DIPPER.

Re:bathrooms in spppaaaaacccceeeee....

[GodfatherofSoul]

Wow, now not only do you have to worry about the sex of the person on the other side of the glory hole, but now you have to worry about the species too!

Re:bathrooms in spppaaaaacccceeeee....

[nospam007]

They'd need to put an Astro Chicken game on there.

Re:bathrooms in spppaaaaacccceeeee....

[hierophanta]

wow! WTF are you smoking? and can i have some?

Space dock

[Anonymous Coward]

One way to solve the launch weight problem is to not launch them. Build spaceships in space and you can build ships that aren't possible if you have to launch them from the Earth.

Re:Space dock

[AchilleTalon]

This idea comes from 2001: A Space Odyssey. However, don't underestimate the effort to collect enough debris to build something useful. And you still have a high energy requirement here to transform these debris into something else.

Re:Space dock

[gmuslera]

Could be interesting if eventually you could build spaceships taking materials from i.e asteroids. With a bit of care one could be turned into another (far smaller) moon and use it as source for raw materials, if of the right kind. Not sure if the fuel itself could be acquired in a similar way eventually.

Re:Space dock

[realityimpaired]

Whoring for Karma? why not....

We'd need one of these before we can start building ships in space in sufficient numbers to be worth it. There's already numerous groups around the world looking in to the technology and feasibility of doing it, and several proposed sites around the world. Alternately, we could also try a launch loop, but either way, our engineering is simply not capable of building something like that yet. "Yet" being the operative word.

As for why we don't build ships at a space station? The logistics of keeping a staff in orbit, and blasting parts into orbit so they can be assembled by staff in orbit, then blasting fuel into orbit so the ship can be fuelled, then blasting a crew and food supplies into orbit so that the ship can actually be launched are far more expensive than simply building craft on terra firma and blasting the whole kit and kaboodle into space. Until we're ready to start manned missions to deep space, it's simply not worth it, economically.

Re:Space dock

[Nethemas the Great]

The raw materials available for building components in space via NEOs (near Earth objects) are orders of magnitude greater than they are on earth. The problems lie more in the host of technologies that do not yet exist for harvesting, transforming, and manufacturing in space. There are further logistical issues regarding getting to the materials. Flying out to an asteroid isn't cheap, neither is returning with the goods.

All that said, the rewards for conquering these technological hurdles is mind boggling. To date we've only been getting our toes wet with respect to researching technology leading to the industrialization of space. Because of which much of this seems more sci-fi than anything. The short-term thinking majority can't conceive of any kind of substantial future in space. But they are the same kind of visionless people that wouldn't have bothered trying to industrialize Earth because it was too hard with solutions difficult to imagine. Explaining our vision for humanity in space to such people is like trying to explain your vision for creating what we know today as a smartphone to a pre-industrialization era person. All you'd get is mockery and ridicule about your pie in the sky, day dreaming flights of fancy.

Re:Space dock

[VanGarrett]

As for why we don't build ships at a space station? The logistics of keeping a staff in orbit, and blasting parts into orbit so they can be assembled by staff in orbit, then blasting fuel into orbit so the ship can be fuelled, then blasting a crew and food supplies into orbit so that the ship can actually be launched are far more expensive than simply building craft on terra firma and blasting the whole kit and kaboodle into space. Until we're ready to start manned missions to deep space, it's simply not worth it, economically.

The logistics do seem quite daunting, but at the same time, removing launch and atmospheric capabilities from the ship's requirements may lend itself to new designs that handle space travel much more effectively, thereby making deep space missions much more practical. As well, the technology that goes into creating the space shipyard will contribute to the colonization of the moon, Mars, and many other worlds; not to mention that the facilities may well serve to produce much of the equipment necessary for said colonization. Also consider that once the facilities are there, the logistics of getting raw materials to it are likely to improve-- the benefactors will be keen on investing in infrastructure for getting the materials into orbit, first of all, but more significantly, the station itself will have the ability to build the vessels and equipment needed to mine the materials from space-borne objects.

There are indeed some technological hurdles to be leaped, but that's really what this whole thing is about, isn't it?

Re:Space dock

[ae1294]

That's fucking genius. We'll just live in space and build the ships from vacuum and satellite debris! That'll be much easier than using metal, ceramic, and glass from earth-bound sources.

We need replicators.

Re:Space dock

[Runaway1956]

I've always been a bit skeptical of elevators. I mean - they are so damned massive, and there is so much stored energy in it - if and when something bad happens, you have a cataclysm on your hands.

The mag lev idea seems a whole lot better, but I'm still a bit skeptical.

I've always favored a railgun concept, mounted on or dug into a mountain. You still have an appreciable quantity of energy being expended in case of an accident, but it would be "aimed" outward, rather than inward. More, I believe the initial investment would be much smaller. Energy consumption after construction was completed would be higher than the elevator, but IMO it's a good tradeoff. Especially if solar energy could be harnessed to operate the guns, it would be a great tradeoff!

Of course, we are lacking the technology to do any of those things at this point. But, it appears to me that the rail gun concept is closer to reality than the monumental task of erecting an elevator or a cable!!

Re:Space dock

[realityimpaired]

Just that you can't launch a human with a railgun... short of having a gun that's many hundreds of kilometers long, the acceleration needed to reach orbit would be lethal. :) It'd work fine for launching robotic payloads, but not for manned space flight.

Re:Space dock

[wagnerrp]

The problem with railguns is that they are only a viable option for raw materials, fuel, and very robustly built structures. The acceleration would be too great for any complex assembly. A maglev launch could be used for more flimsy items, but you're still looking at very long launch rails, and very high accelerations for a direct insertion. For manned launches, the whole concept is completely out of the question. The best you could do would be a first stage replacement, getting the craft up to sufficient velocity that scramjet engines would function.

That said, I would be surprised if we put in the same kind of funding we did in the 60's, and couldn't have a viable launch system built in a decade that would drastically undercut anything else available.

Re:Space dock

[Runaway1956]

Lethal? Not necessarily. A hybrid launching system could be used for manned launches. Put the ship inside the gun, activate the gun at a reduced power setting, and the ship begins moving up the track. As the ship exits the track, rockets kick in to finish lifting into orbit. There is still a considerable energy expenditure, but we could eliminate that first stage rocket - or more likely, keep the first stage rocket, and arrive in orbit with that second (or third) stage fuel tank available for maneuvering.

I can't remember for sure who first suggested that idea, but I want to say that it was Arthur C. Clark.

Re:Space dock

[khallow]

It'd work fine for launching a very few robotic payloads

FIFY. The HARP project showed you can launch electronics and working rockets (with moving parts) via artillery. So it is possible to launch robotics via some sort of high acceleration rail gun or similar thing. You however have to engineer moving parts to handle hundreds to tens of thousands of gees, depending on the system. If you use chemical rockets, you only have to engineer those systems to handle perhaps 2-3 gees.

You save a lot of money by making a smoother ride for your robotics. Bulk materials like propellant or water, or simple manufactured goods like structural stuff doesn't behavior much different.

Re:Space dock

[pixelpusher220]

That and the friction from the atmosphere at ground levels would likely melt the thing anyway. So far the vast majority of our systems are going zero miles per hour when they leave the ground. They don't hit significant speeds until they are well up into the now less dense atmosphere.

Hybrid systems might be doable, but at some point you can't make it go faster at ground level due to the thick atmosphere and it's friction.

Re:Space dock

[Coren22]

Friction is why you do it on a mountain, you get to the less thick atmosphere area. Heck, building one in Bogota CO, or most of Chile would work great.

http://en.wikipedia.org/wiki/Bogot%C3%A1

Re:Space dock

[slick7]

That's fucking genius. We'll just live in space and build the ships from vacuum and satellite debris! That'll be much easier than using metal, ceramic, and glass from earth-bound sources.

We need replicators.

I just hope that the oil companies, Halliburton, Bechtel are not involved.
As for raw materials, the moon is better suited. Ceramics, glass, oxygen, beta cloth, helium3, can be by-products from the moon, however, initial raw materials, as well as the construction shack will have to originate from Earth. Gerard K. O'Neill laid out a plan back in the 60's - 70's.
Also expect independence from Earth by all the colonists on the moon and at the construction workers who will have a "piece of the action" in orbit at the LaGrange sites, if America's history serves me correctly.

Re:Space dock

[Dr Max]

Lets use robots, to make it a bit easier.

Re:Space dock

[Jartan]

That's what's wrong with NASA. They keep concentrating on sending up the kitchen sink and the human in the same ship.

Railguns are cheap and humans are light (comparatively). Send up the habitat+fuel (heavy) on the railgun and the human (very light) on a small rocket. Problem solved.

Re:Space dock

[Teancum]

While the technologies don't exist, the basic principles do exist and machinery which can be adapted for use in space is also being used currently for terrestrial mining operations... including teleoperated mining equipment and extraction techniques which could be applied to a space environment. There are also a number of features to working in a vacuum and microgravity environment that can significantly help in terms of metallurgy.

Two things that constantly plague metal production here on the Earth are the strong gravitational field.... which produces eddies and even prevents some metals from even mixing in large quantities due to extreme differences in mass. The other is the nearly constant presence of oxygen that requires elaborate processes to "reduce" the oxygen in the materials and the manufacturing process. Steel manufacturing processes, for instance, are constantly fighting the oxygen not only in the iron itself, but also in the environment of the blast furnace.

On the Moon this can be done much easier simply by pointing a parabolic solar mirror at some iron ore and waiting for it to melt. Heck, the steel slag left over after the process may not even be the most critical by-product on the Moon as it may be the oxygen you are after in the first place.

I guess what I'm trying to point out is that there are a whole bunch of options, and it isn't like the really hard engineering problems of simply trying to get off of the Earth in the first place. That is a tough challenge, but it is something which has been done. I'm not saying extraction of materials in space is going to be easy, but the reason for the lack of technologies to get it done has more to do with the fact that getting there in the first place is so difficult that the technologies to do anything once you get there haven't even been tried.

Re:Space dock

[RockDoctor]

Flying out to an asteroid isn't cheap, neither is returning with the goods.

Which is why I'd make the first serious target a dead comet (in an asteroid-like orbit). Bring back a lot of volatile reaction mass and suddenly a lot of your other problems get considerably easier.

Time?

[pablo_max]

How much time would that actually add to a trip to say Mars?
As I understood it, you would spend more or less half the trip speeding up and at the 50% mark flip the ship and slow down. That makes it seem like slowing down takes a really long time. I assume since there is either A, very low G forces and thus it takes for ever, or B, the power needs to kept down since puny humans cannot take high G situations very long.
Either way, making a complete stop 1/2 way would make you need to flip the ship at the 25% mark, this making your average speed slow as hell no?
Of course, this is just the way I think it works, which may be bunk. If not, better to only have filling stations on the destinations.

Re:Time?

[Sprouticus]

First, you are assuming the mission is manned, and thus the maxG=1 or close to it. If you take that assumption away you can have a much smaller mass and this acceleration can be increased.

A bigger problem for outside of lunar orbit is the fact that you would limit yourself to very specific trajectories. That would mean you either have a very small window or a much longer flight. Both of which are problematic for the purpose of decreasing flight time and increasing flexibility.

Parking the stations in orbit around moons or planets might be a good idea for machine which need to return to earth, as any vehicle would not need to have return trip fuel on board, cutting the fuel mass by 50%. It might also be good for missions that are multi stop in purpose. Of course the question is why you a rocket for such flights, what is the hurry?

The biggest use I can see is from LEO to GeoSync or from GeoSync to lunar orbit. Of course you still have the same amount of fuel to lift out of the gravity well regardless of whether it is part of the initial launch or gets the fuel later.

However, it does allow for much smaller launch/recovery vehicles and for smaller vehicles to refuel in orbit if the need arises. Space planes, satellites, maybe some vehicle for LEO cleanup which will have to use fuel to do its job. For those types of vehicles, reducing their mass during normal operations would actually save a lot of fuel in the long run because you would not have to move the fuel mass around as part of normal operations.

Re:Time?

[DrgnDancer]

Why not put the "fuel station" in orbit around Mars. Send up an unmanned ship loaded with roughly half the amount of fuel, food, oxygen, water, etc. needed for the mission and put it in orbit around Mars. Later, once everything is verified as arrived and safe, launch a manned ship with roughly half the amount of food, fuel, etc needed for the mission and let it dock with the unmanned station when it gets to Mars to restock. This will allow you to carry roughly half as much consumables on the (by necessity) much larger and more complex manned vehicle. It'll also give you a bit more fudge factor for relatively cheap. If you stock one manned vessel with rough 20% more consumable than you expect to need (just in case), you're adding quite a bit to a single ship's mass. If you add 10% more to each of two vessels, probably less of a big deal.

Re:Time?

[mark-t]

Even *IF* the maximum G were 1, do you know how fast you could get to mars if you could actually maintain that acceleration and deceleration for half of the trip? Your average velocity would be faster than anything mankind has ever achieved outside of a particle accelerator (about half of 1% of the speed of light), and you'd reach the halfway point in less than 2 days.

Re:Time?

[Ephemeriis]

The problem isn't so much in getting from point A to point B in space, as it is with getting to space in the first place.

Let's say you want to send something to Mars. You've got a 1-ton payload... And then it takes 1 ton of fuel to make the trip from Earth orbit to Mars. So you need to lift 2 tons into Earth orbit.

Of course... If you had an orbital gas station you could just lift 1 ton into orbit, and then fuel up at the gas station.

Re:Time?

[Nyeerrmm]

You're misinterpreting how most current spaceflight is done. At present only asteroid/comet/deep space missions use any form of continuous thrust, in the form of low-thrust ion or Hall-effect thrusters. Anything to a major gravitational body will still rely primarily on high-thrust impulses from traditional chemical rocket motors. Though technology on the horizon may be changing that, it is the current state of affairs.

The path to Mars using chemical thrusters is very straightforward -- if you look up the Hohmann transfer, thats basically the way its done. Leave Earth orbit so that your sun centered orbit is elliptical and touches the Mars orbit. When you get to Mars speed up again to catch up (in practice you do a capture burn and do it in a frame where it looks like your slowing down, but nonetheless). If you want to be really clever sometimes you do a major maneuver in the middle to allow you smooth out some of the problems that occur because the planes of the orbits aren't quite the same. All throughout there you do small maneuvers to keep on course. If you want to go faster, you can do faster shorter transfers, but it requires bigger burns on both sides.

However, in order to do this with chemical thrusters, you need a lot of fuel. A 1500 kg probe requires an extra 1100 kg of fuel just for the catching up maneuver, and probably > 3000 kg for the departure burn (I don't have data on that at hand right now). Its logarithmic so if you wanted to get that probe back to Earth you'd have to bump those measures up by factor of 2 or 3. Throw in landing and departing the Martian surface and it just gets uglier. This is why a Mars Sample Return mission is so hard -- you just can't stack that much mass on top of a launch vehicle.

Imagine instead though, that you had a cheap way to get fuel to orbit. 'Space Guns' and other such ideas are primarily ridiculous because they apply 100s of Gs that would kill a person or most hardware. Fuel won't care though -- so use high-cost rockets to get the people and high-value equipment to orbit, fill up empty (expandable?) fuel tanks there with cheap fuel launches, and then get on your way. Maybe ship some more fuel to Mars, but I'm not sure the numbers make sense for that. However, you could definitely use this technology with technology to extract fuel from the Martian environment to make the return leg easier though.

Thats why fuel depots are interesting for space exploration.

Re:Time?

[Nethemas the Great]

The problem trying to be resolved by in space fueling is the elimination of the need to carry it with you from earth on the same launch. Take for instance the most immediate need for this capability, satellite refueling. Presently the lifespan of a satellite is no longer than the fuel supply it was launched with. After this runs out it is no longer possible to correct for orbital decay, nor collision avoidance--an ever growing problem. Launching satellites with less fuel and being able to refuel them in orbit would create substantial launch and replacement cost savings.

Moving out a bit, the goal then becomes moving humans around in space. Humans come at a severe expense of weight due to life support and safety systems. The more weight, the bigger the launcher. The bigger the launcher the more complex and expensive they become both in terms of development, manufacture, launch as well as operation. If we can do away with the need to launch everything together, humans can be sent up in substantially smaller, cheaper, and safer vehicles. Payloads of fuel, and/or hardware don't require anything near the expense of humans, and can be sent up piecemeal with lower costs related to failure. In other words human payloads absolutely can not fail, but non-human ones while detrimental, do not matter so much.

One of the largest hurdles for humans going to places outside Earth orbit is how to return them. Our society doesn't have the will for one-way trips. Unfortunately, return trips require return fuel. We can either send it with the astronauts at great--possibly prohibitive--expense or we can have it already at the destination waiting for them to fuel up for the return trip. If we can manufacture it at the destination, even better.

Re:Time?

[camperdave]

You don't need the fuel at the half-way point. You need it in orbit - at the destinations, as you say. Besides, you don't need to come to a stop to fuel. There's no such thing as stopping in space. All you need to do is match velocity with the tanker. The tanker could have been sent beforehand, or it could be sent afterwards

Re:Time?

[Nethemas the Great]

It wouldn't be necessary to "stop" even if you were to refuel mid-flight. The refueling vessel would be placed in opportune orbit--around the sun, around a planet, etc.. An inbound vehicle would simply intercept the refueling vessel's orbit, refuel, and continue on it's merry way.

Re:Time?

[h4rr4r]

Why do humans onboard mean the maxG=1. I have experienced 5 and that was too much, but people could easily handle a maxG of 2 or so.

Re:Time?

[mark-t]

In a word. Comfort. Anything even modestly over a g would not be livable for a prolonged period of time (that is, anything beyond a few hours).

Re:Time?

[pablo_max]

Would he not burn up all his fuel staying in orbit? I assumed he must use a Lagrange point.

Re:Time?

[CrimsonAvenger]

It wouldn't be necessary to "stop" even if you were to refuel mid-flight. The refueling vessel would be placed in opportune orbit--around the sun, around a planet, etc.. An inbound vehicle would simply intercept the refueling vessel's orbit, refuel, and continue on it's merry way.

It would be harder to put a refueling vessel in an "opportune orbit" than to get it to the destination.

And it would probably require more fuel to match orbits with the refueling vessel in an "opportune orbit" then return to your original orbit than it would be to just fly on past.

Note that LEO is "halfway to anywhere" in the only metric that really matters in space - deltaV required to get there. If you could get to LEO and then replace all the fuel spent getting there, you'd have enough to reach Solar Escape Speed. Plus a few km/s

Re:Time?

[Runaway1956]

"Our society doesn't have the will for one-way trips."

http://www.aolnews.com/2011/01/12/why-volunteer-for-a-one-way-mission-to-mars/
http://newsfeed.time.com/2011/01/12/space-cadets-400-people-volunteer-for-one-way-trip-to-mars/

And, several more hits on Google. Society at large didn't have the balls necessary to sail with that silly Italian named Columbus, either. The job will be done, sooner or later, all the same. SpaceX seems the most likely candidate at this point in time, but it may be China or the EU that gets it done first. Russians? Probably not, but they could surprise me too. India? Ditto - probably not, but they could surprise me.

Re:Time?

[teeks99]

You pretty much nailed it all on the head. The only thing that I wanted to add was that there has been one probe to move between two massive bodies (Earth and the Moon) using a continuous thrust system: the SMART-1 probe with its Ion engine. The downside: it took 13 months (it only took the Apollo astronauts a couple days) and used a series of really strange, constantly expanding orbits (basically a spiral), on the plus side it only took 1/10th of the total propellant mass that a chemically powered spacecraft would.

Ion/Hall/Plasma thrusters are great for moving cargo where you don't care too much about how long it takes (especially in the beginning of the mission). This type of technology could easily be used to move fuel to one of these "Gas Stations" in earth, moon, sun, or mars orbit. You could start this years before the need date (before you get busy testing out the manned space craft) then the chemical fuel could already be there when you're ready to launch the manned space craft.

Re:Time?

[Nethemas the Great]

It doesn't cost anything (fuel) to orbit. It only costs something when you change orbit. As per Newton's first law of motion. Orbits around a planetary body can degrade due to atmospheric drag, however heliocentric orbits (around the sun) do not have this consideration. Halo orbits--the ones involving Lagrange points--are useful for maintaining position relative to two other gravitational bodies such as Earth-Moon, Earth-Sun, etc..

Re:Time?

[Cold hard reality]

A few G's for a few hours are impossible. Let's say 2G for 2 hours, that's a delta-V of 212 km/s. With a rocket Isp of 400 s, the rocketry equation yields that 100% of the vehicle is fuel, while the remaining 0% comprise structure, engines, tankage, and cargo.

Re:Time?

[Cold hard reality]

Except you needed to lift the 1 ton of fuel to the gas station previously, plus extra to account for boil-off, plus the gas station itself, plus extra fuel to account for docking, undocking, and any discrepancy between the required orbit and the gas station's orbit.

Lifting extra tanks just before the mission, into the same orbit, and assembling the ship in space is much more efficient. Gas stations make sense when you've got so much traffic you can use a few large refill boosts to fill up many interplanetary ships. But we're really really far from that point.

Re:Time?

[GodfatherofSoul]

As I recall, Columbus' crew almost mutinied when they thought they weren't going to find land before it was too late to turn around.

Re:Time?

[Runaway1956]

I believe that you recall correctly. However - our mutinous space sailors won't have much doubt that they know where they are going. Mars is up there, they can see it, unlike Columbus' crews, who could not see the "New World", or India, or much of anything for that matter.

Re:Time?

[mark-t]

If you accelerated for only a few hours ('few' being something less than what is tolerable by humans for the amount of acceleration used), you'd have to cost for substantially more than a couple of days (although admittedly, you'd reach Mars pretty quickly... less than a single month).

Re:Time?

[Coren22]

The idea is to have fuel depots in orbit around the Earth, and in the Lagrange points. You launch a ship into orbit, then immediately refuel, head to your destination where there is fuel waiting for you for the return trip.

Re:Time?

[sjames]

That's why it's done more like mid-air refueling rather than pulling into the gas station.

Re:Time?

[mark-t]

A few G's for a few hours is impossible, sure... but can we sustain 1/1000th of a G for several days? If so, we can reach Mars in less than 2 weeks.

Re:Time?

[the gnat]

Plasma [adastrarocket.com] thrusters are great for moving cargo where you don't care too much about how long it takes (especially in the beginning of the mission).

Actually, magnetoplasma engines may be one of the better choices for interplanetary travel - they're a good combination of thrust and efficiency and can reach much higher speeds than chemical rockets. The obstacles to their use are more practical than technological: they're useless in atmosphere, so you still need chemical rockets to get them into orbit, and to really speed up the mission, you need a conventional nuclear reactor powering the engine. It's non-trivial (none of this has been tried, obviously), but if you wanted to make a re-usable interplanetary shuttle, this might be a good option.

Re:Time?

[Cold hard reality]

1/1000th of a G is currently unreachable (for a 100 ton spacecraft you'd need 1000 N thrust, current engines provide 5 N), nor is a suitable power source forthcoming. However this may change in a couple of decades as research continues.

Re:Time?

[Herve5]

Also, an interesting feature of Nasa's call to propositions is it allows for more innovative designs, like the possibility of splitting the required delta-V between two separate crafts.
You now can consider leaving Mars for a return flight with a barebone orbiter that did come up there with all the "snowball effects" related to accelerating for leaving Earth, braking when reaching Mars, then reaccelerating to leave it.
If in these conditions if you need to bring one more ton of fuel to brake on Earth again, the system just becomes almost impossible for mass reasons (you need exponentially large masses of fuel just to accelerate/brake/reaccelerate this last fuel).

With the possibility of in-flight refueling, you can design your return orbiter "naked", with just the fuel to deorbit Mars, then plan an encouter with another, separate orbiter that basically will just leave Earth to bring you that famous last ton of fuel.
And as this second bird just doesn't need to brake on Mars and restart, it simply won't have a snowball effect.

The mass gain is huge: basically, it allows so much extra delta-V that one can design the mission to end in low Earth orbit, instead of performing what is now timidly called the "aerothermodynamic" entry (ie, a design where you just aim at Earth with a big, megawatt/m2-Mach-twentysomething shield in front of you, expect all your kinematic energy to be dissipated in the atmosphere, and pray ;-)

Makes sense...not politically sexy...won't happen.

[Covalent]

This idea is an excellent one...build your spacecraft in orbit and then launch it from there with fuel from an orbital gas station. Significantly less danger for the crew, much faster travel, and shorter periods in outer (read: Cosmic Radiation) space. But it isn't politically sexy, so it probably won't happen.

Reminds me of the fuel stores in WWII.

[jafo]

In WWII, the US was building up a fuel store by fueling up B52s and flying them across the Himalayas. But, depending on weather conditions, sometimes they would need to take on fuel at the depot to make the return trip. The implication in what I've read about this is that they were spending the majority of the fuel on the trip, to deposit a little fuel at the destination, like driving across the state to deliver a couple of gallons of petrol.

Re:Reminds me of the fuel stores in WWII.

[CrimsonAvenger]

In WWII, the US was building up a fuel store by fueling up B52s and flying them across the Himalayas. But, depending on weather conditions, sometimes they would need to take on fuel at the depot to make the return trip. The implication in what I've read about this is that they were spending the majority of the fuel on the trip, to deposit a little fuel at the destination, like driving across the state to deliver a couple of gallons of petrol.

First, we didn't have B52 bombers in WW2. You probably meant B29s.

Secondly, it's more like driving into the middle of a desert to deliver a couple gallons of petrol.

Which has been done repeatedly in history, when exploring new areas that didn't have gas stations. We even do it now in Antarctica.

Re:Reminds me of the fuel stores in WWII.

[LWATCDR]

No they didn't.

There was no B-52 during WWII.
There was no B-52 in service during the Korean war.
The B-52 didn't enter service until the 1950s and still is to this day.

Durring WWII the US would fly fuel of the "HUMP" in a number of planes including the C-46, B-24 and the B-29.
Saying that they used B-52s to fly fuel in WWII is as dumb as saying that your parents used their PC to log onto CompuServe back in the 1950s
Those that do not know history will just make it up as they go.

Re:Reminds me of the fuel stores in WWII.

[ari_j]

That's a really interesting story. I had to do some searching to find more information, as I knew it couldn't be (jet-powered) B-52s handling the task during WWII. It sounds from this Wikipedia article that a variety of aircraft from C-3s to C-87s did the job, with the C-47 being the workhorse.

When I saw this article, though, about fuel stops in space, I was immediately struck with the thought that it would take a lot more fuel to decelerate enough to dock and re-accelerate than it would be worth. It probably makes sense to fuel up in low Earth orbit and possibly in the asteroid belt, before firing off into an escape orbit (of the Earth and the Sun, respectively), but once you're at escape velocity I can't imagine much benefit from stopping for fuel.

Re:Reminds me of the fuel stores in WWII.

[starglider29a]

Nope. I'm with LWATCDR. Check your facts or post on Facebook!

Re:Reminds me of the fuel stores in WWII.

[Nimey]

Wrong. They flew C-47s and C-46s over the Hump to support (among other things) the B-29 bases in China, and I would expect that the cargo planes /would/ need to refuel - people forget how short-ranged planes were back then.

Re:Reminds me of the fuel stores in WWII.

[LWATCDR]

Airplanes are technology. Military aircraft are usually some of the highest technology of their time. This is technology site. If you are going to make a statement of fact with no room for error or interpretation and you are wrong you will get corrected. The point was what exactly? That it is better to have fuel magically appear than to have to ship it? Well yea but that isn't an option in space or in China durring WWII. The facts are that the air lift of fuel did allow the US to attack Japan with B-29s flying from China. It worked. The US did it until bases closer to Japan with sea access opened.

Re:Reminds me of the fuel stores in WWII.

[LWATCDR]

Computers existed, timesharing services existed. Just not a type of computer a PC and a specific service CompuServe.
Same thing. Before you state fact at least check wikipedia. I mean really he was wrong. Not a little wrong but way off in his facts Not to mention there was no point to be made except that pre position supplies had been done before. Heck hit had been done for a long time. I suggest you look up coaling stations. I suggest you just chill out or if you are the poster might I suggest that you leave some room for doubt if you are not sure. Like saying "I heard that", or "I believe that" instead of making a factual statement that isn't. Or best of all if you do make a factual statement that was wrong just saying, "Thanks I blew that one" and letting it go.

Re:Reminds me of the fuel stores in WWII.

[Chris Mattern]

In WWII, the US was building up a fuel store by fueling up B52s and flying them across the Himalayas.

Wow, I didn't know the US had time travel during WWII, getting aircraft that were still over ten years in the future like that.

Re:Reminds me of the fuel stores in WWII.

[teeks99]

That's where the "Strategic Spots" come in. There are certain points along the orbit from earth to X (moon, mars, asteroid, etc) where it would take extremely little thrust from the space ship to drop by there (stop is the wrong word).

Also, as others have mentioned, it would be possible for the "Gas Station" or at least a module of it to come to you as well.

Re:Reminds me of the fuel stores in WWII.

[teeks99]

Launching the fuel station in such a way that matching its velocity is substantially close to being on the escape trajectory you eventually want to be on would be stupid, since you would have to accelerate the entire fuel station to nearly that escape trajectory instead of just bringing the fuel with you, and you'd also have to launch the fuel station close in time to launching your actual mission.

That's the magic of the Lagrange Orbits. They're very cheap to get to from an escape trajectory, but they hang around the body(ies) that they're attached to.

Putting the cart before the horse.

[couchslug]

There is no reason not to develop remote-manned tech for another hundred years and THEN send human tourists with vastly improved technology.
We need remote-manned and robotic tech on Earth, now and for the future. We MUST have it to exploit the PERMANENTLY hostile environment offworld. Humans will have to live in protective enclosures anywhere they go, which reduces them to machine operators either way.
Humans explore nothing, they are passengers. Ditch the terrestrial model of "wooden ships and iron men" because that is an artifact of the time when both men and ships were CHEAP and EXPENDABLE.

Re:Putting the cart before the horse.

[Sprouticus]

you miss the scope of this. there is nothing to say that robotic missions would not need extra fuel. I posted above in more detail, but I can see missions which return from planets/moons to earth as options. Missions with multiple stops (all of jupiters/saturns moons being mapped in details would be awesome), LEO missions where you move around a lot but dont want to waste fuel mass carrying extra fuel mass (space planes, LEO cleanup vehicles, sattelites).

Also allows for small ships to go up the gravity well quickly. You still have to launch the fuel, but once it is in LEO, any vehicle can use it. Combine that with a system which allows space planes to connect to an external tank which never has to return to earth (rent-a-booster system) and you create a flexible system which optimizes the incredible cost of moving around in space. Both locally and interplanetary.

Re:Putting the cart before the horse.

[0123456]

A hundred years from now your space fantasies will look as outdated and ridiculous as 19th century visions of bigger railroads do today.

A hundred years from now, your 'back to the land' peak oil fantasies will be looking as outdated as the Victorians who were worried that by 1950 there would be so many horses in London that the accumulated horse crap would fill the streets thirty feet deep.

Oh, and if the human race does run out of cheap energy, you won't be raising horses on a farm, you'll be fighting in the streets over tins of dog food.

Re:Putting the cart before the horse.

[Arlet]

A hundred years from now, your 'back to the land' peak oil fantasies will be looking as outdated as the Victorians who were worried that by 1950 there would be so many horses in London that the accumulated horse crap would fill the streets thirty feet deep.

And why is that ? We're already hitting peak oil, and we don't have plans for a realistic alternative. Even if we had some decent plans, it would take decades (and a lot of energy) to implement those.

Re:Putting the cart before the horse.

[www.sorehands.com]

The streets of Washington DC is 6 feet deep in horse crap. Sorry, that was the politicians and lobbyists. It is hard to tell the difference.

Re:Putting the cart before the horse.

[camperdave]

Remote-manned (by which I assume you mean remote controlled like radio controlled airplanes and submersible remote operated vehicles) is impractical due to propagation delay. The Moon is 1.3 light seconds away, meaning a round trip signal is almost 3 seconds. Mars is anywhere from 8 to 40 minutes round trip time. That lag makes remote manned impossible. By the time you saw the rock, the rover would have crashed into it as much as 20 minutes earlier Robotic missions will need to have significant on board intelligence, which would be remote commanded.

Re:Putting the cart before the horse.

[Reeses]

It could be argued that in the days of "wooden ships and men" the men were less expendable than they are now.

We're nearing a world population of 7 billion. If you think a few thousand of those aren't "expendable" as long as they enter into the deal knowing all the risks, then you need to do some math.

They're far more "expendable" than they were back when the world population was only a few tens of millions.

We're becoming progressively more worthless.

And the "Wooden ships" part being more expensive is because we've placed opportunity costs on the materials needed to build ships. We can build one rocket out of aluminum, or we can build another million iPhones. Sadly these days, we're choosing the iPhone.

Re:Putting the cart before the horse.

[Runaway1956]

Men and ships are just as expendable today as they were 100, 300, or 600 years ago. It is only your own vanity that makes you think that men's lives are worth more today. As for the expense of the ships - today's ships cost a lot of bucks, yesterday's ships cost a lot of currency as well. That famous Armada that was sunk in the storm off of England's coast was a substantial part of the kingdom's budget. You'll note that the Armada wasn't replaced, in fact, couldn't have been replaced as quickly as the United States replaced her damaged fleets after Pearl Harbor.

Lagrange Points

[decipher_saint]

I've been reading/watching a lot of old sci-fi lately and one of the features that keeps popping up is the idea of a Lagrange point making a moon/mars trip possible.

I mean if you wanted to go to Mars, land and come back you wouldn't do it quite like a trip to the moon. Ideally you build the ship in space at a Lagrange point then shuttle the fuel, men and equipment up there. Then send a ship with a lander capable of breaking Mars orbit AND either a decent sized orbiter for the trip back or park another Lagrange point in relation to Mars before you even go, stop there and gas up and leave.

Expensive and time consuming maybe but I think more dependable.

Re:Lagrange Points

[drinkypoo]

It probably makes sense to build it at the Earth-Moon L1, assuming materials are coming from Earth. Otherwise, L2, since they must be coming from the moon... Hmm, looking at Wikipedia, I see that L2 is proposed as the ideal propellant station site :)

Re:Lagrange Points

[camperdave]

I'm not sure what the draw is with Lagrange points. L1, L2, and L3 (the ones in line with the primary and secondary bodies) are dynamically unstable. It's not like you can park there. L4 and L5 points are much better because they are dynamically stable points, however nobody talks of placing a fuel depot there. You're much better off just building everything in Earth orbit. Sure, send a return vehicle ahead. Send fuel and supplies ahead. But don't bother parking at Mars/Phobos L2, just keep things simple and do a regular orbit.

Re:Lagrange Points

[FleaPlus]

L1, L2, and L3 (the ones in line with the primary and secondary bodies) are dynamically unstable. It's not like you can park there. L4 and L5 points are much better because they are dynamically stable points, however nobody talks of placing a fuel depot there.

Actually, assuming you're talking about a hydrogen/oxygen fuel depot, you'll have a few pounds of propellant boil-off every day (out of several tons total). You can redirect the boil-off for station-keeping, and it pretty much meets the requirements for station-keeping at L2. There's more details in this ULA publication on depot architectures:

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

Re:Lagrange Points

[CrimsonAvenger]

I mean if you wanted to go to Mars, land and come back you wouldn't do it quite like a trip to the moon. Ideally you build the ship in space at a Lagrange point then shuttle the fuel, men and equipment up there. Then send a ship with a lander capable of breaking Mars orbit AND either a decent sized orbiter for the trip back or park another Lagrange point in relation to Mars before you even go, stop there and gas up and leave.

Easier to build it on the moon. And since there is water on the moon, easier to fuel it there.

Alternately, if you don't want to mess up the lunar water supply, you just make LOX on the moon from the rocks. Since LOX is ~5/6 of the mass of your fuel (using LH2/LOX), you only have to ship 1/6 of your fuel from Earthside to the moon.

Then, you launch from the moon into an orbit that uses the Earth as a slingshot to get a bit more oomph out of your reaction mass and off you go to Mars. Or wherever.

Re:Lagrange Points

[camperdave]

But what's the point of L2? You need a depot in Earth orbit to fuel up for the trans-lunar burn, and one in Lunar orbit to fuel up for the trans-earth burn. Why put the lunar depot at L2 as opposed to a lunar orbit?

Re:Lagrange Points

[FleaPlus]

But what's the point of L2? You need a depot in Earth orbit to fuel up for the trans-lunar burn, and one in Lunar orbit to fuel up for the trans-earth burn. Why put the lunar depot at L2 as opposed to a lunar orbit?

I'm by no means an expert, but my understanding is that there's a few different advantages L2 has over LLO:

* Lower delta-V to reach it from LEO (3.43 km/s vs. 4.04 km/s), and -much- lower delta-V to go from there to Earth escape orbit (0.14 km/s vs. 1.4 km/s). This makes it much more practical for sending missions/probes to Mars, the outer planets, or just about anywhere else in the solar system.
* In that likely case that you're using hydrogen/oxygen propellant, boil-off is going to be your primary long-time storage concern. In LEO (and presumably lower orbit) you not only have to worry about shielding a depot from the Sun, but also have to worry about shielding the thermal emissions from a nearby constantly-moving terrestrial body. If you're in EML2, all you need is a sun shield to keep the temperature down.
* I suspect it's much more difficult to dock with a constantly-moving target in lunar orbit than with a more stationary target at a Lagrange point, both in terms of actual maneuvers and mission scheduling.
* There's substantial gravitational anomalies in the Moon, adding stationkeeping costs for maintaining a consistent lunar orbit.

Re:Lagrange Points

[camperdave]

Well, You're going to need a depot in LEO anyway, other wise you're not much better off than shooting for the moon directly. As far as docking, I don't buy it. We dock at the ISS all the time, which is dealing not only with Earth's gravitational anomalies, but with atmospheric drag as well. Once you're in a similar orbit, both you and the depot experience the gravitational anomalies at the same time. Thus they cancel out. As far as station keeping is concerned... well, you've got a depot full of fuel there anyway. That just leaves the delta-V issue, which I guess trumps all the other objections.

Um

[countertrolling]

I take it this will be a 'full service' station, nod nod wink wink

Re:Um

[PPH]

Just an attendant from some third world country sitting behind bulletproof glass with an attitude and some stale candy bars.

Re:Um

[drinkypoo]

I take it this will be a 'full service' station, nod nod wink wink

Yeah, unfortunately, that comes with extra foam.

Could make sense if done right

[jandersen]

It seems like a wasteful solution if you imagine sending up rockets with fuel, but we could freeze it solid and shoot it up with a magnetic rail-gun, perhaps ...

Re:Could make sense if done right

[decipher_saint]

Or LEO with a super-cannon...

http://en.wikipedia.org/wiki/Project_HARP

Re:Could make sense if done right

[jellomizer]

Also of note, People take a lot of resources to survive. So the trick with people is to move then quick so they use less resources. These could be put into orbit and take a decade or two to get into position. Have it sling shot around some planets and enough fuel (non-storage) to "Park It" in spot. For human travel taking a decade or two is way to long. We need fast and light ships to get us to say in mars in a year or two.

Re:Could make sense if done right

[CrimsonAvenger]

Also of note, People take a lot of resources to survive. So the trick with people is to move then quick so they use less resources. These could be put into orbit and take a decade or two to get into position. Have it sling shot around some planets and enough fuel (non-storage) to "Park It" in spot. For human travel taking a decade or two is way to long. We need fast and light ships to get us to say in mars in a year or two.

Umm, no.

the minimum energy hohmann transfer orbit to Mars takes 8 months and change. All the other orbits are faster.

Which means we don't need to worry about trips to Mars taking "a year or two", since they can't take more than eight months without us doing something colossally dumb.

Nor do we have to worry about trips to Mars taking a decade or two - the only way we could manage to take so long to get to Mars is if we drove there using the new Interplanetary Bypass....

Re:Could make sense if done right

[wagnerrp]

That is not correct. Among direct, single impulse maneuvers, the Hohmann transfer is the slowest and requires the least energy. A gravitational slingshot from the moon could be used to offset some energy from the propulsion system, but is indirect. "Fuzzy orbits" operate on a similar principle, but are far more complex to compute and can take even less energy. Multiple passes of an elliptical orbit could take advantage of the Oberth effect, with multiple successive burns at the perigee of each pass. Overall, you end up using more energy than a direct Hohmann, but your engine is used more efficiently, producing more energy for less reaction mass. A long duration burn from an ion drive will consume far more energy, but will still take far longer than a Hohmann transfer.

Re:Could make sense if done right

[CrimsonAvenger]

A gravitational slingshot from the moon could be used to offset some energy from the propulsion system, but is indirect. "Fuzzy orbits" operate on a similar principle, but are far more complex to compute and can take even less energy. Multiple passes of an elliptical orbit could take advantage of the Oberth effect, with multiple successive burns at the perigee of each pass. Overall, you end up using more energy than a direct Hohmann, but your engine is used more efficiently, producing more energy for less reaction mass. A long duration burn from an ion drive will consume far more energy, but will still take far longer than a Hohmann transfer.

All of this is true.

It should be noted that we could also go to Mars by way of a gravity slingshot around Venus, Mercury, and Jupiter as well.

Fortunately, we're not actually colossally stupid, so we're not going to send men to Mars in any spacecraft that takes longer than a Hohmann transfer.

For that matter, we're not all that likely to use an orbit as slow as a Hohmann. Seems to me that I read once that a six month transit to Mars requires only an extra km/s deltaV to achieve. Which would be pretty trivial with an orbital tankfarm to refuel from.

Read the history of polar exploration.

[EWAdams]

They sent out advance parties to place depots along the route, over 100 years ago. Totally obvious thing to do. I can't believe it has taken this long for Nasa to clue in.

Re:Read the history of polar exploration.

[starglider29a]

How much energy did it take to keep the polar caches in place? That's the difference. NASA can't just hang it up there, turn on the anti-gravity, and find it there in 10 years. I mean... explorers sailed to new worlds for centuries using nothing but windpower. Why doesn't NASA do the same thing...

Oh, right... they also have to take their own oxygen, and don't have a medium upon which to float. Gotcha...

Re:Read the history of polar exploration.

[Arlet]

Actually, if you put things in orbit, outside the atmosphere, they just "hang" there forever.

Re:Read the history of polar exploration.

[Nethemas the Great]

And there are such things as solar sails... and technically there is a Dirac sea... :P

Re:Read the history of polar exploration.

[ThatMegathronDude]

Nope. All orbits decay. Some on the time scale of the age of the sun or the universe, but space is not a pure vacuum and all orbiting bodies will eventually fall back down.

Re:Read the history of polar exploration.

[Arlet]

But we're not talking about the age of the sun or the universe, but just a couple of years, maybe decades, at most. On that timescale, there are plenty of stable orbits.

Re:Read the history of polar exploration.

[wagnerrp]

That's not true. The Moon is falling up.

Mmmmmm...

[Daetrin]

Smells like chicken!

Re:Mmmmmm...

[$RANDOMLUSER]

Can someone please explain to me the recent spate of articles about NASA from NetworkWorld?????????

Oh, I get it "Michael Cooney" == "coondoggie".

The hard part

[vlm]

Cryogenic

That's the hard part. Keeping it liquid. Would be a bummer to arrive at mars, get ready to fuel up, and oops we don't have any gas to get home.

The other mysterious part is no mention of water / oxygen / nitrogen / food / medkits / spare parts / etc. You'd think a "supply cache" would have more than just fuel in it.

Re:The hard part

[0123456]

That's the hard part. Keeping it liquid.

Sunshades and a refrigeration plant should work. I believe that's what the Apollo-derived Mars mission plans were going to do so that they could use the LOX/LH2 S-IVB stage for Mars orbit entry.

Re:Sounds Inefficient at best

[0123456]

A) How many trips are we planning to take along the same route anytime soon? This doesn't seem as though it would be practical at all until there was a plan for an established travel lane.

If you're going to the moon on a regular basis, then carrying enough fuel to get to a Lagrange point and refuelling there may well make sense.
Particularly if you can launch fuel there from the moon instead of Earth (e.g. extracted from lunar water).

One possibility would be to fly to the Lagrange point, pick up fuel for landing, then refuel again from lunar water and offload the fuel you don't need at the Lagrange point on the way back. The downside is that if you get to the depot from Earth and can't refuel for some reason, then you die unless someone can rescue you quickly.

Would that be ....

[arthurpaliden]

Self Serve or Manned ?

Re:Would that be ....

[unjedai]

Since it's not in Oregon, it'd be Self Serve.

Re:Would that be ....

[arthurpaliden]

Not being from that state or even the USA I never understood why that is? Safety or votes I mean jobs.....

Re:Sounds Inefficient at best

[jellomizer]

Well even for 1 way trips. It will be better then putting all the fuel on one ship, where the weight of the fuel needs more fuel to keep the ship going fast enough for people. You can take these station years in advanced and get them to slingshot around planets until they are fast enough to match your fast flying ship which will stop by and refill at the same speed the station is moving. Then you can go on accelerating or deceleration after you filled up.

"Gas station". Not "gas" station.

[Anonymous Coward]

(Unless the proposed orbiting fuel depot is actually a"fuel" depot. )

economics

[PastaLover]

I don't think I quite get how this is more economical. Is it actually cheaper to send up a bunch of smaller rockets with fuel as payload than it is to simply send a bigger rocket with enough fuel on it? Can somebody walk us through the math?

Re:economics

[Arlet]

Overall it should be the same. Sending the fuel first still requires the same total take-off mass as sending the fuel with the ship.

The advantage is in the logistics. You can send the fuel ahead of time, using a slow trajectory, and then launch your main ship on a faster trajectory. Or, when the fuel rocket fails, you can send another one before sending your main mission.

Re:economics

[0123456]

Is it actually cheaper to send up a bunch of smaller rockets with fuel as payload than it is to simply send a bigger rocket with enough fuel on it?

Yes.

Flight rate is generally more important to launch costs than size. A small rocket you can fly a thousand times a year will cost you far less than a big one you fly once a year simply because you can mass produce them and reuse them several times before you throw them away, rather than custom-building a new one every time you launch it.

If I remember correctly, the plans for reusing Saturn V stages made no financial sense until it was flying about once a month, for example; at NASA's actual launch rates the savings from reusing them would be less than the costs of developing the technology to do so.

A further issue is that by splitting your hardware and fuel across multiple launches, one exploding rocket doesn't lose your entire multi-billion dollar Mars mission. A near guarantee of losing one payload out of a hundred launches is likely to be better than a 1% chance of losing the entire thing.

Re:economics

[AGMW]

You can send a bunch of cheap(er) unmanned rockets with fuel as the payload and store it in orbit, then you can send a more expensive (reliable) manned craft with the crew. Money and risk reduced.

Better yet, if we're looking at Mars - why not send a bunch of comms- and GPS-style satellites and get them in orbit so when we get there we've got good location and comms stuff all sorted. Send a copy of the ISS there too, but this time as the base to drop people to the surface and drop off place for supply vessels from Earth (food, fuel, etc).

Re:economics

[Nethemas the Great]

Humans are an expensive pain the arse to launch. The smaller their vehicle, the cheaper, and safer they become. Non-human payloads do not require the safety (nor life support) of a human rated vehicle. This makes them significantly cheaper. The expense of a rocket grows exponentially the larger you make them. Smaller rockets are also easier to mass-produce.

Re:economics

[0123456]

Non-human payloads do not require the safety (nor life support) of a human rated vehicle. This makes them significantly cheaper.

Except the 'human-rated' shuttle has not proven to be significantly safer than a typical not-human-rated launcher (i.e. around a 95-98% chance of not catastropically failing).

'Human rating' is a mostly bogus concept, though I'd agree that if you're just launching fuel then you might be willing to live with a less reliable launcher if that significantly reduced costs. If you're launching a billion dollar comsat, you don't want to put it on something that you wouldn't risk putting NASA astronauts on.

Re:economics

[FleaPlus]

I don't think I quite get how this is more economical. Is it actually cheaper to send up a bunch of smaller rockets with fuel as payload than it is to simply send a bigger rocket with enough fuel on it? Can somebody walk us through the math?

Absolutely. Remember that development costs tend to be very important when it comes to rockets. For example, the recently-cancelled heavy-lift Ares V rocket NASA was building was projected to cost at least $32B to develop (ignoring operations costs). This was for a rocket with 188mt capacity. By comparison, SpaceX recently announced a smaller rocket (53mt capacity) which will launch at $100M/flight starting in 2013. Instead of spending $32B to develop a bigger 188mt rocket, NASA could instead spend that money to launch fuel and payloads on 320 Falcon Heavies (16,960mt total payload). This of course ignores the greater economics of scale that could be obtained if you were launching a rocket that many times.

In an optimistic scenario, the Ares V would launch once or twice per year. If you assumed that the Ares V launched twice per year and was completely free to operate (which is false, as it actually would've cost billions more to operate), it would take 45 years before the Ares V would have launched more payload than you could've launched spending the same money on Falcon Heavies.

Re:economics

[khallow]

This is true for fuel, but not for hardware. If the rocket carrying your life support system blows up, you need to build a new one. The only way to have redundancy in hardware is to build two of every component.

No reason to have only one mission. Having multiple copies of everything should be SOP.

How big

[SnarfQuest]

How big does this "gas station" have to be to raise enough Chickens for a Mars mission?

And how much corn will they have to raise to generate the ethanol required to boost enough bugs to thestation to feed all those chickens?

can anyone say...

[rilian4]

Starbase? Captain's Log, Stardate 2054.6. Visited orbiting refueling station on the way to a planned stop at Mars. The attendant did a horrible job on the windshield. Can't see a damn thing...I need better service station attendants. Mr. Spock, windshield status?....

You need propellant to lift the propellant

[starglider29a]

Disclaimer: degreed rocket scientist without time to do the math.

Rather than

1. lift a surplus of propellant to a gas station
2. have the Mars mission lift with just enough energy to park at L5, Phobos or whereever,
3. refuel and thrust away to mars... Instead:
4. launch the required propellant on nearly the same trajectory as the mission, once trajectory confirmed...
5. Launch the Mars mission with enough energy to travel to Mars
6. Rendezvous on the long trip, refuel, carry on

Advantages: putting the heavy lifting on the booster on Earth (where logistics is easier), don't waste energy stopping/pausing and restarting the trajectory.
Disadvantages: You better be sure you can refuel in flight.

Re:You need propellant to lift the propellant

[khallow]

Disadvantages: You better be sure you can refuel in flight.

Among other things that means you may need to launch extra propellant, just in case. I think that alone would negate the slight propellant savings from bypassing LEO and going directly to Mars.

The primary advantage of LEO assembly is that you don't have to go beyond LEO until everything is in place and works. Even a crew lost during a launch failure can be replaced. The scheme also has much easier and more forgiving logistics. You don't have to launch from Earth to hit a small launch window to a particular trajectory (with all the payloads launched relatively close to each other) to Mars, but a much more forgiving orbit in which it is very easy to move things around. Finally, delta v is as low as you can get. So you can use a wider variety of launch vehicles and spacecraft to get there and put things together.

Re:Makes sense...not politically sexy...won't happ

[Anonymous Coward]

Why are they still thinking about chemical fuel? They should be thinking about Ion propulsion with a fission reactor as the power source.

Compartmentalized fuel delivery

[CrowdedBrainzzzsand9]

Perhaps the delivery mechanism for refueling stations can be compartmentalized in a standardized way. Near-space heavy lifters could assign uncommitted cargo space to fuel "packets" that can be tugged later to the fuel stations by other craft.

Re:Makes sense...not politically sexy...won't happ

[0123456]

Why are they still thinking about chemical fuel? They should be thinking about Ion propulsion with a fission reactor as the power source.

They should, but a fission reactor uses EVIL ATOMS, which might cause cancer in space aliens.

This is why killing Ares was smart

[Anonymous Coward]

This is the kind of capability development that is appropriate for a space agency to do.* The lack of orbital refueling capability limits all missions to what we can lift in a single payload. Developing the capability won't be easy or cheap, but with the capability in hand lots of other mission possibilities will be unlocked - for both public ventures and for private enterprises. It's a *much* better way to spend a limited budget than developing a new booster would have been.

Next up: Automated in-orbit assembly.

[*: Assuming it's a space exploration agency, and not a glorified jobs program.]

Only sane concept for ALL consumables...

[trims]

If we ever plan to go to Mars (or other extra-Earth area destination), we need to ship the vast majority of consumables ahead of time. In essence, we need KwikiMart outlets in space.

More to the point: consumables and human space travel have very different criteria: Consumables:

• Can sustain much higher G forces, which means they have a much higher list of launch and propulsion options available
• Most (excepting food) have a much higher tolerance for radiation and acceptable temperature ranges.
• Don't really need to consume much of anything on their own - they tend to be inert, and need very little (or no) upkeep.

Honestly, if we expect to get somewhere, we need to be throwing out these large blobs of food/fuel/equipment in minimal containment vessels, with cheap, slow propulsion systems (i.e. very low mass/thrust ratio). Scatter a dozen along the path to Mars, and a dozen in Mars orbit, launching stuff a year or more before the humans plan to go. Then just build a SMALL crew vessel, with just enough storage space to get it between pit stops along the way, but with kick-ass engines.

Manned vessels are expensive. Make them just big enough for the humans. Put the consumables in the space equivalent of a refrigerator, and let the human vessel dock with the frig every week or so to pick up supplies.

ObCarAnalogy: build a race car and make frequent pit stops. Don't build a Semi with sleeper cab, 1,000L gas tanks, and a double trailer filled with food.

-Erik

Re:Only sane concept for ALL consumables...

[aztektum]

Interesting. Surely there are asteroids large enough to setup permanent or semi-permanent waypoints on, between here and Mars?

A network of bases that could be utilized in emergencies or act as refuel points, so you don't have to launch a vehicle from Earth with the whole load, is an interesting idea.

Of course I'm sure NASA the ESA and others have considered this. I mean if I have, all those large brains surely have too. Yet everything I have read indicates the plan in general is to go straight there.

Transforming Solar power into propellant

[whitedsepdivine]

If somehow they could use solar power to create energy usable by the ship. First you wouldn't need to re-fill the station ever. Second, you could have less weight on the ship to not have such transforming components. I would image these stations will be the most rarely visited gas stations created by man. So you would have a long time between visits to transform the solar power into another energy source.

Re:Transforming Solar power into propellant

[wagnerrp]

How do you propose they create propellant from solar power? You collect energy (light) from the Sun, and transform it to matter using some as yet unknown nuclear mechanism? You can't do that with light, but you could do that with solar wind. Create a giant collection station, with a surface area of hundreds of square kilometers, and shove it at the L4/5 point. The dynamic stability at those points would ensure a space craft would maintain station on its own. With complete capture, you're looking at maybe 20ug/s/km^2. Each square kilometer would capture all of around half a kilogram of protons and electrons per year. That's simply not a consequential amount to be used as a reaction mass in any contemporary engine. You would be better off trying to gather the dust that collects at the L4 and L5 points, or even better capturing nearby asteroids.

if you thought gas prices here were bad

[Cyko_01]

just imagine the cost of filling up in space! (especially since they would have a monopoly on space gas)

The B-52 was a beehive hairdo

[PolygamousRanchKid]

In WWII, the US was building up a fuel store by fueling up B52s

Yes, it maintained a lot of "fuel" to keep those up standing.

and flying them across the Himalayas.

Well, I hope that they didn't break any fingernails, when the pilots tossed them out of the planes . . . Himalayas . . . um, did they have sleds along with the parachutes . . . ?

Re:Van Allen Belts

[Relic of the Future]

Before anyone takes anything an AC says seriously: the Van Allen belts extend up to about 50,000km, while the moon is over 350,000km away. And we've sent humans to the moon.

Re:Van Allen Belts

[tpjunkie]

You mean apart from every Apollo mission that went translunar?

Self serve of full service

[sxmjmae]

Would they be Self Serve 'Gas' Station or would it include full service?

Fuel at Mars

[bobs666]

One of the plans for the mission to Mars is to make the fuel on Mars, from the soil there. The chemistry has been tested on earth. The original plan was to put men on Mars and make the return fuel then, while some 300-500 days pass while the earth comes back around for the return fight window.

Given robots go first and make fuel why not lift it with to a space station for refueling. This way we get the fuel on sight, out of the gravity well. This fuel can be used for landing, blastoff and return. Getting the mass of the fuel, on site and all set up, before we commit people to the flight. This is simply good economy, and safety.

Re:Fuel at Mars

[Runaway1956]

Salutes, bobs666. I get so frustrated with people who want to use robots for space exploration INSTEAD OF men. But, my own prejudices have blinded me a little. Of course it makes sense to automate something like this with robots, to save time and expense for the humans who follow. And, further, robots should be used for initial attempts to explore, just as we have already done on Mars. There is nothing wrong with using robots at all. But, when the robots have prepared the way, I most certainly want to see men putting their boots on the ground! And women, of course. There's not much pont in going to space if there are no women along for the ride!

Re:Fuel at Mars

[jafo]

Hey, thanks to those of you who actually found a point in my post instead of jumping all over the fact that I know absolutely nothing about airplanes. :-)

Apollo Missions

[g0bshiTe]

Did any of the manned missions to the moon require refueling during flight?
Why would we need a refueling station for moon trips now?

Re:Apollo Missions

[CrimsonAvenger]

Did any of the manned missions to the moon require refueling during flight?
Why would we need a refueling station for moon trips now?

To move larger payloads to the moon?

Saturn V was barely up to putting three men and a lander into a earth-moon orbit. If we want to lift something larger than that, we might want to use a dozen Saturn V (or equivalent vehicles) to boost 1000+ tons of fuel to earth orbit, then use one more to put a 200 or so ton spacecraft into Earth orbit, refuel, and off we go to the moon...

Re:Apollo Missions

[Nyeerrmm]

Because Apollo depending on funding that isn't likely to happen now. Once the geopolitical goals were achieved, that money could be better spent other places.

If we want a sustainable program for human expansion into space, things like this will be necessary.

Re:Apollo Missions

[Nyeerrmm]

Depended, not depending. Sorry.

Re:Makes sense...not politically sexy...won't happ

[FleaPlus]

Actually, not only is it not politically sexy, but it's outright politically dangerous. Having fuel depots allows you to use existing rockets for exploration beyond low-Earth orbit, alleviating the need to develop heavy-lift rockets. A number of politically-powerful congressional districts (and congressmen) are heavily banked on NASA building a heavy-lift rocket from Shuttle-legacy components, while that isn't the case for fuel depots. I predict it won't be long before this particular effort is squashed by Congress, perhaps even outright banning it like they did with the TransHab inflatable modules.

Make fuel modular and disposable

[DaveAtFraud]

Make a modular system that includes both a "unit" of fuel and the engine. Strap as many modules on the back of a crew/payload compartment as you need to accomplish the delta-Vs for the mission. Depending on mission, set up the used modules to burn up the atmosphere/hit the moon/end up some place where they don't become problematic space junk (i.e., don't quite use all of the fuel). Crew/payload compartment stays in orbit and gets re-used. Hire commercial space travel company to get people or equipment to/from the crew/payload compartment when parked in LEO (yeah, I know they only do sub-orbital/ballistic now) . Only use heavy lift rockets (or some future, better technology) to lift the fuel modules.

Engineering exercise to determine whether to include the engine with the fuel module and make it disposable too or have a "permanent" engine. My guess is disposable engines will work better since the lifetime and duty cycle are well defined. Using lots of standard fuel modules means they can be mass produced with economies of scale so they're relatively cheap. All other components are reusable.

Cheers,
Dave

Humans are not fit for space travel ...

[zensonic]

http://en.wikipedia.org/wiki/Interstellar_travel

... thus, the money is better spent on other space technology.

http://en.wikipedia.org/wiki/Faster_than_light

do a fuel demo, then we can talk business

[k6mfw]

Over the past decades there have been lots of papers about fuel, transfer of fuel, fuel needed, etc. I'd like to see a large scale demo of fuel transfer. Not some little demo on ISS but something of "man size" magnitude. It looks like this is a good project, I always wanted to try it myself but I just never had enough money.

First objective is launch both at (or close to) same time, and get them to dock. Second, demonstrate transfer of fuel. They do it here on earth but doing it on large scale in space? Pros and cons of cryogenic fuels vs. hypergolic (i.e. hydrazine) fuels.

Then third objective is send that spacecraft beyond LEO, not GEO but a huge distance to show means of actuallly going somewhere. Yes, it will take fuel to get the fuel to orbit but will this increase BEO capability beyond Voyager/Cassini size spacecraft? Will it enable faster Mars transit time? Will it violate the laws of physics (i.e. Rocket Equation)? What will probably shoot this thing down is the money, which is all what we scream about these days.

They are looking for $200M to demo (why cryogenic only? maybe start with this and work on others later). If this shows promise then maybe we'll finally get somewhere.

I say forget trying a HLV, that is a political non-starter. Medium launchers and fuel transfer is needed if want humans beyond earth orbit. Forget trying to build a 130t launcher, the money will never be allocated and if it does it may be yanked next year or soon after. Look how much bitching over SLS, by the time they agree we will all be dead of old age!

This method was one of the modes for Apollo but it was a significant challenge to be sure both rockets will launch (if one can't make it, then the second one is useless). If delay in one, you don't want to be hanging out in LEO for an unknown amount of time, probably can but that will lead to other issues to deal with. They agreed with John Houbolt and went LOR.

H2O is fuel

[bobs666]

Good one! The moon has water.

More over Mars has a CO2 atmosphere. Also on Mars is Magnesium that will burn in a CO2 atmosphere. You move CO2 and processed Metals that will burn in the presence of CO2 in to orbit. And you have a refueling station.

Given robots go first and make fuel lift it with to a space station for refueling. This way we get the fuel on sight, out of the gravity well. This fuel can be used for landing, blastoff and return. Getting the mass of the fuel, on site and all set up, before we commit people to the flight. This is simply good economy, and safety.

Why not stock Argon instead

[fritsd]

Why not Argon instead of Hydrogen and Oxygen?

Seriously, Hydrogen and Oxygen refueling sounds like they want to push the resulting water molecules out the back of the rocket with a standard rocket-fuel-burning momentum.

But what happened to that Colombian company's idea of the VASIMR drive; they were ready to test one out in space, on the ISS, but there are only 2 shuttle missions left and I haven't heard of a mission carrying that drive.

Basically it would work like a giant microwave that accelerates Argon atoms to much higher speeds than a normal rocket, more like a Xenon ion drive, but cheaper.

Can anyone comment as to whether this idea was shelved and why? Does it have problems, does it not work? Or is it because of politics

Argon is a bit uncommon but hardly as rare as Xenon.

Re:Why not stock Argon instead

[Nyeerrmm]

VASIMR is still in development (and its being developed by an American company, Ad Astra, which was founded by an American astronaut of Costa Rican origin). I believe there is a demo going to the ISS in 2014 for station-keeping.

The reason to look at doing this with traditional chemical rockets is that its the hardest case (so transferring the techniques to something inert like xenon or argon would be straightforward), and it also doesn't make the entire effort dependent on VASIMR being proven. It's been talked about for many years, so though I wouldn't call it vaporware, its not something you put on your critical path.

Multiple paths that may be combined in interesting ways is the ideal way to do this kind of long-term tech development.

Wonder what the price per liter / gallon is...

[sp4ni3l]

And we are complaining about gasprices down here, wonder if my creditcard will max out to fill up?

Re:Makes sense...not politically sexy...won't happ

[Cold hard reality]

They thought about it, and it turned out that ion engines and fission reactors have horrible thrust/mass ratios which would mean trips would take a very long time, though they would use a lot less fuel like chemical rockets.

If you can increase an ion thruster's thrust by quite a lot, and downsize a fission reactor by quite a lot, we can talk again.

Re:Makes sense...not politically sexy...won't happ

[Degro]

Are you saying congressional districts have a ceiling?

Expensive Gas!

[DarthVain]

Ha and you though gas was expensive at the pumps last weekend? Just wait till you see what this costs!

What... transporters, then?

[macraig]

What do you suggest, then, to actually get the spare fuel to each of the depots? How do you propose to do that without expending fuel to get there with it in the first place? Can you build us a big stargate? But wait... ooops, how will you get the destination stargate there in the first place? That would require fuel! Maybe you have an insanely long-range quantum transporter in your closet/basement?

There are certainly legions of people who don't watch|read enough, but maybe you've been watching too much science fiction?

Re:What... transporters, then?

[Dr Max]

gotta burn fuel to run a gas station.

ich bin spacenutter

[Thud457]

Screw this "gas station in space" concept, I want a refinery in space.
SPSS + particle accelerator = antimatter.
hell, a electrodynamic tether generator might be worth trying, too.
And it's probably going to be easier to store that antimatter up there in space to boot.
Then we can start going places fast(er).

Re:How does a spacecraft on a trajectory dock?

[rossdee]

You buy a docking computer, and it plays Blue Danube while it guides you in to the rotating landing bay.

Venerable concept

[Opyros]

This is actually one of the oldest ideas in space flight theory; the very concept of a space station arose out of it. As Arthur C. Clarke wrote in Interplanetary Flight (1950):

From the conception of spaceships circling a planet for reconnaissance or refuelling, it was a natural step to consider the possibility of permanent orbital structures—"space stations"—and although this subject is perhaps subsidiary to the main theme of astronautics, it opens up so many important and stimulating prospects that it merits careful study. The idea of space stations was originated, like a good many other things, by Oberth, but was developed in great detail by two Austrian engineers, Captain Potocnik and Count von Pirquet. As first conceived, the space station was regarded largely as a refuelling depot for spaceships on their way to the planets, but it was soon realized that it would perform many other valuable functions.

Very Bad Article

[stevelinton]

The article is very misleadingly written, and the whole "gas stations" idea is misleading.

Think of something more like mid-air refueling.

The sort of mission they are considering might include launching two or three big boosters, one with the real payload and the rest with fuel.
Then transfer the spare fuel to the uppser stage of the booster with the real payload and it has enough fuel for the transfer to a Lunar or Mars transfer orbit (and maybe for orbital insertion at the other end and even the return transfer.

Once you can do that, and assuming you can keep the fuel stable for long enough, you can play the same game again in lunar or Mars orbit.

Bussard Ramjet?

[cashman73]

What about a device kind of like a Bussard Ramjet? Park it out in orbit, or at a Lagrange point, let it collect hydrogen from the solar wind. This could then be compressed and stored, and distributed to whomever stopped by and needed fuel. Or some of it could be used if you needed to make minor course corrections.

What sort of energy can you mine in space?

[AttillaTheNun]

Remote stores of renewable energy is an ideal solution, but what are the possibilities in space? Solar energy is plentiful, at least within the inner planets. Conversion to electricity via solar panels is one possibility, but it seems energy storage is the primary issue. What forms of storage (other than chemical batteries which are expensive due to their weight and relatively short lifespan) are possible without depending on elements that are not readily available in space?

I would be more worried about ....

[WindBourne]

space herpes.

Actually, they need to refocus

[WindBourne]

They need a pluggable TUG approach. Seriously. Climbing out of the gravity well is good for chemicals. But once out of here, we should use a NERVA or other tug to move around. Likewise, in the well, for cargo, we can use either vasimr or a tether. The point is, that there will be no single gas station. HOWEVER, if we have multiple tugs and each can plug in and unplug, then all is good.

Getting to Mars how the USSR got to the Moon

[damburger]

NASA has been told by the president to build heavy life (i.e. Ares V) rockets to facilitate a NEA/Mars mission.

Now someone at the agency has said "screw heavy lift, we are going to assemble our mission in space" directly contradicting the supposed path.

To get people on this Mars mission, the US government is paying for the development of more than one manned capsule, to be launched on more than one rocket.

Its just like the bickering design bureaus that kept the Soviets from mounting a serious challenge to the Apollo programme. The Chinese thank you for giving them a perfect opportunity to catch up and overtake.

In Space. On Trial. Guilty. Of being in space.

[FatLittleMonkey]

Portal 2. Link to