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Boeing's "original" Space Gas Station

Posted by: gaetanomarano - Fri Oct 26, 2007 1:27 pm
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Boeing's "original" Space Gas Station 
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Post    Posted on: Wed Oct 31, 2007 9:28 pm
I want to throw in something to consider: Before and during the first phase of ISS building many in the US saw the assembling work as too much. They preferred less flights and larger (pre-installed) modules.

That's one of the main reasons they chose the heavy-lift launcher Ares V, so that they can avoid a lot of assembling in orbit. This was also done in perspective of Mars flights where an Ares V can put a Mars spacecraft with 4, 5 flights into orbit.

So I see the problem for such a fuel depot in convincing the officials in the US.

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Post    Posted on: Thu Nov 01, 2007 1:27 am
Ekkehard Augustin wrote:
The interest of NASA in depots can be seen by:


I'm SURE that NASA is very interested in fuel depots and ALL new tecgnologies, propulsion engines, new propellents, alternative architectures, etc. but the 20+ years long ESAS plan has nothing new since it's 99% close to an "updated Apollo project"

NASA is like the cars' companies that develop incredible concept-cars (with fuel-cells, hydrogen, electric motors, etc.) but actually build (and WILL build) 99.99% of cars that works with gasoline... :)

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Post    Posted on: Thu Nov 01, 2007 7:31 am
Hello, gaetanomarano,

there is a particular thread about ESAS in this section (Technology) please talk about links between such depots and ESAS in that post because that other thread is the most proper for it.

In THIS THREAD HERE you started - which is very positive - the discussion needs to be kept concentrated on the depot-technology itself. How it will work, docking to it, security, ways or chances to increase the capacity, extending to more different kinds of propellants, accessability and so on.



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(And I do NOT agree to your last post...)


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Post    Posted on: Thu Nov 01, 2007 8:51 am
I think it unwise to change ESAS to much at the moment. An orbital fuel depot would mean major changes in how ESAS would work and I think that if NASA constantly changes what it is proposing to do the US government and public will become so frustrated with them that the whole thing will be cancelled. This is especially true given there is a presidential election coming soon, if things are constantly changed so that prior work is discarded then not enough progress will have been made and it will be easier to cancel by the next president.

I agree that there are a lot of plus sides to having an orbital fuel station but I dont think ESAS should be changed to accommodate one.

As for Boeing building a private one, not a hope in hell. No way are they going to commit the money and resources necessary without at least some form of contract or long term commitment to buy the service. There isn't a market for this at the moment and until someone actually builds and flies a spacecraft designed to be refueled in orbit this will stay a PPT presentation.

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Post    Posted on: Thu Nov 01, 2007 9:04 am
Hello, Andy Hill,

regardless of what gaetanomarano, you or I myself think about links or connections to ESAS let's discuss the depots in this thread here like spacedocks, space assembly yards etc. are discussed in the threads about them.

From my personal point of view and in comparison to what I remember there is far too much emotion and personal interest involved in this thread up to now which is no way positive for the topic itself. There is an ESAS-thread and impcts of Boeings concept and ideas on ESAS should be discussed in that thread to keep emotions off of the discussion about the depot-technology itself.

The ESAS-thread is VSE and ESAS - their nature: Visions? Projects? Studies?...



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Post    Posted on: Fri Nov 16, 2007 11:46 am
Depots like that Boeing propsed may have another interesting advantage also.

I remember having read of a conference on space debris - I am looking for the article - ehere several measures have been discussed to keep the amount of orbital debris from growing.

One of the measures was preventing rockets from exploding. It was claimed that rocket stages should pump off remaining fuel into space.

Under this aspect it would be interesting to let such stages fly to the fuelk depot and pump off their remaining fuel into the depot - LH2 as well as LOX as well as all other propellants like NTO, ADMH and so on.

This way waste of propellant would be avaoided and a bit less transportations from Earth would be required.

...
...
...



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Post    Posted on: Fri Nov 16, 2007 12:14 pm
Ekkehard Augustin wrote:
Under this aspect it would be interesting to let such stages fly to the fuelk depot and pump off their remaining fuel into the depot - LH2 as well as LOX as well as all other propellants like NTO, ADMH and so on.


I think it highly unlikely that spent stages would have enough fuel to make it to a fuel depot. Launch companies would not want to add the extra complexity and weight involved with allowing an orbital fuel transfer when the amount of fuel involved is so small.

A depot able to move from about collecting fuel might be more feasible but even this would probably use more fuel than it would collect and you would stll need some form of docking adaptor on all stages visited.

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Post    Posted on: Fri Nov 16, 2007 1:27 pm
I am thinking under the aspect of technical or technological possiblity here.

Obviously the participants of the conference I am speaking of have data saying that rocket stages usually contain surplus propellant. A small portion of that might be sufficient to letv the rocket slowly approach a propellant depot. If that lasts years I have no problem with it if the rocket doesn't explode during that time. The latest date the rocket must be expected to explode at can be used for calculating the velocity required.

I have read of stages containing surplus propellant even after years yet.

I consider it also NOT to be required that the launch companies add extra fuel - it will be sufficient if companies operating the fuel depot provide particular vehicles that dock to the spent stages, extract the propellant and return to the depot to pump the surplus propellants into the depot.

To get the surplus out of the spent stages should be not that large a problem - this year - or was it last year? NASA was forced one time to pump fuel off the External Tank of the Space Shuttle and they managed to do it. It seems to have been no problem for them. The experiment on refuelling a satellite DARPA has flown also was a success.

The vehicles going from the depot to the spent stage and back can be very small in comparison to the rocket and might consume very small amounts of different propellants as well as they might have quite other engines - like that of Ad Astra for example.



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Post    Posted on: Fri Nov 16, 2007 5:07 pm
I would guess the best use for residual propellant is to minimize the orbit life of the spent stage. This might be achieved at little cost by venting through a thruster in an appropriate direction, especially with cryogenic propellants. Passive means of enhancing solar heating might be used. The aim would be to minimize the perigee, ideally to less than 200km, bringing it within the high-drag regime.


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Post    Posted on: Sat Nov 17, 2007 9:51 am
Hello, xiphius,

spent stages and other larger objects should be kept in space in an easyly accessable parking orbit much rather then burnt up in the atmosphere.

This has been discussed in other threads already. The objects have been put in space at high expenses not only but also are existing technology available in space.

Consequently each one who gets to such an object can apply it as a part of a future spacecraft kept in orbit throughout its whole lifetime- This will be enabled by reusable vehicles like SpaceX's Dragon and the Falcon 9, by t/Space's CXV, the QuickReach2 and the VLA, SpaceDev's Dreamchaser and its boosters in their orbital versions and similar vehicles once at least one of them is available.

The objects already in space will have to be refurbished and repaired to some degree -but the reduction of launch costs by reusability will be that large that it can become economical - more than 90% of the launch costs of expendable rockets are the expendable hardware. So the reduction of launch costs will tend to be 90%. These 90% then are available to be spent alternatively for getting to, repair und refurbishments of und refuelling of the objects already in space I am focussing on at present.

Because of all this - and even more aspects - it will be worth the time to find out how much propellants are left in the tanks of each of all the objects already in space and earliest then to decide about carrying the amounts to an orbital propellant depot by small compact vehicles the tanks of which can be much smaller than those of the spent stages.



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Post    Posted on: Sat Nov 17, 2007 6:31 pm
Hi Ekkehard

You appear to be saying that it is worth using future cheap launches to reuse old upper stages because they were expensive to launch? Cheap, reusable launchers makes 'salvage' missions easier, but at the same time it undermines the case for doing them. In most cases it will be like finding a button and having a coat made to match.


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Post    Posted on: Sat Nov 17, 2007 10:24 pm
A space tug which could scavenge residual propellants for its own use, as opportunities presented themselves en route from one job to another, or during idle time, I would find more credible. Proactively collecting it all into one repository is ... idealistic.


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Post    Posted on: Sun Nov 18, 2007 1:39 pm
Hello, xiphus,

there would be no undermining.

The chep launches still and allways would be required to get to the stages already in space. Salvage missions simply will reestablish controll over them while kept in space.

Because of this the cheap launches still will be required to transport payloads into space that then will be transparted to other destinations by the salvaged stages. Those destinations may be the Moon, other planets and regions of the solar system or even other orbits the launching rockets then don't need to go to.

The salvaged stages wouldn't be brought back down to Earth but kept in orbit.

If this can be done an economical or even profitable way depends on the economics - these aren't considered yet, by far not sufficiently at least.



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Post    Posted on: Sun Nov 18, 2007 2:56 pm
Hi Ekkehard

I had already understood the points you raise, my point was that any scheme to reuse a spent upper stage has to compete with the alternative of launching a new one. Both approaches benefit from falling launch costs, so the availability of cheap launches does not of itself strengthen the case for 'in situ reuse' ( a more correct term than 'salvage', I admit).

Believe me, I am sympathetic to your argument and used to subscribe to it, but experiences in (admittedly more mundane) industry has opened my eyes to the seductive appeal of 'rescuing value' which is being 'wasted'. You can easily find yourself drawn in to making a lot of effort for little or no reward.

You are right to say the economics have to be examined, but I don't think they are promising compared with, for example, refuelling geostationary satellites, retired when they run out of station-keeping propellant. I believe there are companies already addressing that.


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Post    Posted on: Sun Nov 18, 2007 5:44 pm
xiphius wrote:
experiences in (admittedly more mundane) industry has opened my eyes to the seductive appeal of 'rescuing value' which is being 'wasted'. You can easily find yourself drawn in to making a lot of effort for little or no reward.
Well said!


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