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Tankers and/or delivery of propellant into orbit

Posted by: Ekkehard Augustin - Sun Sep 18, 2005 8:04 am
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Tankers and/or delivery of propellant into orbit 
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Post Tankers and/or delivery of propellant into orbit   Posted on: Sun Sep 18, 2005 8:04 am
t/Space's CEV-concept included tankers which would have had to be constructed by Scaled Composites and launched by their concept and vehicles.

The main economic problem of this way would have been the consumption of propellant simply to deliver propellant into the orbit. May be that it is not that diadvantageous but it makes me thinking and doubting about it repeatedly - and I allways end up with thinking about a different way of delivery.

As far as I know the russian Progress vehicle among other cargo delivers propellant to the ISS. But the Prgreess isn't reusable.

So it may be interesting to develop a cargo vehicle which can be used to deliver quickly and at high rate small amounts of propellant together with other cargo into orbit - to service another vehicle waiting there for departure for the moon or - later - Mars and other planets.

Non-propellant-cargo will have to be delivered very often I suppose - to the ISS, to the future Nuatilus and Cargo to be delivered to the moon.

What optimizations are possible or required to enable increased piggypack delivery of propellant?



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Post    Posted on: Wed Sep 21, 2005 2:09 pm
Another idea baout propellant-delivery into orbit - what about delivering the propellant in bound form?

Fro example as far as I know huge amounts of oxygen are bound in the dusts of the earthian deserts. If it is possible to break the oxygen off these dusts it might be a solution to deliver the dust into orbit and store it there. When oxygen is needed as propellant the dust the oxygen could be broken off the dust and be used as propellant.

What's left after the oxygen us broken off could be delivered back to Earth - since it was fertile soil before becoming dust in which oxygen is bound it might be fertile earthian soil again and thus the desertification of the soil would be removed.

How long does it last until the oxygen would be broken off?



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BTW: This would increase the advantages of reusable vehicles or stages - they could deliver back the oxygen-free soil instead of going back empty.


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Post    Posted on: Wed Sep 21, 2005 9:08 pm
Why send dust when you could just send water and use solar power to break it down into Oxygen and Hydrogen and not have to worry about sending anything back down from orbit?

I dont know whether this would be any more efficient than just sending the Oxygen and Hydrogen already split but at least you wouldn't have to worry about the cargo exploding during launch.

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Post    Posted on: Thu Sep 22, 2005 2:07 am
Yeah, the oxygen in desert sand is stored in silicate minerals which are well-nigh impossible to break down. Andy's right, you'd be better of shipping water and solar cells. If you could use a DSS-ATO to heavy-lift the cargo, that would be very good; the ATO ought to be able to put many tons up cheaply. I don't know if it would be practical, but you could also use a giant gun or railgun of some sort to shoot the proppelants most or all of the way to orbit.


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Post    Posted on: Thu Sep 22, 2005 7:52 am
The dust was an example only. I choosed this example because I remember a post arguing againts stroing LOX in orbit because it has - according to that post - the tendency to difund otu of the tank or store into space.

Another argument to be read in another post was the danger of explosion and that it has to be and kept cooled down. This would be avoided in the case of the dust.

The next aspect is that there is Centennial Challenges Prize set by NASA for a technology to get the oxygen out of the lunar Regolith. If such a technology is successfully invented one day then it should be able to break off oxygen from earthian Regolith too and then there is the chance to do that with desertian dusts also.

Another reason to chosse dust of deserts as example is that it doesn't require pressurizing and cryogenic - this would avoid the consumption of store of the carrier for this equipment.

And last but not least the chance to deliver back to Earth fertile soild which is lef over after the oxygen has been broken off may attract the interest of farmers and countries in deserts. This interest could help finance space activities.

NASA has in mind to use oxygen and methane to propell the future lunar lander which would mean that they don't need hydrogen - so why trying to get hydrogen from water?

To send something back down from orbit is no worry in my eyes - in the example I choosed it is a benefit, a revenue: something of no use is sent up and broken off into two components one is of use in orbit - propellant for vehicle leaving into the interplanetary space for example - while the other is of use down on Earth - fertile soil to grow grain by.



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By-comment: It would be an important and need positive progress if in orbit things, products, commodities would be created or produced which are of use down here on Earth and which for this reason would be sent down here. This has to do with the Public-Perception-section and the thoughts about orbital industries


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Post    Posted on: Thu Sep 22, 2005 4:11 pm
Ekkehard Augustin wrote:
And last but not least the chance to deliver back to Earth fertile soild which is lef over after the oxygen has been broken off may attract the interest of farmers and countries in deserts. This interest could help finance space activities.

NASA has in mind to use oxygen and methane to propell the future lunar lander which would mean that they don't need hydrogen - so why trying to get hydrogen from water?

To send something back down from orbit is no worry in my eyes - in the example I choosed it is a benefit, a revenue: something of no use is sent up and broken off into two components one is of use in orbit - propellant for vehicle leaving into the interplanetary space for example - while the other is of use down on Earth - fertile soil to grow grain by.


It must be cheaper and easier to do the processing on Earth and only send into orbit what you need. Then the by-product furtile soil is where you are going to use it (no or minimum transport costs).

The lunar lander uses methane but I thought the trans-orbital stage uses a shuttle engine for thrust. If that is the case you could refuel this stage and make a number of ferry trips rather than launching a new stage each time, just dock your CEV and launch a new lunar lander (you could use the weight saving from using the same stage to transport extra fuel or water).

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Post    Posted on: Thu Sep 22, 2005 5:42 pm
If it chepaer to do it on Earth depends on several factors. For example that would be correct if the focus would be on production of fertile soil and large amounts would be considered - in that case oxygen would be the by-product which is not the focus on.

But my focus is on delivery of propellant into orbit by small portions - and the fertile soil is the by-product which isn't the focus on. It is created bacause of unavoidable joint production.

To deliver propellant by small portions into orbit could be economically advantegous and interesting because this way large amounts of propellant could be delivered over a long period of time. At the end of that period the amount would be large enough to be used for going to the moon.

The small posrtions would allow to deliver it together with other cargo which NASA, the Russians and others are forced to deliver nonetheless. If there is capacity left then it could be used to deliver propellant.

Doing so over several years could save extra-flights to deliver propellant solely - which would avoid consumption of propellant to deliver proeppllant, it would save ressources too.

To do so no pressurized and crygenic containers should be required.

All this together caused me the dust-example - it all has to do with unavoidable joint production.

If that can be done by alternatives to dust or by non-desert dust, toxic waste of the earthian industry then I am content with it. And there is a factor which may make it cheaper to do so in space instead of on Earth: free available energy of the sun.



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Post    Posted on: Thu Sep 22, 2005 6:46 pm
If the main focus is delivery of propellant, then being able to deliver it in a form where there is no by-product is better because all that is delivered is the fuel so you are not sending stuff into orbit (every kg costs money to launch) which you then return to the earth.

With regard to not needing cryogenic or pressurised containers to transport regolith the same is also true of water which has the additional advantage of being needed anyway for astronauts to survive.

It also probably a much simpler process to turn water into fuel than it would be to do the same with regolith, storage of the propellant once it was extracted would be the same in either case.

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Post    Posted on: Thu Sep 22, 2005 7:47 pm
And for that matter, breaking the water down creates hydrogen, which could easily be reformed into methane using carbon dioxide. Well, come to think of it, it might not be practical in space, but it's easier than the regolith-extraction deal. It would be interesting to learn how long it would take a large solar panel to break down a tank of water, and how fast the H2 and O2 would diffuse. There'd be a tradeoff between using a smaller panel and other equipment (weight savings) with loosing propellant to diffusion or boiling (thus you'd need to send up more water in the first place.)

[Edit: an interesting idea in this article: using asteroids between earth and mars as sources for water for propellant. http://www.msnbc.msn.com/id/9073822/page/4 ]


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Post    Posted on: Fri Sep 23, 2005 7:50 am
Let's leave away all arguments like "cheaper", "costs" or "money" here because their validity depends on the markets. And it would have to include the consideration of opportunity costs and marginal costs - which should be done in the Financial Barriers section if at all (it's a little bit complex and abstract). They are mentioned already unrecognizedly.

What I want to reduce is the consumption of propellant for the delivery of propellant - an alternative would be to get a real non-monetary revenue for such a consumption.

I don't want to insist in the Regolith-breaking idea - but the technology a Centennial Challenges Prize has been set for has to be tested under space conditions anyway because it has to work under the conditions of the moon finally.



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Post    Posted on: Fri Sep 23, 2005 2:57 pm
Well, Ekke, I expect that when Andy says "cheaper" he is speaking in thermodynamic terms, not economic. In other words, what he means when he says "cheaper" is that "it requires less launch energy." And regardless of currency or present economic conditions, energy is the final determinant of the feasibility of any space venture.

Reduced to this context, then, the answers are something like this:

The optimum means for shipping and storing chemically available (i.e. in a relatively combustible form) Oxygen would probably be as Nitrous Oxide (Nitrogen being lighter than the oxides in the metal series which are more frequently used in solid fuels; a similar problem in terms of volatility/combustibility)

If in-situ energy is less of an issue and you just want the atoms, it is really really hard to beat good old water, as nothing is ligher than hydrogen, and water itself has fairly impressive molecular density... so if you have a big solar array or a fission reactor and you have a need to store and transport oxygen, all you need is a really big water bottle.

In terms of fuel, if we assume we want hydrogen (which the vaunted Rocket Equation likes best, of course) then your answers are hydrocarbons and water, respectively.

Look, I know we all want this to work, and to be sure there are great things going on in the industry... but it really is true that the chemistry and propulsion technology has been worked out to ten decimal places for at least 40 years.

Materials, construction, avionics, politics, robotics, finance... all of these fields have room for improvement, but the last time I checked, the top two rows of the Periodic Table (where all good rocket propellants come from) has not changed in over a century.

Goddard burned hydrocarbons and LOX in the first liquid-fueled rocket. It is neither accident nor coincidence that Musk is doing the same.


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Post    Posted on: Fri Sep 23, 2005 5:34 pm
Hello, SawSS1June21,

then it sounds different than before. It would be a kind of real costs perhaps in terms of Economics.

Then it would mean that there is a physicval/chemical/technical optimum of technology and use of technology and an economical optimum of that use. Both these optima could be equal but could be different also.

That's a question I am thinking about since long because of other reasons. I seem to observe sometimes that engineers look fpr the physical etc. optimum and seem not to be interested in the economical optimum. I am looking for the reasons. I suppose the fact to be the reasion that space missions are governmental only up to now. I want to avoid to discuss this in this section but I am looking for economical optimal technologies and use of technologies because private space travel companies are urged and forced to look for the economical optimum. This economical optimum may differ from the physical etc. optimum, it may be economical to do something that is physical suboptimal. This was involved in the discussion about the advanteges of air launch alread. Burt Rutan prefers air launch for a non-physical reason - safety of the passenegrs and saftey of the non-involöved public.

So - waht I am looking for here is an economical optimum merely.

And in between I am thinking about the following. If the weight to be launched increases linearly then the amount of the propellant required increases exponentially. This may result in the possibility that to launch the propellant required to leave the orbit for the moon by the CEV together with several cargo launches to the ISS - which have to occur nonetheless - than to leave the weight at those cargo launches and to to do it by a large extra-launch.

That thought is complex and so I still have to think it over - it might apply to the physical optimum too perhaps.



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Post    Posted on: Thu Oct 06, 2005 5:52 pm
Ekke, there's an op-ed piece on SpaceDaily about this topic...

http://spacedaily.com/news/oped-05zza.html

Not particularly in-depth from a technical standpoint (op-ed never is), but it offers some interesting ideas.


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Post    Posted on: Fri Oct 07, 2005 11:17 am
Hello, SawSS1Jun21,

Thank You Very Much for that link - I still have to read it but I surely will do that.

Currently I simply want to mention the article "The Mega-Module Path to Space Exploration (Or: How to Use an HLV)" ( www.space.com/adastra/adastra_mega-modules_051007.html ) - the first half of it considers an orbital fuel and propellant depot. And it does that a way quite interesting for me... I will think about it and play around.

It includes issues fitting into other threads too.



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Post    Posted on: Tue Oct 11, 2005 11:28 am
Hello, SawSS1Jun1,

just this moment I have read the article you linked to - and it seems it is the same as thte one I myself posted a link to.

The article tells some reasons to look for the physical etc. optimum - but in the examples worked out in the article I seem to be faced to non-physical etc. optima. The reason is that the article places all into a larger context - the purposes to be achieved, that transportation capacities and so on. So the reasons are infrastructural, organizational and coordinational ones.

Such context I didn't have in mind while writing the initial post. While I - like at least one example in the article - have in mind an orbital propellant depot I want to avoid vehicles specialised to delivery of propellant except if they return a revenue too. The deoxydised dusts of earthian deserts would be such a revenue - and the Russians obviously have develoed a vehicle which is reusable and can safely deliver cargo from orbit down to Earth. So they would be able to deliver desrt-dusts into the orbit where oxygen could be one out of it and deposited into an orbital propellant depot while the deoxydised dusts can be delivered back to Earth by their newly developed orbit-to-Earth-cargo-vehicle.

The revenue could be the removal of on-going desertification which in turn has the revenue of increasing the ability to produce food etc. and thus help african etc. people. This again in turn could increase the overall worl-wide productivity of people.

The result would be that there are increased resources for spaceflight - resources of propellant as well as ressources of funds.

What the article says could be done in parallel.

When I seem to observe that engineers seem not to be interested in the economical optimum I am missing such a context mostly.

Thank You Very Much again for the article.



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