Author Topic: NASA and Commercial industry combine to outline FTD Propellant Depot plan  (Read 37652 times)

Offline JohnFornaro

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Now to read more than the thread title...

Quote
It's a news article, not a promotion.
So true, so true.  He's pomoting shoes on a different thread.  [Ducks head.  First shoe misses.  OW!  Second shoe connects.]

Seriously, a "real" journalist tells, "just the fax, ma'am".  Which is why the article is so good.

... Russia having experience with on orbit refueling could actually build the depot....

Now that's a good idea for international cooperation, although maybe they only launch some of the pieces, and we assemble it.  Don't forget that the Mounties will have to provide another arm or two.

...The simplest solution is to build two depots at EML1 and in Mars orbit...

Just the one place for starters.

...I was quite surprised to read they think they can store LH2 for years...

That is a "forward looking statement".  The statements in the past have not been this optimistic.  The report says that it's easier to keep it cool than it is to cool it down from a warmed state, so they propose to make it quite chilly down here before launch; insulate it well; and there ya go.  I get the sense that this is something that's just been developed, so it would seem to fit into the game changing category.  Less methane, more hydrogen.

The HLV will come.  No doubt.  First, we need the infrastructure.  Then the HLV; which is first, a tanker; second, a cargo launcher; third, a passenger launcher; all on the same chassis.

...adding more foam/insulation...

And get this:  They don't call for foam!
Sometimes I just flat out don't get it.

Offline blasphemer

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Interesting article, looks like commercial propellant depots and a HLV could be a powerful combination.

What is the advantage of a propellant depot in EML1 over LEO one? It seems to me that LEO-based depot could be refilled easier from Earth, and it would be more effective to refuel "in the middle of the way" than when you are "almost there" (EML).

Offline A_M_Swallow

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...The simplest solution is to build two depots at EML1 and in Mars orbit...

Just the one place for starters.

A depot at EML1 will supply the Moon and one way trips to Phobos & Mars.

If you want the people to return from Mars or have reusable Mars landers somewhere to refuel makes things easier.  For a trip to Mars the return hydrogen will probably need both a sun shield and refrigeration.  There are major mass savings if the return propellant is sent ahead on a SEP.

Launch vehicles do not normally contain propellant refrigeration equipment but a depot could.

Offline kraisee

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A HLV Ė of any kind Ė is not listed in any current ULA or commercial documentation, with experts claiming such a vehicle isnít required under the EELV and propellant depot architecture.

Incorrect.   It just took me all of 60 seconds to locate these documents on ULA's website:

http://unitedlaunchalliance.com/site/docs/publications/DeltaIVLaunchVehicle%20GrowthOptionstoSupportNASA%27sSpaceExplorationVision.pdf
(page 4 shows evolved Delta options to 100mT)

http://unitedlaunchalliance.com/site/docs/publications/EvolvedAtlasToMeetSpaceTransportationNeeds20056815.pdf
(page 4 shows evolved Atlas options to 140mT)

There are other papers out there in addition to these.

Ross.
« Last Edit: 08/06/2010 03:06 PM by kraisee »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline pathfinder_01

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In theory a prop depot in LEO would be a good idea. Only problem is they are using lox\loh not sure how well that stores in LEO.  From what I read either not well or moderately well but maybe there has been some work on it. 

 I think if they are unable to refuel in LEO it favors launching the EDS fully fueled. I agree with the two launches to LEO. It would allow you to use a smaller HLV and the payloads for the mission wouldnít be contrained by the need to fit on to the HLV with the EDS for launch in one shot.

Right now I think there is a tricky knot. Lox\methane stores better than lox\loh but gives less performance. Lox\loh might not store well in Leo due to the heat reflected from the earth but gives the best performance. Hypergolics  store the best but need heat to keep them from freezing which might cause a need for two different depots since the last thing you want around cryogenic propellant is heat.   

I can still see a need for either a hypergolic one or a lox\methane one in a BEO mission just for itís ability to store for longer periods of time. A lunar lander that can spend weeks or months on the moon is not likely to be fueled by lox\loh .  Also LOX\Methane or hypergolics might be useful for NEO mission that lasts for weeks or months. How long would be a reasonable time for lox and methane to be stored in a lunar lander?

Offline jongoff

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Cool article! Wouldn't it be risky if a crew got to a depot and something didn't work? They'd have no fuel and be stranded?

You cannot launch all vehicle(s), depending on the ultimate architecture configuration, totally dry.  Conops would likely dictate:

1.  Some amount of propellant to get to the depot, rendeavous, prox-ops, docking, etc.

2.  If you have a crew you would also "book-keep" the necessary prop to get home just in case for the situation you mentioned above. 

Also, depending on which depot location, and how far in the development of a space transportation network you are, there may be other options like waiting for a rescue mission, trying to fix what's wrong (depots are actually mostly tubes, valves, and pressure vessels, so the valves are the most likely thing to fail--it might be possible to design the thing from the start for servicing/repair), but as Mike says, contingency planning is also a reasonable precaution.

I like what one of the Apollo astronauts said when asked what he would do with his last hours if the LEM Ascent Engine failed to light.  The reporter was expecting some sort of "saying goodbye to the kids" ritual or something like that.  The astronaut instead said "I'd get out and try to fix the darned thing!"

~Jon

Offline Bill White

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I like what one of the Apollo astronauts said when asked what he would do with his last hours if the LEM Ascent Engine failed to light.  The reporter was expecting some sort of "saying goodbye to the kids" ritual or something like that.  The astronaut instead said "I'd get out and try to fix the darned thing!"

~Jon

Norman Mailer reported on this in his book "Of a Fire on the Moon"

At a press conference held in advance of the Apollo 11 mission, Armstrong answered that the question was "unpleasant to think about" and deflected it away.

Mailer reports that Aldrin watched as Armstrong was asked the question (giving him time to prepare his own answer) and a few minutes later Aldrin growled that he'd spend his time working on the "availability of the ascent engine"
EML architectures should be seen as ratchet opportunities

Offline Hop_David

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Another long one...

http://www.nasaspaceflight.com/2010/08/nasa-commercial-combine-outline-ftd-propellant-depot-plan/

This is very exciting!

Some proposed payloads make me wail and gnash my teeth: solar power sats, flags and footprints, or (worst of all) no worthwhile upper stages -- just continue making HLVs to keep congress critters' voting constituents employed.

But this seems like an HLV use that might lead somewhere beyond a dead end.

Offline JohnFornaro

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Quote
Only problem is they are using lox\loh not sure how well that stores in LEO.
The paper referred to in the news article suggests that this is a solvable problem.
Quote
due to the heat reflected from the earth shining from the sun
Fixed that for ya.
Quote
it might be possible to design the thing from the start for servicing/repair)...
Absolutely.  Design for repairability.  I hate, I hate, I hate, that last spark plug in the old VW engine.
Sometimes I just flat out don't get it.

Offline jongoff

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Quote
Only problem is they are using lox\loh not sure how well that stores in LEO.
The paper referred to in the news article suggests that this is a solvable problem.

Yeah, it's an issue for LEO, but the key is keeping a good ops temp and not leaving your cryogens sitting doing nothing for a long time, but keeping a high throughput going.

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Quote
due to the heat reflected from the earth shining from the sun
Fixed that for ya.

Actually, in LEO it is mostly the nice warm earth blocking the nice cold sky that screws up the thermal environment.  EML-1 is at the same solar distance as the earth, but has 1/10th the net heat flux into the tanks due to this effect.

Quote
Quote
it might be possible to design the thing from the start for servicing/repair)...
Absolutely.  Design for repairability.  I hate, I hate, I hate, that last spark plug in the old VW engine.

Indeed.  Part of the point of doing a demo depot, *and then using it*, is to make sure you understand the maintenance issues and have fixed any design issues that crop up before you build more or bigger depots.

~Jon
« Last Edit: 08/06/2010 04:09 PM by jongoff »

Offline pathfinder_01

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Actually, in LEO it is mostly the nice warm earth blocking the nice cold sky that screws up the thermal environment. 



Perhaps Marv the martian can fix that for us with his "Illudium Q-36 Explosive Space Modulator".  :)
« Last Edit: 08/06/2010 04:26 PM by pathfinder_01 »

Offline JohnFornaro

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in LEO it is mostly the nice warm earth...
I have so much more to learn.  Why then, does that Boeing proposal have the sun umbrella?  I understand that the demo is in LEO, but that the final depot will be in EML-1, right?

I need to read your report again, a bit more slowly.
Sometimes I just flat out don't get it.

Offline pathfinder_01

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in LEO it is mostly the nice warm earth...
I have so much more to learn.  Why then, does that Boeing proposal have the sun umbrella?  I understand that the demo is in LEO, but that the final depot will be in EML-1, right?

I need to read your report again, a bit more slowly.

At L1/L2 you donít have a large object radiating heat (earth/moon) therefore the only source of heat is the sun. Block it and you can get things really cold.  In fact a mars depot will have a problem keeping the oxygen from freezing.

Offline Bill White

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Why would it be "either/or" for LEO depots and EML-1 depots?

Why not both, or all of the above, to accommodate launch sites at different Terran inclinations?

After all, amortizing depot R&D costs over multiple facilities would seem to lower the per unit cost per depot. I recall Steve Squyres explaining that building Spirit and Opportunity cost 125% of what it would have cost to build only one - by building two the per unit cost was 67.5% of the per unit cost for one.

Seems to me that an EML-1 depot would make a LEO depot more valuable and useful, and vice versa.
EML architectures should be seen as ratchet opportunities

Offline pathfinder_01

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Why would it be "either/or" for LEO depots and EML-1 depots?

Why not both, or all of the above, to accommodate launch sites at different Terran inclinations?

After all, amortizing depot R&D costs over multiple facilities would seem to lower the per unit cost per depot. I recall Steve Squyres explaining that building Spirit and Opportunity cost 125% of what it would have cost to build only one - by building two the per unit cost was 67.5% of the per unit cost for one.

Seems to me that an EML-1 depot would make a LEO depot more valuable and useful, and vice versa.


LEO and EML 1 have different thermal requirements and could possibly have different requirements for propellants.  It isnít LEO vs. EML. It is just that the need of an LEO depot is not quite as clear as the need for an EML one.  Not that LEO wonít have depots, but for exploration and for technological development using lox\loh an EML (or at least one in a higher orbit) makes the most sense.
 
If the concept proves it  self and is viewed as possible profitable , I expect some commercial player to pick up the technology maybe improve it and put them elsewhere.

I can think of an LEO depot being very useful in two ways. If hypergolics or if something more storable than hydrogen is used for propellant then a LEO depot could act as a receving point for an electric propulsion tanker.  Allowing you to launch when the tanker is not in LEO and allowing you to maximize mass to orbit with smaller rockets. The LEO depot could be used to refuel a 2nd stage that could be used for EDS. Allowing you to build an HLV with only two stages.

Offline Bill White

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It isnít LEO vs. EML. It is just that the need of an LEO depot is not quite as clear as the need for an EML one.

I certainly agree with this. If I had to choose only one, I'd also choose an EML depot over a LEO one.

However, when log rolling for political purposes it seems to me that answering "both" or 'all" as often as possible is merely prudent.
EML architectures should be seen as ratchet opportunities

Offline Hop_David

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Quote
in LEO it is mostly the nice warm earth...
I have so much more to learn.  Why then, does that Boeing proposal have the sun umbrella?  I understand that the demo is in LEO, but that the final depot will be in EML-1, right?

I need to read your report again, a bit more slowly.

In either location, you'll need an umbrella.

In LEO, the earth takes up almost half the sky, reflects a lot of sunlight and emits its own infrared radiation. When you have two heat sources moving around the depot, a single disk isn't adequate shade.

So for LEO depots, ULA proposes a conical shade pointing north.

Here's a pic:


At EML1 or 2 earth and moon will be negligible heat sources, so a single disk shade blocking the sun would be adequate.


Offline nooneofconsequence

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At EML 1/2 the "reflected" IR from the sun off the moon is significant and depends on moon/earth phase - peaks at full/zenith . The radiated (e.g. "black body") IR constant component isn't.
« Last Edit: 08/06/2010 07:22 PM by nooneofconsequence »
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline Hop_David

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At EML 1/2 the "reflected" IR from the sun off the moon is significant and depends on moon/earth phase - peaks at full/zenith . The radiated (e.g. "black body") IR constant component isn't.

Thanks, I didn't know that. Could you give me references for further reading?

A conical shade pointing north seems like a good solution for a roughly equatorial LEO depot. But I'm having a hard time imagining a nice shade that would protect from both sun and moon for a depot in a halo orbit about EML1/2.


Offline nooneofconsequence

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At EML 1/2 the "reflected" IR from the sun off the moon is significant and depends on moon/earth phase - peaks at full/zenith . The radiated (e.g. "black body") IR constant component isn't.

Thanks, I didn't know that. Could you give me references for further reading?

A conical shade pointing north seems like a good solution for a roughly equatorial LEO depot. But I'm having a hard time imagining a nice shade that would protect from both sun and moon for a depot in a halo orbit about EML1/2.



THE INFRARED MOON: DATA, INTERPRETATIONS, AND IMPLICATIONS

For amusement (and an example of lunar "black body" radiation), here's the moon in infrared during an eclipse(from APOD):


Fun and games with near infrared you can do yourself (using HyperHAD CCD's in video cameras you can get for a song):
http://www.moonposter.ie/infrared.htm

Many, many references on this. The reason the Apollo LM was covered in gold foil was IR reflectivity.
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

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