Author Topic: NASA and Commercial industry combine to outline FTD Propellant Depot plan  (Read 54782 times)

Offline upjin

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Propellant Depots have lots of issues that will need to be addressed before it is viable and ready.  I eventually see a marriage of HLV + propellant depots at some point, unless some other type of propulsion system comes to the front of the pack.

Offline pathfinder_01

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Propellant Depots have lots of issues that will need to be addressed before it is viable and ready.  I eventually see a marriage of HLV + propellant depots at some point, unless some other type of propulsion system comes to the front of the pack.

Unless the propulsion system is propellantless and somehow requires no mass to generate energy for propulsion, a propulsion depot can be of benifet no matter the kind of propulsion. It is more the location/types of propellant depots and amounts of propellant that are infulenced by technology which in turn infulences the kind of HLV you need.

For instance if lox\hydrogen depots don't work in LEO then you need an HLV capable of at least lifting a fully fueled EDS stage to push your capsule to L1 if you intend to use a lox\hydrogen EDS.

If electric propulsion works, then loh might not be a good cargo because of boil off in which case methane or hypergolic could be prefered and used in both EDS and perhaps lander. This favors cargo rockets that just go to LEO rather than going all the way to L1.

If electric propulsion works then departing from L1 and fueling up there for a mars trip makes a lot of sense. If not then departing from LEO might be a better idea. The first favors a smaller HLV the second a larger one. The first requires no propelant depot in LEO the second requires less chemical propellant in the L1 depot than if no mars craft are visting. 

If you use methane or esp. hypergolic depots you may need more a rocket capable of more lifting power than if you use hydrogen. Although the density of methane and hypergolics could help quite a bit(i.e. the tank+insulation would wiegh less than an hydrogen one).

If you have a depot in LEO, then lifting a partially filled EDS or using a 2nd stage for an EDS or an EDS with tanks only sized for departure rather than departure and earth orbit could make sense. If not then thoose don't work.

For electric propulsion a depot can allow you to reduce mass by contatianing the propellant for a return trip which can either lead to a quicker travel time or ability to carry more mass. For chemical it could make reuse of chemical rockets more possible.  This reuse could drive demand for propellant. Argon to tug things around and whatever chemical proellant.

In theory ISRU for propellant could also play a role, but I think that is going to be much further down the road. ISRU and clossed loop however could reduce the amount of mass long term missions require which could infulence the launch rate.(i.e The ISS's water recycing system saves 2 progress flights a year).

Electric propulsion likewise infulences the kind of launcher. Do I need an HLV to move a decent amount to L1 or the moon or could a rocket that just goes to LEO do? It could use a LEO depot to recive propelllant while the tanker is out of LEO.

Inflatables and better solar panels would drop the mass of a spacraft somewhat but that mass could be spent on more radiation sheilding. Aerobraking\aerocapture reduce the amount of propellant needed for any mission.

Offline kkattula

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Propellant Depots have lots of issues that will need to be addressed before it is viable and ready.  I eventually see a marriage of HLV + propellant depots at some point, unless some other type of propulsion system comes to the front of the pack.

According to the OP article, NASA, ULA, et al, seen to think it's just a matter of engineering at this point.  $500m budget in under five years to demo LO2 & LH2 storage, transfer & handling. 

They're not talking about the really complex issues such as zero boil-off and zero-g transfer. Micro-g settling and boil-off sufficient for station keeping propulsion, is good enough.

Offline Xplor

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A real beyond LEO mission in 2016 would be incredible!!!

Exploration needs near term accomplishments to focus and sustain it.  Constellation, Obama's proposal, the Senate and House proposals all have the first missions in 2020 someday.  Here is a proposal that moves the first mission into a single presidential election cycle. 

Furthermore, this proposal is agnostic regarding future launch.  Depots enable real missions with existing launchers, the Direct plan includes depots and even Constellation would have benefited hugely from the inclusion of depots.

Offline MP99

Quote
With effective design, analysis indicates that total system boil-off can be held to 0.01 percent per day...

That sounds pretty good for a Mars mission - you'd retain 95+% even for the return TEI burn.

I do have a couple of question regarding orbital mechanics for a LEO depot, though. I understand how the spacecraft would rendezvous with the depot, but is the depot likely to be in the required orbit for the spacecraft to then undertake it's insertion burn? If not, is a plane change (or similar) going to be required before insertion?

At what altitude would the depot be stationed?

What protocols would the spacecraft need to follow to avoid plume impingement on the depot when it undertakes it's insertion - just make sure it's 'X' miles away (laterally) first? I suspect these are much more energetic burns than anything that happens within miles of ISS (to take an example).

cheers, Martin

Offline Hop_David

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I understand how the spacecraft would rendezvous with the depot, but is the depot likely to be in the required orbit for the spacecraft to then undertake it's insertion burn?

I envision LEO depots giving upper stages enough propellent to reach EML1 or 2 depots. At the apogee of these orbits, plane changes are cheap.

EML1 or 2 moves 360 degrees over 28 days. By choosing the time you drop from EML1 or 2, you can choose the longitude of perigee when a launch window occurs. As I mentioned earlier, plane changes are cheap from a high apogee. So you can choose orbit inclination as well as longitude of perigee.

After dropping from the lofty heights of EML1 or 2, the ship will be moving almost escape upon reaching perigee. And, as discussed above, you can make the perigee velocity vector darn near parallel with the V infinity vector for trans Mars insertion (or insertion to whatever deep space destination you have in mind).

Offline HappyMartian

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A lunar lander that can spend weeks or months on the moon is not likely to be fueled by lox\loh . 


Liquid hydrogen liquid oxygen propellants may be perfectly feasible if the lander is landing at location that is permanently shaded and has ice... Propellant tankers going to and from an EML1 or 2 propellant depot to the permanently shaded Lunar locations would most likely use liquid hydrogen and liquid oxygen propellants.

Cheers!


Edited.
« Last Edit: 08/08/2010 03:38 am by HappyMartian »
"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

Offline clongton

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A lunar lander that can spend weeks or months on the moon is not likely to be fueled by loxloh . 


Liquid hydrogen liquid oxygen propellants may be perfectly feasible if the lander is landing at location that is permanently shaded and has ice... Propellant tankers going to and from an EML1 or 2 propellant depot to the permanently shaded Lunar locations would most likely use liquid hydrogen and liquid oxygen propellants.

Cheers!


Edited.

Or landed *anywhere* and then parked in the shade.
It will stay just s cold.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline HappyMartian

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Or landed *anywhere* and then parked in the shade.
It will stay just s cold.


At some locations you might need a very large beach umbrella to create enough shade...

You know, I was thinking that there must be a lot of infrared and visible light that the surface of the Moon reflects or emits during the day at noon. If you could build a high enough inflatable wall out of Mylar it would, in most locations, keep your lander somewhat cool and also a large area of the lunar surface around it as well.

Just before launch, deflate your wall and move it safe distance away or store it somewhere behind a big rock. Of course, if it was going to be a night launch, you could deflate the wall earlier and have lots of time to store it. Night launches would mean you wouldn't be in a big rush to get the deflation and storage job done and that would be good.

Instead of a wall, or an umbrella, you might try a ball like Echo 2, which was a 41.1-meter, 135 ft, in diameter. Maybe something a lot bigger would create enough shade...

See: Project Echo

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

Cheers!



"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

Offline Xplor

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A lunar lander that can spend weeks or months on the moon is not likely to be fueled by loxloh . 


Liquid hydrogen liquid oxygen propellants may be perfectly feasible if the lander is landing at location that is permanently shaded and has ice... Propellant tankers going to and from an EML1 or 2 propellant depot to the permanently shaded Lunar locations would most likely use liquid hydrogen and liquid oxygen propellants.

Cheers!


Edited.

Or landed *anywhere* and then parked in the shade.
It will stay just s cold.

A multi layer sun shield above and MLI on the surface to minimize lunar radiation and a window to deep space and you have an ideal place to store cryos anywhere on the moon.  This could be simple deployable at an unimproved location using passive storage, or more extensive with active cooling at a lunar base protecting "permanent" dewars.  Such a sizeable LO2/LH2 storage "farm" not only can store the propellants for the Ascender, but also commodities for the base and also provide the ideal storage for fuel cells to supply copious power through the lunar night.

Offline DavisSTS

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Are prop depots at least welcomed in both the Senate and House bill?

Offline Mr. Justice

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Offline Jorge

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Boiloff is only half of it. Need to demonstrate propellant transfer as well. Simply parking the LSAM would not demonstrate that.
JRF

Offline Jorge

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Are prop depots at least welcomed in both the Senate and House bill?

The House bill does not provide enough funding for one.

The Senate bill does provide funding for flagship technology demonstrators but leaves which demonstrators up to NASA.
JRF

Offline Mr. Justice

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Boiloff is only half of it. Need to demonstrate propellant transfer as well. Simply parking the LSAM would not demonstrate that.

Hasn't that been proven with the ISS, MIR and on other occasions.

Offline Jorge

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Boiloff is only half of it. Need to demonstrate propellant transfer as well. Simply parking the LSAM would not demonstrate that.

Hasn't that been proven with the ISS, MIR and on other occasions.

No, that's hypergolic propellants. The whole point here is cryogenic propellants (otherwise, would controlling boiloff even be an objective?). That has never been demonstrated.
« Last Edit: 08/13/2010 01:45 am by Jorge »
JRF

Offline Mr. Justice

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Boiloff is only half of it. Need to demonstrate propellant transfer as well. Simply parking the LSAM would not demonstrate that.

Hasn't that been proven with the ISS, MIR and on other occasions.

No, that's hypergolic propellants. The whole point here is cryogenic propellants (otherwise, would controlling boiloff even be an objective?). That has never been demonstrated.

Wouldn't the actual transfer mechanism be the same? To be honest, I don't know how it is done today on the ISS.

Offline Jorge

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Would a LSAM in left to loiter in Lunar orbit for several months not demonstrate the ability to minimize boil-off just as well as a "depot demonstrator?" It seems like possibly a good 2 for 1 deal. 

Boiloff is only half of it. Need to demonstrate propellant transfer as well. Simply parking the LSAM would not demonstrate that.

Hasn't that been proven with the ISS, MIR and on other occasions.

No, that's hypergolic propellants. The whole point here is cryogenic propellants (otherwise, would controlling boiloff even be an objective?). That has never been demonstrated.

Wouldn't the actual transfer mechanism be the same? To be honest, I don't know how it is done today on the ISS.

ISS uses a bladder-based system with a nitrogen pressurant. Finding a bladder material that can remain flexible at liquid hydrogen temperatures will be a challenge. Likewise nitrogen will freeze at liquid hydrogen temperatures; helium must be used. And the transfer lines must be thermally pre-conditioned, while the ISS system can operate at room temperature.

So no, they're going to need to be different. A lot different.
JRF

Offline Proponent

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The attached paper by lays out methods of handling cryogenic fluids in a depot; see the table on page 5 for a quick summary.  In particular, inertial settling (rotating the depot about its longitudinal axis) was subsequently tested an Atlas AV-017 (short paper attached).

Offline jongoff

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Are prop depots at least welcomed in both the Senate and House bill?

The House bill does not provide enough funding for one.

The Senate bill does provide funding for flagship technology demonstrators but leaves which demonstrators up to NASA.

Though it does specifically mention (last time I looked) cryogenic propellant depots as a technology area NASA could study in its flagship program.  Ie it specifically allows NASA to spend money on it, but doesn't go so far as to require *it* to be the FTD mission that actually gets funded.

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