Author Topic: Propellant Depots - General Discussion  (Read 238118 times)

Re: Propellant Depots - General Discussion
« Reply #1040 on: 07/12/2017 07:15 AM »
I am new to the forums and have not had time to read the past 10 years of post on this thread but one thing I have yet to see. Has anyone suggested getting a majority of the propellant from the Moon?
The main reason I ask is that the element that makes up 40% of the Moon's surface also accounts for 80% of the mass of rocket propellant.
As an example, if SpaceX were to use a propellant depot supplied by the Moon they would only need one launch of the tanker variant to provide the fuel for the journey to Mars rather than the 5 suggested by Musk. This would make the entire venture much more feasible.

Offline MATTBLAK

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Offline TrevorMonty

Re: Propellant Depots - General Discussion
« Reply #1042 on: 07/12/2017 10:44 AM »
Google "cislunar 1000".

Offline titusou

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Re: Propellant Depots - General Discussion
« Reply #1043 on: 07/12/2017 03:05 PM »
Well, I just happened to finished reading from page1, yes call me crazy :)

I would suggest you start from p31, which will teleport you back to ~2010.

Before 2010 there is a lot of debate about Direct/Jupiter HLV, but those are really not relevant to what we have today: SLS is a done deal, Falcon9 become reuse-able.

Also, if you see jongoff post, read his stuff in detail. I personally think he has most knowledge regarding PD within this thread.

I think moving forward the key thing is how to realize the concept. The benefit is clearly there, technology is also there (if utilize settling, non-settling is a different story). How to make it happen is probably the most challenging part, aka: who is going to pay for the first PD?


Titus

Offline Zed_Noir

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Re: Propellant Depots - General Discussion
« Reply #1044 on: 07/13/2017 09:56 AM »
I am new to the forums and have not had time to read the past 10 years of post on this thread but one thing I have yet to see. Has anyone suggested getting a majority of the propellant from the Moon?
The main reason I ask is that the element that makes up 40% of the Moon's surface also accounts for 80% of the mass of rocket propellant.
....

Getting propellant from the Moon in the short term (next dozen years) will not be very variable.

The main issues are setting up Lunar mining operations, Lunar propellants processing & storage facilities, Lunar surface mobility systems, Lunar spaceport, cis-Lunar transport logistics and finally some kind of orbital propellant depot. IMO all these issues require just about as much budget each as either the SpaceX BFR or the SpaceX BFS, which you have to do to go Mars anyways.

The current SpaceX Mars plan only requires the BFR, the BFS spacecraft & the BFS tanker plus a lot of bulk propellants. So only 3 budget line items as compares to the over a dozen line items for getting propellants from the Moon.

Maybe when there is a fleet of 300 mT reusable launch vehicles available you could set up a Lunar propellants supply system to an orbital propellant depot.

Offline MATTBLAK

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Re: Propellant Depots - General Discussion
« Reply #1045 on: 07/13/2017 12:25 PM »
I have often thought that the best use of lunar oxygen production in the short term would be as breathing gas for Outpost inhabitants. Of course; if polar ice is actually found to be more plentiful than expected, the infrastructure could grow on from there.
« Last Edit: 07/13/2017 12:26 PM by MATTBLAK »
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Online oldAtlas_Eguy

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Re: Propellant Depots - General Discussion
« Reply #1046 on: 07/13/2017 10:30 PM »
In the long run ITS would probably spur the development of Lunar propellants and the creation of L2 depots. It would make the transport of cargo and personnel to the Lunar surface much cheaper enableing a tremendous lowering of the costs of the infrastructure which would then be bootstrapping by fueling ITS on the surface then using a ITS tanker variant (no reentry shielding since it would never return to Earth) to transfer liquids to L2 and return to Lunar surface. 100 flights by the tanker would transport ~ 38,000mt in just 1 year of operations. This is not a small scale operations. At $10/kg for the liquids purchased at the Lunar surface is $380M in purchases from the "miners". In fact the liquids prices at the Lunar surface could be as high as $30/kg and still be cheaper than prop delivered to L2 from Earth. At $30/kg that is > $1B/yr in sales for just payload + another $3B in propellant sales to the tanker to deliver the liquids to L2 which then would have a Value/price of <$150/kg at L2. So the total sales of all liquids from the "miners" could be as much as $4B with just a single ITS tanker in operation which is replaced each year.

At which when this takes place the investments into infrastructure and exploration/development of resources would probably be more than $10B per year for all of cis-Lunar space. To put this into perspective this level of commercial development funding would be equivalent to the NASA budget for government centered contracted activities for just operations and exploration (which is only $8B currently) would be like having $40+B sized budget for these areas of activities in NASA.

But we will have to wait. The private investment funds have yet to freely flow.

Offline Archibald

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Re: Propellant Depots - General Discussion
« Reply #1047 on: 10/06/2017 01:27 PM »
If BFR can lift 150 mt, and needs 1100 mt to refuel, then it would take 8 flights, and that would left some margin for boiloff (although methane and LOX boils less than LH2).

I've been on this forum since 2008 and closely followed the quest for propellant depots by JohnGoff and many others.
I think SpaceX architecture validates the usefulness of prop depots. It is an enormous force multiplier.

Online oldAtlas_Eguy

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Re: Propellant Depots - General Discussion
« Reply #1048 on: 10/07/2017 01:26 AM »
If BFR can lift 150 mt, and needs 1100 mt to refuel, then it would take 8 flights, and that would left some margin for boiloff (although methane and LOX boils less than LH2).

I've been on this forum since 2008 and closely followed the quest for propellant depots by JohnGoff and many others.
I think SpaceX architecture validates the usefulness of prop depots. It is an enormous force multiplier.
Actually the tanker can lift 220mt of prop. So only 5 for 1,100mt.

Offline Archibald

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Re: Propellant Depots - General Discussion
« Reply #1049 on: 10/07/2017 11:02 AM »
thank you.

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