Author Topic: Propellant Depots - General Discussion  (Read 304462 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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Offline 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.
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Offline 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.
...you have been found guilty by the elders of the forum of a (imaginary) vendetta against Saint Elon - BLAAASPHEMER !

Offline jongoff

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Re: Propellant Depots - General Discussion
« Reply #1050 on: 08/11/2018 04:22 AM »
I know this thread is a little old, but I wanted to mention we'll be presenting a paper on the orbital dynamics of using a LEO propellant depot for interplanetary missions at this year's AAS Astrodynamics Specialists Conference in Snowbird, UT on the 22nd. This is a follow-on to a paper we did last year (that I blogged about here on Selenian Boondocks: https://selenianboondocks.com/2018/02/aas-paper-review-practical-methodologies-for-low-delta-v-penalty-on-time-departures-to-arbitrary-interplanetary-destinations-from-a-medium-inclination-low-earth-orbit-depot/)

This year's paper "RAAN Agnostic 3-Burn Departure Methodology for Deep Space Missions from LEO Depots" extends the methodology in the previous paper to show that a mid-inclination depot (say ISS-like orbit) can support missions to a wide range of destinations with only modest dV penalties even though the depot plane doesn't line up with the desired departure asymptote at the desired departure date. We're illustrating the concept showing how a LEO micro-depot could refuel LauncherOne-class small rocket upper stages (and small storable kick stages) to enable a string of 8 back-to-back missions to 4 planets and 4 NEOs in a five month timeframe. It's pretty sweet. I'll make sure to post the paper, the presentation slides, and a writeup on Selenian Boondocks once it's done, but I figured I'd mention it here.

~Jon

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Re: Propellant Depots - General Discussion
« Reply #1051 on: 08/11/2018 05:28 AM »
Propellant Depots: hey NASA etc... Just do it!!
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Offline GWH

Re: Propellant Depots - General Discussion
« Reply #1052 on: 08/11/2018 06:55 AM »
Jon, what would the viability of launching from a high inclination orbit like the ISS be?

An idea I have been fascinated by (but never researched the viability of) is fueling departure stages for small payloads via utilizing rideshare and excess capacity on visiting vehicles.

Offline speedevil

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Re: Propellant Depots - General Discussion
« Reply #1053 on: 08/11/2018 09:42 AM »
Jon, what would the viability of launching from a high inclination orbit like the ISS be?

An idea I have been fascinated by (but never researched the viability of) is fueling departure stages for small payloads via utilizing rideshare and excess capacity on visiting vehicles.
The related idea of rideshare payloads of low value having oxidiser added only shortly after the main payload has been delivered by the upper stage departs occurred to me.
This could considerably reduce the risk profile of small ride-alongs with propellant, eliminating any risk to the primary payload, and simplifying the flight approval process.

Offline jongoff

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Re: Propellant Depots - General Discussion
« Reply #1054 on: 08/11/2018 07:05 PM »
Jon, what would the viability of launching from a high inclination orbit like the ISS be?

An idea I have been fascinated by (but never researched the viability of) is fueling departure stages for small payloads via utilizing rideshare and excess capacity on visiting vehicles.

That's pretty much the very idea I've been looking at for the last few years. I actually like an ISS coorbital depot location a lot. ISS orbit is high enough inclination that except for very low C3 targets, you can make a low-penalty three-burn departure work for even pretty gnarly departure asymptotes, and since there's a lot of traffic to the altitude that is usually volume instead of mass limited, it gives you a lot of options for buying leftover propellant.

In the case of SpaceX, they ought to have a few tonnes of leftover LOX/Kero and Helium in their upper stage after dropping Dragon off. Any money from that excess propellant would basically be pure profit. ULA, once they're flying Vulcan, should also have a lot of excess prop capacity in an ISS-like orbit. If you say had to give NGIS a $10M discount to fly on Vulcan instead of Antares, and you added an extra 2-3 solids, you could get somewhere in the neighborhood of 15 tonnes of excess propellant as a secondary payload for a delta-cost in the range of $25M--which is also cheaper than bulk launch on a reusable Falcon 9.

And going to your last point, when you combine those benefits with refueling smallsat launcher upper stages (and possibly storable kick stages for the more challenging destinations), an ISS coorbital depot would allow the Rocketlabs, Virgin Orbits, and Fireflys of the world send smallsat payloads to anywhere in the solar system at not a huge premium to the cost of launching those payloads to LEO.

~Jon

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Re: Propellant Depots - General Discussion
« Reply #1055 on: 08/11/2018 07:06 PM »
Propellant Depots: hey NASA etc... Just do it!!

If NASA doesn't do it, I wouldn't be surprised if a foreign space agency decided to go after something like this. It would be a good niche for a country to carve out for itself.

~Jon

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Re: Propellant Depots - General Discussion
« Reply #1056 on: 08/28/2018 05:34 PM »

Offline Asteroza

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Re: Propellant Depots - General Discussion
« Reply #1057 on: 08/29/2018 12:51 AM »
Propellant Depots: hey NASA etc... Just do it!!

If NASA doesn't do it, I wouldn't be surprised if a foreign space agency decided to go after something like this. It would be a good niche for a country to carve out for itself.

~Jon

Since you are advising Orbit Fab, I assume they are trying to implement the ISS co-orbital propellant depot with the 3 burn exit strategy you mentioned...

How would a similar strategy work out for a prop depot parked in sun terminator riding SSO orbit to work with SSO bound customers? Those usually aren't so volume limited so rideshare prop hauling is harder, but then again such a depot can double as a space corral type platform for cubesat class sensors as an expandable single platform version of the A-train earth observation fleet...

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Re: Propellant Depots - General Discussion
« Reply #1058 on: 08/29/2018 01:44 AM »
Since you are advising Orbit Fab, I assume they are trying to implement the ISS co-orbital propellant depot with the 3 burn exit strategy you mentioned...

Actually, I haven't explicitly been working with OrbitFab on the ISS co-orbiting depot/3-burn departure concept, though I think one of my coauthors has been working with them a little. The depot in our paper was more of a pet concept I've been working on for the past few years, focused on bigger things--refueling microsat launcher upper stages with LOX/Kero/storables to enable dedicated BLEO launches. Though the two ideas aren't mutually exclusive.

Quote
How would a similar strategy work out for a prop depot parked in sun terminator riding SSO orbit to work with SSO bound customers? Those usually aren't so volume limited so rideshare prop hauling is harder, but then again such a depot can double as a space corral type platform for cubesat class sensors as an expandable single platform version of the A-train earth observation fleet...

From a standpoint of refueling spacecraft, SSO and near-ISS are the two areas I would focus on, as that's where the most existing/planned spacecraft are. From what I've heard talking with smallsat launch providers, most of them expect to have leftover mass on most flights, and having something dense and inert like a water tank or Xenon tank that can takeup spare space probably makes a lot of sense. Is that what you were asking?

~Jon

Offline Asteroza

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Re: Propellant Depots - General Discussion
« Reply #1059 on: 08/29/2018 07:31 AM »
Quote
How would a similar strategy work out for a prop depot parked in sun terminator riding SSO orbit to work with SSO bound customers? Those usually aren't so volume limited so rideshare prop hauling is harder, but then again such a depot can double as a space corral type platform for cubesat class sensors as an expandable single platform version of the A-train earth observation fleet...

From a standpoint of refueling spacecraft, SSO and near-ISS are the two areas I would focus on, as that's where the most existing/planned spacecraft are. From what I've heard talking with smallsat launch providers, most of them expect to have leftover mass on most flights, and having something dense and inert like a water tank or Xenon tank that can takeup spare space probably makes a lot of sense. Is that what you were asking?

~Jon

Sort of. Larger launches could expect a larger rideshare prop tug to propel itself+tank to a depot (Sherpa comes to mind), but what are your thoughts on the smaller launchers? The amount of rideshare mass isn't that high, which cuts into chances of a tug+tank, and some of the potential providers don't have restartable upper stages to rendezvous with a depot which would suggest mere rideshare tank separation like a cubesat ejection. Does that end up needing an OTV to go catch rideshare tanks with StickyBooms? Or is there a fundamental expectation that normally, restartable upper stages will come to the depot (grappled by a depot StickyBoom and perhaps hard berthed to a visiting vehicle mount) to do two way propellant transfers (deposit or pickup)?

Err, let me split that and say pure prop delivery when the rideshare provider can't come themselves, and the restartable upper stage club, who are expected to deposit regularly by visiting themselves before disposal (with a nice tether drop opportunity for depot reboost) but might occasionally come for pickup (not only to refuel themselves and depart with original BLEO payload, but perhaps refuel after dropping the original LEO payload and pickup the actual smaller departure BLEO payload from the depot itself, which was a cargo deposit left earlier). There's also the case of depositing propellant for a waiting cargo deposit (propellants for electric thruster payloads that are cargo deposits at the depot) rather than the upper stage itself (think cubesats with a stack of ejectable 3U water tanks).

Which I suppose quickly devolves into the cases for scavengable ullage from liquid upper stages themselves (LOx, hydrogen or kerosene)(hypergols?), delivered storable propellants to be converted for upper stages (aka water delivery being slowly converted to LOx/LH2 at the depot), and delivered storable for electric driven payloads (so water, and noble gases like xenon?)

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