On Orbit fuel depot

SpaceNut · 2016-06-03 06:54:08

Using how long satelites stay in orbit for life span

The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years

and the quantity of gas bottles lofted to orbit for the depot we now have a bench mark to build support vehicles to make use of them other wise we have a very dangerous situation if they stay with any seperation between each of them and more so as a larger target for space junk to strike....

kbd512 · 2016-06-03 16:21:03

SpaceNut wrote:

Using how long satelites stay in orbit for life span
The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years
and the quantity of gas bottles lofted to orbit for the depot we now have a bench mark to build support vehicles to make use of them other wise we have a very dangerous situation if they stay with any seperation between each of them and more so as a larger target for space junk to strike....

It would be to the benefit of everyone if NASA devoted more time and money to the Q-thruster technology. If it doesn't work, we can always continue using reaction mass. If it does work, then satellites will be self-deployed once in orbit. Space junk will have a limited life in LEO before reentry occurs. If there's even a chance of eliminating propellants for maneuvering and orbit changes, that opportunity should be vigorously pursued. The potential cost savings is truly staggering and the reduction in the quantity of space junk floating around Earth will measurably reduce associated flight risks.

SpaceNut · 2016-06-26 21:59:12

With a depot in orbit of hydazine for the GEO satelites and xenon gas for the ion drives used to guide the refueling station to each we could make use of the refueling satelites to build up the depot in orbit.

SpaceNut · 2017-07-06 21:27:19

Distributed Launch and Orbital Propellant Depots

GW Johnson · 2017-07-08 10:18:39

Propellants, if loaded into very strong canisters with a small solid motor, can be shot into orbit with a large light gas gun more economically than any possible rocket launch. "Strong" is the key word here: tens of thousands of launch gees. The light gas gun puts you into a surface-grazing transfer ellipse.

The small solid is what circularizes you into LEO. It, too, must be very stout, which puts extremely severe restrictions onto the solid motor design. Such things are not "off-the-shelf" in any sense of the word. I have done such motor designs for gun-launch ground testing, so I know they are possible. But not easy. Not at all.

Now, this sort of scheme is too uncontrolled to do precision orbital entry for rendezvous purposes. You will need some sort of space tug to go and get these propellant loads. If nobody is in a hurry, some sort of solar electric propulsion might be a pretty good choice for that. Think a steady stream of small loads fetched and added to a depot. Storables like MMH and NTO should be transportable that way, for way under $100/pound. Cryogenics? Not so sure.

Falcon-Heavy flown expendably promises fully-loaded payload delivery at around $1000/pound. (Current launchers are closer to $2500/pound.) A good guess says that being flown recoverably might cut that in half to around $500/pound. If second stages could be recovered and reused, a wild guess then says cost maybe gets cut in half again to around $250/pound.

At that per-pound cost level, given all the wild guess uncertainties, rocket launch and light gas gun launch get to be sort-of cost-competitive. Rocket launch avoids the high-gee restrictions of gas gun launch, and enables precision rendezvous. That should be worth some cost difference.

Exciting prospects either way, no?

GW

SpaceNut · 2017-07-08 11:10:57

What it does for space is not launching fuel as payload when we need a very large structure in orbit together. It reduces the subassmbly complexity of parts in LEO. All of which when we couple the cheap launch of fuel up to this large structure makes going further faster more pausible.

Terraformer · 2017-07-08 13:24:03

I wonder how cheaply we could launch propellent, and other resources, for using an OTRAG style system of mass produced rocket stages?

If we could get the cost for launching 1 tonne payloads down to $200k, and have a depot available, then that opens up a lot of possibilities. Such as launching our interplanetary vessel in one or two launches of Falcon Heavy, and doing a lot of the outfitting, provisioning, and fuelling on orbit. We could support a Lunar base, even without Lunar propellent production. If we've developed tugs to collect the packages, then we can use them to collect dead satellites and start clearing up our orbit before Kessler punishes us for littering.

SpaceNut · 2018-09-22 19:20:29

I posted alot of stuff for this topic elsewhere due to topic drift which means now to put all the thoughts together on a narrow topic I will need to search for them...

The reasons for orbiting fuel depots are?
1. To have for emergency refuel or to send fuel elsewhere.
2. To refuel because the rocket is empty after launch.
3. To off load carrying more mass than needed out of a gravity well.
4. Because we can not make all the fuel from insitu resources that we need to launch from mars surface.

SpaceNut · 2019-11-09 11:59:22

The benefits for LEO is great if we can store and achieve the mass quantities for long duration as its needed in the Starship design but thats a methane Lox system. But going with a Lunar depot would need other fuel types as we lack carbon in large quantities to create the fuel for use of which a mars depot seems very sound once we get over the energy collection issues..

SpaceNut · 2020-01-02 19:10:10

What we know about reuseability has to do with space x recycling of first stages and the capsule but with no experience with refueling either of these once on orbit. The Dragons thrusters could be done as we have been doing the ISS with those fuel types but thats not going to get us out of LEO as these are not powerful enough to be able to go anywhere but back to earth.
Getting usueability for lunar or at mars is only going to work if the refueling is of the same type of fuels that we can make at either places.
The moon we are hopefully for LH2 LOX but its not a confirmed thing for quantity that can be done.
The Mars is in a simular situation with the LCH4 Lox is a time and energy requirement to quantity needed that is the issue.

SpaceNut · 2021-08-18 19:11:50

boiloff post using starship cargo with no depot

Using the starship cargo to loft 150 Mt of fuels to a depot looks better and better every day as the cycles between launching of the bfr/ starship from 1 launch pad will mean a lot of boil off would occur to a waiting starship since after just 2 months and 2 cycles of fuel the issue is the header tanks will have dropped and the first load will only be 80mt of that first fueling....

Since we need 1200 Mt or so for a mars trip we will need to ensure that boiloff off is not an issue before we start the journey. So a load and go is what will be required from the depot to perform.

GW Johnson · 2021-08-21 12:22:00

Spacenut:

If you limit the payload sent to Mars, you can reduce the propellant that must be loaded in LEO to go there. The max payloads the Starship can take to Mars are bigger than what it can ferry up to LEO (about 170-180 tons), using my analysis assumptions and the best numbers I can find. Here's the data to Mars:

A summary of the results (masses in metric tons):

Trajectory Payload Propellant

Hohmann 353 1200

Faster 248 1200

Hohmann 150 686

Faster 150 879

These data came from my posting on "exrocketman" titled "Rocket Vehicle Performance Spreadsheet", and dated 9 Feb 2021. The rocket performance spreadsheet is the best one I have come up with yet. "Faster" refers to the 2-year abort trajectory, which features a 4.3 month one-way trip to Mars at average planetary distances. Hohmann is an 8.6 month one-way trip at average planetary distances. The 6 month trip favored recently lies between these two extremes.

GW

GW Johnson · 2021-08-22 09:30:33

The original topic of this thread was an on-orbit fuel depot in Earth orbit, presumably low Earth orbit (LEO). That would be near 300 km altitude, more-or-less eastward, not at high inclination (unlike the ISS). As long as the ISS is up there, we might want a second facility near or at the ISS. Or maybe not, I dunno.

The trick here is to figure out what exactly you want that low-inclination LEO facility to do, and just how you are going to keep it supplied.

First thing to do is "inventory" the types of propellant systems that are likely to visit low-inclination LEO. Ideally you should be able to serve them all.

There are the storable propellant combinations, which do not have boiloff problems or risks, and need no venting. Generally speaking there are two or three of these. From the US and the west, there are two. The oxidizer is nitrogen tetroxide (NTO), but there are a couple of hydrazines: Aerozine-50 and MMH. From the Russian side, there is the same NTO, and a hydrazine or hydrazine blend that I am not familiar with. That is what they have been bringing to the ISS for many years now. So you are looking at a bigger NTO storage tank, and two or maybe three different smaller hydrazine tanks.

The easiest technology to implement for all of these is the same as the tank systems in the vehicles that use them: bladdered tanks.

The cryogenic propellant combos do include a non-cryogenic material. That would be the kerosene in kerosene-LOX systems. In the US and west this would be the spec material RP-1. I don't know what the Russians use, but it should be similar enough to RP-1 to mix together. Kerosene is a room-temperature storable. So, we will need a bladdered tank for kerosene.

The rest of the liquid propellants are all cryogenic materials. Those would be liquid oxygen (LOX), liquid hydrogen (LH2), and liquid methane (LCH4). All of these suffer boiloff risks and require venting systems, at the very least. In all probability, each will require its own cryocooler, and probably its own re-liquification equipment to "recycle" the vented vapors.

The technologies in the vehicles that use these are always free-surface tanks that operate at a pressure above the vapor pressure of the material that is stored within, usually significantly above the triple point. As boiloff proceeds, tank pressure rises. Periodically, unless the propellant is used, you have to vent-off the excess vapor and do something with it.

I am not sure what the depot storage tank approach should be with these cryogenic materials. One option is the same free-surface tank technology as the vehicles that use it. The other might be some sort of "syringe"-like system, but probably not a bladder system, because venting is incompatible with bladders.

The free-surface option is simpler and supported by mature technologies, but requires ullage thrust for transfers. The "syringe" option avoids ullage thrust for transfers FROM the depot tank, but requires a cryogenic piston seal technology that is not yet mature and ready-to-apply. Venting via the piston would be difficult, but from the other end, not so difficult, and there are real problems with liquid vapor separation at the vent, wherever it is.

Balancing those considerations, ullage thrust is ALWAYS REQUIRED for transfers TO the depot tank, because the vehicles transferring propellant to the depot are equipped with free-surface tanks. Given that situation, my first inclination is to use the same free-surface tank technology in the depot. If you have to have ullage thrust for transfers TO the depot, then just use it for transfers FROM the depot.

So we are looking at an NTO bladder tank, 2 or 3 hydrazine blend bladdered tanks, a bladdered kerosene tank, a big free-surface LOX tank (or tanks), a smaller free-surface LH2 tank, and a smaller free-surface LCH4 tank, plus as-yet unspecified systems for providing ullage thrust down in the 0.001 gee range.

The (at least initial) concept for building up supplies would be to effect some sort of rendezvous between the depot and the vehicles or spent stages sent to LEO, so that unused propellants can be transferred to the depot. Thus over time inventories can be built up. This does impose some limitations on launch windows and mass ratios for vehicles sent to LEO, and it will also very probably require some sort of "space tug" propulsion on the depot to enable the rendezvous capability, as well as provide ullage thrust.

A side benefit of this is after unused propellant extraction, spent stages can ALWAYS be positively deorbited over the Pacific, unlike what the Chinese just recently did. But the deorbit thrust has to come from some as-yet unidentified source. Solid propellant cartridges come to mind, as the deorbit burn does not have to be all that precise (the Pacific is a big place). You need enough impulse to effect about a 100 m/s delta-vee.

I think there is a real opportunity here to do the in-space demonstrations of electric propulsion as the means of ullage thrust and "space tug" rendezvous capability for this depot facility.

For those not yet versed in the issues and nuances of tank technology, see http://exrocketman.blogspot.com, specifically "Propellant Ullage Problem And Solutions", dated 18 August 2021.

And now to the floor is open for others to contribute.

GW

Last edited by GW Johnson (2021-08-22 09:50:50)

GW Johnson · 2021-08-28 07:36:37

No one seems to want to contribute.

GW

tahanson43206 · 2021-08-28 08:11:01

For GW Johnson re #64

The talent pool currently available in the forum is small.

There are nearly 8 billion people ** out there ** on Earth these days. If there is someone you think would be interested in helping, and whose qualifications would complement yours, we (forum members) have the opportunity to extend an invitation.

If you would prefer to delegate responsibility for communication, please ask the four Administrator/Moderators for help.

There are no guarantees but on the other hand, it is certainly ** possible ** assistance might be forthcoming.

(th)

SpaceNut · 2021-08-28 11:33:48

Current starship has to with fleet quantities of boosters, tanker count and re-flight rates.

All we have is falcon 9 which has to turn out a second stage with engines every 2 weeks to achieve a 2 launches a month.

We are not even at a re-fly rate of 1 in a 2 month, so we have a long way to go for sending 2 cargo and a crewed to mars even when playing payload transit time games for fuel for each ship.

Void · 2021-08-28 20:55:35

GW Johnson,

I do have some notions. Of course it has not been my profession at all to deal with
these things.

I note that you seem to allow for electric propulsion on the depot.

I have been wondering about "Hot Gas Thrusters". The little that I have found on
the web suggests that they have an ignitor, and storage tanks, and solenoids to
simultaneously
activate the Oxygen and Fuel feed. If this is true, then they are
very much a departure from liquid engines, or of course solid engines.

Perhaps I will go down in flames for what I will suggest soon in this post, but
at least I flapped my wings and tried.

I see that you are sort of avoiding cryogenic propellants. I think you are doing well
to do as makes sense.

I understand that boil off is a very costly item in any mission plan.

But for the B.O. Blue Moon, they propose to route the boil off to fuel cells.
That is in interesting notion. Not the one that I am going to suggest, but to partially
get to my suggestion, I wonder if you did do that, could you route the water output
to a solar concentrator, and bring it to a very high temperature to emit as thrust?

That starts to get to what I am interested in. I anticipate that for electric propulsion
either solar or nuclear would be used. I am thinking that Nuclear Fission will be a hard
sell anywhere close to the Earth.

Where Solar Electric could be an option, can we think of "Really, Really hot gas thrusters"?
That is is we can have very light weight solar concentrators to heat up both the Oxygen
and fuel, can we then feed them to a hot gas thruster? Would we have an advantage doing that?

I don't know where the limits of utility might be in that sort of activity. But where I am
going is that if you know that you can move your depot to where you might want it, you may
anticipate that you can make the tanks larger, and expect a % of boil off, that can then
perhaps not go to waste.

A further consideration as concerns Starship in particular, is that it needs chilled
propellants, so in my mind, you either have to have active cooling, or pull a partial vacuum
on the propellent tanks, to chill the liquids down to SpaceX specs. This would be a very
nasty waste, unless you could use the vapor outputs to maximum advantage. I am hoping that
solar chemical may be the answer for that. Heat the vapors as much as can be productive,
convey them to a thruster, mix and ignite.

For these depots, I would not exclude the use of other propulsion methods as auxiliary, and
to be able to aero-burn. I am anticipating a depot that toggles from a LEO orbit to a height
excentric
orbit repeatedly. While the Earth is expected to be the original source of
propellants, we can perhaps think that it may be possible in the future that some propellants
would come from locations not of the Earth.

So, fill up LEO, boil off/Solar Electric to eccentric orbit, Starship stops off and gets more
Propellants and then on the the Moon, Mars, or whatever. Of course the Starship still has
to receive refueling prior to that in LEO. But with Solar hot gas thrusters, and solar
electric, good chemical fuels can be provided in deeper space than LEO.

The completion for the depot would be an alteration of orbit to allow grazing the Earth's
atmosphere in order to bring the depot back closer to LEO.

I would not have considered heating Oxygen to high temperatures, but I believe it is done in the Raptor engines. It seems to me that I learned that the Soviets had
achieved this while the Americans worked on the fuel side.

Well, that's about it for now.

Even if I am all the way wrong, I anticipate that there are things to learn in all of this.

You have been an instructor, from what I seem to have discovered.

Done.

Last edited by Void (2021-08-28 21:01:24)

Void · 2021-08-29 08:53:22

I guess until I am told to buzz off, I will continue.

Some things have occurred to me since the last post. I feel that an internal
combustion engine(s) should be included.

I presume that a solar shade will be included, which might also serve as an aerobraking
device and perhaps a solar concentrating mirror.

We have so much experience with internal combustion engines, and fuel cells are fussy.
I am not even sure that a fuel cell exists that is reliable for Methane and Oxygen.

The source of fuel for the internal combustion engine would be coupled with thermal
regulation of the Methane and Oxygen tanks. That would be done by gas "Draw Down", to
use evaporative cooling on the fluids.

As long, as the tanks are not fully filled with chilled propellants, it would not be
a problem to let the propellants warm up to just below boiling. However, as the tanks
got filled, it would be desirable to chill them down to SpaceX specs.

Where previously I thought to further heat the exhaust or propellant gasses further and
use them to do thrust bursts fairly close to the creation of the fluid gasses, I know
am aware the the primary exhaust outputs of the internal combustion motor would be
H20, and CO2, which may be possible to manage in storage as compressed gasses, liquids,
or solids. Both of these products could be useful in many different choices of ways.

Thrust, life support, product to sell to other users.

If it is to be used on demand for thrust, then there are many heating devices that can
add energy. I would really like to consider nuclear, but that will be to dangerous
near the Earth. Otherwise, unlike solar panels, an M/G set could be revved up from idle
to produce electric power to heat a propulsion fluid. Engine heat may also contribute.

Solar panels cannot be revved up, but a Motor/Generator set can be.

The internal combustion motors could also directly drive impellers/pumps.

There are technologies that can use electricity to heat up water for thrust. I would
think this could work for CO2.

Solar concentrating mirrors could also convert the fluids to very hot vapors to thrust
with.

One thing I hope may be useful would be centrifugal propellant tanks. The dry mass would
not spin, just the fluids of vapors and liquids.

This could be accomplished, perhaps by drawing off vapors from one end of the tank. An
impeller might be involved to reject liquids. Then at some part of the tank the pressurized
vapors would be input to the tank to induce both spin, and linear segregation. That is
I would not only want the fluids to be spun into a centrifugal spin, but it might be
possible to push the fluids more towards one end of the tanks, while it also spins. This
may work well enough to extract the fluids, and send them into a starship. It may also
make it easy to just take vapors out of the tanks.

A final thing to mention, for now, would be electric propulsion. Where a solar panel
mostly offers a relatively stead amount of electricity, to achieve that it has to be
oriented properly to the sun. It can also degrade in the space environment.

An M/G set could drive electric propulsion methods. It also could ramp up quite a lot, if
there are preferred times and locations in space where more or less propulsion is desired.

Done for now.

Last edited by Void (2021-08-29 08:58:00)

GW Johnson · 2021-08-31 09:57:27

Hi Void:

I wasn't avoiding cryogenic propellants, I was just pointing out that one has to handle them very differently from storables, because of the vapors created by boiloff. So far, the best option still appears to be free-surface tanks with application of ullage thrust to settle the globules into one end during the transfer.

You can use bladdered tanks for the storables, because there isn't any vapor formation to vent. You just apply gas pressure between the tank shell and bladder to squeeze the bladder. It works just like the squeeze bag of icing used when decorating a cake. But there is no way to do venting with that, and no ready-to-apply cryogenic bladder material technologies.

Let's see, a 10 metric ton facility would have an Earth weight of 98,100 N. To move that at 0.001 gee requires a thrust force near 98 N. If the electric thruster is, say, 100 milli-N at 1 KW power draw, we would need to fire up about a 1000 of them, or else build one 1000 times larger. So the power draw is 1000 times larger, for 1 MW.

That's awfully big. So I dunno about electric propulsion thrust. Gotta think more about that.

GW

SpaceNut · 2021-08-31 20:18:31

The electric would be I think for movement over time as you need yet another engine and fuels to make use of the ability of the ion format not just a large power wattage source.

tahanson43206 · 2021-09-01 05:39:36

For GW Johnson re #69

Google found this snippet that suggests there may exist an ion engine design able to deliver 5.4 Newtons ...

Ion Thruster Prototype Breaks Records in Tests, Could ... - Space.com
www.space.com › 38444-mars-thruster-design-breaks-records
Oct 13, 2017 · It generated 5.4 Newtons of thrust, which is the highest level of thrust achieved by any plasma thruster to date," added Gallimore, ...
Missing: vasimr | Must include:vasimr

I was trying to find a report on what VASIMR can achieve ...

If you needed 98 Newtons, then 25 of whatever this is would produce the thrust for electric ullage. Power can be solar in LEO.

The tanker/depot is a permanent fixture in LEO, so it can have as much solar power as needed.

(th)

Calliban · 2021-09-01 05:58:56

I would be amazed if it turned out that linear thrust was a more efficient method of providing gravity than rotation. Why not just design a fuel depot that can be spun up to 1E-3 g when the spacecraft docks with it? If you use an electric motor to spin a flywheel, then the spin will not need a drop of propellant. When transfer of propellant is completed, apply a brake to the flywheel and spin is reduced to zero through conservation of momentum. You would need only a very small electric motor and solar panel to make this work, and efficiency of the DC motor would be around 80%. You could even recover energy in a battery or hydraulic cylinder ready for next use.

Last edited by Calliban (2021-09-01 06:04:38)

tahanson43206 · 2021-09-01 06:09:02

For Calliban re #72

Please use imgur.com to store a png or jpg of your sketch of forces that would be at work in your design.

I can't tell from words how it would work, but (hopefully) a simple hand drawn sketch captured as a screenshot or phone image would make everything clear.

My expectation is that rotation would cause fluid to move to the outer edge of whatever configuration is planned, so that fuel would move away from the receiving vessel instead of toward it, but I am probably just not understanding your vision.

(th)

Calliban · 2021-09-01 07:14:04

TH, I will have a go at drawing something later. But think of it like this. We are attempting to transfer liquid propellant from one tank to another. Ideally, we would like to be able to do this without the complication of pumps, I.e we want to be able to drain one tank into another. The way to do this in normal gravity on Earth, would be to put the receiver tank beneath the donor tank and connect a hose between the bottom of the donor tank and the top of the receiver tank, so that gravity pulls liquid out of one tank into another. To equalise pressure, ullage gas from the bottom tank (which is filling up) must be transfered to the top (donor) tank, either through the hose, or through another connection between the tops of the tanks. So far, so good.

To do the same thing in space, using gravity produced by rotation, the same basic principle applies. To get a net flow from the donor tank in the fuel hub to the receiver tank in our Starship, the liquid level in the donor tank needs to be closer to the axis of rotation than the liquid level in the receiver tank. The only thing that complicates this arrangement compared to the same thing in Earth gravity, is that centre of gravity (and axis of rotation) will change as fluid is transfered from one tank to another. There needs to be enough ballast in the system to ensure that as one tank empties into another, the donor tank remains closer to the centre of rotation than the receiver tank. That can be done by adding enough static ballast to one side or another, or maybe something cleverer like a trim system, which would ensure that centre of mass stays in the middle as propellant is transfered.

As for the spinning arrangement: Angular momentum is conserved, just like all other forms of momentum. Imagine a spacecraft attached to an electric motor, with a weight attached to the other end of the electric motor. If you apply current to the electric motor, the weight will spin in one direction, the spacecraft will spin in the opposite. When you want to reduce spin to zero, just apply a brake between the spinning spacecraft and the counter rotating weight. As their angular momentum is equal and opposite, both will stop rotating, w.r.t each other and any external observer.

A rotating fuel hub like this, does not therefore need to expend propellant in order to transfer fluids from one tank to another. It should also be able to function without need for pumps, unless designers opt for a trimming system. There is no requirement for flexible or moving parts to come into contact with the cryogenic propellants. All propellant movements are accomplished by draining one tank into another by gravity, through solid stainless steel pipework.

One could in fact design a trimming system that adjusted centre of gravity using water, without any pumps. Imagine our refuelling hub is like a rotating disc. Along the circumference of the disc, we would mount water tanks. The bottom of each water tank would be connected to those either side of it, such that we have a ring of interconnected water tanks around the circumference. The Starship docks at one side of the disc, the refuelling tanks sit on the other. The disc is initially balanced, with centre of gravity in the middle and is spun up. As propellant drains from the refuelling tanks into the Starship, centre of gravity begins to shift away from the refuel tanks towards the Starship. When this happens, the spin axis will shift, moving towards the Starship. Water tanks on the Starship side will then be uphill compared to the other side. Water will then flow through pipes between the tanks until the centre of gravity returns to dead centre. No pumps needed. A passive, self-regulating system that keeps spin axis in the same place even as propellant is transfered.

Last edited by Calliban (2021-09-01 07:40:46)

Void · 2021-09-01 07:40:57

Without strong emotions:

Some Links: (Checking existing thinking to be found on the web)
https://en.wikipedia.org/wiki/Propellant_depot

There are quite a few. I have seen the idea of a double hull. I think that is so
that a vacuum insulation can be used to reduce absorption of heat.

Sunshade. Obviously a thing to consider.

I must dispute your statement here (th), from your post #71:
Quote:

The tanker/depot is a permanent fixture in LEO, so it can have as much
solar power as needed.

We should not limit the idea in that way. Lunar Starship, I believe is to be filled
in an elliptical orbit, perhaps as far out as the Van Allen belts at aphelion. I
intend that that means the furthest point of the orbit from the Earth.

I posted some materials, that I think may have been overlooked. I guess no reading
was done further back than GW's last post.

I feel I have some materials that should be considered. That does not indicate that
I think they are above discarding, but the progression of posts here make it seem
that the material was not even reviewed.

Depots could be in LEO, Eccentric orbits, near the Moon, particularly if propellants
can be lifted up from the Moon. It could also be possible to have Depots for Mars.

A Depot might also toggle between LEO and a Eccentric orbit.

My posts #67 and #68.

Among other things I proposed spinning the fluids in the depot tanks. An improvement
to that would be to have tanks that have a bit of taper. That way the liquids would
end up at one end of the tank. Simply using a centrifugal pump might work for that,
as you would be able to separate out the liquids and gasses. I am thinking that using
using the gasses is the preferred method.

Also, how do you chill the propellants to SpaceX specs? Mine consumes propellants, to provide energy, but it outputs water and CO2, which may have
uses and values.

Callaban,

I don't dispute the worth of considering your proposals. Pumps would add mass, but
so would a flywheel, which would need motors and controls, all being added mass.

Done.

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#51 2016-06-03 06:54:08

Re: On Orbit fuel depot

#52 2016-06-03 16:21:03

Re: On Orbit fuel depot

#53 2016-06-26 21:59:12

Re: On Orbit fuel depot

#54 2017-07-06 21:27:19

Re: On Orbit fuel depot

#55 2017-07-08 10:18:39

Re: On Orbit fuel depot

#56 2017-07-08 11:10:57

Re: On Orbit fuel depot

#57 2017-07-08 13:24:03

Re: On Orbit fuel depot

#58 2018-09-22 19:20:29

Re: On Orbit fuel depot

#59 2019-11-09 11:59:22

Re: On Orbit fuel depot

#60 2020-01-02 19:10:10

Re: On Orbit fuel depot

#61 2021-08-18 19:11:50

Re: On Orbit fuel depot

#62 2021-08-21 12:22:00

Re: On Orbit fuel depot

#63 2021-08-22 09:30:33

Re: On Orbit fuel depot

#64 2021-08-28 07:36:37

Re: On Orbit fuel depot

#65 2021-08-28 08:11:01

Re: On Orbit fuel depot

#66 2021-08-28 11:33:48

Re: On Orbit fuel depot

#67 2021-08-28 20:55:35

Re: On Orbit fuel depot

#68 2021-08-29 08:53:22

Re: On Orbit fuel depot

#69 2021-08-31 09:57:27

Re: On Orbit fuel depot

#70 2021-08-31 20:18:31

Re: On Orbit fuel depot

#71 2021-09-01 05:39:36

Re: On Orbit fuel depot

#72 2021-09-01 05:58:56

Re: On Orbit fuel depot

#73 2021-09-01 06:09:02

Re: On Orbit fuel depot

#74 2021-09-01 07:14:04

Re: On Orbit fuel depot

#75 2021-09-01 07:40:57

Re: On Orbit fuel depot

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