Author Topic: Cislunar Transporter, what do we know?  (Read 30515 times)

Offline Asteroza

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Re: CIS Lunar Transporter, what do we know?
« Reply #40 on: 05/26/2023 05:26 am »
Dumb Transporter question;

I would assume the baseline is LEO delivery by New Glenn, but is Lockheed beholden to Blue Origin for LEO delivery per se?
Especially if you launched it mostly empty?

Tankers to fill Transporter are essentially fungible as long as you have a solar powered cryocooler onboard the Transporter.
So, as long as you can RPOD a tanker vehicle to it, they could accept propellant deliveries from anyone.
Someone could even cheat and launch a water tanker and an electrolysis unit in theory, as long as you have the time to waste cracking water.

Offline TrevorMonty

Re: CIS Lunar Transporter, what do we know?
« Reply #41 on: 05/26/2023 07:05 am »
Dumb Transporter question;

I would assume the baseline is LEO delivery by New Glenn, but is Lockheed beholden to Blue Origin for LEO delivery per se?
Especially if you launched it mostly empty?

Tankers to fill Transporter are essentially fungible as long as you have a solar powered cryocooler onboard the Transporter.
So, as long as you can RPOD a tanker vehicle to it, they could accept propellant deliveries from anyone.
Someone could even cheat and launch a water tanker and an electrolysis unit in theory, as long as you have the time to waste cracking water.
Read old paper on LEO depot that converted water to Hydrolox. LEO wasn't great location, only had sunlight for just over half time and reflective heat from earth made it harder for cryocoolers.

Offline JCRM

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Re: CIS Lunar Transporter, what do we know?
« Reply #42 on: 05/26/2023 10:11 am »

Someone could even cheat and launch a water tanker and an electrolysis unit in theory, as long as you have the time to waste cracking water.
Put the solar-thermal cracking unit on the depot, and launch/transport/store the water in its solid phase until split.

Offline tea monster

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Re: CIS Lunar Transporter, what do we know?
« Reply #43 on: 05/26/2023 10:31 am »
Isn't the whole point of storing it as water that you don't have the cryogenic storage and subsequent boil-off and leak problems that you would have with liquid hydrogen?

The water could be sent up as a block of ice and just chuck a sunshade onto the tanker module.  Subsequent thawing out of the ice to water and then cracking it might be a lot less effort than keeping a full-time cryogenic storage facility running out at  the Gateway.

EDIT: Having a system to convert ice to fuel would be good practice for doing the same procedure on the surface of the moon with lunar ice. Eventually, when the lunar transport system matures, you could even supply the Gateway fuel depot with ice from the surface of the moon.
« Last Edit: 05/26/2023 10:35 am by tea monster »

Offline TrevorMonty

Re: CIS Lunar Transporter, what do we know?
« Reply #44 on: 05/26/2023 12:26 pm »
Isn't the whole point of storing it as water that you don't have the cryogenic storage and subsequent boil-off and leak problems that you would have with liquid hydrogen?

The water could be sent up as a block of ice and just chuck a sunshade onto the tanker module.  Subsequent thawing out of the ice to water and then cracking it might be a lot less effort than keeping a full-time cryogenic storage facility running out at  the Gateway.

EDIT: Having a system to convert ice to fuel would be good practice for doing the same procedure on the surface of the moon with lunar ice. Eventually, when the lunar transport system matures, you could even supply the Gateway fuel depot with ice from the surface of the moon.
If transporting water from LEO to Gateway still need a couple fuel launches to fuel tanker so it deliver water.

Offline DrHeywoodFloyd

Re: CIS Lunar Transporter, what do we know?
« Reply #45 on: 05/26/2023 12:31 pm »
Dumb Transporter question;

I would assume the baseline is LEO delivery by New Glenn, but is Lockheed beholden to Blue Origin for LEO delivery per se?
Especially if you launched it mostly empty?

Tankers to fill Transporter are essentially fungible as long as you have a solar powered cryocooler onboard the Transporter.
So, as long as you can RPOD a tanker vehicle to it, they could accept propellant deliveries from anyone.
Someone could even cheat and launch a water tanker and an electrolysis unit in theory, as long as you have the time to waste cracking water.
Read old paper on LEO depot that converted water to Hydrolox. LEO wasn't great location, only had sunlight for just over half time and reflective heat from earth made it harder for cryocoolers.

Would you be able to provide a link concerning "... Read old paper on LEO depot that converted water to Hydrolox..."

Surely it would not be cost effective to ship water up to LEO, and have to crack it into. it's component hydrogen and oxygen, because of the volumes involved? I would posit it would need huge solar arrays, that approx 50% of the time will not be generating electricity as depot would pass behind the Earth... I would posit that as the NG second stage is using BE-3U that use LOX and LH2, then logically it would be better transport up LH2 and LOX, but with bigger tanks... as for whether there would be a need for a cryocooler in LEO I would say not as posit that there would many resupply missions and so some boil off may be acceptable because the level of reflective heat coming from the Earth as was stated previously by another poster.

Offline tbellman

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Re: CIS Lunar Transporter, what do we know?
« Reply #46 on: 05/26/2023 03:04 pm »
Surely it would not be cost effective to ship water up to LEO, and have to crack it into. it's component hydrogen and oxygen, because of the volumes involved? I would posit it would need huge solar arrays, that approx 50% of the time will not be generating electricity as depot would pass behind the Earth... I would posit that as the NG second stage is using BE-3U that use LOX and LH2, then logically it would be better transport up LH2 and LOX, but with bigger tanks...

Indeed.  A hypotetical 100% efficient electrolyser needs 142 MJ per kilogram of hydrogen produced, but real-world electrolysers need around 180 MJ/kg or more.

If we go by TheRadicalModerate's estimate of 116 tonnes of hydrolox needed, and assume a 1:6 ratio (by mass) between hydrogen and oxygen needed (roughly typical for hydrolox rocket engines), that would require 3 TJ, or 830 MWh.  Allow half a year for electrolysing that, and assume you are in sunlight 67% of the time, and you would need 280 kW from your solar panels.  That's way more than what ISS has, for comparison.

And this with somewhat optimistic assumptions.

Note also that ~1:6 ratio between hydrogen and oxygen that engines want.  The output from the electrolysis is in a ration of 1:8.  This means that you will be lifting some 25-30% more mass than if you lifted hydrolox in the wanted ratio, or ~149 tonnes instead of ~116 tonnes.

Offline RDMM2081

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Re: CIS Lunar Transporter, what do we know?
« Reply #47 on: 05/26/2023 04:35 pm »
This is a very fun thread to daydream about. Can I just add how excited I am for the CT.  It sounds like quite possibly the first true "Space Ship". At least the first one which, at least theoretically, is intended to be reused in space indefinitely. Picturing this thing making multiple trips between LEO and NRHO for fueling runs just tickles all the SciFi bits for me.  Will be very fun to watch it evolve, and hear about the mission dynamics, conops, engineering trades, capabilities, and finally watch it fly!

Offline TrevorMonty

Re: CIS Lunar Transporter, what do we know?
« Reply #48 on: 05/26/2023 06:13 pm »
Surely it would not be cost effective to ship water up to LEO, and have to crack it into. it's component hydrogen and oxygen, because of the volumes involved? I would posit it would need huge solar arrays, that approx 50% of the time will not be generating electricity as depot would pass behind the Earth... I would posit that as the NG second stage is using BE-3U that use LOX and LH2, then logically it would be better transport up LH2 and LOX, but with bigger tanks...

Indeed.  A hypotetical 100% efficient electrolyser needs 142 MJ per kilogram of hydrogen produced, but real-world electrolysers need around 180 MJ/kg or more.

If we go by TheRadicalModerate's estimate of 116 tonnes of hydrolox needed, and assume a 1:6 ratio (by mass) between hydrogen and oxygen needed (roughly typical for hydrolox rocket engines), that would require 3 TJ, or 830 MWh.  Allow half a year for electrolysing that, and assume you are in sunlight 67% of the time, and you would need 280 kW from your solar panels.  That's way more than what ISS has, for comparison.

And this with somewhat optimistic assumptions.

Note also that ~1:6 ratio between hydrogen and oxygen that engines want.  The output from the electrolysis is in a ration of 1:8.  This means that you will be lifting some 25-30% more mass than if you lifted hydrolox in the wanted ratio, or ~149 tonnes instead of ~116 tonnes.
If we get to stage that lunar Hydrolox is cheap enough to supply LEO, there would still be case for launching LH2 to use up surplus LOX.


Offline punder

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Re: CIS Lunar Transporter, what do we know?
« Reply #49 on: 05/26/2023 06:25 pm »
If we get to stage that lunar Hydrolox is cheap enough to supply LEO, there would still be case for launching LH2 to use up surplus LOX.
Or sell it to others as propellant, chemical feedstock, etc.

Offline JCRM

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Re: CIS Lunar Transporter, what do we know?
« Reply #50 on: 05/26/2023 07:59 pm »
Surely it would not be cost effective to ship water up to LEO, and have to crack it into. it's component hydrogen and oxygen, because of the volumes involved?
Water is denser than hydrogen and oxygen.
Quote
I would posit it would need huge solar arrays, that approx 50% of the time will not be generating electricity as depot would pass behind the Earth...
and that's a problem because?
Depots tend to have nothing *but* time




Indeed.  A hypotetical 100% efficient electrolyser needs 142 MJ per kilogram of hydrogen produced, but real-world electrolysers need around 180 MJ/kg or more.

I did say solar thermal, not solar-electric, but yes, it still needs a lot of sunlight.
[/quote]
Quote
and assume a 1:6 ratio (by mass) between hydrogen and oxygen needed (roughly typical for hydrolox rocket engines),
Or let's not.

If you can think of no other uses for the oxygen in orbit, design the engine to burn the propellant stoichiometrically, and take the performance hit, which is far less than the hit for discarding the extra oxygen.

Quote
that would require 3 TJ, or 830 MWh.  Allow half a year for electrolysing that, and assume you are in sunlight 67% of the time, and you would need 280 kW from your solar panels.  That's way more than what ISS has, for comparison.
It needs around half the collection area for thermal than electric, and luckily Mylar parabolas are cheap and lightweight.

The biggest advantage, is solid water is both inert and sloshless.  A minor one  is at some future point in time ice mining may stop being a sci-fi trope.

I wish I could take the credit for the idea, but it's all NASA's, having the Mars Gateway supplied with water by commercial cargo providers;

Offline TheRadicalModerate

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Re: CIS Lunar Transporter, what do we know?
« Reply #51 on: 05/26/2023 09:59 pm »
So here's a different, possibly stupid, architecture:  What if you launched the CT "bus", with the propulsion/thrust structure, avionics, IVF¹-like stuff, RCS, and a few hundred m/s worth of delta-v, and then launched a set (or sets) of dumb tanks to mate with it?

I blundered into this one thinking about how you get a really high capacity CT launched with the engine bells taking up lots of volume, which would have been much better used for LH2 tanks.  The only solution to that problem I could think of was to launch the whole CT upside-down, which I think probably violates the center-of-mass height limitation for almost any launcher out there, and almost certainly adds a bunch of tank stringer mass to stiffen the the tanks to support launch stresses coming from the thrust structure vibrating at the top.

But if you launch the bus and the tanks separately, none of those structural things is a problem.  You also get the following very nice properties:

1) You can make the tanks in several different sizes, to suit mission requirements.  120t-capacity tanks for Blue Moon launch easily on a New Glenn.  If you have a nuke you're servicing, you can make the biggest possible LH2 tank you want.  If you're building a GEO satellite servicer, you can make smaller tanks to enhance maneuverability, and you can put grappling and servicing payloads on the top of the tanks.  Same thing for Blue Moon non-hydrolox consumables and deployable payloads.

2) A tank that doesn't have to support managing vibrations from the bus needs less pressure-stabilization, which makes it thinner and lighter.  There's some minimum pressure that the RL10 or BE-7 impellers need to avoid cavitation, but that pressure is almost certainly lower than what you need to get an integrated vehicle to survive launch.  And thrust loads for the CT in space are very small.

3) If you have a common docking and prop transfer interface, the CT can pop the tank off the bus and it can be berthed to the Blue Moon, reducing risk.  (This obviously assumes an arm on the Gateway.)

4) You could stack tanks together.  This might obviate the need for New Glenn to implement refueling at all:  It could just launch a pre-filled tank, dock it to either the bus or a previously-launched tank, and it's done.  It's not like you need giant downcomers to run a 50kN-100kN hydrolox engine.  It's not the most dry-mass-efficient architecture, but the way the numbers are working out, the CT has about 15t of extra wet mass to play with before it risks needing more than 3 NG launches.  If modular architecture costs a couple extra tonnes, things should still close.  And if the tanks are cheap to make, the CT could just discard them and go back to LEO propulsively.

5) If you want reusable tanks, modularity might make aerobraking easier.  If the CT pops the tanks off, the tanks can aerobrake easily, while the bus itself can do a propulsive braking back into LEO for a tiny amount of prop.  That would improve the CT duty cycle, if they get enough demand that the duty cycle needs improving.

6) If you ever do build a lunar hydrolox operation (by launching water off the Moon and electrolyzing it in NRHO), then the ability to pop tanks on and off makes the logistics a lot cleaner.  And you could build a tank variant with enough shielding to make aerobraking a full tank into LEO easy.

7) And the ever-present political angle, in hopes of finding an acceptable way to kill SLS:  You know who knows how to make hydrolox tanks pretty well?  Boeing.²

Note that there's nothing that requires that you launch the bus and the tanks separately; if they fit easily, no problem.  But if you need huge tanks, you can easily launch the bus separately on almost any commercial medium-lifter.
__________
¹Integrated Vehicle Fluids, the key technology package for ACES, and the thing they mostly didn't implement for Centaur V.  There was a hydrolox-fueled internal combustion engine that powered a wide variety of accessories, including a cryocooler, pressurized gaseous H2/O2 for thrusters, ullage pressurization, a generator to charge batteries or directly power stuff, etc.  Once again, I'm assuming that LockMart buys ULA.

²And they hardly ever drop LOX domes!

Online deadman1204

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Re: CIS Lunar Transporter, what do we know?
« Reply #52 on: 05/27/2023 12:57 am »
Water ice has a larger volume than liquid ice. So storing it as ice is not ideal.
As well, your not gonna be cracking it as a solid. That makes it to difficult to handle.
As well, sunlight is 500 degrees in space. So still gonna need serious cooling no matter what your doing.

Offline Hug

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Re: CIS Lunar Transporter, what do we know?
« Reply #53 on: 05/28/2023 02:54 am »
Looking at the case where the architecture is extended so that the transfer vehicle returns to LEO to be refueled the propellant requirement increases to 170 tonnes in LEO with a proportional increase in dry mass to around 20 tonnes.

Now those are some interesting numbers, because that's around about what is expected for New Glenn Second Stage. Obviously the numbers have a bit of play given your stated 23 ton dry mass, but these numbers are getting to the point where it's not easy to fit in the fairing; it's the size of the second stage itself.

So Lunar Clipper is Blue's reusable Glenn hydrogen upper stage that they want to send to the Moon. The theoretical mass of Cislunar Transporter lines up with what you would roughly expect* of Lunar Clipper and Lunar Clipper would be suited to fill this role. It also doesn't really make sense for Blue and Lockheed to develop these two systems simultaneously (assuming that Lunar Clipper is still happening) because it would be borderline redundant for Blue. And like, how much pertinent experience does Lockheed have with large aerobreaking ZBO hydrogen stages that Blue won't have spades more of?

But why would they declare it's Lockheed project if it is so much Blue underneath? And here I have to go borderline conspiracy theory; Blue don't want to handle discussion of that program yet so they hid under a Lockheed umbrella. I mean they still have yet to officially announce even Clipper. Or maybe it's more of a derivation or alternate version + program setup makes it look good to NASA to have Lockheed lead the separate element?

*A little bit on the low side; but you could underfill it + margin.

Next thought:  It could be an NG S2 variant.  But:

1) LockMart would hate that.  They're gonna want to go into the orbital prop business big-time, and the last thing they want is to be completely dependent on Blue technology.
To this I would say that Blue is prime and spending like $4 billions (min) of Bezos money on this, I would imagine Bezos wants the majority of that to stay within his own company. And it's their architecture to decide not Lockheed's. I mean hell they appear to be doing a lot of the crew cabin work now as well.

Now I am biased, because this is what I thought it would be before the announcement; so I could just be letting cope blind me. But I think it's reasonable.
« Last Edit: 05/28/2023 02:56 am by Hug »

Offline TheRadicalModerate

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Re: CIS Lunar Transporter, what do we know?
« Reply #54 on: 05/28/2023 03:29 am »
Next thought:  It could be an NG S2 variant.  But:

1) LockMart would hate that.  They're gonna want to go into the orbital prop business big-time, and the last thing they want is to be completely dependent on Blue technology.
To this I would say that Blue is prime and spending like $4 billions (min) of Bezos money on this, I would imagine Bezos wants the majority of that to stay within his own company. And it's their architecture to decide not Lockheed's. I mean hell they appear to be doing a lot of the crew cabin work now as well.

Now I am biased, because this is what I thought it would be before the announcement; so I could just be letting cope blind me. But I think it's reasonable.

Blue's pretty much obligated to build what they bid, and the bid says that LockMart is building the CT.  Jeff's now in a position where he has to execute, or it's all over.  If LockMart can take that engineering off his plate, he'll be happy to let them.

Now, I wouldn't be incredibly surprised if LockMart (presumably) gobbling up ULA was only the first step.  The BE-4 deal is a thorn in both Blue's and ULA's side, and the thorn will be transferred to LockMart if they do indeed eat ULA.  So a Blue/LockMart Space merger/acquisition/spinoff/what-have-you isn't beyond the realm of possibility.

But long before any subsequent merger, I think Tory's been hot to trot on doing ACES for real for a while, and I think he's talked LockMart into believing it's a good idea.  That's a lot of tech that Blue doesn't need to worry about.  However, unlike Blue, LockMart knows just how to sell it to the military.

Offline Hug

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Re: CIS Lunar Transporter, what do we know?
« Reply #55 on: 05/28/2023 05:46 am »
They certainly did say that Lockheed was leading and building/what not, but without specifics I just feel like it gives enough room for Blue to be involved. I mean technically, SLS is NASA's rocket despite most things being built by contractors. The thing with ULA is is that we didn't get much out of Blue before the announcement; but the one thing we did get was a list of contractors. And there isn't any mention of ULA on that list (as far as I'm aware). And I feel like if they were going to be used in any major capacity they would've had to be included.

Offline JCRM

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Re: CIS Lunar Transporter, what do we know?
« Reply #56 on: 05/28/2023 11:33 am »
Water ice has a larger volume than liquid ice.
And? solid water is denser than the equivalent liquid hydrogen and liquid oxygen, so what's the problem?
Quote
So storing it as ice is not ideal.
stores easily. the only difficult part is if liquid water turns solid while it's being stored



Quote
As well, sunlight is 500 degrees in space. So still gonna need serious cooling no matter what your doing.
Put it in a cardboard tube painted solar white, and give it a gentle roll. Stays solid.

Quote
As well, your not gonna be cracking it as a solid. That makes it to difficult to handle.
How? sure, the lack of convection makes melting ice slower, but neither time or heat heat are a problem at a depot. Take the ice bag out of the white cardboard tube, and put it in a Mylar box with an opening facing the sun
« Last Edit: 05/31/2023 08:35 am by JCRM »

Offline Greg Hullender

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Re: CIS Lunar Transporter, what do we know?
« Reply #57 on: 05/28/2023 02:48 pm »
As well, sunlight is 500 degrees in space. So still gonna need serious cooling no matter what your doing.
Where do you get this? I figure the blackbody temperature at Earth's distance from the sun to be 279 K or about 42° F.

Obviously real materials will vary a lot, but I don't see how you can say 500 degrees.

Offline Steven Pietrobon

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Re: CIS Lunar Transporter, what do we know?
« Reply #58 on: 05/30/2023 08:05 am »
And? solid water is denser than liquid oxygen, so what's the problem?

Sorry. LOX has a density of 1.149 kg/L, which is greater than the density of water ice at 0.917 kg/L.

https://www.govinfo.gov/content/pkg/GOVPUB-C13-26d428ad4ca587866a90da5f71b4a727/pdf/GOVPUB-C13-26d428ad4ca587866a90da5f71b4a727.pdf
https://en.wikipedia.org/wiki/Ice
« Last Edit: 05/30/2023 08:08 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline TheRadicalModerate

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Re: CIS Lunar Transporter, what do we know?
« Reply #59 on: 05/30/2023 09:20 pm »
And? solid water is denser than liquid oxygen, so what's the problem?

Sorry. LOX has a density of 1.149 kg/L, which is greater than the density of water ice at 0.917 kg/L.

https://www.govinfo.gov/content/pkg/GOVPUB-C13-26d428ad4ca587866a90da5f71b4a727/pdf/GOVPUB-C13-26d428ad4ca587866a90da5f71b4a727.pdf
https://en.wikipedia.org/wiki/Ice

Nothing wrong with answering a non-sequitur based on bad data with good data, but it doesn't really change the fact that it was a non-sequitur in the first place.

We entertain bad ideas, ideas with bad supporting evidence, and off-topic ideas all the time here.  But it's better when only 2 out of 3 of those things are true.

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