Starship Artemis Contract & Lunar Starship

[spacenut]

I believe the "depot" Starship will have all connections needed as well as shading if needed and solar panels for refrigeration of boil off.  Not that hard to do.  Then the Lunar Starship can refuel and go on it's way.  There will probably be another refueling Starship depot in lunar orbit or at least at the LL1 location for not only the moon but for Mars if needed.  Like what was said, all Starships outgoing Starships will not have to be changed.  There will be depots, tankers, cargo, satellite launchers, and human rated Starships, all modified for it's particular use.  The way they have built Starship, it can be completely modular. 

[Paul451]

There will probably be another refueling Starship depot in lunar orbit or at least at the LL1 location for not only the moon but for Mars if needed.

It probably doesn't make sense to have a "depot" in lunar orbit (or L1/2, or NRHO or wherever). But rather, a non-EDL tanker-depot that to moves propellant betwixt Earth orbit and lunar orbit. Having all the depot-like features lets you take a longer, easier trajectory to the moon and back without losing excess prop versus a regular EDL tanker.

Of course, this reinforces the point about modularity, being able to mix'n'match different features for different ships in different roles.

[DanClemmensen]

There will probably be another refueling Starship depot in lunar orbit or at least at the LL1 location for not only the moon but for Mars if needed.

It probably doesn't make sense to have a "depot" in lunar orbit (or L1/2, or NRHO or wherever). But rather, a non-EDL tanker-depot that to moves propellant betwixt Earth orbit and lunar orbit. Having all the depot-like features lets you take a longer, easier trajectory to the moon and back without losing excess prop versus a regular EDL tanker. Presumably this has been discussed in the refuelling thread (which is a thing that really exists and should be used.)

Of course, this reinforces the point about modularity, being able to mix'n'match different features for different ships in different roles.

The term "depot" limits our thinking. The hardware is a non-EDL fuel transport Ship. "Depot" is a role the Ship takes if it stays in a single orbit. That same Ship can carry fuel to other locations.

[sdsds]

Right now it is unclear if the NASA-led HLS effort will ever progress to a 'sustainable' architecture. For the currently planned HLS missions no propellant refilling is required in the cis-lunar vicinity. At most a refilling may be needed in a highly elliptical Earth orbit. I believe (but cannot prove) that for each HLS mission SpaceX plans to first fill a depot in LEO. That depot will propel itself (and some extra prop) to HEEO, where the extra prop will be transferred to an outbound HLS.

The idea that depots move themselves around doesn't mean they aren't depots, and moving prop between depots is not needed for currently contemplated HLS missions.

[OTV Booster]

Help me understand how the qd will do this?
Back to back the ports will not line up. Ie methane will correspond not to a methane port but a lox. Then the male female concern
What am I missing here?


Edit  to add
I suppose valves and a purge would help but the m/f port leaves questions

You are not missing anything. The existing QD port is not androgynous. This means that you cannot mate two "ordinary" Starships. That in turn means that there must be another type of ship that can mate with "ordinary" Starships, OR that you must employ adaptor hardware. I feel that the simplest approach is to build a Depot that can mate with "ordinary" ships. The Depot would have an "ordinary" QD port in the usual place, but it would also have a separate SQD port like the one on the tower, probably on the opposite side of the Ship.

I think it could be better to have a second QD port with switched gender a bit lower on the depot and the docking ports also a bit lower so to match the distance between the two of the QDs. This way, when ship and depot dock together the QD on the ship mates with the lower QD on the depot. This way you minimize plumbings between the QDs with minimal structural differences. What do you think about it?

Edit to add: this way you only modify the design of the docking ports on depots, which will be waaay less than ships and tankers...

Yes, all modifications are on Depot, none on "ordinary" Ship.
But, Depot must launch when stacked on SH at the pad, never to return. Therefore, it must have an "ordinary" QD port in the standard place. The special Depot "SQD" port may be anywhere convenient as long as it can be mated to another Ship's "ordinary" QD after SHip docks to Depot.

I still like the idea of a single mirrored QD on the depot and using a gender bender on the ground side QD. This saves mass and plumbing complexity.


Depot launches will be infrequent so installing a gender bender on the GSE won't have all that much impact on launch tempo. The mirror QD will throw a kink into fabrication but again, depots promise to be a very small part of the overall production.

[OTV Booster]

Refueling in space will doom Starship getting to the Moon before Chinese do..
Nothing will change and will take a miracle over come needless and basically useless concept and will slip further and further behind.. Should have applied modernized KI.S.S, Apollo era straight to the point that worked.. This won`t as too many things easy to go wrong and 1 missed refueling or worse,, Mission done for..
Good fortune trying..

The SS system architecture, including refueling, was already set when the HLS contract was let. The reasoning on the low SX bid was that the system they were already building would be capable of doing a moon landing with only the lander itself being a somewhat custom build, and the overall operational plan being flexible enough to adapt.


NASA could have rejected the bid as being too technically immature but they didn't. If you look close at the commercial programs NASA has introduced, they have always promoted the idea that NASA would be only one of many users. SpaceX is the only company to turn this ideal into a reality. Blue will most likely follow.

[OTV Booster]

Gents,
    refueling pro/con...  androgynous...  location of the QD... honestly it's been discussed at length before.  Please take that discussion to the refueling thread if you don't mind.

Asking again....
Has anyone seen an image with the docking cones for refueling AND the HLS cosine thrusters?  Or do they somehow not exist together on the lander?

Haven't seen it, but not to worry. Neither has made it to prototype yet and in the finest of SpaceX traditions, may look quite a bit different when they show up.

[meekGee]

I still like the idea of a single mirrored QD on the depot and using a gender bender on the ground side QD. This saves mass and plumbing complexity.

Depot launches will be infrequent so installing a gender bender on the GSE won't have all that much impact on launch tempo. The mirror QD will throw a kink into fabrication but again, depots promise to be a very small part of the overall production.

I like that too, but we're focusing too much on the connectors/ports and not on what lies within.

I am not sure if it's ideal to use the same set of plumbing for onloading and offloading, for 0-g and for 1-g, for fast transfer and for slow transfer, even for full-tank vs partial-tank.

And possibly if it's advantageous/necessary to tap off different places on the tanks, it might dictate more ports.

Not saying it's necessarily so, just that the port solution is tied to the overall plumbing problem.

(Rant) How come in no Sci-Fi ever is there mention of fuel slosh, evaporation and collapse, or even pressurization?   Hell even in the fusion powered super high thrust drives of the expanse, nobody thought about what happens when you execute a sharp maneuver and half your propellant slams against the far wall at many meters per second... (/Rant)

[jarmumd]

Gents,
    refueling pro/con...  androgynous...  location of the QD... honestly it's been discussed at length before.  Please take that discussion to the refueling thread if you don't mind.

Asking again....
Has anyone seen an image with the docking cones for refueling AND the HLS cosine thrusters?  Or do they somehow not exist together on the lander?

Haven't seen it, but not to worry. Neither has made it to prototype yet and in the finest of SpaceX traditions, may look quite a bit different when they show up.

Yeah, that's fair.  I guess it just seems like they are in the same spot?  Construction photos of the latest ships show the docking cones right above the tank, just below the pez-dispenser.  Seems like the HLS cosine landing thrusters are in the same spot, right above the tank, just below the crew elevator.  I guess I'm trying to figure out if the cones would go above the thrusters?  Would they go on the back away from the elevator, and maybe change the thruster locations?

[Paul451]

Pics

Haven't seen the aft end of the system, nor the male version, nor the... [shrug] docking sensor box between the rear legs.

[OTV Booster]

I still like the idea of a single mirrored QD on the depot and using a gender bender on the ground side QD. This saves mass and plumbing complexity.

Depot launches will be infrequent so installing a gender bender on the GSE won't have all that much impact on launch tempo. The mirror QD will throw a kink into fabrication but again, depots promise to be a very small part of the overall production.

I like that too, but we're focusing too much on the connectors/ports and not on what lies within.

I am not sure if it's ideal to use the same set of plumbing for onloading and offloading, for 0-g and for 1-g, for fast transfer and for slow transfer, even for full-tank vs partial-tank.

And possibly if it's advantageous/necessary to tap off different places on the tanks, it might dictate more ports.

Not saying it's necessarily so, just that the port solution is tied to the overall plumbing problem.

(Rant) How come in no Sci-Fi ever is there mention of fuel slosh, evaporation and collapse, or even pressurization?   Hell even in the fusion powered super high thrust drives of the expanse, nobody thought about what happens when you execute a sharp maneuver and half your propellant slams against the far wall at many meters per second... (/Rant)

Well duh! They use a transporter to put the fuel where they want it. 

[OTV Booster]

Gents,
    refueling pro/con...  androgynous...  location of the QD... honestly it's been discussed at length before.  Please take that discussion to the refueling thread if you don't mind.

Asking again....
Has anyone seen an image with the docking cones for refueling AND the HLS cosine thrusters?  Or do they somehow not exist together on the lander?

Haven't seen it, but not to worry. Neither has made it to prototype yet and in the finest of SpaceX traditions, may look quite a bit different when they show up.

Yeah, that's fair.  I guess it just seems like they are in the same spot?  Construction photos of the latest ships show the docking cones right above the tank, just below the pez-dispenser.  Seems like the HLS cosine landing thrusters are in the same spot, right above the tank, just below the crew elevator.  I guess I'm trying to figure out if the cones would go above the thrusters?  Would they go on the back away from the elevator, and maybe change the thruster locations?

With all the wacky stuff they make work they may use an engine bell as a docking cone.


More seriously, the engineering crew is probably scratching their head over the question and are waiting for some real data to see what structural leeway they have. Something like an actual docking with strain gauges plastered all over the place.


Along those lines we may see a crane tethered and supported hover test with landing engines and/or an orbital build with some landing engines to see what leeway they have on that end of the problem. Inch by inch. Step by step...

[OTV Booster]

I still like the idea of a single mirrored QD on the depot and using a gender bender on the ground side QD. This saves mass and plumbing complexity.

Depot launches will be infrequent so installing a gender bender on the GSE won't have all that much impact on launch tempo. The mirror QD will throw a kink into fabrication but again, depots promise to be a very small part of the overall production.

I like that too, but we're focusing too much on the connectors/ports and not on what lies within.

I am not sure if it's ideal to use the same set of plumbing for onloading and offloading, for 0-g and for 1-g, for fast transfer and for slow transfer, even for full-tank vs partial-tank.

And possibly if it's advantageous/necessary to tap off different places on the tanks, it might dictate more ports.

Not saying it's necessarily so, just that the port solution is tied to the overall plumbing problem.

(Rant) How come in no Sci-Fi ever is there mention of fuel slosh, evaporation and collapse, or even pressurization?   Hell even in the fusion powered super high thrust drives of the expanse, nobody thought about what happens when you execute a sharp maneuver and half your propellant slams against the far wall at many meters per second... (/Rant)

Once there is enough acceleration to keep the propellant settled ISTM a lot of problems go away. If they need to tap off at different levels (because of ice?) a stand pipe would be lighter and less complicated than multiple GSE ports (if I understand you correctly). As for different plumbing for GSE and SSE (Space Support Equipment tm), once it's settled, pressure would be a reasonable analog for 1g flow - but yeah, ya got to do it to really know.

Methinks a key element in the transfer will be getting all maneuvering except settling acceleration finished and the propellant slosh damped before the transfer starts. Hmm, maybe that's not possible. They may have to do continuous reorientation for thermal reasons. If its not one damned thing, it's another.

Maybe if the linked ships do a rotisserie rotation (yeah, try that with a Sun shade) it will overcome the 90 minute orbital influence. It'd be ugly but reasonably predictable. Let 'er flow but not slosh. Never fight the changing CoM, work with it. Might have to stop and do a reset periodically.

Minimizing settling acceleration to save propellant has been a constant theme that sounds reasonable, but is it? Assuming the transfer is at VLEO (or maybe VVLEO) and the acceleration is prograde, the propellent is being moved in the direction it ultimately has to go. There would be a lot of parasitic mass being dragged along but as the depot fills the proportion of dry mass goes down. Sounds like an argument for the highest ISP maneuvering engines they can come up with. And an argument for dropping the main engine count on the already highly specialized depot build.

[TheRadicalModerate]

Gents,
    refueling pro/con...  androgynous...  location of the QD... honestly it's been discussed at length before.  Please take that discussion to the refueling thread if you don't mind.

Asking again....
Has anyone seen an image with the docking cones for refueling AND the HLS cosine thrusters?  Or do they somehow not exist together on the lander?

Haven't seen it, but not to worry. Neither has made it to prototype yet and in the finest of SpaceX traditions, may look quite a bit different when they show up.

Yeah, that's fair.  I guess it just seems like they are in the same spot?  Construction photos of the latest ships show the docking cones right above the tank, just below the pez-dispenser.  Seems like the HLS cosine landing thrusters are in the same spot, right above the tank, just below the crew elevator.  I guess I'm trying to figure out if the cones would go above the thrusters?  Would they go on the back away from the elevator, and maybe change the thruster locations?

The cones need to go on the dorsal side.  No clue the angular separation, but I'd be surprised if it was more than 20º.  The wider they are, the tighter the tolerances on how close to simultaneously all four probes have to be hitting the cones, no?

The thrusters can be mounted anywhere along that angular arc.  I don't see why the cones would have an impingement problem.

We've seen so little testing of possible thruster systems that I think they must be planning on using SuperDracos for Option A.  Landing mass should be somewhere around 300t with the ascent prop.  I've been figuring the Raptor shutdown height as 100m, with -10m/s residual velocity.¹  That yields about 710kN of thrust, which is 10 SDs, arranged in 5 pods, 70º apart.  Shouldn't be too hard to keep them out of the way of the drogues.

The potential fly in the ointment is they also need SDs for initial ascent.  If they fix the backflow bug, there's no layout problem.  But if they don't fix the bug, and they need 8 separate SDs to get the HLS high enough to start the Raptors without FOD risk, now you're looking at 9 pods, 40º apart.

That would be getting a little crowded.

__________
¹I'm too lazy to graph this, but you can trade higher thrust for a shorter burn time.  But to do that, you can't be hovering at 100m.  It'll take forever to get the HLS to fall that far.  Hence the -10m/s velocity.

[meekGee]

Once there is enough acceleration to keep the propellant settled ISTM a lot of problems go away. If they need to tap off at different levels (because of ice?) a stand pipe would be lighter and less complicated than multiple GSE ports.

Probably true.  It's my favorite route too.  Especially with co-aligned staggered docking.

That decision will drive internal plumbing, and internal plumbing will drive external ports.

E.g. staggered docking might call for dual ports, again depending on the internals.

[TheRadicalModerate]

Once there is enough acceleration to keep the propellant settled ISTM a lot of problems go away.

You need to deal with slosh during docking.  Even if the prop is settled all the way in the -z or -x direction, the moment that the Starship needs to adjust attitude, or brake before contact, all the prop is coming unglued, and will likely slam into an inconvenient surface just as capture is occurring.  For a tanker, we're talking about >100t of prop here, so even a tiny Δv is going to result in a big force when things hit the far wall.

We should consider the possibility that most available prop (except a couple of tonnes) may need to be in a header tank, if the Starship is to be the active vehicle during docking.  What would this mean?

1) Tankers would need to keep the prop load in a 100t header tank.  That's a fair amount of parasitic mass, but it does have the nice property that the tank is also a dewar, which would eliminate all boiloff concerns.

2) Depots have wildly different mass profiles at different parts of the accumulation cycle, so they have to be passive.

3) HLS Starships are a weird case.  Ideally, they'd launch full, which would reduce the amount of prop the depot needed to accumulate.  But if they're still pretty full and they're the active vehicle to the depot's passive vehicle, then they slosh.  So maybe they're fueled with exactly the amount of prop that gets them to RPO with the depot, with the 'D' then performed with an almost-empty Ship?

4) This also has a big impact on any D2 + HLS + HLS replacement scheme for SLS/Orion.  In that case, both HLS Starships will have a lot of prop, so the slosh is going to be a big deal during docking--and the docking is occurring in lunar orbit, where an accident is even worse than in LEO.  The same will also be a problem if the HLS Starship has to dock with the Gateway, which is clearly going to be the passive vehicle.

This might be another situation where carrying a D2 on the nose could be beneficial:  HLS Starship would never dock with anything except a D2 or Orion, both of which are the active vehicle and easy to control without slosh.  You could also leave the HLS Starship stood-off from the Gateway, using the D2 to ferry the crew, but this fails to meet some of the SLT requirements.

[Paul451]

The cones need to go on the dorsal side.  No clue the angular separation, but I'd be surprised if it was more than 20º.  The wider they are, the tighter the tolerances on how close to simultaneously all four probes have to be hitting the cones, no?

Pixel-counting the image above, the distance between the cones (centre/centre) is almost exactly half the width of the ship, ~4.5m. So the the cones would be about 30º apart.

Arbitrarily assuming the legs are 1.5m further from the CoM of the male ship, they'll have a 25º arc-angle at the tips (relative to the CoM), but the same 4.5m gap.

Looking at the image, I doubt you could go wider without hitting internal plumbing/spacing issues. They could have gone narrower, however, which perhaps suggests that more width is better, either for docking alignment/control authority, or for stability after docking during thrust/xfer?

[TheRadicalModerate]

The cones need to go on the dorsal side.  No clue the angular separation, but I'd be surprised if it was more than 20º.  The wider they are, the tighter the tolerances on how close to simultaneously all four probes have to be hitting the cones, no?

Pixel-counting the image above, the distance between the cones (centre/centre) is almost exactly half the width of the ship, ~4.5m. So the the cones would be about 30º apart.

Arbitrarily assuming the legs are 1.5m further from the CoM of the male ship, they'll have a 25º arc-angle at the tips (relative to the CoM), but the same 4.5m gap.

Looking at the image, I doubt you could go wider without hitting internal plumbing/spacing issues. They could have gone narrower, however, which perhaps suggests that more width is better, either for docking alignment/control authority, or for stability after docking during thrust/xfer?

I agree that 20º is too narrow, but it looks a lot less than 180º.  Note, however, that the socket openings aren't normal to the Ship, which makes them a little hard to judge.

The front flaps are less than 180º dorsally, and the sockets are well within the angular distance of the front flaps.  They're also set narrower than the width of the Pez door, which, if it's dispensing two Starlinks that effectively make a square inscribed in an 8m circle, then the angular distance of the door should be 90º.¹

I think we're looking at about 5m centers on the sockets.

If you have 5 pods of SDs, they're spaced at 72º angles, and they can be tucked underneath the Pez door.  Something like the attached?

PS:  They don't have to be below the Pez door, because there won't be a Pez door on the HLS.  The question was whether the jets would impinge on the sockets.  Doesn't look like it to me, even if they're slightly above them.

______________
¹That makes the door 2*4.5*sin(45) = 6.4m wide, which is the body length cited in the FCC application for v3.  That's... wrong... because the v3's should be in a square inscribed on a 4m circle, to stay in the payload envelope.  It could be that the FCC app includes hinges that swing out to support various deployed gizmos, since the dimensions are for reentry debris analysis.  It could also be that birds in the Pez dispenser don't need to follow the static envelope rules.  And finally, there could be some slop in the door width, making it ~7m.

[OTV Booster]

Once there is enough acceleration to keep the propellant settled ISTM a lot of problems go away.

You need to deal with slosh during docking.  Even if the prop is settled all the way in the -z or -x direction, the moment that the Starship needs to adjust attitude, or brake before contact, all the prop is coming unglued, and will likely slam into an inconvenient surface just as capture is occurring.  For a tanker, we're talking about >100t of prop here, so even a tiny Δv is going to result in a big force when things hit the far wall.

We should consider the possibility that most available prop (except a couple of tonnes) may need to be in a header tank, if the Starship is to be the active vehicle during docking.  What would this mean?

1) Tankers would need to keep the prop load in a 100t header tank.  That's a fair amount of parasitic mass, but it does have the nice property that the tank is also a dewar, which would eliminate all boiloff concerns.

2) Depots have wildly different mass profiles at different parts of the accumulation cycle, so they have to be passive.

3) HLS Starships are a weird case.  Ideally, they'd launch full, which would reduce the amount of prop the depot needed to accumulate.  But if they're still pretty full and they're the active vehicle to the depot's passive vehicle, then they slosh.  So maybe they're fueled with exactly the amount of prop that gets them to RPO with the depot, with the 'D' then performed with an almost-empty Ship?

4) This also has a big impact on any D2 + HLS + HLS replacement scheme for SLS/Orion.  In that case, both HLS Starships will have a lot of prop, so the slosh is going to be a big deal during docking--and the docking is occurring in lunar orbit, where an accident is even worse than in LEO.  The same will also be a problem if the HLS Starship has to dock with the Gateway, which is clearly going to be the passive vehicle.

This might be another situation where carrying a D2 on the nose could be beneficial:  HLS Starship would never dock with anything except a D2 or Orion, both of which are the active vehicle and easy to control without slosh.  You could also leave the HLS Starship stood-off from the Gateway, using the D2 to ferry the crew, but this fails to meet some of the SLT requirements.

ISTM that there are three points where slosh could be a problem.

1) Approach and stationkeeping preliminary to hookup. Ship and depot are parallel and roughly aligned for hookup close enough for the arms to reach. Solution: Very slow maneuvering with no avoidable jerks. Stop and allow slosh to settle as necessary. Apply settling thrust on both ships as necessary. Given the potential mass disparity between ships, some combination of deep throttling and clustering of small maneuvering engines would be called for.

2) Hookup of arms and drawing ships together to make the QD connection. Solution: slow and gentle. Give time for settling thrust and propellant viscosity to settle things down.

3) Propellant transfer and maneuvering for thermal control. Solution: Until we have a sense of expected thermal mitigation maneuvers we have no specifics on the forces that will slosh the propellant. In a general way we can say gentle without jerks is good. Another general point is that it will be best to introduce propellant at the bottom of the tank so that the mass and viscosity of the proceeding propellant acts as a damper on violent movement. Periodically stopping the transfer to give some settling time may he necessary. It may also be beneficial for the propellant inlet tube to have two or more valved outlets at the tank bottom so that if a swirl (for example) builds up the incoming fluids can be switched to counter it.

Until it's worked out it will be a slow and tedious process, probably slowest for the first tanker transfer and faster as the propellant volume increases.

[TheRadicalModerate]

1) Approach and stationkeeping preliminary to hookup. Ship and depot are parallel and roughly aligned for hookup close enough for the arms to reach. Solution: Very slow maneuvering with no avoidable jerks. Stop and allow slosh to settle as necessary. Apply settling thrust on both ships as necessary. Given the potential mass disparity between ships, some combination of deep throttling and clustering of small maneuvering engines would be called for.

This is the most fraught.  Ultimately, prox ops and docking is a control problem.  You can make the control loop as long-duration as you want, but it does no good if you can't predict the next state with some bounded amount of error.  That's hard to do.

Even extremely low-speed collisions of Starship parts that aren't designed for colliding (i.e., the probes and drogues) is very, very bad.  Getting the Ships close enough while avoiding the collisions is very difficult.

2) Hookup of arms and drawing ships together to make the QD connection. Solution: slow and gentle. Give time for settling thrust and propellant viscosity to settle things down.

I think this is pretty easy.  Whatever slosh force you have to absorb during retraction is no greater than the force you applied to retract in the first place.

3) Propellant transfer and maneuvering for thermal control. Solution: Until we have a sense of expected thermal mitigation maneuvers we have no specifics on the forces that will slosh the propellant. In a general way we can say gentle without jerks is good. Another general point is that it will be best to introduce propellant at the bottom of the tank so that the mass and viscosity of the proceeding propellant acts as a damper on violent movement. Periodically stopping the transfer to give some settling time may he necessary. It may also be beneficial for the propellant inlet tube to have two or more valved outlets at the tank bottom so that if a swirl (for example) builds up the incoming fluids can be switched to counter it.

Until it's worked out it will be a slow and tedious process, probably slowest for the first tanker transfer and faster as the propellant volume increases.

It can't be so slow and tedious that the depot accumulation cycle is too long.

I'm starting to think that propellant containment may be a better way to go.  A sump tank at the base of the Starship can be very light:  it only has to withstand hydrostatic forces during launch (i.e. the ullage pressure inside the sump is the same outside the sump), and the lateral forces are completely determined by the forces applied while maneuvering.

And it's a cheesy dewar.  You've still got some ullage gas to conduct/convect heat from the outer walls, but you can reduce that pressure as much as you want with very little boil-off, because the prop in the dewar stays cold.

The fly in the ointment is sizing the tanks for all of the needed applications.  I don't know how to do that.