totm dec 2023 Artemis Discussion Thread

[sevenperforce]

1 hour ago, tater said:

Note that FH is supposed to be getting a ~200m3 fairing for the Space Force, so that's on the table as well.

Note for clarity, I do not in fact mean using the carbon fiber fairing AS the vehicle, I meant to use the identical mold line, since the forces on the vehicle would be well understood by SpaceX.

So in this case the aeroshell around the Dragon pressure vessel and removable nose cone would be fairing shaped. It would seamlessly transition to the mold line of any cargo/tankage, etc. The legs flush to fairing mold line, etc. Actual tankage slightly smaller dia. Assuming you need every cubic cm of volume. If you can et away with a smaller vehicle, then it can have the fairing separate normally.

Let's suppose the crew cabin based on the Dragon 1 pressure vessel -- loaded -- comes in at 3.5 tonnes. Dragon 1 had a dry weight of 4.2 tonnes but part of that was aeroshell and heat shield, so shaving off 700 kg while adding in crew, consumables, ECLSS, engines, and tanks seems reasonable. Volume is limited and safety is paramount, so storables are going to be necessary. Assuming a vacuum specific impulse of 316 seconds and flying all the way back to LEO, that's going to require something on the order of 20 tonnes of props. Lunar liftoff mass of 23.5 tonnes corresponds to a necessary liftoff thrust of around 46 kN or one AJ-10. Fortunately, hypergols have great bulk density, so we'd be looking at needing only 15.4 cubic meters of tankage on the ascent vehicle. An octet of capsule-shaped tanks inside the specified OML accommodates this easily. 

The challenge is getting that from LEO to the lunar surface. This time, four engines certainly won't do it, and six won't fit in the same OML (assuming the same RL-10C-1-1s). So let's try and squeeze five engines under there. We'll make the LOX tank slightly smaller than the 5.2 meters to allow for some sort of landing legs to fold down from the OML, but we'll keep the LH2 tank at the full diameter:

By my math, this gets a volume of 116.94 cubic meters on the lower stage, allowing for 42 tonnes of hydrolox. Assume a slightly worse mass ratio than Centaur, given that we need landing legs and more structural support -- let's say 4.5 tonnes tank and structure, plus another tonne of RL10s. So dry mass on the lower stage is 5.5 tonnes plus our 24-tonne upper stage, which gets us 3.93 km/s Δv. Nowhere near enough (and besides, this stack exceeds what Falcon Heavy can put into orbit, meaning the lower stage also needs to circularize).

We are volume-limited here by the AJ-10, so we can't really add more hydrolox. If we want to get that full 5.93 km/s Δv required to reach the lunar surface, then we need to seriously shrink the ascent stage. The lunar module came in at 4.7 tonnes with 2.4 tonnes of propellant, but that's not enough for us; we need to get all the way back to LEO. We need something like 14 tonnes of propellant to get from the lunar surface to LEO, ignoring added tankage mass.

On the positive side, the LM was only 2.83 meters high including the engine, allowing us to add another 4.2 meters of height to the lower stage tanks, increasing our volume by 89.6 cubic meters and bumping our propellant load up from 42 tonnes to 74 tonnes. This stack would have a total mass of 99.2 tonnes, meaning that Falcon Heavy will leave it 756 m/s short of reaching orbit. It will need to burn 15.5 tonnes of hydrolox to reach orbit, leaving it with 58.5 tonnes in reserve...about 600 m/s short of what it needs to go from LEO to the lunar surface.

Of course you can imagine replacing the liquid hydrogen with liquid methane....

[tater]

At the time I assume we  were using the "naked FH stage 2" you worked out, In which case the vehicle needs LOI/landing, and return to Earth. (a gazillion pages up whichever thread)

[Exoscientist]

 Congress becoming concerned with the frequent delays of the Artemis program, that China may beat us back to the Moon:

US must beat China back to the moon, Congress tells NASA.
By Mike Wall published 3 days ago
'It's no secret that China has a goal to surpass the United States by 2045 as global leaders in space. We can't allow this to happen.'
https://www.space.com/us-win-moon-race-china-congress-artemis-hearing

  Bob Clark

[Spaceception]

If they're concerned with delays, they shouldn't listen to Mike Griffin, he basically wants a return to the Constellation program - which was cancelled due to budget overruns and delays, and restart Artemis, which, while also suffering from budget overruns and delays, has the benefit of being far along development at this stage. His idea relies on the Block II SLS to launch twice by 2029, when SLS Block 1b won't be ready until 2028. And he calls for restarting the Lunar lander contract, using the same contractors who are building SLS/Orion, which with their track record likely means delays into the 2030s, and budget overruns in the billions. 

If Congress wants astronauts to land on the Moon before China, and for that matter, before 2030, it needs to commit to the current plan, especially if they want the US to remain "global leaders" in 2045, considering that China's space program is actively pivoting towards reusable rockets. Something the private industry is also doing in the US, so it would do well on us to maintain that momentum instead of cutting it short.

It also assumes China won't suffer delays just like us. Their inital plan is leaner than ours, granted, but it relies on a Long March 5 derivative that isn't set to launch until at least 2027, and in the long term, a rocket that's still in development and won't fly until 2033. 

[darthgently]

39 minutes ago, Exoscientist said:

 Congress becoming concerned with the frequent delays of the Artemis program, that China may beat us back to the Moon:

US must beat China back to the moon, Congress tells NASA.
By Mike Wall published 3 days ago
'It's no secret that China has a goal to surpass the United States by 2045 as global leaders in space. We can't allow this to happen.'
https://www.space.com/us-win-moon-race-china-congress-artemis-hearing

  Bob Clark

It's Apollo all over again.   Let's just raid the museums and put an Apollo LEM and SM on top of whatever is close to working right now

[KSK]

I think I sprained an eyeball reading that article and the Ars Technica equivalent.

Because nothing says asserting dominance like panicking at the bogeyman and bodging together a slightly larger flags and footprints mission.

You won the Space Race guys. You won it on July 20th 1969. Outside of the Space Force hawks, I'm pretty sure that the public response to anything China does on the Moon is going to be a hearty meh, or a a golf clap followed by a snarky 'you're only 50 years late to the party'.

[kerbiloid]

On 1/20/2024 at 6:47 PM, KSK said:

You won the Space Race guys. You won it on July 20th 1969. Outside of the Space Force hawks, I'm pretty sure that the public response to anything China does on the Moon is going to be a hearty meh, or a a golf clap followed by a snarky 'you're only 50 years late to the party'.

Yeah, the flags are important, the flags are good.

California? Meh.

 

[magnemoe]

On 1/20/2024 at 4:47 PM, KSK said:

I think I sprained an eyeball reading that article and the Ars Technica equivalent.

Because nothing says asserting dominance like panicking at the bogeyman and bodging together a slightly larger flags and footprints mission.

You won the Space Race guys. You won it on July 20th 1969. Outside of the Space Force hawks, I'm pretty sure that the public response to anything China does on the Moon is going to be a hearty meh, or a a golf clap followed by a snarky 'you're only 50 years late to the party'.

Agree, down the line the real issue is probably south pole bases and real estate.  You want it because it might make an profit in 50 years. 

[SunlitZelkova]

12 hours ago, magnemoe said:

Agree, down the line the real issue is probably south pole bases and real estate.  You want it because it might make a profit in 50 years. 

The idea of blockading or claiming territory on the Moon is ridiculous though. There would be no way to enforce it.

The whole “we need to get there first to secure territory/freedom” is the dumbest thing ever.

[sevenperforce]

On 1/22/2024 at 4:48 AM, SunlitZelkova said:

The idea of blockading or claiming territory on the Moon is ridiculous though. There would be no way to enforce it.

Or is there?

On 1/22/2024 at 4:48 AM, SunlitZelkova said:

The whole “we need to get there first to secure territory/freedom” is the dumbest thing ever.

Agreed. This stuff is all going to be super cooperative for the foreseeable future.

[AstroWolfie]

I read the article and this is my reaction to the guys who want the usa to go to the moon for "freedom/territory"

[Exoscientist]

On 9/29/2023 at 8:28 PM, Exoscientist said:

Nevertheless, it is possible to do a single launch of the SLS with a light-weight Apollo-sized lander with all the components of Orion capsule/Service Module/lunar lander all carried on that one single SLS launch.

 The NRHO was chosen because it has a lower delta-v requirement to get there than going to low lunar orbit. Here’s the delta-v requirements:

 
 This earlier post expanded out:

Possibilities for a single launch architecture of the Artemis missions, Page 4: lightweight landers from NRHO to the lunar surface.
https://exoscientist.blogspot.com/2024/01/possibilities-for-single-launch.html

 A major flaw in the design of the SLS was that the Orion capsule was saddled with a too small service module:

 

 Rather than giving  Orion a larger service module than Apollo’s due to its twice larger size,  it was instead given one 1/3rd smaller. Why? It stems from the earlier, now cancelled Constellation program. Constellation was to have rocket the Ares 1 to carry astronauts to LEO in the Orion capsule, and a larger launcher the Ares V to carry the other lunar mission elements to rendezvous with the Orion in LEO for the flight to the Moon.

 However, the Ares I was powered by a single SRB as the first stage and that did not have enough power to get a large service module and the Orion to LEO. Then the service module was cut down in size. 

  But when Constellation was cancelled it was decided to keep the Orion, and with that its service module also. But now the decision to use a smaller service module made no sense.  The Ares I was cancelled so it made no sense to use limitations on the size of the service module coming from a rocket that wouldn’t be used.  

 But government programs have inertia. It’s hard to change programs already decided on. It becomes like they are fixed in stone. Since the Orion capsule is kept, its service module is kept as well. 

 It would be a relatively easy fix, both technically and financially,  to increase the size of the service module propellant tanks so that the service module could carry the Orion and an Apollo-sized lunar lander to low lunar orbit with enough propellant left over to carry the Orion back to Earth again.

 The only problem is convincing NASA to do it. It’s because of that too small service module that NASA had to come up with other destinations at the Moon that the Orion could reach and come back from. Thus was selected the NRHO orbit(near rectilinear halo orbit).

 Since the NRHO is decided upon, could we get a lunar lander that could be used on the SLS to get a single launch lunar landing architecture that staged from NRHO? The answer is yes. If we made it an Apollo-sized lander but hydrolox powered instead of using storable propellant engines.

 The hydrolox lunar lander would need low-boiloff tech. But ULA has done a lot of research on this in regards to their ACES(Advanced Cryogenic Evolved Stage) so the tech likely could be used in the near term for a lunar lander.

 

  Bob Clark

[Cuky]

2 hours ago, Exoscientist said:

could we get a lunar lander that could be used on the SLS to get a single launch lunar landing architecture that staged from NRHO? The answer is yes. If we made it an Apollo-sized lander but hydrolox powered instead of using storable propellant engines.

 

Whilst I agree with most of your post this is the part that I don't. Whilst yes, with some different design choices, they could have done what they did in Apollo that wouldn't make much sense tbh. Back then the goal was to get to the Moon and return back and do it before Soviets do it. Now the goal is not to just go to the Moon and come back, the goal is to go to the Moon, stay there for longer period of time and when the crew comes back different crew can take over from where they left. It is not about going to the Moon, it is about staying on the moon. And Apollo, or any vehicle/program designed as a modern version of Apollo wouldn't be able to pull that off.

 

Also, if I am not mistaken Orion itself is one big confused spacecraft which can't decide what it wants to be. It was designed to fly astronauts to the Moon, but also as a transportation to the ISS and possibly other stations. I think I have also seen some plans to use it for Mars missions as well where astronauts would get into LEO on Orion, dock with big Mars vessel in which they would be for the duration of the flight. Orion would stay as a life boat and go to the Mars and back and then return crew to the Earth once they come back.

And as fighter planes have shown, trying to make one design to be at the top of the game in many different aspects results in a compromised design that is good enough at everything but is mastering nothing and is usually much more expensive.

Edited January 25 by Cuky

[darthgently]

3 hours ago, Cuky said:

And as fighter planes have shown, trying to make one design to be at the top of the game in many different aspects results in a compromised design that is good enough at everything but is mastering nothing and is usually much more expensive.

Yes, then the uni-design ends up with several different "specialization" flavors that all end up different enough that logistics isn't helped as much as hoped but similar enough that none are great at their "specialization". 

 

[tater]

6 hours ago, Exoscientist said:

  But when Constellation was cancelled it was decided to keep the Orion, and with that its service module also. But now the decision to use a smaller service module made no sense.  The Ares I was cancelled so it made no sense to use limitations on the size of the service module coming from a rocket that wouldn’t be used.  

This is literally SLS 101. Constellation separated crew/cargo, and had a launch vehicle that was supposed to put a stack in LEO that Orion could dock to to do the lunar mission. SLS cannot ever accomplish this, not even with Orion moved to another LV.

6 hours ago, Exoscientist said:

 It would be a relatively easy fix, both technically and financially,  to increase the size of the service module propellant tanks so that the service module could carry the Orion and an Apollo-sized lunar lander to low lunar orbit with enough propellant left over to carry the Orion back to Earth again.

How is this an easy fix? It can't do this as has been demonstrated here over and over again. SLS never gets 60-70+ tons to TLI (70 as the min for a legit Artemis mission, slightly lighter might allow a sortie lander like Apollo).

Easy fix, go back in time and set a reasonable SLS baseline capability—which must be some substantial increase over Saturn V or it's a non-starter. At least 70t to TLI if it is saddled with Orion.

[RCgothic]

I do agree a larger service module on Orion would be better, given where we've ended up. It would actually improve SLS Block 2's co-manifest payload to NRHO as well, as SLS B2 can throw more combined mass of Orion/ESM and payload to NRHO than Orion can actually brake into that orbit and still return.

SLS might *possibly* be able to do a single stack Apollo style mission with an Apollo LM *if* the ESM is upgraded with an additional 6.5t of propellant and 0.6t dry mass. The total mass to TLI would then be ~ 55t including the payload adaptor and intermediate fairing. Block 2's stated capabilities are 49t to TLI, so on paper it's a no-go although they might be sandbagging a bit.

But I don't know why we'd want to.

Which is what we keep coming back to in this discussion. Apollo style with SLS gets ~3days on the surface every other year and a few hundred kg of samples each time at most, after a multi-year delay to develop a lander that small. Artemis HLS style gets potentially months on the surface per crew launch and tonnes of sample return, with scope to bypass SLS entirely and go multiple times a year and an architecture that also works for Mars, with landers that have already cut metal.

I just don't understand why anyone would prefer Apollo-style.

Edited January 26 by RCgothic

[tater]

11 minutes ago, RCgothic said:

Which is what we keep coming back to in this discussion. Apollo style with SLS gets ~6h on the surface every other year and a few hundred kg of samples each time at most, after a multi-year delay to develop a lander that small. Artemis HLS style gets potentially months on the surface per crew launch and tonnes of sample return, with scope to bypass SLS entirely and go multiple times a year and an architecture that also works for Mars, with landers that have already cut metal.

Apollo 17 was on the surface over 3 days. So slightly longer is possible. The trick is that if NRHO is the mission architecture, the stay must be ~6.5 days, as that's the phasing for the next Gateway (or just CSM) pass if it is in NRHO. The only way you get a small sortie lander is with Orion in LLO, allowing an arbitrarily short lunar sortie.

Note that once you are stuck for 6.5 days, all elements need to have margin for abort contingencies that are very different from LLO architecture contingencies.

[darthgently]

1 hour ago, tater said:

Apollo 17 was on the surface over 3 days. So slightly longer is possible. The trick is that if NRHO is the mission architecture, the stay must be ~6.5 days, as that's the phasing for the next Gateway (or just CSM) pass if it is in NRHO. The only way you get a small sortie lander is with Orion in LLO, allowing an arbitrarily short lunar sortie.

Note that once you are stuck for 6.5 days, all elements need to have margin for abort contingencies that are very different from LLO architecture contingencies.

So considering issues that may lead to missing a lunar launch to rendezvous window I'd think the ability to stay 13+ days would make sense.  Maybe paired with the ability for the NRHO element to be able to drop an automated 6.5 day  life support resupply when passing if launch is not possible?

[tater]

3 hours ago, darthgently said:

So considering issues that may lead to missing a lunar launch to rendezvous window I'd think the ability to stay 13+ days would make sense.  Maybe paired with the ability for the NRHO element to be able to drop an automated 6.5 day  life support resupply when passing if launch is not possible?

That's basically another lander. The longer stay duration is actually an Artemis goal, any lander designed to stay past 6.5 days (or just for any contingency) needs that ~2 week level of consumables anyway. Say Gateway/Orion is heading back in 6.5 days and it's time to leave. They are counting down to leave the surface (they have some launch window, but the smaller the lander the closer to instantaneous the launch window will be)—any issues with  he count down at all that pushes launch past the window and they are there another 6.5 days unless the lander/ascent stage has a lot of margin.

[Exoscientist]

17 hours ago, RCgothic said:

I do agree a larger service module on Orion would be better, given where we've ended up. It would actually improve SLS Block 2's co-manifest payload to NRHO as well, as SLS B2 can throw more combined mass of Orion/ESM and payload to NRHO than Orion can actually brake into that orbit and still return.

SLS might *possibly* be able to do a single stack Apollo style mission with an Apollo LM *if* the ESM is upgraded with an additional 6.5t of propellant and 0.6t dry mass. The total mass to TLI would then be ~ 55t including the payload adaptor and intermediate fairing. Block 2's stated capabilities are 49t to TLI, so on paper it's a no-go although they might be sandbagging a bit.

But I don't know why we'd want to.

Which is what we keep coming back to in this discussion. Apollo style with SLS gets ~3days on the surface every other year and a few hundred kg of samples each time at most, after a multi-year delay to develop a lander that small. Artemis HLS style gets potentially months on the surface per crew launch and tonnes of sample return, with scope to bypass SLS entirely and go multiple times a year and an architecture that also works for Mars, with landers that have already cut metal.

I just don't understand why anyone would prefer Apollo-style.

 

Your estimated extra propellant of 6.5 tons required might not be including the required propellant to also get the Orion back to Earth. I estimated 10 tons extra propellant required.

 But anyway, this latest blog  post was to keep the current size service module, still stage from NRHO not low lunar orbit, but use a hydrolox lander to deal with the larger delta-v needed for staging from NRHO. The proposal would still be heavier to TLI than before though. The Orion/service module weighs 26.5 tons. A 15 ton lander would bring the TLI mass to 41.5 tons. I made two suggestions to deal with this added mass to TLI: adding a Centaur V at 50-ton size as a 3rd stage or going back to the J-2X engine  for the Boeing EUS upper stage that had been planned. A preliminary calculation suggest they should be able to do > 42 tons to TLI.

A ca. 2 ton mass lunar crew module should be able to do over a week stay on the Moon based on the Cygnus module. The uncertainty is in whether the usage described in the article below includes independent life-support on the Cygnus or if it is taking life-support from the Orion:

ORBITAL PROPOSES FUTURE DEEP SPACE APPLICATIONS FOR CYGNUS.
SPACEFLIGHT INSIDER
MAY 1ST, 2014
Orbital’s proposal, outlined in this PDF, involves docking a Cygnus spacecraft with Orion to serve as a habitation and logistics module on longer flights. For these missions, the re-purposed Cygnus would be called the Exploration Augmentation Module (EAM). With its current life support systems used to transport pressurized cargo and experiments to the ISS, Cygnus is stated as being already suitable for the long term support of a crew. While berthed to Orion, Cygnus could support a crew of four for up to 60 days. Cygnus also has the capability of storing food, water, oxygen, and waste and features its own power and propulsion systems. The EAM would utilize the enhanced configuration Cygnus, which will begin flying larger cargoes to the ISS beginning with CRS-4 in 2015. An even larger version is also being proposed, featuring a 4-segment pressurized cargo module.

https://www.spaceflightinsider.com/missions/commercial/orbital-proposes-future-deep-space-applications-cygnus/

 As to why this approach, the Starship HLS is still uncertain for an Artemis III or Artemis IV timeline. Even if SpaceX succeeds at flights to LEO, they still need to demonstrate reusability and orbital cryogenic refueling.

 This approach still allows sustained lunar presence because it would not use SLS for cargo and habitat delivery. That would use far cheaper commercial launchers instead.

 

  Bob Clark

Edited January 27 by Exoscientist
Typo

[darthgently]

18 hours ago, RCgothic said:

I just don't understand why anyone would prefer Apollo-style.

I was jesting about pulling Apollo out of museums.  Unless we are going to set up a more permanent presence that can explore deeper lunar science, long term habitation, mining, power generation, dust management, hydroponics, ISRU, and a thousand other challenges I don't think we should bother going there at all.  But if another major power establishes a base on the Moon, we need one also.  We don't have to be first, but balance of power is important.  And first doesn't hurt

[tater]

7 hours ago, Exoscientist said:

The Orion/service module weighs 26.5 tons. A 15 ton lander would bring the TLI mass to 41.5 tons.

A 15 ton lander (Apollo LM) is not doing a RT from NRHO. It;s also not going to have consumables or comfort for a 6.5 day stay on the surface. Whatever small lander does, it also needs contingency I would think (another NRHO orbit).

 

[SunlitZelkova]

On 1/26/2024 at 11:38 PM, Exoscientist said:

 As to why this approach, the Starship HLS is still uncertain for an Artemis III or Artemis IV timeline. Even if SpaceX succeeds at flights to LEO, they still need to demonstrate reusability and orbital cryogenic refueling.

 This approach still allows sustained lunar presence because it would not use SLS for cargo and habitat delivery. That would use far cheaper commercial launchers instead.

Starship HLS already has a prototype flying in the form of the current ships, and has already appeared in metal in the form of mockups. Even the tanker variants have been manufactured in some form, IIRC. How is this new lander going to get ahead of something that already exists?

If we look at a very casual, off the top of my head list of what a rocket needs to do before flying-

1. Become a concept (be birthed as an idea)
2. Undergo preliminary design
3. Build prototype
4. Undergo testing
5. Get certified
6. Fly

Starship is currently at Stage 4, HLS is inbetween 3 and 4. Yours is currently at 1. Especially if this lander is going to be contracted out to someone like Boeing or Northrop Grumman, how do you expect these companies with their oldspace way of doing things to overtake Starship development?

If you had made this proposal in 2019 I think it would make sense. But there is just no reason to do this now, at this point in time.

We have a historical precedent in these types of discussions. During the Apollo era, many argued for utilizing the already available Gemini technology to produce an alternative lunar lander to Apollo just in case the CSM and LM weren't ready in time to meet Kennedy's goal. The legendary James Webb correctly saw this as simply siphoning off already limited resources, that would extend the date of a lunar landing and not quicken it. On the other side of the globe, the Vladimir Chelomei proposed his UR-700 as an alternative to the N1. This siphoned off resources that could have been put into N1 development, and was one of numerous reasons why the Soviets never landed on the Moon with crew. Your proposal to start building a new lunar lander now is also reminiscent of how it took the Soviets until 1964 to start serious work on a crewed lunar landing.

There is just no way an expendable lander starting development in 2024 is going to beat Starship HLS to flight, considering HLS began development in what, 2020 or 2021?

Also, this approach is not sustainable because the lander can't be reused. It would have to be thrown away every single time.

Reusability is what makes a presence sustainable, not whether it uses SLS or not. It isn't like LEO where you can get away with launching a hundred Soyuzes while your economy is trash. Launching stuff to the Moon is expensive. Reusability of at least the lander must be involved or you will only end up with a flag and footsteps program.

Ideally we would do away with Orion and have Starship HLS be the ferry to and fro LEO, and it would dock at the ISS/Axiom Station and then crew would descend in a Crew Dragon. I also feel like reentry at lunar speeds is way more dangerous and risky than adding another "propulsively break here" phase to the mission.

[darthgently]

2 hours ago, SunlitZelkova said:

it would dock at the ISS/Axiom Station and then crew would descend in a Crew Dragon.

Agree with all but this.  No reason to dock at ISS when empty Crew Dragon could be launched to meet them in LEO parking orbit.   Then Tanker SS can refuel HLS with no human presence.  No reason to decommission ISS in a rapid and unscheduled manner with unnecessarily proximal refilling activities and Dragon can meet HLS directly.  All at a more sane orbital inclination than ISS orbits also

[Exoscientist]

4 hours ago, SunlitZelkova said:

Starship HLS already has a prototype flying in the form of the current ships, and has already appeared in metal in the form of mockups. Even the tanker variants have been manufactured in some form, IIRC. How is this new lander going to get ahead of something that already exists?

 

 Not exploding is an important requirement for a rocket, especially for one intended to carry crew.

 For the alternative proposal using a hydrolox stage for the propulsion of a lunar  lander, this propulsive stage already exists and been flown multiple times for the upper stage of the Ariane 4 rocket.

 For the Cygnus capsule, it has been flown multiple times as a unmanned cargo craft and is planned to be a manned component of a space station. As I mentioned though I’m not certain it has it’s own independent life support systems. The Cygnus itself weighs 2, 000 kg. I don’t think adding life-support would add too much more to that mass.

  Robert Clark     

Edited January 28 by Exoscientist
Added link to Ariane 4 hydrolox upper stage