First space station in LEO to match the ISS in mass?

[Tywin]

What do you think?

[AmigaClone]

At first glance it appears that Orbital Reef is the only one of those with current plans to get close (if not larger) than the current ISS volume.

On the other hand, based on current plans, the Axion Station will first be assembled as part of the ISS. I suspect that neither the mass nor the volume of the combined ISS-Axion station is likely to be surpassed by any of those proposals - at least individually.

[Hog]

C'mon, there'll never be another similarly sized space station. Shuttle retired in 2011.

[Robotbeat]

C'mon, there'll never be another similarly sized space station. Shuttle retired in 2011.

Why not? Starship is launching soon and will be similar in size to Shuttle but >5 times the payload capacity and less than a tenth the launch price. Similar launch vehicles are under development, like New Glenn.

If anything, we're just getting started.

[Dalhousie]

C'mon, there'll never be another similarly sized space station. Shuttle retired in 2011.

"Never" is a very long time.

[Bob Shaw]

The ISS has a lot of mass tied up in the truss structure and the now old-fashioned PV arrays, so any modern station would naturally be smaller mass though the internal volume might well be higher. I think that habitable volume is a better test here than mass.

[Coastal Ron]

It depends on the use case. If the use case is for micro-gravity, then there is likely to be little need to build 450mT or larger space stations.

However if the use case is artificial gravity space stations, which would have to rotating designs, then such stations could easily exceed 450mT in mass.

But as of today there isn't a use case that supports any large stations after the ISS is decommissioned.

[eriblo]

Technically HLS after refueling but I guess the intent was "dry mass of a space station intended for long term occupation in LEO" 

[Timber Micka]

During Phase 2 China will double the mass and internal volume of Tiangong by launching the flight spares of the 3 modules, after which there will be a not yet defined Phase 3 where the station will host foreign or private modules.
The station is going to get pretty big. ISS-sized ? I don't know to be honest, but it is the station that has the best chance of reaching the size of the ISS

[Robotbeat]

I agree habitable or pressurized volume is probably a better metric than mass. Tiangong is current a quarter the mass and a third the pressurized volume of ISS, but with second and third phase could equal the pressurized volume of ISS.

Other relevant figures of merit would be power and crew.

I tend to like the average crew number figure of merit.

I wish the US and China cooperated in space, although it makes some sense why not.

[JulesVerneATV]

There are some real science websites reporting on 'Vast' it plans to kick off the next Space Age by launching the first commercial space station. Under construction with plans to launch next year, the Haven-1 space station, also some other websites with less credible info where you might take anything it writes as possible sensationalist tabloid, it with a pinch of salt




ISS is currently a mass Approximately 410,000 kilograms (900,000 lb)

the Von Braun Wheel Station Crew Size 80
http://www.astronautix.com/v/vonbraunstation.html


Vast Space with Haven-1 and Haven-2 info
https://forum.nasaspaceflight.com/index.php?topic=55810.0

[DanClemmensen]

I voted "other", because I think a station consisting of linked Starships will be the quickest and easiest.

[Jim]

The one that will hasn't been conceptualized at this time.

[StraumliBlight]

Technically HLS after refueling but I guess the intent was "dry mass of a space station intended for long term occupation in LEO" 

The ISS masses ~420 tons, while a V2 Starship stores 1600 tons of propellant alone.

A single partially fuelled HLS lander would have more mass than the ISS and the same payload volume (~1,000 m³).

[AmigaClone]

The one that will hasn't been conceptualized at this time.

Or at least a space station design that hasn't been made public so far.

[spacenut]

I don't think we need another station that large.  Astronauts conducted about every experiment in near zero gravity known to man.  Either a manufacturing station or a spinning station with Mars gravity for experiments using Mars gravity may be needed.  I see no need for anymore zero g experiments unless a private company wants to do so. 

Starship and even New Glenn could build a 0.38g station maybe. 

[sdsds]

I agree with those who think mass isn't a particularly good figure of merit. It's a decent proxy for how 'impressive' a station seems though. (Is being 'impressive' what ISS was all about?) The 'crew size' metric might be a good proxy for how useful a station is, assuming crew time has some utility.

The one I propose is 'mass flow rate' (though not exactly in the rocket engine sense). Combined up-mass and down-mass, maybe not just cargo but the mass of the visiting vehicles as well?

[jongoff]

I agree with those who think mass isn't a particularly good figure of merit. It's a decent proxy for how 'impressive' a station seems though. (Is being 'impressive' what ISS was all about?) The 'crew size' metric might be a good proxy for how useful a station is, assuming crew time has some utility.

The one I propose is 'mass flow rate' (though not exactly in the rocket engine sense). Combined up-mass and down-mass, maybe not just cargo but the mass of the visiting vehicles as well?

You could do something with how many person-months of occupancy does it support on orbit per year?

~Jon

[Robotbeat]

It’s possible next generation large stations won’t be research-focused or tourism-focused or manufacturing-focused at all. They may be datacenters in pressurized volumes that have humans only for maintenance and upgrades (and may not be permanently inhabited… although if the datacenter is large enough…probably multiple Gigawatts…, this process would be continual and so you’d just keep people up there).

ISS has a pressurized volume of about 1000 cubic meters. A 1MW datacenter rack has a volume of about 2 cubic meters. At 50% space utilization efficiency, a 250MW orbital datacenter would have about as much pressurized volume as ISS. At $10/W, that’s about a $2.5B facility. the filled racks would be about 2t per MW, so about 500t for the server equipment (although this is rarely optimized for weight so could probably be reduced) and I dunno, maybe around 100t for the pressure vessel and shielding. Not counting power and thermal management, which would probably about 2500t and 1000-2000t, respectively. May be additional polyethylene or water mass for radiation shielding, although probably the equipment will be arranged to mostly be self-shielding (and the coolant reservoir could do dual-purpose here).

4000t approximately.

[Jim]

It’s possible next generation large stations won’t be research-focused or tourism-focused or manufacturing-focused at all. They may be datacenters in pressurized volumes that have humans only for maintenance and upgrades (and may not be permanently inhabited… although if the datacenter is large enough…probably multiple Gigawatts…, this process would be continual and so you’d just keep people up there).

why bother with pressurized volume for that?  Just trusses with racks would be easier. 

[Robotbeat]

Because most electronics are not vacuum qualified.

Russians usually have used electronics in sealed nitrogen pressure vessels for this reason. The extra mass of the pressure vessel is not a problem compared to the overall costs of vacuum certification for stuff, especially with lower launch costs

 and being in vacuum would make servicing them harder. Air also helps cool components not directly liquid cooled.

[DanClemmensen]

It’s possible next generation large stations won’t be research-focused or tourism-focused or manufacturing-focused at all. They may be datacenters in pressurized volumes that have humans only for maintenance and upgrades (and may not be permanently inhabited… although if the datacenter is large enough…probably multiple Gigawatts…, this process would be continual and so you’d just keep people up there).

why bother with pressurized volume for that?  Just trusses with racks would be easier.

Yep. Why should I let messy stinky humans with their humid air into my nice clean vacuum-filled server room? If they need to come in here they can suit up.

[Robotbeat]

It’s possible next generation large stations won’t be research-focused or tourism-focused or manufacturing-focused at all. They may be datacenters in pressurized volumes that have humans only for maintenance and upgrades (and may not be permanently inhabited… although if the datacenter is large enough…probably multiple Gigawatts…, this process would be continual and so you’d just keep people up there).

why bother with pressurized volume for that?  Just trusses with racks would be easier.

Yep. Why should I let messy stinky humans with their humid air into my nice clean vacuum-filled server room? If they need to come in here they can suit up.

Does your laptop work in vacuum? Your GPU?

[Robotbeat]

Might make sense to have it nitrogen filled instead of air. But in either case, humidity can be completely scrubbed out of the atmosphere (edit: actually you might want some humidity for static electricity dissipation). Crews can use an oxygen mask. But vacuum makes design a headache.

[Robotbeat]

Relevant (but wrong scale for this)
https://www.datacenterdynamics.com/en/news/axiom-space-to-develop-orbital-data-center-on-its-commercial-space-station/

[Robotbeat]

Roughly a 20MW orbital data center would have the same mass as ISS’s 400t. Probably too small to be permanently crewed and maybe too small to be worthwhile, but there you go.

[Robotbeat]

I agree with those who think mass isn't a particularly good figure of merit. It's a decent proxy for how 'impressive' a station seems though. (Is being 'impressive' what ISS was all about?) The 'crew size' metric might be a good proxy for how useful a station is, assuming crew time has some utility.

The one I propose is 'mass flow rate' (though not exactly in the rocket engine sense). Combined up-mass and down-mass, maybe not just cargo but the mass of the visiting vehicles as well?

You could do something with how many person-months of occupancy does it support on orbit per year?

~Jon

I think I agree with this. Orbital data centers would basically just be man-tended satellites, mostly not used for habitation.

[Jim]

Because most electronics are not vacuum qualified.

Russians usually have used electronics in sealed nitrogen pressure vessels for this reason. The extra mass of the pressure vessel is not a problem compared to the overall costs of vacuum certification for stuff, especially with lower launch costs

 and being in vacuum would make servicing them harder. Air also helps cool components not directly liquid cooled.

they aren't going to use COTS server hardware, so just make vacuum rated

Being in the vacuum and not in can would be easier to service. No humans needed, just R&R the rack with the problem with a robotic spacecraft. And do the real repair at the spot on earth.

Cold plate cooling is easy

[Jim]

Does your laptop work in vacuum? Your GPU?

not that hard to fix.  just a larger heat sink/radiator

laptop form factor isn't good for a server anyways,

[Robotbeat]

Now you have to qualify all that stuff for outgassing, etc.

[Robotbeat]

Because most electronics are not vacuum qualified.

Russians usually have used electronics in sealed nitrogen pressure vessels for this reason. The extra mass of the pressure vessel is not a problem compared to the overall costs of vacuum certification for stuff, especially with lower launch costs

 and being in vacuum would make servicing them harder. Air also helps cool components not directly liquid cooled.

they aren't going to use COTS server hardware, so just make vacuum rated

using COTS hardware is the cheapest option. ESPECIALLY in the early days.

Being in the vacuum and not in can would be easier to service. No humans needed, just R&R the rack with the problem with a robotic spacecraft. And do the real repair at the spot on earth.

Cold plate cooling is easy

vacuum rated robotics are also much more expensive.

[jongoff]

Because most electronics are not vacuum qualified.

Russians usually have used electronics in sealed nitrogen pressure vessels for this reason. The extra mass of the pressure vessel is not a problem compared to the overall costs of vacuum certification for stuff, especially with lower launch costs

 and being in vacuum would make servicing them harder. Air also helps cool components not directly liquid cooled.

they aren't going to use COTS server hardware, so just make vacuum rated

using COTS hardware is the cheapest option. ESPECIALLY in the early days.

Being in the vacuum and not in can would be easier to service. No humans needed, just R&R the rack with the problem with a robotic spacecraft. And do the real repair at the spot on earth.

Cold plate cooling is easy

vacuum rated robotics are also much more expensive.

Using COTS hardware isn't just about it being the cheapest option. COTS electronics also tend to be significantly ahead of the performance of space rated hardware. It's also the only likely approach that easily scales. The amount of computing power in even a single 20MW data center would likely dwarf the total computing power that's been launched in space to-date. Maybe you could make something more space rated that had good performance, cost, and the ability to scale up to that quantity of processors fast enough. But frankly I think that putting them in a pressure vessel full of dry nitrogen seems a whole lot more likely to actually get you to an affordable and scalable space data center architecture.

(though to be fair, I'm still pretty skeptical about space data centers outside of edge computing myself, and for edge computing, I'd likely use something more like what Jim's talking about).

~Jon

[Jim]

Using COTS hardware isn't just about it being the cheapest option. COTS electronics also tend to be significantly ahead of the performance of space rated hardware. It's also the only likely approach that easily scales. The amount of computing power in even a single 20MW data center would likely dwarf the total computing power that's been launched in space to-date. Maybe you could make something more space rated that had good performance, cost, and the ability to scale up to that quantity of processors fast enough. But frankly I think that putting them in a pressure vessel full of dry nitrogen seems a whole lot more likely to actually get you to an affordable and scalable space data center architecture.

(though to be fair, I'm still pretty skeptical about space data centers outside of edge computing myself, and for edge computing, I'd likely use something more like what Jim's talking about).

~Jon

a pressure vessel with n2 in it is much different than a habitable module. 

But I am thinking the servers could be Starlink type electronics.    A server farm is going to be a lot of the same chips.  More than all that has flown to date (Starlink excluded).  If orbital server farms are viable, then developing space rated chips should be too. 

[Jim]

they aren't going to use COTS server hardware, so just make vacuum rated

using COTS hardware is the cheapest option. ESPECIALLY in the early days.
[/quote]hard

there are no COTS server pressure vessels.  Plenty of COTS spacecraft hardware to support vacuum rated servers.