Replacing ISS with BFS

[Zed_Noir]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

[guckyfan]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

This would require a major redesign, driving cost. IMO the main advantage of using BFS instead of a conventional space station is low cost.

If you make it a permanent station a Bigelow BA-2200 might be the better option.

[su27k]

I'm in the camp that if you try to do this, it needs to be permanent. Wet workshop idea is not that crazy, given Ixion is proposing the same for Centaur/ACES, but I think for that to work as replacement to ISS, it needs a new propulsion module.

Apparently there was a similar concept to turn a Shuttle Orbiter into space station, see https://forum.nasaspaceflight.com/index.php?topic=44197.0 and links inside.

[Zed_Noir]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

This would require a major redesign, driving cost. IMO the main advantage of using BFS instead of a conventional space station is low cost.

If you make it a permanent station a Bigelow BA-2200 might be the better option.

It is not intended as a permanent orbital platform. Rather it is to get more habitable volume with a reusable BFS for LEO missions without implementing a wet workshop concept.

[TripleSeven]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

This would require a major redesign, driving cost. IMO the main advantage of using BFS instead of a conventional space station is low cost.

If you make it a permanent station a Bigelow BA-2200 might be the better option.

It is not intended as a permanent orbital platform. Rather it is to get more habitable volume with a reusable BFS for LEO missions without implementing a wet workshop concept.

https://www.wired.com/2012/03/space-station-columbia-1991

a fairly clever adaption...but than as now NASA loves a build program not really a workable program

[JamesH65]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

This would require a major redesign, driving cost. IMO the main advantage of using BFS instead of a conventional space station is low cost.

If you make it a permanent station a Bigelow BA-2200 might be the better option.

Quite. To make a BFS usable as an extension to the ISS or a replacement, you need to do the approximately the same amount of work as you have to do to make a BA-2200, plus the cost of the BFS in the first place. After all, they are going to need the same level of life support, workshops stuff etc.  BFS would be the equivilent of a BA-2200 with engines. So, just send up a couple of BA-2200.

[glennfish]

https://en.wikipedia.org/wiki/MOOSE

[RDoc]

Quite. To make a BFS usable as an extension to the ISS or a replacement, you need to do the approximately the same amount of work as you have to do to make a BA-2200, plus the cost of the BFS in the first place. After all, they are going to need the same level of life support, workshops stuff etc.  BFS would be the equivilent of a BA-2200 with engines. So, just send up a couple of BA-2200.

Except that the BFS can be easily brought back to be worked on, upgraded, etc.

What's the point to having a pressurized volume stay in orbit for more than a few years? We don't have large permanent manned platforms floating around doing oceanography. We use ships that go out, do the work, come back, get refitted, then go back out.

[guckyfan]

Quite. To make a BFS usable as an extension to the ISS or a replacement, you need to do the approximately the same amount of work as you have to do to make a BA-2200, plus the cost of the BFS in the first place. After all, they are going to need the same level of life support, workshops stuff etc.  BFS would be the equivilent of a BA-2200 with engines. So, just send up a couple of BA-2200.

Except that the BFS can be easily brought back to be worked on, upgraded, etc.

What's the point to having a pressurized volume stay in orbit for more than a few years? We don't have large permanent manned platforms floating around doing oceanography. We use ships that go out, do the work, come back, get refitted, then go back out.

A BFS reworked so much that the tanks can be used as habitable volume won't be able to land. I see the advantage of BFS as a space station right there, in the ability to land and service it.

[LMT]

Quite. To make a BFS usable as an extension to the ISS or a replacement, you need to do the approximately the same amount of work as you have to do to make a BA-2200, plus the cost of the BFS in the first place. After all, they are going to need the same level of life support, workshops stuff etc.  BFS would be the equivilent of a BA-2200 with engines. So, just send up a couple of BA-2200.

Except that the BFS can be easily brought back to be worked on, upgraded, etc.

What's the point to having a pressurized volume stay in orbit for more than a few years? We don't have large permanent manned platforms floating around doing oceanography. We use ships that go out, do the work, come back, get refitted, then go back out.

And often those big ships are leased.  One might do the same with ITS station spacecraft.  That is, lease them out as temporary ISS replacements, mfg plants, tourist resorts, etc., as a way to help fund their eventual use elsewhere, as on Mars.

If ITS craft were modified to purpose, stations could in theory offer 0-1 g artificial gravity, thereby increasing versatility and value.

Some posts exploring these notional "Richie-class" stations: 1 2 3 4 5 6 7

[su27k]

There is no need to consider the wet workshop concept for the BFS in LEO.

Just have more and bigger header tanks in place of the main propellant tanks. The BFS will of course have to be put in orbit with less engines and empty along with minimum solar arrays. An austere BFS.

But you get an orbital platform with about 6 times the habitable volume of a regular crewed BFS. You will have to added the interior fittings, experiments and  external power systems with additional BFS flights.

This would require a major redesign, driving cost. IMO the main advantage of using BFS instead of a conventional space station is low cost.

If you make it a permanent station a Bigelow BA-2200 might be the better option.

Quite. To make a BFS usable as an extension to the ISS or a replacement, you need to do the approximately the same amount of work as you have to do to make a BA-2200, plus the cost of the BFS in the first place. After all, they are going to need the same level of life support, workshops stuff etc.  BFS would be the equivilent of a BA-2200 with engines. So, just send up a couple of BA-2200.

Not exactly. BFS crew version would already have 800 m^3 or so crew space outfitted on the ground, it would also have a built-in solar array/radiator that can support this volume. If you go with wet workshop then there're additional on orbit work to do similar to BA-2100, but BFS has a built-in advantage.

But more importantly I believe BFS has a much higher probability of actual becomes real then BA-2100.

[Steve D]

How do you access the wet workshop? A tunnel through the header tank that is still full of lox?

[Elmar Moelzer]

I don't think the wet workshop would be needed. Just make it a version with just a hand full of crew cabins (instead of 40) and leave the rest mostly open space maybe a few lockers for things. ISS may have more pressurized volume but that is not all open, from what I understand. The BFS should be big enough without any modifications.
The crew version of BFS should be able to support a crew of 100 people for 4+ months. That includes supplies, life support, power from solar panels. It should be enough to support a relatively small crew of researchers (make it 6 like ISS or maybe a few more than that), for long enough missions to conduct pretty much any kind of experiments.
At 5 to 7 million a launch, you can afford launching it several times a year, with different crews, experiments and even orbits and it would still cost less than even a single cargo resupply flight to the ISS does now.
Why would there be a need to make it permanent and/or a wet workshop?

[speedevil]

At 5 to 7 million a launch, you can afford launching it several times a year, with different crews, experiments and even orbits and it would still cost less than even a single cargo resupply flight to the ISS does now.

Remember, that price was cost price, not to customer price.
(but even $60M, which I was assuming above does not change this meaningfully)
Probably somewhat more, as there would be either a purchase price, or a cost for remaining on orbit.

[Elmar Moelzer]

Remember, that price was cost price, not to customer price.
(but even $60M, which I was assuming above does not change this meaningfully)
Probably somewhat more, as there would be either a purchase price, or a cost for remaining on orbit.

Details will differ from mission to mission, I presume, but I would think that the price would be less than a CRS mission. At that cost, NASA (or anyone) can do several missions a year and still pay less than the cost of maintaining the ISS right now (not even including the cost of crew rotations). I don't think that leaving the whole thing in orbit as a permanent station makes sense at those prices. Would be a waste of a perfectly good BFS too

[speedevil]

I don't think that leaving the whole thing in orbit as a permanent station makes sense at those prices. Would be a waste of a perfectly good BFS too

If you have a BFS in orbit, all the time, you are wasting it anyway, from the perspective of a launch vehicle company, and they would charge as such. Launches would certainly rise in price, if you want to hang onto a LV for six months.

[Elmar Moelzer]

If you have a BFS in orbit, all the time, you are wasting it anyway, from the perspective of a launch vehicle company, and they would charge as such. Launches would certainly rise in price, if you want to hang onto a LV for six months.

That is a good point! On the other hand, there is little difference between the thing being in LEO for 6 months or being on it's way to Mars for about the same time (and then some more time back). It would probably have less wear than on a Mars mission because the re- entry would be comparably benign.

[RonM]

It really depends on what experiments are being done and much it costs.

Running BFS like a giant Dragonlab would be good for most experiments. Big advantage in landing, refitting, and relaunch. Same for orbital manufacturing. Fly up, use microgravity to make whatever, land and unload finished product, relaunch. No need for visiting vehicles.

Long term experiments would require a permanent station. Maybe better to launch large modules via BFS Cargo and assemble a station instead of modifying a BFS. Depends on the overall cost.

[RDoc]

It really depends on what experiments are being done and much it costs.

Running BFS like a giant Dragonlab would be good for most experiments. Big advantage in landing, refitting, and relaunch. Same for orbital manufacturing. Fly up, use microgravity to make whatever, land and unload finished product, relaunch. No need for visiting vehicles.

Long term experiments would require a permanent station. Maybe better to launch large modules via BFS Cargo and assemble a station instead of modifying a BFS. Depends on the overall cost.

Well, long term experiments that require human maintenance might require a permanent station, but how many of these are there?

My notion is to have a permanent but non-maned station in orbit that one or more BFS's could dock to. It would supply a lot of power, station keeping(maybe), large instrumentation, and a venue for long term, unmanned experiments.

[MikeAtkinson]

My notion is to have a permanent but non-maned station in orbit that one or more BFS's could dock to. It would supply a lot of power, station keeping(maybe), large instrumentation, and a venue for long term, unmanned experiments.

Power (higher than standard BFS), multiple docking ports, long duration space exposure (>2 years), human tended long duration experiments (>6 months) are all things that a relatively small station can provide but which are difficult or impossible for BFS.