The space island group

[Emperor of the Titan Squid]

In the 1980s and 90s, the was an organization known as the space island group. they intended to build and operate there own fleet of space shuttles, and to bring the fuel tanks to orbit. how credible is the idea of a fuel tank station, or using tanks for on-orbit infrastructure? What if we could bring SLS fuel tanks to orbit? how economical would this be compared to inflatables? How would we design a rocket if we wanted to bring the tanks to orbit?

[Bill Phil]

On orbit tankage would need both passive and active cooling. Sun shields, coolant, and stuff like that. It makes a lot of sense. If you have a logistical system with propellant depots and space tugs you don't have to launch everything in one launch. You wouldn't have to bring a lander for a lunar mission, for example. It would've been placed somewhere for later rendezvous by a tug.

[mikegarrison]

At least the STS was powered by hydrogen. Living inside a kerosene tank would be nasty. Some of those aromatics never go away.

[Bill Phil]

11 minutes ago, mikegarrison said:

At least the STS was powered by hydrogen. Living inside a kerosene tank would be nasty. Some of those aromatics never go away.

SLS is hydrogen, besides the SRBs.

[Emperor of the Titan Squid]

49 minutes ago, Bill Phil said:

On orbit tankage would need both passive and active cooling. Sun shields, coolant, and stuff like that. It makes a lot of sense. If you have a logistical system with propellant depots and space tugs you don't have to launch everything in one launch. You wouldn't have to bring a lander for a lunar mission, for example. It would've been placed somewhere for later rendezvous by a tug.

If we could launch a second, smaller spacecraft, such a dragon, carrying the radiatiotors, that could work. As long as it can carry them. We could also send a crew separately from the radiators. It would require a crew and some supplies anyway, to fill it with air.

[Emperor of the Titan Squid]

How good would it be, compared to sending inflatables ?

 

[Nibb31]

I don't the SLS core can actually reach orbit. The upper stage does the job of finalizing the orbit. The Shuttle was different, because keeping the ET attached wouldn't prevent the OMS circularization burn. It would just cause a payload penalty.

I don't think Space Islands ever planned to operate their own Shuttle fleet. They simply wanted to reuse the ETs and NASA was actually open to the idea as long as they would get assurance that the ET wouldn't become a hazard.

The whole "wet lab" concept is another one of those false good ideas. It seems attractive at first, but when you start looking at the actual engineering details, it quickly gets impractical. Outfitting a spent tank requires more than just an airlock on it. For example the insulation foam on the ET (or the SLS core) isn't meant to withstand vacuum. You would rapidly end up floating in a cloud of orange foam debris. And there are hundreds of other details that would need to be thought out.

 

[Emperor of the Titan Squid]

25 minutes ago, Nibb31 said:

I don't the SLS core can actually reach orbit. The upper stage does the job of finalizing the orbit. The Shuttle was different, because keeping the ET attached wouldn't prevent the OMS circularization burn. It would just cause a payload penalty.

I don't think Space Islands ever planned to operate their own Shuttle fleet. They simply wanted to reuse the ETs and NASA was actually open to the idea as long as they would get assurance that the ET wouldn't become a hazard.

The whole "wet lab" concept is another one of those false good ideas. It seems attractive at first, but when you start looking at the actual engineering details, it quickly gets impractical. Outfitting a spent tank requires more than just an airlock on it. For example the insulation foam on the ET (or the SLS core) isn't meant to withstand vacuum. You would rapidly end up floating in a cloud of orange foam debris. And there are hundreds of other details that would need to be thought out.

 

Good point about the insulation. The space island group wanted to put insulation inside the tanks, Which would solve the problem but be very costly. And yes they seriously wanted to operate a shuttle fleet.

[Bill Phil]

2 hours ago, Nibb31 said:

I don't the SLS core can actually reach orbit. The upper stage does the job of finalizing the orbit. The Shuttle was different, because keeping the ET attached wouldn't prevent the OMS circularization burn. It would just cause a payload penalty.

I don't think Space Islands ever planned to operate their own Shuttle fleet. They simply wanted to reuse the ETs and NASA was actually open to the idea as long as they would get assurance that the ET wouldn't become a hazard.

The whole "wet lab" concept is another one of those false good ideas. It seems attractive at first, but when you start looking at the actual engineering details, it quickly gets impractical. Outfitting a spent tank requires more than just an airlock on it. For example the insulation foam on the ET (or the SLS core) isn't meant to withstand vacuum. You would rapidly end up floating in a cloud of orange foam debris. And there are hundreds of other details that would need to be thought out.

 

The core gets the second stage to a very eccentric orbit. If it can restart ( not a given) then it could make orbit.

[Nibb31]

33 minutes ago, Bill Phil said:

The core gets the second stage to a very eccentric orbit. If it can restart ( not a given) then it could make orbit.

It can't.

[Nibb31]

3 hours ago, Emperor of the Titan Squid said:

Good point about the insulation. The space island group wanted to put insulation inside the tanks, Which would solve the problem but be very costly. And yes they seriously wanted to operate a shuttle fleet.

But that would be a totally different rocket. Have you got a source for their intentions of having their own shuttles ?

[Bill Phil]

57 minutes ago, Nibb31 said:

It can't.

Just checked with someone working on the project, it wouldn't have to restart the engines to enter LEO.

[_Augustus_]

6 hours ago, Nibb31 said:

I don't the SLS core can actually reach orbit. The upper stage does the job of finalizing the orbit. The Shuttle was different, because keeping the ET attached wouldn't prevent the OMS circularization burn. It would just cause a payload penalty.

I don't think Space Islands ever planned to operate their own Shuttle fleet. They simply wanted to reuse the ETs and NASA was actually open to the idea as long as they would get assurance that the ET wouldn't become a hazard.

The whole "wet lab" concept is another one of those false good ideas. It seems attractive at first, but when you start looking at the actual engineering details, it quickly gets impractical. Outfitting a spent tank requires more than just an airlock on it. For example the insulation foam on the ET (or the SLS core) isn't meant to withstand vacuum. You would rapidly end up floating in a cloud of orange foam debris. And there are hundreds of other details that would need to be thought out.

 

The SLS core stage CAN reach orbit, but on EM-1 and EM-2 they will put it on a highly eccentric trajectory instead because they're not putting anything in LEO anyway and they don't want to leave an SLS core stage in orbit because it's a giant hazard.

[Emperor of the Titan Squid]

5 hours ago, Nibb31 said:

But that would be a totally different rocket. Have you got a source for their intentions of having their own shuttles ?

Yes. http://www.spaceislandgroup.com/vehicles-systems.html

[magnemoe]

On 2.9.2016 at 11:37 PM, Bill Phil said:

On orbit tankage would need both passive and active cooling. Sun shields, coolant, and stuff like that. It makes a lot of sense. If you have a logistical system with propellant depots and space tugs you don't have to launch everything in one launch. You wouldn't have to bring a lander for a lunar mission, for example. It would've been placed somewhere for later rendezvous by a tug.

Some of the follow up after the centaur upper stage point in this direction. And yes it makes sense for heavy missions without needing an giant rocket. 
However for an space tug you probably want an nerva as an bare minimum of ISP. 

[Bill Phil]

1 minute ago, magnemoe said:

Some of the follow up after the centaur upper stage point in this direction. And yes it makes sense for heavy missions without needing an giant rocket. 
However for an space tug you probably want an nerva as an bare minimum of ISP. 

For a space tug you'd probably want electric propulsion for bulk payloads, where time is not an issue. But a chemical tug would do well for small payloads. Nerva needs a shadow shield, although we can certainly make their performance even better than the old designs, which makes that less of an issue. Plus, we could use LANTR for higher thrust but lower ISP. Thing is, lower ISP for a LANTR is somewhere around 600 seconds.

[magnemoe]

30 minutes ago, Bill Phil said:

For a space tug you'd probably want electric propulsion for bulk payloads, where time is not an issue. But a chemical tug would do well for small payloads. Nerva needs a shadow shield, although we can certainly make their performance even better than the old designs, which makes that less of an issue. Plus, we could use LANTR for higher thrust but lower ISP. Thing is, lower ISP for a LANTR is somewhere around 600 seconds.

An vasmir might work well, you don't want to stay to long in the van allen belt so you want decent trust, This however makes the fuel depot pointless. I guess you would have an docking adapter containing an fuel tank for the vasmir, it docks with you satellite, takes it to LKO, for an probe to moon or outward it would give an higher Ap but no circulation, after releasing payload it would dry the adapter tank before releasing it on an deorbit trajectory before doing an orbital match for its next mission, this involes an plane change so its better done high. 

[Bill Phil]

14 minutes ago, magnemoe said:

An vasmir might work well, you don't want to stay to long in the van allen belt so you want decent trust, This however makes the fuel depot pointless. I guess you would have an docking adapter containing an fuel tank for the vasmir, it docks with you satellite, takes it to LKO, for an probe to moon or outward it would give an higher Ap but no circulation, after releasing payload it would dry the adapter tank before releasing it on an deorbit trajectory before doing an orbital match for its next mission, this involes an plane change so its better done high. 

It doesn't make the fuel depot pointless. It just means you can get away with a much smaller (and thusly cheaper) one.

[Emperor of the Titan Squid]

Why would you need a smaller depot?

[Nibb31]

14 hours ago, Emperor of the Titan Squid said:

Yes. http://www.spaceislandgroup.com/vehicles-systems.html

I love the introductory sentence. "95% of statistics are pulled out of thin air". Then it goes on to "many of the engineers" that worked on the space shuttle, who now work at Space Island Group... as if it was  actually more than 2 guys in a shed (and I'm not even sure they have a shed).

[Emperor of the Titan Squid]

I wish that there were a mod for this.does anyone know of one?

Edited September 4, 2016 by Emperor of the Titan Squid

[Bill Phil]

6 hours ago, Emperor of the Titan Squid said:

Why would you need a smaller depot?

If you're using plasma engines, your depot can be smaller because plasma engines have high isps. Plus, you wouldn't need to bring any oxidizer around.

[Emperor of the Titan Squid]

2 hours ago, Bill Phil said:

If you're using plasma engines, your depot can be smaller because plasma engines have high isps. Plus, you wouldn't need to bring any oxidizer around.

Ah, that makes more sense.

[Emperor of the Titan Squid]

What all would we need to do to outfit the tank?

[Nibb31]

5 hours ago, Emperor of the Titan Squid said:

What all would we need to do to outfit the tank?

You wouldn't outfit the tank. You would need to design a whole new stage. As mentioned, it would need internal insulation, or several tons of coating on the outside to prevent shedding foam. On the inside, you would need airlocks between the tanks, and some sort of docking device. It would need station-keeping if you want to dock to it, which means power (solar panels), avionics, RCS, navigation, comms...  You probably wouldn't want live directly inside a tank that has been filled with H2, LOX and helium, and the coatings on the inside of the tank wouldn't be very pleasant, so you would probably need some sort of inflatable bladder to fill the tank with a breathable atmosphere and serve as liner/padding. Then you would need to install the wiring, fluid loops, air ducts, assemble walls and floors and install the equipment...

The whole outfitting job would probably take months or years of EVA and IVA assembly, and many delivery flights to bring up the equipment.

Having a large empty volume isn't nearly as valuable as some people think. It's what you put inside that volume that matters. In the end, it's much cheaper to build your habitat on the ground and have it operational immediately for orbital work.