Partial G Space Station

Radial rotation

One initial idea is to use Bigelow Aerospace inflatable space stations for partial gravity research, because these stations have a much larger diameter than anything that fits in a payload fairing.

A larger diameter station could be used to generate artificial gravity.

Spinning something with the diameter of ISS modules along their long axis would mean a tall astronaut's chest would be in zero G and his head would be "falling up", so these are clearly not suitable for zero gravity research. Spinning them along the short axis would mean the docking bay is under gravity, which means the station would have to be spun down for docking and undocking - and it might even be impossible to spin the station while the crew's "escape boat" is docked!

I have not been able to find the dimensions of the largest Bigelow module, but judging from [1] the BA 330 appears to have around twice the diameter of the Galaxy, so 8 meters across. TODO: calculate how fast it needs to spin for various G levels.

The basic idea is to assemble a rigid "Ikea style" floor inside the inflatable walls, so the force of supporting equipment and astronauts does not hit the inflatable walls. There can be a ramp and/or ladder up to the airlock, which is on the rotational axis.

Pros:

• Uses an off the shelf space station component.
• The air lock is on the rotational axis, so craft can be docked without spinning down the station.
• Can probably be launched in one go. The only on-orbit assembly will happen inside the already pressurized station.
• There is a lot of living space inside a BA 330, possibly as much as 100 square meters of partial gravity floor.

Cons:

• An "ikea style" floor would need to be installed inside the walls.
• The gravity level at the floor would be higher than at head height, by about 40% for a 1.70 meter astronaut.
• Matching the rotation of crew capsules to that of the station will complicate docking and supply stowage.

Tethered/dumbell configuration

Another proposal is to attach two components to each other with a tether or truss and rotate them around each other. This has the advantage that it can be done entirely using solid space station components.

Pros:

• Uses off the shelf space station components, except for the tether or truss.
• Uses all solid compartments.
• Has been done before briefly, on a Gemini mission.

Cons:

• Less living and laboratory space.
• The station needs to be "spun down" before crew capsules can dock and undock. Does this have "life boat" safety implications?