|
||||||||||
|
Larger, cheaper, better ... maybe.
Inflatables are flexible pressure vessels that are launched collapsed and inflated in orbit or on the moon. Current designs for inflatables consist of many layers of flexible, but not stretchy, fabric, plastic, and foam.
The really big advantage of inflatables is that you can launch larger volumes in smaller payload shrouds.
If the Transhab data are to be believed, they are also somewhat lighter and more bulletproof than hard shells. My only reason to doubt the data is that in the past month the NASA Transhab team at JSC added another 4 inches to the thickness of the Transhab shell, to accommodate another layer of debris shielding and multi-layer insulation.
Inflatables aren't a panacea.
They're not yet off-the-shelf technology. Despite the fancy artwork on the NASA web sites (and a bit of hype) about Transhab, there are still many, many questions to be asked and a few potential show-stoppers for this technology. We have a lot of development work to do before we can rely on inflatables.
Right now, NASA does not know how to fold up the Transhab for launch, how it will be supported for launch, anything at all about the connecting equipment beyond the cartoon stage, and next to nothing about interior outfitting. They have a chunk of Transhab shell in Thermal-Vacuum Chamber B right now, getting ready for a test to find out if they can squish enough air out of it to make a difference for launch and to test its response to being folded up and squished.
Inflatables might not be the lowest weight, either; we need to look at the whole program. The pressure shell is the lightest and cheapest component of a space station; it's the interior outfitting and external equipment that makes the cash registers ring. Although the pressure shell might be lighter, the need to deploy the internal systems into the inflated shell and additional external structure required to support the shell could be show-stoppers.
On-orbit outfitting is an expensive process. All the parts have to be designed to move safely through the openings of the docking mechanisms and then assembled inside. That means we have a lot of additional launch weight for the support structures and pressure vessels to carry in the interior outfitting.
Inflatables on the moon might be a different story.
Most of the stuff inside an inflatable module can be made from in-situ lunar material. The cloth layers are made of glass fibers, and the debris shield is alumuminzed Kapton. NASA is uses polyurethane foam with lots of big holes in it to hold the layers of debris shield apart, but almost any substance could perform that function. The interior structure and external hard stuff is all aluminum.
So, to deploy an inflatable habitat on the moon, the only part of the current design that really needs to be imported from Earth is three layers of food-grade plastic for the air bladder.
We will need quite an industrial infrastructure on the moon before we can use in-situ material for inflatable habitats on the moon, but we'll get there.
|
|
|