NASA designs an actual spaceship

The Nautilus-X MMSEV is the closest NASA has come to a design for an honest-to-goodness spaceship in decades. There has already been extensive discussion over at Selenian Boondocks and Hobbyspace, and this is probably a couple weeks late on the subject. However, this is an idea that has considerable merit and deserves further study. So, I uploaded the Holderman powerpoint to Google Docs, and here it is:



If you click on the "open in new window" button, then you can view it in full screen.

There is a lot that I like about this design - in fact, much of it looks like items on my list of technological stepping stones to space. For one thing, it is modular. Yes yes absolutely yes. Several launches are required to put it together, all of which could be done with existing vehicles (with one exception which I'll get to later). It includes a centrifuge, which might mitigate some of the bone loss effects of microgravity. It includes inflatable modules. Above all it is a spaceship - its environment is space, it has no landing gear or reentry heat shield.

Now, there are some things I don't like about the Nautilus-X.

That big core section would require a single launch, probably on something heavier than anything in stock today. It has RV-style slide-outs for the command deck and a large airlock. Worst of all, it has flat walls - probably due to the slide-outs. The flat walls and slide-outs are brand-new technology that introduce unnecessary failure modes and complexity. This could be redone as two pieces with curved walls: the radiation mitigation chamber is one piece, the airlock and command deck are another, set "sideways" to make a T shape. These two smaller pieces could then probably be launched on existing launch vehicles.

The centrifuge radius is an educated guess. We don't know the minimum gee required to reduce or eliminate bone loss. That particular centrifuge would produce no more than a few percent of a gee (i.e. about lunar gravity at 4RPM by my estimate) before problems due to high angular velocity start to occur. If a few percent gee is enough to slow or stop bone loss, great! If not, then this centrifuge would be an added layer of complexity for limited benefit. There would be benefits, no doubt, particularly for things like eating and ablutions, but the primarily-intended benefit would be missing. The bearings on the centrifuge - allowing nearly frictionless rotation while not allowing atmosphere to escape - are going to be a novel engineering challenge.

The MMSEV is intended for very long duration missions, up to two years. Unlike satellites in low earth orbit, which spend half their time in Earth's shadow, the MMSEV would be out in cislunar space or interplanetary space constantly being exposed to the sun. The entire craft would have to do a slow "barbecue roll" to avoid overheating one side, most likely along its long axis in the opposite direction of the centrifuge. Canfield joints at the end of the beams holding the big solar panels would allow them to continuously track the sun during the barbecue roll.

It's a good start.

Update Mark Holderman responds.