One of the more interesting modules that was originally going to be part of ISS was the Japanese-built Centrifuge Accomodations Module (CAM). The CAM was designed to provide the facilities for testing the impact of reduced and hypergravity–over a range of 1 milligee up to 2 gees of acceleration–on various biological specimens. Tests on these specimens, up to and including rats, would give us valuable information on the impact of gravity levels we might encounter on other planetary surfaces than earth, as well as giving us some data on what levels of artificial gravity might be required to prevent the debilitating effects of microgravity on people.
As I’ve discussed before on this blog, our knowledge of the impact of gravity levels other than microgravity and 1 gee are almost virtually nonexistant. We have billions of data points at 1 gee, and we have hundreds of data points in microgravity, but we have a few tantalizing hints from the six Apollo lunar landings–nowhere near enough data to make responsible projections. It may turn out that only a little bit of gravity can go a long way (if the negative effects are driven by fluid distribution in the body like I think it is), or it could turn out that even Martian gravity isn’t enough.
This is the kind of information we really need to learn if we’re ever going to be a spacefaring society, and CAM would have provided that data. Unfortunately, in 2005, the partially completed module was canceled, due to budget overruns and issues with trying to schedule a launch before the Shuttle was to be retired. The module has been sitting outside at a space center in Japan ever since.
At the time, that may have sounded like a reasonable decision, but now that it is looking like ISS won’t be splashed in 2015/2016, and with the new emphasis on manned deep space exploration, it would be nice if that decision could be undone. The Augustine Committee mentioned research on the impacts and mitigation of reduced gravity effects on the human body as one of the reasons for extending the ISS’s operations to 2020.
Unfortunately at this point the team has been disbanded for long enough, and the hardware exposed to the elements long enough that resuscitating the CAM is probably not in the cards. More importantly, like most other ISS modules, CAM was designed to be launched on the Space Shuttle. While it is possible to develop an adapter for EELVs that could allow ISS modules to be launched on them, such a system has yet to be funded. So for now, it looks like restarting the CAM project as originally formulated is probably a dead end.
So here’s my crazy idea. What about modifying a Dragon capsule to house the centrifuge experiment and its supporting equipment racks?
Most of the volume in the CAM design was actually storage rack–10 of the 14 ISPRs in the module were set aside for storage, and only 4 were planned for science. The actual centrifuge itself was about 2.5m in diameter, but not very thick. Looking at the Dragonlab datasheet, I wonder if it would be possible to make another copy of the centrifuge assembly itself and fly it as a payload on a DragonLab flight to ISS. Looking at the available volume, it looks like you could fit the centrifuge and possibly as many as 1-3 of the 4 payload racks that were originally slated for the science mission. I’d need to do a quick CAD model to see if the ISPRs would fit as-is, or if you’d need to go with some other science rack configuration. And such a setup wouldn’t have all the capabilities that the original CAM had, but it would give you some of the most important functionality. Also, being part of a reenterable spacecraft, there would be the benefit that you could bring the setup back to earth to repair, modify, and upgrade it from time to time.
Looking at the sizing, this might require a dedicated Dragon airframe for the project. The centrifuge assembly itself is too big to fit in the door in one piece! It might actually be necessary to build the capsule around the centrifuge. But there’s enough experimentation that would need to be done over the years, that it would probably make sense to do it that way. The duration of DragonLab missions are listed as up to 2 years. At that rate, you could do long-duration experiments, but still have the thing back down for maintenance, upgrades, and refitting frequently enough that it might allow you to make some design simplifications. Also, basing the CAM inside a Dragon capsule would mean that the team designing the science hardware could focus just on the experimental apparatus, instead of having to design a full spacecraft like the original CAM. That might save a lot of time and money compared to trying to complete the original CAM. Lastly, the Dragon capsule can be either docked to the station, or can serve as a freefloater, whichever makes more sense scientifically.
[Note: It might also, just barely fit with the Orbital Sciences Cygnus spacecraft. I don’t have internal dimensions for that, but judging from the external dimensions, there’s a chance. If someone who has data on what the layout of the usable volume for Cygnus is, that would be helpful.]
By offloading all of the work other than the apparatus itself, and by using a relatively inexpensive launcher, this could be a way for international partners to contribute. Either Japan could provide the apparatus, or if they’re not interested, this could be a way to involve India or China in the ISS program. It would also be something well within the capabilities of Canada or the UK as well.
In fact, it might even be possible to do this entirely as a commercial venture or as a privately funded not-for-profit venture. A commercial venture would be risky, since you would need some sort of guarantee that someone would actually pay for the data. A not-for-profit with a wealthy benefactor who would be willing to subsidize the experiment, (much as has been done for many university science labs, telescopes, and other not-for-profit scientific facilities) might make more sense. Imagine the Stanford or Caltech or MIT Orbital Centrifuge Lab, or the Bill and Melinda Gates Orbital Centrifuge…
As far as a spacefaring society is concerned, CAM would’ve been one of the most useful experimental hardware on the ISS. It may be too late to restart the CAM module as originally conceived, but Dragon–if successful–may provide another chance at making the ISS truly relevant.