The Annoyed Man wrote:As far as the effectiveness of lubricants in space, I have an anecdotal but I'm-pretty-sure-it's-true story to offer. As some of you know, my family was part of the Caltech/JPL community. My parents were professors there, and my father in law was a JPL engineer who designed and built guidance packages for a number of spacecraft. One of my good friends who was one of my racetrack pit-partners was also a technician at the Carnegie Institute facility on the Caltech campus, and they were building a gyroscope to be used in one of these guidance packages that was to be sent into space—I think it might have been the Hubble Telescope. The problem was how to lubricate the bearing points of the spinning gyroscope's axis. This is less of a critical issue for a gyroscope that is going to return to earth because of the sheer length of time the lubricant will have to hold up for one that is not going to return. They had a meeting about how to procure a lubricant with the properties of tackiness so that it would adhere well to the parts to be lubricated without migrating to places that did not need it, low volatility so that it would not evaporate away, the ability to absorb tremendous shearing forces, and yet the ability to maintain a thin film at the points of contact between moving parts. Brian got up, left the meeting, went out to the parking lot, and retrieved the can of Bel-Ray motorcycle chain lube from under the seat of his motorcycle. He brought it into the meeting, explained its properties, demonstrated it, and—according to what he told me—the decision was reached to use tiny amounts of motorcycle chain lube at the points of contact. Instead of spending thousands of dollars on research and sophisticated materials, a $3.95 can of chain lube saved the day.
I love those kinds of stories, and I have another one involving my father in law, who saved the government from spending a million dollars on a spacecraft part with a $1.98 piece of wood.
Yeah, last time I was hands-on with any space hardware (which was about 5 years ago), we just used Braycote for everything. Not quite as mundane as motorcycle chain oil, but not exactly gee-whiz exotic super-science stuff either. Cost and availability seem almost completely independent of how well something will work in space - some really expensive stuff just plain won't work, but sometimes the stuff you buy off the shelf at the auto parts store is just fine.
Regarding the idea of heat-transfer, if you'll let me return to my physics-major roots for a bit:
There are 3 mechanisms of heat transfer: conduction (which we're all familiar with - works by direct contact), convection (which we're probably still all familiar with - depends upon circulation of a working fluid), and radiation (which, as TAM pointed out, doesn't require any sort of transmission medium). In a vacuum, radiation is the only one that works. Unfortunately, it's also the least efficient. So TAM, your basic premise is correct. One subtlety is that you don't need to be visibly glowing to radiate energy - low-energy wavelengths like infrared work okay, too. It's been a while since I've had to think about this, but pretty sure that the Stefan-Boltzmann Law says that you radiate more energy at higher temperatures (which makes sense), so you'd reject more heat once the thing got hot enough to start glowing, but you'd be doing so before then as well. It would still probably take a pretty long while to cool down once you reached that point.
For reference, we use giant radiator panels to keep the International Space Station cool (I actually work with those) - radiator systems are a pretty basic part of spacecraft design. If you purpose-built a firearm to use in space, you'd probably have to design a cooling system for it.
