...when Significant Other is out of the country.
So I was reading the inimitable Atomic Rockets (again), and was looking over the life support section when I had a thought. Life support is a really big pain in the ass when you're designing spaceships, either for half-assed sci-fi novels like I do, or for actually really real, like NASA engineers (assuming NASA actually designs spaceships anymore, instead of shitty hundred billion dollar space hovels where the computers don't even work right). Anyway, what follows is the idea:
There's a way to eliminate the problem of life support altogether--algae tanks, sewage boilers, oxygen candles, and all. The only catch is the crew has to leave their bodies in long term parking at the spaceport.
If you assume that the contents of a human brain can be uploaded onto a computer, and that a sufficiently powerful computer can run an emulation of a human brain (much like a PC can emulate, say, a Nintendo Entertainment System for those of us having an attack of 80s nostalgia years after we sold the old box in a yard sale), then the crew can have their minds uploaded into the ship's computer and leave their bodies behind.
Sensory information isn't a problem--anyone who has ever had a dream could tell you that the brain cannot distinguish between actual data from the sense organs and stuff the brain just made up on its own. I would imagine if you can upload a brain, you understand enough about it to feed it fake sensations. The crew can experience being on a spaceship (or riding the Orient Express, or laying around on the beach in Key West, or whatever they like) despite being just a bunch of zeroes and ones on the mainframe. For long, boring trips, they can simulate whatever distractions they like, or just reduce their "frame rate" to near-zero. If there's an emergency or an unexpected situation at their destination, they can speed up their frame rate and run multiple simulations of it, so that they can try out multiple solutions and practice whatever they decide to do--possibly in a fraction of a second of real time.
For a spaceship designer, this combines all the advantages of an unmanned vessel and a manned one. The mass and expense of the crew and their support systems are lost, but you still have humans around to give the computer orders if necessary. You can have as large a crew as you want and not pay any penalties for it. If the mission isn't expected to be too dangerous, they can even bring along their families without this being catastrophically stupid, like it was in "Star Trek: The Next Generation".
There are a few problems, however. First, from a practical perspective, if you can run a human brain on a computer, you can almost certainly run something much much smarter on the same computer. So why are you bothering with people at all? (This was always the elephant in the room during space fighters vs. missiles/unmanned drones debates at SDN, especially when the compsci people showed up talking their argle-bargle and the beleaguered space fighter people would shout, "If computers are so great, why are there people on ANY of the space ships? Huh?! Huh huh?!" Or they would have, if they weren't so dumb they actually thought space fighters were a good idea).
Second, the "upload a brain, get a person inside the computer" idea assumes that the dualists are right and the body is just a machine for moving the mind around. This is by no means certain. How can you have, say, a flight-or-fight reaction if you don't have adrenal glands? How do you feel something in your gut if you don't have one? Of course, the computer can just send digital hormones to a digital brain the same way it sends digital sensory input, but I can see stories where digitized space crews struggle to hold on to their humanity because the bureaucrats and engineers who designed the system left those out.
The third problem is, of course, that the crew won't be able to leave the ship when they arrive at their destination unless they can upload to a different computer, or maybe loaner bodies, either organic or mechanical. Bringing their bodies along with them defeats the point of the exercise; if they're colonists, maybe you can grow them new bodies once you arrive (Walter John Williams has a short story, "Incarnation Day" where this is not only how humans are colonizing nearby stars, but how children are raised until they're adults and can pull their own weight in society).
Fourth, there's a little bitty existential problem here: have you actually transferred a mind, or did you just make a duplicate and now there are two copies of the crew? This crops up a lot in debates about Star Trek's transporters, which, thanks to the efforts of writers who apparently never thought this through, actually kill the original and create a clone. I don't quite know how to get around this one. Maybe you try to pull a Ship of Theseus where the crew member is, at least momentarily, simultaneously in control of his organic body and a digital copy on the computer before the body is shut down, so there's no discontinuity of consciousness, but I have a vague feeling that this is cheating somehow and I'm not smart enough to figure out why. Any other way, it seems to me from the point of view of the original crew member, he puts his head into some Clarketech do-funny, and then they kill him. Putting him into hibernation until the ship gets back and the digital copy is turned off is just killing someone else (and pointless besides). Arguing that there's some kind of property of the human mind which allows it to be converted into digital form but never copied, only transferred, is just lame. Allowing unlimited copies of the same individual to run around everywhere--and believe me, if it's possible, it will happen--is going to throw a huge wrench in conventional ideas of what it means to be human. Not that that's necessarily bad in science fiction, but if you're trying to write a simple story about an intrepid space crew without worrying about keeping their fragile meaty bodies alive, then "Oh yeah, in our society, people duplicate themselves at will" is a really big huge thing to have to ignore.
Anyway, as the title suggests, this is what I think about when Significant Other is out of the country for a week. I need her to come home so I can go back to thinking about sex again.