If you can dig up a copy of the 1962 book "Space Medicine" by U. Slager, it's really interesting. It makes you realize how many questions they needed to answer experimentally before going into space. For example, how much acceleration can someone withstand. How much vibration and tumbling. Minimum and maximum survivable temperatures. How long can you be exposed to a vacuum. This was the era of putting people on rocket sleds to see what happens ( http://en.wikipedia.org/wiki/John_Stapp ). My favorite factoid from that book is that guppies can tolerate 10000G for 30 sec. It also describes a guy who survived 482 degrees F for 4 minutes.