O'Neill Cylinders

The O’Neill cylinder is named after an American physicist and space scientist who sought to engage his students by getting them to think about big problems—space settlement, in particular. He also led symposiums where the concepts behind large, permanent space habitats—including the cylinder that bears his name—were hashed out. The basic principle is fairly simple. Construct a cylinder at least half a kilometer in diameter so that it can be rotated at low speed and provide 1 g of art...

 Amniotic Sac as Space Suit

The most fundamental innovation is the evolution of another fluid-filled sac, the amnion. in which the embryo floats. Amniotic fluid has roughly the same composition as seawater, so that in a very real sense, the amnion is the continuation of the original fish or amphibian eggs together with its microenvironment, just as a space suit contains an astronaut and a fluid that mimics the earth's atmosphere. All of the rest of the amniote egg is add-on technology that is also required for life in a...