But, I started learning just how much fun it was to stay on earth and work on a lot of different space projects, so I have no regrets. I have a private goal to leave Earth, just once, and look at the world from space and the stars beyond the atmosphere. That goal may be nearer than we think. The answer is all of them. Be interested in everything.
Astrobiology is a forum for lifelong learning.
I have a bachelor's degree in biology, but almost enough credits to be a chem major. I have a master's degree in cell and molecular biology, but I also took a lot of physics, engineering, computer, and math courses. I'm an amateur astronmer. Recently, I've started studying anthropology, sociology, political science, everything about the evolution and effect of intelligence. I have never understood how people could ever be bored.