Yes and actually NASA do loads of work with bacteria and viruses. Viruses are thought to be the origin of biological life on earth. Viruses are not considered living but you can a type of maths to figure out what genera or family came from what family, viruses end up being older than dinosaurs. So if you like biology and not so much space, you could still work for NASA. And yup, water on NASA could be a sign of previous life.