I believe the purpose of science is, at the root, a deep, natural curiosity and a determination to find answers to questions.
What motivates us to find these answers is, I think, where things get interesting.
I feel there are some who seek answers to, for example, earth sciences with an aim toward manipulating them for our (human) use. I feel there are some who seek answers with an aim toward protecting them from manipulation. And finally I feel there are some who are comforted by reducing the number of mysteries in the world, with an aim toward feeling more in control of our existence and destiny. Many people are frightened by mystery.