NASA hasn't closed the door on the possibility — and the man in line to be the agency's next chief is a champion of the idea.

The world's most famous telescope is celebrating in style with new views of Mars, nebulas and a galaxy that reminds us of home.

In the years since, Hubble has gathered more than 1.6 million observations and 430 terabytes of data. The telescope has revealed that supermassive black holes nestle at the heart of most large galaxies,