The Chandra X-Ray Observatory, which is responsible for some of the most sublime images we have, only requires about two kilowatts of electricity. That's about 17,500 kilowatt-hours a year. That's nothing. The Department of Energy found that an average American household used about 10,000 kilowatt-hours of electricity a year in a comprehensive study from 2001.
So, imagine one of those huge suburban manses with a heated indoor pool and eight bedrooms. It uses as much power as Chandra needs to peer across the universe at things like the remnants of a supernova.