Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 September 24 To Fly Free in Space Credit: STS 41-B Crew, NASA Explanation: What would it be like to fly free over the seas and clouds of Earth? The first to experience such an "untethered space walk" were NASA astronauts Bruce McCandless and Robert Stewart during Space Shuttle mission 41-B in 1984. McCandless, pictured above, used a Manned Maneuvering Unit (MMU) to move in and around the...