Early Saturday evening, Mission Control told astronauts that a new spectrograph that spacewalkers also installed passed both its tests. Atlantis crew responded with what has become customary whooping it up.
Even with two spacewalks remaining, including the repair of a major instrument Sunday, NASA managers were handing out accolades and declaring the telescope already improved.
"We're enjoying the moment and savoring it," Hubble program manager Preston Burch said at a news conference Saturday afternoon.
In a video sent to Earth taken before the spacewalk, Mike Massimino, who spacewalked Friday and will do so again Sunday, compared dealing with Hubble to a heavyweight fight. But he also was looking like the winner in such a bout.
"We don't warranty any of the work," Massimino joked for the camera in a heavy New York accent. "Labor's not guaranteed."
The high-stakes job unfolded 350 miles above Earth. Orbiting so high put Atlantis and its astronauts at an increased risk of being hit by space junk.
Earlier, Grunsfeld and his spacewalking partner, Andrew Feustel, accomplished their first task, hooking up the $88 million Cosmic Origins Spectrograph.