JUDY WOODRUFF: And one more item tonight: a behind-the-scenes look at the effort to save the Hubble space telescope. That's the subject of tonight's edition of "Nova," which chronicles this year's complex attempt by NASA astronauts and engineers to repair Hubble during a 12-day mission.
Here's an excerpt looking at what space-walking astronauts Drew Feustel and John Grunsfeld faced.
The narrator is Rushmore DeNooyer.
DREW FEUSTEL: I'm ready, John. Let's go do this. Oh, this is fantastic.
RUSHMORE DENOOYER: Drew and John's first task is the number-one science priority for the mission: install a much more powerful wide-field camera.
They'll loosen one bolt, remove the old camera, insert the new camera, and re-tighten the bolt. It's one of the simplest jobs on the entire mission.
But, early on, there's a big problem. When Drew tries to loosen the bolt holding in the old camera, it refuses to budge.
DREW FEUSTEL: No turning.
RUSHMORE DENOOYER: If Drew can't get this bolt loose, the first job on the first space walk will grind to a halt.
JOHN MACE GRUNSFELD: Mass, the MTL is slipping.
RUSHMORE DENOOYER: The only people who can solve this are the ones outside with their hands on Hubble, John and Drew. Yet, they're not alone. A space walker with a problem has a vast network supporting him, five astronauts inside the shuttle, Tomas Gonzalez and Christy Hansen in mission control, and, behind them, engineers who know Hubble better than anyone else on the planet.
MARK JAROSZ, Goddard Space Flight Center: We know the telescope. We know what hardware is broken. We know what the interfaces are. We need a -- a flathead screwdriver or a certain kind of wrench or whatever.
RUSHMORE DENOOYER: Now, as Drew struggles to loosen a stuck bolt, engineers call up all the information they have on that bolt, starting with its torque, the turning force needed to loosen it.