STS-109: Columbia’s Hubble Upgrade and the Leaking Spacesuit

Servicing Mission 3B, flown on space shuttle Columbia as STS-109 in early 2002, was the fourth visit to the Hubble Space Telescope. What happens when Hubble must be fully switched off for the first time, and a spacesuit fails at the same moment?

Why the mission was split

NASA divided Hubble's third servicing mission into two parts so astronauts could reach the telescope as soon as possible to replace its gyroscopes, which are needed to point it accurately. Servicing Mission 3A got Hubble running again. Servicing Mission 3B, scheduled for spring 2002, was to complete the planned upgrades. Over 12 days and five scheduled spacewalks it would add a new science instrument, the Advanced Camera for Surveys, bring an infrared camera back to life, and install new solar arrays and a new power control unit.

The crew

Scott Altman, a two-time shuttle veteran, commanded the mission. Duane Carey was pilot, on his first space flight, and Nancy Currie was flight engineer, with three previous flights. Four astronauts trained for the spacewalks: veterans John M. Grunsfeld, James H. Newman and Richard M. Linnehan, and Michael J. Massimino, who was making his first flight.

Solar arrays and the power control unit

The first spacewalk replaced the old arrays with the third version of Hubble's solar arrays. These were rigid and did not roll up like earlier designs. Being more robust, they raised Hubble's power intake by about 20 to 30 percent.

Next came the power control unit, Hubble's power switching station, which distributes the electricity generated by the arrays and batteries to the rest of the telescope. Replacing it required Hubble to be completely powered down for the first time. As the narration notes, one cardinal rule in space is that if something is working well, you don't turn it off.

The leaking spacesuit

During the shutdown, Grunsfeld and Linnehan were suiting up for the next spacewalk. A crew member monitoring Grunsfeld's suit reported a large bit of water at the bottom of the battery, and Houston was told Grunsfeld would have to be taken out of the suit. The water came from the suit's liquid coolant system. Because parts of Hubble were already shut down, the crew quickly resized another spacesuit so the spacewalker could get out before the spacewalk had to be cancelled. The start was late, but the power control unit was successfully changed out in a spacewalk of seven hours.

Camera and cooler

The astronauts then installed the Advanced Camera for Surveys, which lets Hubble capture wider views of the universe at higher resolution than before. They also revived NICMOS, one of Hubble's most critical instruments, which had been dormant for two years, by installing a cryocooler for its infrared detectors.