Astronauts Prepare to Rig Impromptu Hubble Shades

The Discovery astronauts gathered parachute cord, alligator clips and spare thermal blankets Monday for a tricky fifth and final spacewalk to rig the Hubble Space Telescope with impromptu sunshades.

Astronauts Mark Lee and Steven Smith were scheduled to leave the safety of Discovery’s cargo bay air lock late Monday night for a four-hour spacewalk to repair tattered insulation peeling away from critical equipment bays on the space telescope.

The unscheduled spacewalk, along with additional repair work carried out during a cargo bay excursion Monday, should shore up the insulation and keep Hubble cool enough to continue normal operations until the next shuttle servicing mission in three years.

“We expect [the repairs] to fully ensure the telescope will not have major thermal problems between now and December ‘99,” said Kenneth Ledbetter, a senior Hubble manager.

Discovery’s seven-member crew accomplished the primary goal of the 82nd shuttle mission Monday when astronauts Gregory Harbaugh and Joseph Tanner completed a $350-million overhaul of the $3.1-billion observatory.

Working in alternating two-member teams, Harbaugh, Tanner, Lee and Smith carried out four back-to-back spacewalks to install two new science instruments and new data recorders and to replace a variety of other components showing signs of wear and tear.

During a six-hour, 34-minute spacewalk Sunday night, Harbaugh and Tanner replaced a solar array drive controller and installed protective covers over magnetic sensors at the top of the telescope some four stories above Discovery’s cargo bay.

“Boy, I’m glad I’m not too afraid of heights,” Tanner said as he and Harbaugh rode the shuttle’s 50-foot-robot arm to the top of the telescope.

“I’m glad you’re not too!” said Harbaugh. “Be sure you’re tethered!”

“I am, and I’m looking for more tethers to attach,” Tanner joked.

Throughout the spacewalk, the astronauts marveled at the view of Earth 370 miles below and the thrill of riding the robot arm to such lofty heights above the shuttle.

“Looks like you’re riding your Harley there, Joe,” Lee called from the crew cabin as arm operator Steven Hawley hoisted the spacewalkers high above the cargo bay.

“It’s a great ride too,” Tanner replied. “Not as much wind noise, though.”

With the Hubble overhaul complete, the astronauts turned their attention to a last-minute repair job, mounting two spare thermal blankets over two large tears in the insulation that protects the top of the telescope.

Lee and Smith faced a somewhat trickier task repairing gaps in the insulation over critical equipment bays.

If all goes well, Hubble will be released back into open space at 10:41 p.m. today, clearing the way for Discovery’s return early Friday.