Discovery crew complete second space walk

Shuttle Discovery spacewalkers completed what was arguably the most daunting task of the latest mission to the International Space Station. The repair mission wrapped-up Monday at 3:01 p.m. EST, after seven hours in the vacuum of space.

Mission specialists Piers Sellers and Mike Fossum worked on the station's Quest airlock and replaced a cable that provides power to the mobile transporter.

The transporter is essentially a cosmic rail car that moves astronauts along the station's growing network of trusses.

The transporter is capable of carrying the Canadian-built robotic arm which is required for building the ISS and servicing the station once complete.

The transporter cable unexpectedly failed last December during the assembly of a truss for one of the station's massive solar arrays. The truss is meant to generate electricity to support the space station crew and scientific experiments.

Shuttle crew members may conduct a third and final spacewalk Wednesday, to complete several bonus housekeeping and repair tasks.

After that, the six-person crew (European Space Agency astronaut Thomas Reiter, who was aboard the shuttle, starts a multi-month stay on the ISS) has been cleared to return to Earth July 17.

Photography: NASA

Source: Discovery Channel Reports, July 10 edition