Spaceflight Now: STS-106 Mission Report

Spacewalking astronauts to wire up station modules

Posted: August 30, 2000

After docking, the astronauts will not immediately enter the station or even open any hatches. First, Lu and Malenchenko are scheduled to stage a six-and-a-half-hour spacewalk the day after docking to connect four power cables between Zarya and Zvezda and four video and data cables.

The power cables, in a strip of four stretching 26.9 feet, will permit electricity generated by future U.S. solar arrays to power systems in Russian modules as needed. The video and data cables, also in a strip of four, stretch 16 feet.

Astronaut Ed Lu and cosmonaut Yuri Malenchenko rehearse making cable connections on a training mockup of the service module during a training session in the hydrolab at Star City. Photo: NASA-JSC
"As the station gets bigger and the solar arrays start to get blocked (by other modules), we need to share power between the different segments and the different modules," said lead flight director Phil Engelauf.

"And these external cables will be connected up in anticipation of ... when we will start generating power."

The spacewalkers also plan to hook up a 20-foot-long fiber optic telemetry cable that will be used during future Russian spacewalks and re-mount a Russian magnetometer on an extended boom near the rear of Zvezda. The magnetometer will provide a backup means of determining the station's orientation in space.

The magnetometer is located near the far end of Zvezda. To get there, Lu and Malenchenko, carrying cable spools and tools, will ride the shuttle's robot arm from Atlantis's payload bay to Zarya 45 feet away. From there, they will pull themselves, hand over hand, along handrails up to the magnetometer work site using two safety tethers each.

Astronaut Lu practices installation of magnetometer on the service module in the hydrolab at Star City. Photo: NASA-JSC
"When they're working on the magnetometer boom, they'll be about 110 feet away from the space shuttle, which is twice as high as astronauts were when we worked on the top of the Hubble Space Telescope," said Mike Hess, a NASA spacewalk planner.

"So it'll be a very different view for this crew, it'll be the equivalent of working on about the 11th story of a 13-story building when they're working on the magnetometer."

Lu, who will be identifiable by red stripes on his spacesuit, said he and Malenchenko are "really looking forward to getting a chance to see this view, of looking down and seeing the space shuttle with the Earth in the background. We're expecting a pretty incredible view."

That view comes at a price, however: The distance Lu or Malenchenko might have to quickly traverse in an emergency to reach the safety of the shuttle's airlock.

But Hess said the spacewalkers could make it back into the airlock in 10 to 15 minutes if necessary and each spacesuit has a 30-minute supply of emergency oxygen.

Spacewalk outside the international space station during last shuttle mission in May. Photo: NASA-JSC
"The added risk involved in the EVA is in terms of rapid safing," Hess said. "From a rapid safing standpoint, we're still within our 30-minute limit, which is what the suit can easily take care of. So we should easily be able to get back inside if there's a problem."

Once the magnetometer head is mounted on its boom, Lu and Malenchenko will work their way back "down" the station stack toward the shuttle, stopping at the Zvezda-Zarya docking interface to hook up the power and data cables.

As they did going "up" the stack, the spacewalkers will take special care to avoid protruding antennas on the Zarya module and two docking targets on Zvezda's hull. "They'll snake over one target and under another," Hess said.