NASA: Robots critical to Endeavour's mission on space station

Two robots will work as a team and one robotic arm is set to 'walk' outside of ISS

The crew of the space shuttle Endeavour is getting ready to launch into what NASA is calling its most technical mission yet - one that will call on the power of three separate robots.

Endeavour is set to launch at 7:17 a.m. EDT Saturday, carrying aloft a seven-person crew on a 16-day mission to expand the Japanese laboratory housed on the International Space Station.

The highly complex mission will include five spacewalks, the use of three robotic arms, two working together and one that will actually "walk" across the outside of the space station.

Holly Ridings, lead space station flight director for the Endeavour mission, said it is one of the most technical undertaken by NASA. The mission goals couldn't be reached, she added, without the use of NASA robotics technology.

"The length of the mission, the five spacewalks, the robotics used almost every single day and 13 crew members makes it a big puzzle and all those pieces need to fit together correctly to get everything done," said Ridings, adding that NASA space missions will become increasingly dependent on robots.

"We have learned a lot about robotics and about working together with robot," she said. "Our spacewalkers are involved in activities while the robotic arms are looking at them and giving us camera views. The choreography of the different robotic arms is really complicated, and we've learned a lot about it and we do it well. Robotics is really one of the things that NASA has a lot of experience in and it's allowing us to do some wonderful things on the space station."

Endeavour is scheduled to dock with the space station early Monday morning. Then the real hard work begins on Tuesday when two astronauts will take the mission's first spacewalk with the help of two robotic arms.

Ridings explained that as the astronauts begin their work outside the space station, a robotic arm will lift a 4-ton piece of the Japanese complex out of the shuttle's payload bay. This piece, which has been dubbed a "front porch", will be permanently attached to the outside of the Japanese module. It is designed to hold its own payloads, as well as host experiments that need to be conducted in outer space.

Once the station's robotic appendage called the big arm has extracted the porch from the shuttle, it will be handed off to the space shuttle's own robotic arm. While the shuttle's arm holds the porch, the station's arm will move itself about 50 feet down the length of the space station by basically moving much like a child's Slinky toy.

Ridings explained that either end of the big arm can be used as the base, just as either end can be used as a gripping hand. Once the arm hands off the porch, it's gripper end will swing over and attach to the space station and the end that was originally attached to the station will let go and free itself to be the gripping hand.

Ridings said the robotic arm has several redundancies built into its software so five to seven things would have to go wrong for the arm to lose its grip on the space station and float away into space.

Once the arm has completed what NASA calls its "walkoff," it will reach out and take back the porch and move it into place against the Japanese module. The porch then should automatically attach itself.

The robotic arms are slated to conduct seven similar hand-offs between the two arms during the mission.

Meanwhile, there is a third robotic arm attached to the Japanese module that will be used for the first time next week. This the arm, installed at the station in June, 2008, will pick up and move payloads to the porch. "It'll be the first time we've used that robotic arm with a heavy payload on the end of it," said Ridings, who will be working in Mission Control while Endeavour is aloft. "We've had practice runs with it but this is the first time we've grabbed something and moved it around."

During the mission, the astronauts also will be installing new batteries that are designed to hold the power generated by the space station's solar arrays. Switching out the station's solar batteries has never been attempted before.

This past March, the crew of the space shuttle Discovery unfurled and set up the last set of energy-harvesting solar arrays that were attached to the International Space Station. The solar arrays, which are designed to gather energy through 32,800 solar cells, will produce enough energy to power 42 2,800-square-feet homes. That will double the amount of power that goes to science experiments onboard the station.

It also means it's enabling the space station to support more astronauts. Just last month, the traditional three-person crew was doubled to six when a Russian spacecraft brought three more people aloft. When the crew of the Endeavour arrives Monday, the station will hold a record 13 people.

Copyright © 2009 IDG Communications, Inc.

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