The International Space Station’s robot arm grabbed Dextre and moved it into an
overnight parking position. The new robotic system will be activated on a power
and data grapple fixture located on the
Mission Specialists Rick Linnehan and Robert L. Behnken
completed the third spacewalk of the STS-123 mission at 1:44 a.m. EDT. The
excursion lasted six hours and 53 minutes.
With Mission Specialist Mike Foreman coordinating spacewalk
activities from inside the orbiting complex, Linnehan and Behnken installed a
spare parts platform and tool handling assembly for Dextre. Among other tasks,
they also checked out and calibrated Dextre’s end effector and attached
critical spare parts to an external stowage platform.
Dextre is the third and final component of the Mobile
Servicing System developed by
The technology behind Dextre evolved from its famous
predecessor Canadarm2. Dextre is the world’s first on-orbit servicing robot
with an operational mission, and it lays the foundation for future satellite
servicing and space exploration capabilities.
While one arm is used to anchor and stabilize the system,
the other can perform fine manipulation tasks such as removing and replacing
station components, opening and closing covers, and deploying or retracting
mechanisms. To grab objects, Dextre has special grippers with built-in socket
wrench, camera, and lights.
The two pan/tilt cameras below its rotating torso provide
operators with additional views of the work area. Currently, astronauts execute
many tasks that can only be performed during long, arduous, and potentially
dangerous spacewalks. Delivery of this element increases crew safety and
reduces the amount of time that astronauts must spend outside the station or
routine maintenance. Some of the many tasks Dextre will perform include:
installing and removing small payloads such as batteries, power switching
units, and computers, providing power to payloads, manipulating, installing,
and removing scientific payloads.
Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly.
Unfortunately, Rick Linnehan and Robert L. Behnken were
unable to attach a materials science experiment to the
Space shuttle Endeavour Pilot Gregory H. Johnson and
Expedition 16 Flight Engineer Garrett Reisman operated the station’s robot arm
during the spacewalk.
The astronauts have two more missions to complete. The
fourth spacewalk will be used to replace a remote power control module and test
a shuttle tile repair material. The repair material test was originally
scheduled for Discovery’s mission last October, but was rescheduled so that
problems with the station’s solar arrays could be addressed.
The goal is to complete this test before space shuttle Atlantis flies to the Hubble Space Telescope in August. Unlike missions to the space station, Atlantis’ crew members wouldn’t be able to wait on the station for another shuttle to bring them home if Atlantis was damaged.
Behnken and Foreman are slated to begin the mission’s fourth
spacewalk at 6:28 p.m. Thursday.
On the fifth spacewalk, mission specialists Robert L. Behnken and Mike Foreman will store on the station the boom that attaches to the shuttle’s robotic arm for heat shield inspections. The boom is being stored on orbit since the next shuttle will not have enough room to carry both the boom and the larger JAXA module in the cargo bay.
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