WASHINGTON, June 17 (Xinhua) -- Two astronauts finished the fourth spacewalk of Atlantis mission, safely re-entering the International Space Station at 6:54 p.m. EDT (2254 GMT) on Sunday, according to NASA TV.

Mission Specialists Patrick Forrester and Steven Swanson began the excursion at 12: 25 p.m. EDT (1625 GMT) and quickly went to work preparing the new truss segment for operation. The new component was installed onto the station on June 11. Most of the truss work centered on activating the Solar Alpha Rotary Joint (SARJ), which will allow the new truss solar arrays to track the Sun.

Early in the spacewalk, Forrester verified the installation of a mechanism that will drive rotation of the SARJ, and Swanson installed a TV camera. Then, the duo removed the final launch restraints on the SARJ before removing a keel pin and drag link to clear the path for the station's mobile transporter.

They also installed a computer network cable onto the Unity module and removed a Global Positioning System antenna. Finally, the orbital duo completed the installation of a piece of debris shielding on the Destiny laboratory.

The two spacewalkers wished their fathers well for Father's Day before closing the outer hatch of Quest airlock.

"Absolutely, a lot of fathers on this flight and we're all enjoying a great Father's Day," added astronaut James Reilly inside the station.

Forrester and Swanson conducted Atlantis mission's second spacewalk. Mission Specialist James Reilly and John Olivas conducted the other two.

Sunday's excursion is the 88th spacewalk devoted to station assembly and maintenance.

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"Currently, they have all six computers up while we do some additional troubleshooting to understand the environment and how if affects the computers," said Mike Suffredini, NASA's ISS program manager. Full story

NASA clears shuttle Atlantis to land next week

WASHINGTON, June 16 (Xinhua) -- NASA's Mission Control Center told the Atlantis crew Saturday that space shuttle's thermal protection system is cleared for re-entry.

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Astronauts complete multitask in 3rd spacewalk

WASHINGTON, June 15 (Xinhua) -- While Russian and U.S. flight engineers are trying to fix the failed computer system on International Space Station (ISS), two astronauts finished the third spacewalk on Friday, accomplishing multi-task.

Mission Specialists James Reilly and John Olivas started the spacewalk at 1:24 p.m. EDT (1724 GMT), and they were back inside the Quest airlock at 9:22 p.m. EDT (0122 GMT).