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| Zarya/Unity Assembly Space Walks |
| Overview |
Once Zarya and Unity are attached, Ross and Newman will conduct three spacewalks, or EVAs, to connect power and data transmission cables between Unity, the mating adapters and Zarya; to install antennas and remove protective covers from some exterior equipment; and to install spacewalking gear that will be used on later assembly missions. One approximately six-hour spacewalk will be carried out every other day, with the first occurring on the fifth day of the mission, the day after the Zarya rendezvous and docking.The first spacewalk will consist primarily of attaching umbilicals and connectors between the mating adapters, Unity and Zarya. Ross and Newman will begin by setting up the Shuttle payload bay and worksites for the three spacewalks. A slidewire will be installed for safety and to provide clearance while the spacewalkers connect umbilicals between the first mating adapter and Unity. Eight umbilicals will be connected, four primary and four backup. Following the umbilical connections, Ross and Newman will remove thermal covers from the exterior computers, called multiplexer-demultiplexers (MDMs), on Unity. Command checks between Mission Control, Houston, and Mission Control, Moscow, will be conducted the next day, day six of the flight, while the crew pressurizes the Orbiter Docking System vestibule, completes leak checks and prepares S-band communications equipment for installation on the second spacewalk. The ground control checks will include verifying the ability to command Zarya from Houston via the Moscow control center. The mating adapter attached to the Zarya will be pressurized via remote commands and checked for leaks. Filters and fans in Unity and Zarya will be powered on as well. On the second spacewalk, day seven of the mission, Ross and Newman will install six handrails and other worksite interfaces as well as remove hatch and petal launch restraints from both the left and top berthing ports on Unity. The two astronauts also will install antennas on the port and starboard hatches of Unity for an S-band early communications system as well as a cable for that communications system that runs to the Zarya. Finally a sunshade for the MDM computers will be installed as well as covers for the trunnion pins which latched Unity in the Shuttle cargo bay. The next day, day eight, the day before the final spacewalk, the crew will enter Unity and Zarya through the Shuttle docking mechanism for the first time. Once inside, portable fans and lights will be installed along with additional components of the S-band early communications system. The crew will perform an early checkout of the early communications system, exterior components of which were installed by Ross and Newman on the previous day. They also will transfer spare equipment from Endeavour to the station modules. Inside the Zarya, they will checkout the video teleconference capability of the early communications system, conduct a photographic survey of the interior, and replace filters. The third and final spacewalk will be mostly devoted to tasks that prepare for future station assembly work and not activities needed specifically for Zarya and Unity assembly. The astronauts will start out disconnecting a wiring harness on one of Unity's mating adapters and safely covering the connectors. Next, tool boxes will be stowed on the outside of Unity for use by future assembly spacewalkers. Ross and Newman then will venture to the far end of Zarya to install a handrail that cannot be installed on the module prior to launch due to the fairing that covers the module during liftoff. Near the end of the third spacewalk, Ross will test fire the Simplified Aid for Extravehicular Activity Rescue jet backpack. The SAFER backpacks act as a type of space lifejacket, available for use by a crew member in the event they become untethered and need to fly back to the station. During an earlier flight test, on Shuttle mission STS-86, a valve failed and prevented the propulsion jets on the backpack from firing. The valve was redesigned and extensively tested on the ground, however this test, during which Ross will remain tethered at all times, will assist in checking out the new design. The next day, Endeavour will undock from the new station, completing the first International Space Station assembly mission. 
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Editorial Contact Ed Campion
Technical Contact USA Web Master
