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| STS-104 Spacewalks: Installing a Spacewalking Portal |
| Overview |
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Astronauts Mike Gernhardt and Jim Reilly will conduct three spacewalks while Atlantis is docked to the International Space Station to install, outfit and flight test a new airlock. Called the Joint Airlock, the new station component will accommodate both Russian and U.S. spacesuits and space-walking gear for future excursions from the station. During the Extravehicular Activities (EVAs), as the spacewalks are technically described, Gernhardt will be designated extravehicular crew member 1 (EV1), distinguishable by red stripes around the legs of his spacesuit, and Reilly will be EV2, with an all-white spacesuit. Atlantis' Pilot Charlie Hobaugh will serve as the intravehicular activity crew member (IV), coordinating the spacewalk activities from within the shuttle cabin. Astronaut Janet Kavandi will be operating the shuttle's robotic arm during the space walk while, aboard the station, Expedition Two Flight Engineer Susan Helms, assisted by fellow Expedition Two crew member Jim Voss, will operate the station's robotic arm. The internal hatches will be closed between Atlantis and the station during the first two spacewalks, although they are planned to be open for the third spacewalk, which is planned to begin from the newly installed station airlock rather than from Atlantis' airlock. The first spacewalk is planned for Flight Day 4 of the mission, the day after Atlantis docks to the station. During the first spacewalk, planned to last almost seven hours, the space walkers will assist as Helms, using the station's robotic arm, lifts the new station airlock from Atlantis' payload bay and attaches it to a port on the station's Unity connecting module. During much of the first spacewalk, Reilly will work from a foot platform attached to the end of the shuttle's robotic arm, operated by Kavandi. The first major task for the spacewalkers will be for Gernhardt to remove an insulating cover, nicknamed the "shower cap," from the airlock's Common Berthing Mechanism, the mechanism that will attach to Unity, while the airlock is in the payload bay. Gernhardt also will remove protective covers from the berthing mechanism's seals. The "shower cap" and seal covers will later be stowed by the spacewalkers in a tool locker in Atlantis' payload bay for the trip back to Earth. While Gernhardt is removing the covers, Reilly will work on the side of the airlock, installing devices, nicknamed "towel bars," that will later serve as attachment points for four high-pressure oxygen and nitrogen tanks outside the new airlock. Reilly also will temporarily affix several thermal covers to the airlock exterior, positioning them for a later full installation on the third spacewalk. Next, Gernhardt will disconnect a cable that provided shuttle electrical power to heaters on the airlock, called Launch To Activation or LTA heaters. Then Reilly will take the disconnected power cable and the removed airlock covers to a Tool Stowage Assembly (TSA) on the starboard side of the shuttle's payload bay to stow them. With the power cable between the shuttle and new airlock disconnected, Helms will begin to latch the station's Canadarm2 onto a fixture on the new airlock. While Helms and Voss lift the airlock from Atlantis' cargo bay and maneuver it into position to attach to the Unity module, Gernhardt and Reilly will wait inside the still-depressurized shuttle airlock, recharging their spacesuits by connecting to air and power from the shuttle. As Helms works with the station's arm, Kavandi will maneuver the shuttle's arm into positions to provide television camera views to assist Helms. Once the station airlock is poised high above the shuttle payload bay only a few feet from its attachment point on the station, Gernhardt and Reilly will leave the shuttle's airlock. If needed, the two spacewalkers will provide on-the-spot observations for Helms to assist with aligning the airlock as it is attached to Unity. Once the new airlock has been attached to the station, Gernhardt will then connect a cable that will provide station power to the new component, the final major task planned for the spacewalk. Second Spacewalk: Air for the Airlock The second spacewalk, planned to last about 5½ hours, will be on Flight Day 7. The internal hatches between the shuttle and station will be closed at the end of Flight Day 6 to prepare for the second spacewalk, allowing the shuttle's cabin pressure to be reduced slightly as part of a protocol that protects spacewalkers from decompression sickness. The major objective of the second spacewalk is to attach and connect two -- one oxygen and one nitrogen -- of four oxygen and nitrogen tanks to the exterior of the new station airlock. The remaining two tanks are planned to be installed during the mission's third spacewalk. During the second spacewalk, Gernhardt will be tethered to the end of the shuttle's robotic arm for much of the work. Helms will be operating the station's arm to lift the tanks from the shuttle's payload bay and maneuver them to the new airlock on the station. As the spacewalk begins, Helms will latch the station arm onto the first tank, an oxygen tank, in Atlantis' payload bay. After the station arm is latched onto the tank, Gernhardt will release latches that held it in place in the shuttle for launch. Helms will then lift it from the shuttle bay and maneuver it to the new station airlock. After releasing the latches, Gernhardt will get on the shuttle's robotic arm and Kavandi will fly him up to the station airlock. Meanwhile, Reilly will install foot platforms and guideposts at the station airlock in preparation for installing the tank. When Helms has moved the tank into position near the airlock, Gernhardt and Reilly, both working in foot platforms on the station's exterior, will take the tank from the arm as Helms releases it. The spacewalkers will then latch it into place on the airlock exterior, clamping it to some of the "towel bars" installed on the first spacewalk and using guideposts installed by Reilly to ensure that the tank is properly aligned. Gernhardt will then connect hoses from the tank to the airlock. The same tasks will basically be repeated to lift the second tank, a nitrogen tank, from the shuttle's cargo bay and install it onto the station airlock, although some foot platforms will have to be repositioned. Then, while Reilly finishes connections for the second tank, Gernhardt will install insulating covers on several airlock fixtures, including the four pins that helped latch the airlock in place during its time in the shuttle bay and the grapple fixture held by the station's robotic arm to attach the airlock to the station. Third Spacewalk: The First from the International Space Station Airlock The third spacewalk will be conducted on Flight Day 9 and is planned to last about 5 1/2 hours. Although it can be conducted successfully from the shuttle airlock if needed, the third spacewalk is planned to begin from the new station airlock, both to serve as a flight test of the new station addition and to make the spacewalk and mission's work as efficient as possible. Preparations for the third spacewalk also are planned to include a new protocol to purge nitrogen from the body before the start of a spacewalk and thus protect the spacewalkers from decompression sickness. The new protocol, which involves breathing pure oxygen while exercising vigorously, will preclude the need for spacewalkers to spend long hours at reduced cabin pressure immediately before a spacewalk. It will allow the internal hatch between the new airlock and the station to remain open longer before a spacewalk begins yet still reduce the time that spacewalkers must prebreathe pure oxygen in their spacesuits before venting air from the airlock and venturing outside. The primary objective of the third spacewalk will be to install the final two tanks -- one oxygen and one nitrogen -- on the exterior of the new station airlock. The task will basically mirror the procedures used during the second spacewalk to remove the first two tanks from the shuttle's payload bay and install them on the airlock exterior. In addition to installing the final two tanks, the spacewalkers will connect a cable to the airlock that will enable communications with Russian spacesuits during future station spacewalks. They also will install several handholds on the airlock exterior and install insulating covers over grapple fixtures on the newly installed air tanks. |
Editorial/Technical Comments: ShuttlePresskit
EVA Timeline for STS-104 Spacewalks: Installing a Spacewalking Portal
Time
Event
002/17:10
EVA 1 Start
002/17:20
EVA 1 Setup
002/17:50
EVA 1 PCBM Cover Removal
002/17:50
EVA 1 Towel Bar Installation
002/18:30
EVA 1 Launch To Activation (LTA) Jumper Removal
002/18:55
EVA 1 Cleanup/Airlock Ingress
002/20:05
EVA 1 SSRMS Maneuver Airlock to Pre-Install
002/20:55
EVA 1 Airlock Egress to continue EVA
002/21:10
EVA 1 Starboard CBM Inspection
002/22:00
EVA 1 Airlock Attached to Unity
002/22:25
EVA 1 Mate Airlock-Unity Jumper
002/23:15
EVA 1 Cleanup
003/23:55
EVA 1 Ingress
005/17:05
EVA 2 Start
005/17:15
EVA 2 Setup
005/17:30
EVA 2 Oxygen-Nitrogen Tank 1 Installation
005/18:40
EVA 2 Oxygen-Nitrogen Tank 4 Installation
005/20:15
EVA 2 Grapple Fixture & Trunion Cover Installation
005/21:45
EVA 2 Cleanup
005/22:15
EVA 2 Ingress
007/18:40
EVA 3 Start
007/18:55
EVA 3 Setup
007/19:25
EVA 3 Oxygen Tank 2 Installation
007/20:35
EVA 3 Nitrogen Tank 3 Installation
007/22:25
EVA 3 Lab Launch To Activation (LTA) Cable Stow
007/22:40
EVA 3 Grapple Fixture Cover Installation
007/23:10
EVA 3 Cleanup
007/23:40
EVA 3 Ingress
