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| Two Spacewalks to Lay Groundwork for Future ISS Construction |
| Overview |
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Astronauts Dan Barry and Patrick Forrester are to perform two spacewalks while Discovery is docked to the International Space Station during STS-105. Barry will be designated Extravehicular crewmember 1 (EV1) and wear red stripes on his spacesuit. Forrester, designated EV2, will wear an all-white spacesuit. Discovery Pilot Rick Sturckow will be the Intravehicular crewmember (IV), coordinating the spacewalk activities from within the shuttle's cabin. Discovery Commander Scott Horowitz will control the shuttle's robotic arm during the spacewalk. The spacewalkers will install equipment on the exterior of the station for future maintenance and construction work on the outpost. Both spacewalks will originate from Discovery's airlock, and the two astronauts will be tethered to the shuttle's robotic arm for much of the work. The primary objective of the first spacewalk, planned for Flight Day Seven and to last about 6½ hours, is to install an Early Ammonia Servicer on the station, a system that contains spare ammonia for the station's cooling system. Ammonia is the fluid used in the radiators that cool the station's electronics. The EAS will be installed on the truss, called the P6 truss that holds the station's giant U.S. solar arrays, associated batteries and the cooling radiators. During the first spacewalk, Barry and Forrester also will attach an experiment to the outside of the station's airlock that will collect information on how various materials weather the space environment. The experiment, called the Materials International Space Station Experiment (MISSE), is housed in two carriers that will be attached to the station's exterior for an extended duration. As Barry and Forrester exit Discovery's airlock, Horowitz will maneuver the shuttle's robotic arm into position to latch onto a grapple fixture on the EAS, bolted to a carrier in the shuttle's payload bay for launch. After Horowitz has latched the arm onto the EAS, Barry and Forrester will go to the pallet, called an Integrated Cargo Carrier, and begin loosening the six bolts that hold the unit in place. In addition, Barry will translate hand-over-hand up to the station's Destiny Lab, where he will pick up a foot platform to be used during installation of the EAS. With the bolts free, Horowitz will begin lifting the EAS, with Barry and Forrester holding on to handrails on the EAS as well, up to the station. Horowitz will maneuver the spacewalkers and EAS up to the position on the station's P6 truss where the EAS will be installed. There Barry will attach the foot platform and secure himself to it. Horowitz will release the arm's grip on the EAS, basically handing off the unit to Barry. Forrester will then help Barry align the unit over its attachment position and move it to a "soft dock," where it will be preliminarily held in place by a hook mechanism closed and locked with a pip pin inserted by Forrester. Forrester will then tighten a bolt to firmly attach the EAS in position on the truss. The two spacewalkers will then unfurl and attach cables to supply station electrical power to heaters on the EAS, completing the installation. That done, the spacewalkers will hold on to the station arm again as Horowitz lowers them back to Discovery's payload bay, pausing at the station's Z1 truss to allow Barry to put the foot restraint in a stowed location needed for upcoming mission STS-110/8a. In Discovery's cargo bay, Barry and Forrester will move to the carrier platform and release the two Passive Experiment Containers containing the MISSE investigations from their launch restraints. With each of the spacewalkers holding an experiment container, they will hold onto the arm while Horowitz maneuvers them up to the station's airlock. There they will let go of the arm and clamp the MISSE carriers to two separate airlock handrails. The second spacewalk, planned to last up to 5½ hours, will be performed on Flight Day Nine of the mission and will focus on preparations for future station assembly, installing handrails on the Destiny lab and laying heater cables for a future station truss segment. Horowitz will again be operating the shuttle robotic arm to maneuver the spacewalkers, who will be hanging on to the arm at times. As the spacewalk begins, Barry and Forrester will take with them from Discovery's airlock two bags containing the heater cables they will install on the station. Called Launch to Activation heater cables, they will be used on shuttle mission STS-110 to power heaters on the station's S0 truss segment, the center segment of the station's truss structure, more than 300 feet long. In addition, they will take with them two bags holding 11 new handrails they will install on the Destiny Lab, called Orbit-Installed Handrails. Barry and Forrester will hold on to the shuttle arm, carrying the heater cable bags, as Horowitz lifts them to the station's Destiny lab. There, they will temporarily attach the bags to handrails, one on the port side of the lab and another on the starboard side. Barry will install six handrails on the lab's starboard side while Forrester installs five handrails on the port side. The spacewalkers also will relocate two existing lab handrails. With the handrails installed, the spacewalkers will then feed the heater cables along the rails on either side of the lab, connecting one end to the station and placing the other end in position for use when the S0 truss segment is delivered on STS-110. |
| EVA Timeline for Two Spacewalks to Lay Groundwork for Future ISS Construction |
| Time | Event |
| 005/17:05 | EVA 1 Start |
| 005/17:35 | EVA1 Early Ammonia Servicer Install PT 1 |
| 005/18:35 | EVA 1 Early Ammonia Servicer Install PT 2 |
| 005/21:35 | EVA 1 Materials International Space Station Experiment Install |
| 005/22:50 | EVA 1 Clean Up |
| 005:23:20 | EVA 1 Ingress |
| 005/23:35 | EVA 1 End |
| 007/17:05 | EVA 2 Start |
| 007/17:35 | EVA 2 S0 Launch To Activation Cable Install |
| 007/21:05 | EVA 2 Clean Up |
| 007/23:20 | EVA 2 Ingress |
| 007/23:35 | EVA 2 End |
Editorial/Technical Comments: ShuttlePresskit
