STS-102/ISS-5A.1 Mission Objectives

Discovery’s STS-102 (5A.1) flight is focused on outfitting the International Space Station (ISS), particularly the new U.S. laboratory, Destiny. It also will bring to the station the new Expedition Two crew, to replace the Expedition One crew which will come home on Discovery.



The crew transfer, the first for the station, is among the mission’s top priorities. Expedition One Commander Bill Shepherd, Soyuz Commander Yuri Gidzenko and Flight Engineer Sergei Krikalev will be replaced by Expedition Two Commander Yury Usachev and Expedition Two flight engineers Susan Helms and Jim Voss.



The transfer will take place in a carefully orchestrated, one-at-a-time process that ensures three current members of the station crew will be able to come home, at any time during the switch, aboard the Soyuz spacecraft attached to the station. Expedition Two crewmembers officially join the station when they install their seat liners in the Soyuz.



Equipment transfer to the ISS and outfitting Destiny for the arrival of the Space Station Remote Manipulator System (SSRMS), the space station’s robotic arm scheduled to be launched on STS-100 (6A) no earlier than April, also is among the major priorities of Discovery’s flight. Much of that equipment will be transferred from the Multi-Purpose Logistics Module (MPLM), a pressurized moving van module designed to be taken into orbit, attached to the space station, and then, after unloading, brought back to the orbiter’s cargo bay for return to Earth.



The Italian-built MPLM, named Leonardo, will be attached to the nadir, or Earth-facing, berthing port of the Unity node. Before that can happen a docking port, Pressurized Mating Adaptor 3 (PMA 3), must be removed from that berthing port. It will be attached to an adjacent berthing port on Unity’s left side.



Leonardo brings six systems racks to the station. Among them are two robotic workstation racks for control of the station’s robotic arm and the four cameras mounted on it. Two are DC-to-DC Converter Units (DDCUs) which convert electrical power from the station’s solar arrays to a form usable by station systems and experiments. One is the U.S. Lab Avionic 3 rack with components supporting both the Ku-Band communications system and the command and control system. The sixth is a Crew Health Care System rack.



The Ku-Band is used for high data rate communications, including downlink of television pictures. The command and control system is operated from the U.S. laboratory and controls the attitude or orientation in space of the station, using four 800-pound gyroscopes mounted in the Z-1 Truss of the ISS.



The PMA 3 move will be made during a space walk by Voss and Helms on Flight Day 4. The space walk will be preceded by transfer of a spacesuit and two Simplified Aids for EVA Rescue (SAFER) devices from the station to the shuttle shortly after docking on Flight Day 3.



Once outside Discovery’s airlock, Voss and Helms will disconnect PMA 3 cables and then Mission Specialist Andy Thomas, operating the shuttle’s robotic arm, will move it to its new location.



The space walkers subsequently will take the Lab Cradle Assembly from Discovery’s cargo bay and install it atop Destiny. Its first application will be to support the Launch Deployment Assembly of the SSRMS. Later in the space walk they will take the Rigid Umbilical from the cargo bay and install it onto Destiny. It is designed to provide power, data and video links between the SSRMS and Destiny.



Leonardo is to be attached to the station on Flight Day 5 and the ISS crew will begin unloading it the following day. Hatches will be closed between the shuttle and the station in preparation for the mission’s second space walk by Thomas and Mission Specialist Paul Richards. During that space walk they will take an External Stowage Platform from the cargo bay and install it onto Destiny, then hook up power cables for the orbital replacement units, spares, to be stowed on it. They will stow the first of those spares, a Pump and Flow Control Subassembly for ammonia coolant.



Among racks to be transferred by the ISS crew will be the Human Research Facility, the first scientific rack to be brought to the station. While it is significant in that it marks the beginning of major research capability on the station, its transfer is a lower priority than transfer of the six systems racks, the three resupply stowage racks and the four resupply stowage platforms from Leonardo-indeed it will be the last of the racks to be transferred. While the experiment rack will be activated and checked out, the Ku-Band and a communications outage recorder must be working to support data recording and downlink.



After transfer of the Human Research Facility, transfer of materials into Leonardo will begin. Such materials-batteries at the end of their designed lives, used filters, packing materials and garbage are examples-will be returned to Earth.



Other priorities include activation and checkout of transferred racks, operation of the IMAX camera by the station crew, a series of tests supporting station assembly, ISS reboost if adequate propellant is available and a fly-around of the ISS by the orbiter after undocking to photograph and videotape the station.