STS-128: Station Resupply, Repairs, and Flight Experiments

During August and September 2009, the space shuttle Discovery carried out STS-128, delivering experiment racks, life-support equipment, and external spares to the International Space Station and rotating one resident astronaut. The station had begun supporting six long-term crew members. The mission expanded research and living facilities while repairing existing equipment and preparing for the later installation of the Tranquility node and Cupola observation module.

Commander Frederick Sturckow and pilot Kevin Ford handled the flight, while Patrick Forrester, José Hernández, John Olivas, and European Space Agency astronaut Christer Fuglesang worked on robotic-arm operations, spacewalks, and payloads. Nicole Stott arrived at the station aboard Discovery, and Timothy Kopra returned to Earth on the shuttle. There were seven people on both the outbound and return flights, with the long-term crew handover taking place during the docked mission.

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The main pressurized cargo was loaded into the Leonardo Multi-Purpose Logistics Module. Built in Italy and owned by the United States under a cooperative arrangement between the two countries, this pressurized transport module could be attached to the station by a robotic arm. Crew members could move equipment at normal cabin pressure, then return the module to the shuttle payload bay for the journey home. Boeing participated in ground payload processing, inspection, and launch integration.

Six systems or research racks were loaded for this mission: a Fluids Integrated Rack, Materials Science Research Rack, laboratory freezer, air-revitalization equipment, crew sleeping compartment, and second treadmill. The materials rack supported heating, cooling, and solidification research, while the freezer preserved samples. The treadmill and sleeping compartment supported long stays. The formal report also lists resupply platforms, storage racks, and cargo bags that made use of the module’s available loading positions.

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Thunderstorms and problems with the position indication of a liquid-hydrogen fill-and-drain valve repeatedly delayed launch. Engineers cycled the valve and examined historical data before approving the flight. Discovery lifted off from Kennedy Space Center’s Launch Pad 39A at 03:59:37 on August 29. Times in this article are Coordinated Universal Time; locally, it was still the evening of August 28.

After reaching orbit, one vernier attitude-control thruster registered an unusually low temperature. Analysis indicated a leak, and the associated manifold was isolated. Unable to use the full vernier system in the usual way, the crew used the primary reaction-control thrusters for rendezvous. Discovery achieved initial docking capture with the station at about 00:54 on August 31, followed by sealing and connection operations. A robotic arm moved Leonardo to Harmony’s Earth-facing port, allowing cargo transfer to begin.

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One major task of the three spacewalks was replacing the ammonia tank assembly on the P1 truss. Olivas and Stott first detached the old assembly and temporarily secured it to the station’s robotic arm. They also retrieved the European Technology Exposure Facility and materials-exposure experiment samples. On a later spacewalk, Olivas and Fuglesang installed the new tank, connected its fluid and electrical interfaces, and secured the old assembly in Discovery’s payload bay for return to Earth.

The crew also replaced a rate gyro and remote power-control module, routed cables for a future node, and installed a positioning antenna for visits by Japan’s cargo spacecraft. Some connections could not be completed as originally intended because of interface orientation or cable-length problems, leaving hardware for later work. Ground controllers activated the installed ammonia tank, restoring the configuration of the associated external thermal-control equipment.

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Outside the station work, the TriDAR sensor developed by Canada’s Neptec collected data during approach, docking, departure, and flyaround. It combined laser triangulation with lidar imaging and used the target’s geometry to calculate relative position and attitude. This flight supplied orbital technology-demonstration data; the shuttle’s actual rendezvous remained under its established flight systems and crew.

During reentry, a thermal-protection tile on the underside of Discovery’s left wing carried a bump about 0.35 inches high for a boundary-layer transition experiment. Thermocouples recorded heating changes as the local airflow changed from laminar to turbulent. The mission report noted that measurements did not fully match the transition time, Mach number, and temperature distribution, and that roll maneuvers and steps between other tiles might affect some changes. The data provided flight measurements for improving models of the reentry thermal environment.

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After equipment was unloaded and return cargo loaded, Leonardo was placed back in Discovery’s payload bay. The report lists pressurized cargo, external spares, and samples among the outbound and inbound loads, and records completion of the transfer tasks. The experiment equipment delivered to the station became facilities for subsequent research, while the retrieved exposure samples required further examination on the ground.

Discovery completed undocking at about 19:26 on September 8, flew around the station, and conducted post-departure thermal-protection inspections. Weather in Florida did not meet landing requirements, so the shuttle returned to Edwards Air Force Base. Discovery landed on Runway 22 at about 00:53 on September 12; the local date was September 11. STS-128 supported station operations through equipment deliveries, crew rotation, and repairs, while collecting engineering data on rendezvous sensing and reentry heating.

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