While docked, the STS-105 crew attached the Italian-built Leonardo Multi-Purpose Logistics Module directly to the station's Unity node for unloading of it's cargo. Equipment transferred to the station included two EXPRESS Racks to be installed in the station's U.S. laboratory Destiny. EXPRESS stands for Expedite the Processing of Experiments to the Space Station. The racks will house a variety of scientific experiments, which can be changed out in space.
Mission Specialists Daniel Barry and Patrick Forrester spent a total of 11 hours and 45 minutes outside the space station during two space walks. The first space walk involved installing the Early Ammonia Servicer on the station's P6 truss and attaching the first external experiment, called the Materials International Space Station Experiment, on the handrails of the ISS airlock. The servicer contains spare ammonia that can be used in the space station's cooling systems, and will support the thermal control subsystems until a permanent system can be activated. During the second space walk, they strung two 13.7-meter, or 45-foot, heater cables and installed handrails down both sides of the Destiny laboratory.
Discovery also carried a number of small scientific payloads as a part of the "Small Payloads Take Youth into Orbit" program. Among them is Simplesat, a satellite, which used inexpensive commercial hardware to demonstrate Global Positioning System attitude control and payload-assisted fine pointing while free flying in low Earth orbit.
Other experiments conducted as a part of this program were the Cell Growth in Micrgravity experiment, Microgravity Combustion experiment, and the Space Experiment Module-10. The Space Experiment Module -10 flew in the Shuttle's payload bay and contained 11 separate student experiments.
Two Detailed Supplementary Objectives (DSOs) were flown on STS-105 (Spaceflight and Immune Function; Spatial Reorientation Following Spaceflight). A DSO is a NASA-sponsored investigation performed by Space Shuttle crewmembers, who serve as the test subjects. These studies are designed to require minimal crew time, power, and stowage. Biomedical DSOs focus on operational concerns, including space motion sickness, cardiovascular deconditioning, muscle loss, changes in coordination and balance strategies, radiation exposure, pharmacokinetics and changes in the body's biochemistry.
Six Development Test Objectives (DTOs) were also performed during this mission (Crosswind Landing Performance; Single-String Global Positioning System; Space Vision Laser Camera System). A DTO is a NASA-sponsored investigation that is performed by Space Shuttle crewmembers to evaluate new hardware and procedures involving the orbiter, its subsystems, and its support equipment.
Discovery departed the space station on August 20, 2001, to return the Expedition Two crew (Yury Usachev, Susan Helms, and James Voss) to Earth after a successful five-month stay onboard the station.