STS-89 launched on January 22, 1998 and was the eighth of nine planned missions to Mir and the fifth involving an exchange of U.S. astronauts.

Thomas spent approximately 4 months on the orbiting Russian facility before returning to Earth when Discovery docked to Mir in late May during STS-91.

SPACEHAB Payloads included the Advanced X-Ray Detector (ADV XDT), Advanced Commercial Generic Bioprocessing Apparatus (ADV CGBA), EORF, Mechanics of Granular Materials (MGM) Experiment, Intra-Vehicular Radiation Environment Measurements by the Real-Time Radiation Monitor (RME-1312), Space Acceleration Measurement System (SAMS), VOA and the Volatile Removal Assembly prototype for the ISS Water Recovery System.

In-cabin payloads included the Microgravity Plant Nutrient Experiment (MPNE), Shuttle Ionospheric Modification with Pulsed Local Exhaust (SIMPLEX), Closed Equilibrated Biological Aquatic System (CEBAS), TeleMedicine Instrumentation Pack (TMIP), Global Positioning System Development Test Objective (GPS DTO), Human Performance (HP) Experiment, MSD, EarthKAM, Orbiter Space Vision System (OSVS) Shuttle Condensate Collection (RME-1331), Thermo-Electric Holding Module (TEHM), Space Linear Acceleration Mass Measurement Device (DSO 914), Co-Culture Experiments (CoCult) and the Biochemistry of 3-D Tissue Engineering (BIO3D).

The white inside line in the shape of the number eight and the nine stars symbolize the flight's numerical designation in the Space Transportation System's mission sequence.