Launch from Cape Canaveral (KSC); landing on Edwards AFB. Fifth Space Station Assembly Mission ISS-05-3A.

Following a two day solo flight the Discovery docked with ISS on October 13, 2000 and the transfer of equipment and supplies into the ISS started. On flight day 3 the Z1 Truss was installed. ITS Z1 is an early exterior framework to allow the first U.S. solar arrays on flight 4A to be temporarily installed on Unity for early power.

The first EVA was performed by William McArthur and Leroy Chiao on October 15, 2000 (6h 28m). The S-band Antenna Support Assembly was relocated on the Z1 Truss. The Z1 starboard bulkhead thermal shrouds were removed and stowed. The port Extravehicular Tool Storage Devices were released and transferred from the Spacelab Logistics Pallet to the Z1 Truss. The Z1-to-Node 1 umbilicals, or cables, were connected. The Space-to-Ground Antenna dish was installed onto the boom and the boom was deployed.

The second EVA by Peter Wisoff and Michael Lopez-Alegria occured on October 16, 2000 (7h 07m). The Pressurized Mating Adapter 3 was grappled by the shuttle's robotic arm and installed on the Unity Connecting Module nadir port. The primary and secondary cable bundles were connected between the Pressurized Mating Adapter 3 (PMA-3) and the Unity Module. Also, latches were opened on the Z1 Truss

The third EVA by William McArthur and Leroy Chiao was conducted on October 17, 2000 (6h 48m). Two DC-to-DC Converter Unit-Heat Pipes were installed on Z1. The Z1 keel pin assembly was then relocated to another location on Z1. The Z1/P6 launch locks were removed, then the Assembly Power Converter Units jumpers were also removed from the Pressurized Mating Adapter 2 to allow for installation of four Z1 cables. The starboard Extravehicular Tool Storage Device was released and transferred from the Spacelab Logistics Pallet to the Z1 Truss.

The fourth and final EVA by Peter Wisoff and Michael Lopez-Alegria was performed on October 18, 2000 (6h 56m). A grapple fixture on the Z1 Truss was removed. The Z1 utility tray was deployed and its umbilical launch restraints released. The Z1 Manual Berthing Mechanism latches was cycled and opened. Peter Wisoff and Michael Lopez-Alegria performed one safety protocol test -- a flight evaluation of SAFER, which means "simplified aid for EVA rescue".

Due to bad weather at both landing areas the Discovery had two additional days in space and was diverted to the Edwards AFB.