At about 3:50 p.m. Central time, Mission Specialist Nancy Currie will power up the shuttle's 50-foot-long robotic arm and use it to grapple the Unity connecting module, a procedure scheduled to begin at 4:06 p.m. Currie then will hoist the 12.8-ton Unity module out of Endeavour's cargo bay and carefully place it in position perpendicular to the shuttle. One of the mating adapters on Unity, called pressurized mating adapter 1 (PMA-1), will be latched to Endeavour's docking system using a mechanism identical to that used during Shuttle/Mir dockings. Currie will maneuver Unity precisely to within a few inches of the Shuttle's docking mechanism and then put the mechanical arm into a "limp" mode. Commander Bob Cabana will then fire Endeavour's thrusters to force the mechanisms together.
Preparations for tomorrow's capture of Zarya will continue as the crew equalizes the air pressure between Endeavour and Unity's mating adapter. The astronauts then will enter the adapter to install caps on air vents between PMA-1 and Unity, and then readjust the Shuttle and mating adapter's air pressure to about 10.2 pounds per square inch. This equalization of air pressure between Unity's mating adapter and Endeavour's cabin is done to provide better structural performance of the docking mechanism during the capture and attachment of Zarya.
The crew also will perform a check of connections with the docking mechanism located on the other end of Unity, called PMA-2, that will attach to Zarya. For the check, the docking ring on that adapter will be extended and retracted using controls located on the aft flight deck of Endeavour. Unity and its two mating adapters will form a complex 15 feet wide and about 36 feet long - taller than a 3-story building - towering above Endeavour's payload bay.
This evening, astronauts Jerry Ross and Jim Newman will check out the various tools they will use during the three scheduled spacewalks to be conducted later in the flight, and begin an early set-up of the Shuttle airlock in preparation for that first spacewalk on Monday. Later, Commander Bob Cabana and Newman will check equipment needed for tomorrow's rendezvous with Zarya, including laptop computer displays and a hand-held laser ranging device. Checks also will be performed of the Orbiter Space Vision System, an alignment aid for operations with the Shuttle's mechanical arm that will be used during the capture and attachment of Zarya.
Newman and Russian cosmonaut Sergei Krikalev also will take time to take part in an on-line interview by the New York Times at 11:01 p.m. Central time.
Endeavour is trailing Zarya by about 7,600 statute miles, narrowing the distance to the Russian-built module by almost 500 statute miles with each orbit. Endeavour is orbiting the Earth every 90 minutes at an altitude of 202 statute miles. An engine firing will be performed late today to raise the Shuttle's orbit and adjust the rate at which Endeavour is closing in on Zarya, which is currently in an orbit of about 240 statute miles. All of Endeavour's systems are in excellent condition.