The mission was originally scheduled for launch from Pad 39A, and the shuttle was rolled out and placed on that pad, but due to contamination, a "rollaround" to Pad 39B was made.
The closing speed remained the same until the next reaction control system firing, at 8:34 p.m. CST (MET 1/17:07). The NH burn changed the shuttle's velocity by 4.6 ft/s (1.4 m/s), adjusting the high point of Endeavour's orbit and fine-tuning its course toward a point 40 miles (64 km) behind HST. The next burn, an orbital maneuvering system firing designated NC3, was scheduled for 9:22 p.m. (MET 1/17:55) and changed Endeavour's velocity by 12.4 ft/s (3.8 m/s). Endeavour's catch-up rate was adjusted to about 16 nautical miles (30 km) per orbit and put it eight nautical miles (15 km) behind HST two orbits later. A third burn of just 1.8 ft/s (549 mm/s), called NPC and designed to fine tune two spacecrafts' ground tracks, at for 9:58 p.m. CST (MET 1/18:31). The multiaxis RCS terminal initiation or "TI" burn, which places Endeavour on an intercept course with HST and set up Commander Dick Covey's manual control of the final stages of the rendezvous, occurred at 12:35 a.m. (MET 1/21:08). Covey maneuvered Endeavour within 30 ft (10 m) of the free-flying HST before Mission Specialist Claude Nicollier used Endeavour's robot arm to grapple the telescope at 3:48 a.m. EST, when the orbiter was several hundred km east of Australia over the South Pacific. Nicollier berthed the telescope in the shuttle's cargo bay at 4:26 a.m. EST. Everything was on schedule for the first planned spacewalk scheduled for 11:52 p.m. EST. After capture, additional visual inspections were performed using the camera mounted on the 50 ft (15 m) long shuttle remote manipulator arm.
Earlier in the day, controllers at the Space Telescope Operations Control Center at the Goddard Space Flight Center uplinked commands to stow HST's two high-gain antennas. Controllers received indications that both antennas had nested properly against the body of the telescope, but microswitches on two latches of one antenna and one latch on the other did not send the "ready to latch" signal to the ground. Controllers decided not to attempt to close the latches, as the antennas were in a stable configuration. The situation was not expected to affect plans for rendezvous, grapple and servicing of the telescope.
Story Musgrave and Jeffrey A. Hoffman started the first EVA about an hour earlier than scheduled by stepping into the cargo bay at 10:46 p.m. EST. They began by unpacking tools, safety tethers and work platforms. Hoffman then installed a foot restraint platform onto the end of the shuttle's remote manipulator arm, which he then snapped into his feet. Nicollier drove the arm from within the shuttle and moved Hoffman around the telescope. Meanwhile, Musgrave installed protective covers on Hubble's aft low gain antenna and on exposed voltage bearing connector covers. The astronauts then opened the HST equipment bay doors and installed another foot restraint inside the telescope. Musgrave assisted Hoffman into the restraint and Hoffman proceeded to replace two sets of Remote Sensing Units. These units contain gyroscopes that help keep Hubble pointed in the right direction. By 12:24 EST Hoffman had finished swapping out RSU-2 (containing Gryos 2-3 and 2-4) and then swapped out RSU-3 (containing Gryos 3-5 and 3-6). The astronauts then spent about 50 minutes preparing equipment for use during the second space walk and then replaced a pair of electrical control units (ECU3 and ECU1) that control RSUs 3 and 1. The astronauts also changed out eight fuse plugs that protect the telescope's electrical circuits. Hubble now had a full set of six healthy gyroscopes.
The astronauts struggled with the latches on the gyro door when two of four gyro door bolts did not reset after the astronauts installed two new gyro packages. Engineers who evaluated the situation speculated that when the doors were unlatched and opened, a temperature change might have caused them to expand or contract enough to keep the bolts from being reset.
With the efforts of determined astronauts in Endeavour's payload bay and persistent engineers on the ground, all four bolts finally latched and locked after the two spacewalkers worked simultaneously at the top and bottom of the doors. Musgrave anchored himself at the bottom of the doors with a payload retention device which enabled him to use some body force against the doors. Hoffman, who was attached to the robot arm, worked at the top of the doors. The duo successfully latched the doors when they simultaneously latched the top and bottom latches.
The spacewalkers also set up the payload bay for mission specialists Tom Akers and Kathy Thornton who would replace the telescope's two solar arrays during the second spacewalk. In anticipation of that spacewalk, Musgrave and Hoffman prepared the solar array carrier which is located in the forward portion of the cargo bay, and attached a foot restraint on the telescope to assist in the solar array replacement.
Musgrave and Hoffman's spacewalk became the second longest spacewalk in NASA history lasting 7 h 50 min. The longest spacewalk occurred on STS-49 in May 1992 during Endeavour's maiden flight. Spacewalking crew members during that flight were Thomas D. Akers, Richard J. Hieb and Pierre J. Thuot. A number of spacewalks have since surpassed these. (See List of spacewalks and moonwalks)
In spite of the kink in array (about a panel and a half from the end), after a review by HST program managers, flight controllers decided to continue with the pre-flight plan and attempt to roll up and retract the solar arrays at the end of the first EVA. The stowage of the solar arrays is a two step process with the initial step involving the rolling up of the solar arrays and the second step involving the actual folding up of the arrays against the telescope. Each array stands on a four foot mast that supports a retractable wing of solar panels 12 m long and 2.5 m wide. They supply the telescope with 4.5kW of power.
Akers started the EVA by installing a foot restraint on the RMA for Thornton and proceeded to begin disconnecting three electrical connectors and a clamp assembly on the solar array. He had a slight problem with the clamp assembly but had the connectors demated by 11:17 p.m. EST. Thornton held the array in place so that it would not drift freely after being detached. The solar arrays weigh 160 kg (352 lb) and are 5 m long when folded. The astronauts dismounted the damaged array at 11:40 p.m. EST above the Sahara (during a nighttime pass to minimize electrical activity), and Thornton held the array until the next daylight pass (approximately 12 min) before throwing it overboard at 11:52 p.m. EST over Somalia. The jettison during daylight allowed the astronauts and flight controllers to accurately track its position and relative velocity. The release by Thornton imparted zero velocity to the arrays and then the orbiter did a small burn to put some distance between it and the array. The array, moving away from Endeavour at 5 ft/s (1.5 m/s), separated about 11 to 12 miles (18 to 19 km) each orbit. The crew then installed a new array, (finishing around 1:40 EST) and rotated the telescope 180 degrees. They then replaced the second solar array which was stowed away for return to ESA. After the 6.5 hour EVA, successful functional tests were performed by the Space Telescope Operations Control Center (STOCC) on four of HST's six Gryos. Gyros 1 and 2 were not able to be tested due to the orientation of the telescope and were tested during the crew sleep period Monday afternoon (December 6, 1993).
Following the WFPC installation, Hoffman changed out two magnetometers on board HST. The magnetometers, which are located at the top of the telescope, are the satellite's "compass". They enable HST to find its orientation with respect to the Earth's magnetic field. Both original units were suffering from problems of background noise. During installation, two pieces peeled off the magnetometers. The EVA lasted 6 hours and 47 min.
Pilot Kenneth D. Bowersox, using Endeavour's RCS system, performed two orbital manueuvers and boosted HST from a 321 by 317 nautical mile (594 by 587 km) orbit to a 321.7 by 320.9 nautical mile (596 by 594 km) circular orbit at 9:14 p.m. EST. COSTAR functional tests were also completed. There was some concern about the health of the onboard HST DF-224 computer and recently installed memory and co-processor when a memory dump failed. After much analysis by a team at the GSFC, it was determined that the dump failure was due to noise on the communications link between the spacecraft and the ground.
The fifth EVA began on December 8, 1993 at 10:14 p.m. with a "go" for airlock depress over the Indian Ocean with Musgrave and Hoffman performing the EVA. Musgrave's EVA suit failed its initial leak check, and Musgrave performed steps on the 5 lbf/in² (34 kPa) contingency checklist. He rotated the EVA suit's lower arm joints and the suit passed two subsequent leak checks. The EVA started at 10:30 EST and lasted 7 h 21 min.
Musgrave's and Hoffman's first task was to replace the solar array drive electronics and they began the SADE operation while ground controllers initiated the first step in solar array deployment by commanding the Primary Drive Mechanism (PDM). Endeavour was placed in free drift to disable any RCS firings that could disrupt the solar arrays and the PDM motors were engaged at 10:48 p.m. The latches were unlocked but the arrays failed to rotate to the deploy position. No motion was detected and the STOCC sent commands to drive a single array with two motors with no success. Finally, the astronauts cranked the deployment mechanism by hand and deploy was successful. After the SADE was swapped out, the crew fitted an electrical connection box on the Goddard High Resolution Spectrograph at 3:30 a.m. EST and it passed its aliveness test. The crew then installed some covers on the magnetometers, fabricated onboard by Claude Nicollier and Kenneth D. Bowersox. These covers would contain any debris caused by the older magnetometers that showed some signs of UV decay. The EVA ended at 5:51 a.m. EST bringing the total EVA time for this mission to 35 h 28 min. The HST High Gain Antenna (HGA) was deployed at 6:49 a.m. EST and completed by 6:56 a.m. EST. Release time for HST was set for 2:08 a.m. EST.