On Flight Day Three, HST was sighted by astronaut Jeffrey A. Hoffman using a pair of binoculars and he noted that the right-hand solar array was bent in a 90-degree angle. These 40 foot solar arrays, built by the European Space Agency (ESA), are planned to be replaced during the second spacewalk because they wobble 16 times a day each time the telescope heats up and cools off as it passes from the dark side of the Earth to its light side and vice versa.
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 feet per second, adjusting the high point of Endeavour's orbit and fine-tuning its course toward a point 40 miles 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 feet per second. Endeavour's catch-up rate was adjusted to about 16 nautical miles per orbit and put it 8 n.m. behind HST two orbits later. A third burn of just 1.8 feet per second, 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, occured at 12:35a.m. (MET 1/21:08).Commander Richard O. Covey maneuvered Endeavour within 30 feet 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 miles east of Australia over the South Pacific. Nicollier berthed the telescope in the shuttle's cargo bay at 4:26 a.m. EST.
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 antennae. Controllers received indications that both antennae 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 antennae are in a stable configuration. The situtation is not expected to affect plans for rendezvous, grapple and servicing of the telescope.
HST was captured by Swiss astronaut Claude Nicollier shortly before 5am EST on 12/4/93 and everything has gone on schedule for the first planned spacewalk scheduled for 11:52 p.m EST on 12/4/93. After capture additional visual inspections were performed using the camera mounted on the 50ft long shuttle remote manipulator arm.
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 replaced the telescope's two solar arrays during the second spacewalk which began at 10:35 p.m. EST today. The solar arrays provide power to the telescope. 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.
Inspite 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 attemp 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 40 feet long and 8.2 feet wide. They supply the telescope with 4.5kW of power.
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