While the crew slept, the Shuttle continued to close in on the Hubble Space Telescope at a rate of about 125 statute miles with each 90 minute long orbit of Earth. At the time the crew woke this morning, Discovery trailed the telescope by about 330 statute miles.
The crew will fire the Shuttle's thrusters at 12:38 p.m. today to slightly raise Discovery's orbit and slow the closing rate on Hubble. Another engine firing will be conducted about 48 minutes later to further adjust the closing rate and aim Discovery to reach a point eight nautical miles behind the telescope -- the starting point for the final phase of the rendezvous -- about three hours later. Just before Discovery reaches that point, European astronaut Jean-Francois Clervoy will power up the robotic arm and lift it to a position just above its latches along the left edge of the Shuttle cargo bay.
At 4:28 p.m., Discovery will reach the starting point and fire its thrusters again to begin the final phase of rendezvous, putting the Shuttle on a course to directly intercept the telescope on the next orbit of Earth. As Discovery closes the final distance to Hubble, four small course correction engine firings will fine-tune the approach and Clervoy will raise the arm high above the payload bay, poised to latch onto the Hubble's grapple fixture.
When Discovery reaches a point about half a mile away and directly beneath the telescope, Commander Curt Brown will take over manual control of the Shuttle. Brown, assisted by Pilot Scott Kelly, will gently maneuver the 110-ton Shuttle to within 35 feet of the orbiting observatory to allow Clervoy to capture it with the arm. After the arm has latched onto the telescope, Clervoy will lower it into a cradle in the aft cargo bay. Using controls in the aft cockpit of Discovery, Payload Commander Steve Smith will then latch the telescope in place, where it will remain for the next four days. Hubble is planned to be latched into the bay at about 7 p.m. Once the telescope has been secured in the payload bay, Clervoy will release the arm and use it to perform a television survey of the Hubble's exterior.
The first of three planned Hubble maintenance spacewalks is planned to begin at 1:40 p.m. Wednesday.