Encyclopedia Astronautica
1998.12.06 - STS-88 Mission Status Report # 07


Astronaut Nancy Currie gently mated the 12.8-ton Unity connecting module to Endeavour's docking system late Saturday afternoon, successfully completing the first task in assembling the new International Space Station.

Deftly manipulating the shuttle's 50-foot-long robot arm, Currie placed Unity just inches above the extended outer ring on Endeavour's docking mechanism, enabling Commander Bob Cabana to fire downward maneuvering jets, locking the shuttle's docking system to one of two Pressurized Mating Adapters (PMA's) attached to Unity. The mating occurred at 5:45 p.m. Central time, as Endeavour sailed over eastern China.

The new connecting node, to which the Russian-built Zarya control module will be mated later today, towered almost three stories over Endeavour's cargo bay, awaiting the arrival of the Zarya, which was launched from Kazakstan on Nov. 20 on a Russian Proton rocket.

After Unity was attached to the docking mechanism, the vestibule running between Unity's PMA-2 and the Orbiter Docking System was pressurized and the hatch was opened. Cabana and Jerry Ross entered the new module's adapter for the first time and placed caps over vent valves in preparation for the crew's entrance into Unity later this week.

The astronauts also extended and retracted the docking ring on PMA-1, to which the Zarya module will be mated after it is grappled by Currie around 5:46 p.m. Central time this afternoon.

The grapple of Zarya will follow a carefully choreographed rendezvous by Cabana and Pilot Rick Sturckow. Mission Specialists Jim Newman and Sergei Krikalev will use a number of rendezvous tools and hand-held lasers to provide range and closure rate information as Endeavour narrows the gap between itself and the Zarya. The rendezvous will begin about 12:30 p.m., with the final major maneuver planned for about 3:14 p.m. This terminal initiation burn will place Endeavour on a path to arrive about 500 feet below Zarya for the start of the final phase of the rendezvous.

Working from the aft flight deck, Cabana will manually guide Endeavour in a looping maneuver to a point 250 feet above Zarya, where he will slowly close in on the 21-ton module for its grapple by Currie. Zarya will be the heaviest object ever handled by the shuttle's robot arm, exceeding the Compton Gamma Ray Observatory by about 7,000 pounds.

Once Zarya is mated to Unity, the International Space Station components will rise some 76 feet above Endeavour's bay and have a combined weight of 35 tons. When it is fully assembled a few years from now, the new station will span the length of a football field and have a mass of more than a million pounds.

While Endeavour orbits the Earth at an altitude of about 241 by 134 statute miles, Zarya continues in orbit at an altitude of about 240 statute miles with all of its systems operating in excellent fashion.

Before the astronauts began an abbreviated 7-hour sleep period at 3:36 a.m. Central time, Cabana fired the shuttle's jets to keep a safe distance from a spent Delta II rocket casing during the sleep period. U.S. Space Command had alerted Mission Control that the shuttle would be passing near the debris from a Nov. 6 launch of communications satellites from Vandenberg Air Force Base, Calif., and Flight Director John Shannon decided to have Cabana make the maneuver to ensure the crew's sleep would not need to be interrupted.

When the crew awakens at 10:36 a.m. to begin preparations for their rendezvous, Endeavour will be about 20 miles farther away from Zarya than originally planned. However, the rendezvous burn schedule will not be affected.

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