Spaceflight Now: STS-92 Mission Report

Space station expands to include new docking port
BY WILLIAM HARWOOD
SPACEFLIGHT NOW

Posted: October 16, 2000
Updated: 05:30 p.m.; 07:50 p.m.

  PMA
The PMA-3 docking port is moved into position above Discovery's nose in front of the Unity module. Photo: NASA TV/Spaceflight Now
 
In a well-oiled team effort, the Discovery astronauts successfully attached a new $20 million shuttle docking port to the international space station today after getting off to a slightly rocky start.

Japanese robot arm operator Koichi Wakata, living up to his reputation as an artist with the shuttle's robot arm, deftly maneuvered the 2,500-pound shuttle mating adapter to within a few inches of a berthing mechanism on the station's Unity module.

After spacewalkers Peter "Jeff" Wisoff and Michael Lopez-Alegria helped him fine-tune the adapter's alignment, Wakata carefully moved pressurized mating adapter No. 3 a few inches closer still until four latches in the berthing mechanism were close enough to engage.

Working at Wakata's side, shuttle pilot Pamela Melroy then sent commands from a laptop computer on the shuttle's flight deck to retract the latches, pulling PMA-3 snugly into place.

A few moments later, she sent additional commands to tighten 16 motor-driven bolts with a force of about 1,500 pounds each, firmly locking the new docking port to the Unity module and completing one of the major goals of the 100th shuttle mission.

"This was a very good day," said lead flight director Chuck Shaw. "We completed all of our mandatory objectives. ... We're real happy about the progress we've been making."

After connecting power and data lines between PMA-3 and the space station, Wisoff and Lopez-Alegria re-entered Discovery's airlock, bringing two balky work stands inside with them for impromptu repairs.

While they were unable to connect one power cable because of an unusually tight fit, engineers were expected to develop a work-around in time for connection during spacewalks Tuesday or Wednesday.

Commander Brian Duffy and Melroy, meanwhile, carried out the first of three reboost maneuvers, pulsing Discovery's jets 18 times over a half-hour period to boost the apogee, or high point, of the station's altitude by about five miles.

Three 30-minute reboost sessions are planned to raise the station's altitude without using the lab's limited supplies of on-board fuel.

Depending on how the orbit ultimately is affected, launch of the station's first full-time crew aboard a Russian Soyuz rocket -- currently scheduled for Oct. 30 -- likely will slip a day or so.

Today's spacewalk began at 10:15 a.m. and ended at 5:22 p.m. It was the 52nd spacewalk in shuttle history and the eighth dedicated to space station construction.

  PMA hoist
The new docking port is hoisted high above the payload bay by the shuttle's robot arm. Photo: NASA TV/Spaceflight Now
 
McArthur and Leroy Chiao plan to stage the ninth such assembly spacewalk Tuesday, beginning around 10:30 a.m. A fourth and final spacewalk by Wisoff and Lopez-Alegria is on tap Wednesday.

"I think the two most difficult EVAs are behind us," said flight controller Daryl Schuck, who helps oversee spacewalk training. "The next two are just as important, but I think we're really on our way to a very successful mission from an EVA perspective."

The PMA-3 docking port installed today will be used for he next two shuttle linkups with the international space station.

In December, a huge set of solar arrays will be installed atop the $273 million Z1 truss, which Discovery's crew mounted on Unity's upward-facing, or zenith, port on Saturday.

The U.S. laboratory module, Destiny, will be attached to PMA-2 -- the port Discovery currently is docked to -- in late January. At that point, stabilizing gyroscopes in the Z1 truss will be activated, along with the station's main communications system.

Getting PMA-3 into place was thus the major objective of the crew's second spacewalk and with Wakata, the hardware was in good hands. He is nicknamed "the Man" because of his skill with the shuttle's 50-foot-long robot arm, a reputation he more than lived up to today.

Because of the station's orientation as it is docked with Discovery, Wakata had no direct line of sight to the interface between the new docking port and the Unity module.

Unity's nadir port, which normally faces down toward Earth as the station flies along, was pointed toward Discovery's nose, forcing Wakata to rely on verbal cues from Wisoff and Lopez-Alegria and data from a computerized television system.

Adding yet another level of complexity, a camera on the end of the robot arm that was installed specifically to help Wakata position PMA-3 had no power because of a short circuit last week.

But he made it look easy, despite some initial concern.

  PMA mate
Watched by one of the spacewalkers, PMA-3 is eased into its port on the Unity module. Photo: NASA TV/Spaceflight Now
 
The difficult traverse from the shuttle's cargo bay to the overhead mounting position was held up at one point when Lopez-Alegria voiced concern about how close the docking port appeared to be from one of the Russian Zarya module's solar arrays.

"You guys must be looking at this, but that PMA looks awfully close to the FGB's solar arrays," he said, using the Russian acronym for Zarya.

"We're keeping an eye on it," Chiao reported from the flight deck.

"Wow, that's deceiving from here."

"Mike, we'll take a look," Wakata said.

But the shuttle was in orbital darkness and the astronauts could not get a good view on their closed-circuit television cameras. So Wisoff pulled himself "up" the space station stack to a point between Unity and Zarya and reported Wakata actually had five to six feet of clearance.

The only other problem today involved a half-hour delay when Wisoff and Lopez-Alegria ran into trouble operating four latches used to help hold PMA-3 on its payload bay launch pallet.

The latches were designed to hold the docking module in place while the spacewalkers removed 16 primary launch restraint bolts.

After a bit of troubleshooting, the spacewalkers simply pressed ahead with removing the launch restraint bolts while flight controllers discussed the latch problem.

"Who's scripting this, anyway?" Wisoff wondered aloud at one point.

In the end, he was told to increase the torque applied by his electronic power wrench and this time around, the latches opened normally. Wakata, who had already grappled PMA-3 with the robot arm, then lifted it from the pallet and moved it into place for attachment.

Throughout the day, Wisoff and Lopez-Alegria paused to enjoy the view from 240 miles up.

"And just FYI, you're right over the middle of Libya," Chiao radioed from the shuttle's flight deck.

"Oh, check it out, the center pivot irrigation down there, Jeff," Lopez-Alegria said. "Oh, you're busy, never mind."

"It's all right."

"Look at that, I see the line of dusk, I see trees (or Trieste, Italy)," Lopez-Alegria said. "Beautiful! What a view."

With the completion of today's spacewalk, Discovery's crew has logged 13 hours 35 minutes in two successful excursions. Total space station EVA time to date is 55 hours and 50 minutes.

Video vault
The Pressurized Mating Adapter 3 docking port is lifted from Discovery's payload bay and attached to the space station in this animation.
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