Spaceflight Now: STS-92 Mission Report

Spacewalkers to lend a hand building space station today
BY WILLIAM HARWOOD
SPACEFLIGHT NOW

Posted: October 15, 2000

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  Training
Astronaut Bill McArthur wears spacewalking suit during training for his upcoming mission. Photo: NASA-JSC
 
Astronauts Leroy Chiao and William McArthur are suiting up for a planned six-and-a-half-hour spacewalk today to electrically connect a massive structural truss that was installed on the international space station Saturday.

They also plan to deploy a large Ku-band dish antenna, reposition an S-band antenna array and mount a tool box on the station's hull for use by future assembly crews.

The wiring hookups will be tested by Russian flight controllers as the station-shuttle complex pass over Russian ground stations.

"The primary plan is for this reconfiguration to be commanded by the Russian control center, which means we have to be over Russian ground sites," McArthur said in a NASA interview.

"And so that adds to the complexity of the choreography, because if we're not over a Russian ground site, then our options are either to wait until we come back around to that side of the world, which could be a significant loss of time for us, or to command that reconfiguration from onboard. So we'll see how that goes.

The spacewalk is officially scheduled to begin at 10:32 a.m., but Chiao and McArthur are running a bit ahead of schedule and may float out of Discovery's airlock a bit early.

The $273 million Z1 truss houses four massive gyroscopes that will keep the station properly oriented and stable once they are activated early next year. The truss also will serve as the temporary mounting point for a huge set of solar arrays scheduled for delivery in early December.

The S-band and Ku-band antennas will serve as the station's primary communications link to mission control in Houston. But like the gyroscopes, the communications system will not be activated until after arrival of the U.S. laboratory module Destiny in late January.

Here is a remarkably detailed description of today's spacewalk, or EVA, from a pre-flight NASA interview with McArthur:

"Our first task on this EVA is to configure the (shuttle's robot) arm itself to support the EVA," he said. "And so, when I come out of the airlock, Leroy will have hooked me up to the end of the robotic arm. Then (robot arm operator Koichi Wakata) is going to take me to a location between the US segment and the Russian segment of the space station, and we'll then configure the arm with a bracket that I can stick my feet in. It's called an Adjustable Portable Foot Restraint.

"And so, once the arm is configured, I will then clip my boots into this bracket on the end of the arm. And then Koichi will be able to maneuver me. And so ... Koichi is going to stick me underneath Z1, and I will release the first six cables from their temporary location on Z1 and attach them to the Node.

"Then while we're doing some commanding, turning that electrical power back on to those connectors and off to the second set of connectors, Koichi is going to move me up into position by a device called the S-band Antenna Support Assembly. Then Leroy and I will get in position. I'm on the arm. Leroy will be in another foot restraint fixed to the side of Z1. And we're working now on the side of Z1, which is on the left side of the payload bay of the space shuttle. And so, we have to release a series of bolts. And we'll do that with these electrical wrenches - and we call them Pistol Grip Tools; they look like, you know, very sophisticated electric screwdrivers - and we'll release a series of bolts and electrical connectors that will free up this large S-band antenna assembly.

"Then Koichi will pull me away from Z1. I will rotate the S-band antenna 180 degrees so it points toward the Node. And then Koichi will move me over in position. We'll put it in a temporary location, and, while Leroy holds it, I'll bolt it back down. And this is a temporary location because it will not actually be put into its final or its first usable location and activated until the next flight.

"And, gosh, we're just getting warmed up at this point. So then after we're finished with the S-band antenna assembly we'll move some small components around - some of these foot restraints, these foot brackets - we'll move them in position for the next task.

"Once the electrical reconfiguration is complete, Koichi will stick me back down underneath the Z1 and I'll then release the next set of four cables and attach them to the Node. And then we'll be ready for pretty nominal power status onboard the space station.

"Now, the next task will be to release another communications antenna, the Space-to-Ground Antenna - and we call it SGANT, but it's Space-to-Ground Antenna - and it's in the K-band system. It would only communicate through the TDRS or Tracking and Data Satellites - and this one really looks like an antenna. It's a large parabolic dish, somewhat fragile. Okay, so it makes us a little bit nervous.

"Anyhow ... we'll release this antenna. And then I have this T-bar that comes out of the base of the antenna, and I'm sort of holding it off to the side. And then Koichi will move me aft in the payload bay; Leroy will be guiding the antenna as well, and will guide it clear of the Z1 structure itself.

"Leroy then moves over to the left side of Z1 - left side as you're facing forward - and positions himself near this boom that's folded down on that face of Z1. So, Koichi will move me over on the end of the arm. I'll rotate the antenna around, present it to Leroy, and then Leroy will begin bolting it to this boom. I have to, at that point, get off the arm, crawl along Z1, around underneath the antenna, to attach one of the bolts and a couple of electrical connectors that provide power and data to the antenna.

"Once that's all said and done, Leroy moves around to sort of the topside of the boom. And then we, by hand, we just fold the boom out. And once the boom's folded out, Leroy's got a couple of bolts that he attaches to the base to hold it in position. And then the K-band system is simply waiting to be activated on Flight 6A.

"I go back up, get back on the arm, and our last primary task on that is for me to go to the back of this pallet, this bracket that's in the payload bay, which is holding Pressurized Mating Adapter No. 3, and I release a toolbox that's attached to it. Koichi brings me around and on the, you know, looking from the tail, on the right side of Z1, I'll then install this toolbox which contains tools that will be used both by us and by EVA crewmembers throughout the life of the station, both station crewmembers and subsequent shuttle crewmembers who come up and do assembly ops.

"Then it's back up to the interface between the Russian segment and the US segment. We'll brake the arm. We'll take all these, all this equipment back off that I attached to the arm: the foot brackets and things like that. Koichi then lets me hitchhike on the arm back down to the airlock. And we're finished with EVA one."

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