The crew insignia for STS-97 depicts the shuttle docked to ISS in low Earth orbit after the activation of the P6 electrical power system. Gold and silver are used to highlight the portion of the station that will be installed by the STS-97 astronauts. The Sun, central to the design, is the source of energy for ISS. Photo: NASA

The shuttle Endeavour is poised for launch on a dramatic mission to attach a huge set of solar arrays on the international space station, a $600 million addition that will provide the power needed to finally begin scientific research.

Stretching 240 feet tip to tip - longer than the wingspan of a 747 jumbo jet - the 35,000-pound P6 solar array, the largest structure ever deployed in space, will make the space station one of the brightest "stars" in the night sky.

More important, the four solar cell blankets in the P6 array will generate 19.1 kilowatts of useable electrical power. And that will free up the U.S. section of the space station from dependence on much smaller Russian solar panels and enable NASA to launch its high-tech laboratory module, Destiny, in late January.

To attach, activate and instrument the P6 arrays, astronauts Joseph Tanner and Carlos Noriega plan to carry out three spacewalks during Endeavour's mission.

One will be devoted to physically connecting the massive array and cranking open the arrays; a second will be needed to wire it into the station's electrical system; and a third will be used to install a special instrument to measure the electric shock hazard future spacewalkers might face as the increasingly large station plows through Earth's extreme upper atmosphere.

"I've been a flight director for 14 years and what we're about to do is one of the most exciting and challenging missions I've ever had the pleasure to work on," said lead flight director William Reeves.

"The significance of this is we'll now provide enough power to install the lab on the next flight and start doing useful science work on the space station."

Throw in the cost of a shuttle launch and the price tag for assembly flight 4A approaches $1 billion. But commander Brent Jett assured reporters recently that "we think we have a pretty good chance to pull this mission off successfully."

Endeavour sits atop Kennedy Space Center's launch pad 39A. Photo: NASA-KSC

Shuttle Endeavour is scheduled to lift off at 10:05:45 p.m. EST Nov. 30 from pad 39B at the Kennedy Space Center. Joining Jett will be pilot Michael Bloomfield, Canadian robot arm operator Marc Garneu and spacewalkers Tanner and Noriega.

As with all station assembly flights, Endeavour's countdown will be adjusted to hit zero at the moment Earth's rotation carries the launch pad into the plane of the space station's orbit. The launch window will close a few minutes later.

By launching directly into that orbital plane, the crew can minimize propellant usage and improve the odds of reaching an emergency East Coast runway in the event of an engine failure early in flight.

It will take Endeavour two days to catch up with the international space station. If all goes well, Jett will guide Endeavour to a docking the afternoon of Dec. 2.

Looking on from inside will be the station's first full-time crew, commander William Shepherd, Soyuz pilot Yuri Gidzenko and flight engineer Sergei Krikalev.

Shepherd and company, known as Expedition One, were launched aboard a Russian Soyuz rocket Oct. 31 and docked with the station two days later. They will not return to Earth until mid February.

The station currently consists of a U.S. module called Unity, which is attached to a Russian-built NASA-financed storage module called Zarya. The Russian command module Zvezda is docked to the far end of Zarya and the Soyuz spacecraft that ferried the Expedition One crew to the station is docked to Zvezda's aft port.

An unmanned Progress supply ship is docked to the Zarya module's downward-facing port. It will be undocked Dec. 1 to make way for Endeavour's docking the next day at a nearby port on the Unity module.

An artist's illustration of Endeavour docked to the space station with the new solar arrays unfurled. Photo: NASA

Shepherd and his crewmates currently are limited to living and working inside the Zarya and Zvezda modules. The Unity node is sealed off from the rest of the station because there is not enough electrical power available to keep its heaters on and to properly control its temperature.

Once the P6 solar arrays are installed, the station will have more power than it can immediately use and the Expedition One crew finally will be able to begin utilizing the roomy Unity module.

Unity features six hatches, or ports: One on each end and four around its circumference. A short tunnel called pressurized mating adapter No. 1 - PMA-1 - leads from one of Unity's end hatches to Zarya. A second PMA, used for previous shuttle dockings, is attached to the other end hatch.

A massive structural truss, known as the Z1 truss, was attached to Unity's upward-facing, or nadir, port during an October shuttle flight. A new shuttle docking port, PMA-3, was attached to the Earth-facing, or nadir, port during the same mission.

While past shuttle flights have docked to PMA-2, Endeavour's crew will dock to the downward-facing PMA-3. That will enable them to install the P6 solar arrays on top of the Z1 truss.

PMA-2 will be removed and temporarily relocated during the lab installation flight in January so the Destiny laboratory module can be attached directly to Unity's forward port. PMA-2 then will be attached to the far end of Destiny for subsequent shuttle dockings.

"This is a unique and exciting time to be working in human spaceflight operations," said Tommy Holloway, NASA's space station program manager. "We're not only building a world-class research and technological development facility, but we're also providing a bridge to the future for human exploration of the solar system."

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