First Wing of World's Largest Solar Array Deployed in Space

JOHNSON SPACE CENTER, Houston, Texas, December 4, 2000 (ENS) - How and when to finish unfurling the world’s largest set of solar panels 235 miles above the Earth on the International Space Station is a decision that will be made today by officials at the National Aeronautics and Space Administration (NASA).

The solar array wing on the right side of the space station was deployed by American astronauts Carlos Noriega and Joe Tanner during a seven hour space walk Sunday, but some of the tension cables on the $600 million project appear to be slack.


International Space Station Alpha before deployment of new solar wings (Photos courtesy NASA)
NASA engineers are assessing whether the problem will interfere with unfurling of the left wing. That operation could be delayed until Tuesday when astronauts on the space shuttle Endeavour conduct their second of three spacewalks after their day of rest today.

The Endeavour lifted off from the Kennedy Space Center in Florida on Thursday night on an 11-day mission to the International Space Station. The Endavour's five crew members brought the first of eight sets of solar arrays that will make up the space station’s electrical power system.

"Since we are in a good, safe posture, there's no reason to be in a big hurry and deploy the other blanket until we absolutely understand what we saw, or what we're looking at right now," explains NASA flight director Bill Reeves from his office at the Johnson Space Center in Houston.

On Sunday, astronauts attached the truss containing the solar panels to the space station. A software problem prevented the latches and retention pins on the wings from opening so the panels could be deployed. New software uploaded to the shuttle opened all latches and pins, except one pin on the left wing.

It took less than 14 minutes for the first folded wing to spread to its full 115 feet.

The future of construction on the space station will depend on the ability of the astronauts to install the solar panels, which will provide power to the extra-terrestrial outpost. The two additional spacewalks planned this week, on Tuesday and Thursday, are designed to finish wiring the solar wings and to install other equipment on the space station.


International Space Station commander Bill Shepherd
Space station commander American Bill Shepherd and his two Russian crewmates pilot Yuri Gidzenko and flight engineer Sergei Krikalev have been on board since early November. Although they are working together, the two crews will not greet each other face-to-face until Friday after completion of the last space walk to install and activate the new 17-ton solar array tower.

Once unfurled, the solar panels will measure 240 feet, which is longer than a Boeing 777 jet. At 38 feet across, the solar panels will make the orbiting space station one of the brightest objects in the night sky. Only the moon and the star Sirius will be brighter.

Each solar array wing is the largest ever deployed in space, weighing over 2,400 pounds and using nearly 33,000 solar arrays, each measuring eight square centimeters with 4,100 diodes.


One component of the solar space array (Photo courtesy NASA)
The solar panels will generate 65 kilowatts of electricity at peak power, four times the output of the smaller Russian panels which currently are on the space station.

Without this extra power, the space agency could not launch its Destiny science lab in January. About 19 kilowatts will be required for the Destiny lab, which could be launched even if only one of the two solar wings is deployed.

By the time the $60 billion space station is completed in 2006, NASA will have installed three more sets of solar wings. Each is designed to last 15 years and will keep operating even if individual solar cells are pierced by bits of space debris.

The space station is a joint project of the United States, Russia, Europe, Canada and Japan.