U.S. Department of Energy

    NASA Faces a Torn Solar Array and Worn Joint on the Space Station

    October 31, 2007


    Photo of a solar array consisting of many rectangular sheets of solar cells connected into a single blanket that accordions together for storage. A tear separates a seam between two pairs of rectangles, causing distortions in the bottom edge of the blanket. Below the blanket is a metal support truss for the solar array.

    A tear was discovered on one of the solar arrays that the astronauts on the International Space Station attempted to deploy on Tuesday.
    Credit: NASA TV

    Astronauts in the International Space Station (ISS) discovered a tear in one of its solar power arrays while deploying it on Tuesday, October 30th. Spacewalkers from the Space Shuttle Discovery latched and bolted the space station's oldest solar power module into its new permanent location on October 30th, allowing the ISS crew to begin unfurling its solar arrays. Called the P6 module, it was originally installed in a vertical orientation in the center of the space station, providing a temporary source of power. When additional solar arrays were added over the past two years, the P6 solar arrays had to be retracted to allow the new modules to rotate freely. Now in its final location on the end of the port side of the station, the solar arrays could once more be deployed.

    One "wing," consisting of two solar arrays, deployed easily, but a tear developed in one of the solar arrays when deploying the second wing, bringing that deployment to a halt. As of October 30th, the National Aeronautics and Space Administration (NASA) was still assessing how to proceed with the array. Once the P6 array is fully unfurled, the space station will have six of its eight solar wings deployed, each of which can produce nearly 33 kilowatts of solar power. The final module is scheduled to be delivered sometime after September 2008. See pages 33 to 41 (PDF pages 37 to 45) of the press kit (PDF 9 MB) for the current shuttle mission, STS-120, as well as the future launch schedule and a NASA animation of the ISS assembly sequence. Download Adobe Reader.

    The solar power systems are also creating other headaches for NASA during this space shuttle mission. Early on the morning of Sunday, October 28th, a spacewalker discovered metal shavings in a rotating joint that allows the starboard solar arrays to stay aligned with the sun. Concerned that the joint may be damaged, NASA disabled it and revised and extended a spacewalk scheduled for Thursday, November 1st. The spacewalk will now be used to further examine the rotary joint and will add a day to the shuttle mission. On October 30th, while moving the P6 module, shuttle astronauts examined the port solar rotating joint and were relieved to find no damage. See NASA's Space Shuttle Web page and the Web page for the current mission.