Juno Spacecraft Solar Panels Complete Testing by NASA

The three massive solar panels that will provide power for NASA's Juno spacecraft during its mission to Jupiter have seen their last photons of light until they are deployed in space after launch.

The last of the Jupiter-bound spacecraft's panels completed pre-flight testing at the Astrotech payload processing facility in Titusville, Fla., and was folded against the side of the spacecraft into its launch configuration.

This is the first time in history a spacecraft has used solar power so far out in space (Jupiter is five times farther from the sun than Earth). To operate on the sun's light that far out requires solar panels about the size of the cargo section of a typical tractor-trailer you'd see on the interstate highway. Even with all that surface area pointed sunward, all three panels, which are 2.7 meters wide (9 feet), by 8.9 meters long (29 feet), will only generate about enough juice to power five standard light bulbs -- about 450 watts of electricity. If the arrays were optimized to operate at Earth, they would produce 12 to 14 kilowatts of power.

The launch period for Juno opens Aug. 5, 2011, and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 8:39 a.m. PDT (11:39 am EDT) and remains open through 9:39 a.m. PDT (12:39 p.m. EDT). Five-year cruise to Jupiter, arriving July 2016 One year at Jupiter will complete the mission (orbiting the planet 32 times).

Source: NASA Juno