May 28, 2011 06:25 GMT  ·  By
Technicians at Astrotech's payload processing facility in Titusville stow solar array #2 against the body of the NASA Juno spacecraft
   Technicians at Astrotech's payload processing facility in Titusville stow solar array #2 against the body of the NASA Juno spacecraft

A couple of days ago, the last of the three massive solar panels that will power up NASA's next Jupiter-bound spacecraft was folded into its final launch configuration, after having successfully completed a wide array of tests meant to assess its functionality.

The tests were carried out by engineers at a Titusville, Florida-based Astrotech payload processing facility. The folding solar arrays that will go on the Juno spacecraft are very large, when compared to the space probe's body.

On Thursday, May 26, the arrays saw their last photons until they will be deployed in space, later this year. At this point, NASA plans to launch the vehicle on August 5, 2011, aboard a medium-lift Atlas V delivery system.

The space probe will be launched to space from the Space Launch Complex-41 at the Cape Canaveral Air Force Station (CCAFS), also in Florida, and its entire mission is scheduled to last about one Earth year. During this time, it will orbit the gas giant about 33 times.

These passes will help experts get more insight into the structure of the Jovian atmosphere, on the electromagnetic phenomena taking place at the two poles, into the magnetosphere, auroras and so on.

Given that the gas giant is located about five AU from the Sun, the task of energizing the probe using only solar panels is a daunting one. An AU (astronomical unit) is the mean distance between Earth and the Sun, or around 93 million miles.

In order to produce the necessary amounts of energy, the three solar panels are 2.7 meters wide and 8.9 meters long (9 by 29 feet) each. Regardless, the amount of energy they will be able to produce from available photons will only be able to light up five lightbulbs.

This is the equivalent of about 450 watts of electricity, at 5 AU. If installed and optimized for operations here on Earth, the arrays are so efficient that they could produce12 to 14 kilowatts.

“Completing the testing and stow of solar panels is always a big pre-launch milestone, and with Juno, you could say really big because our panels are really big,” explains researcher Jan Chodas.

“The next time these three massive solar arrays are extended to their full length, Juno will be climbing away from the Earth at about seven miles per second,” the mission official goes on to explain.

Chodas holds an appointment as the manager of the Juno mission, at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California. He adds that the first stage of the United Launch Alliance Atlas V launch vehicle already made its way to Florida.

This rocket is of a two-stage design, featuring five solid rocket boosters. Over the next few weeks, it will be assembled and tested at SLC-41.