Juno on the rotation stand

Preparing the craft on June 16, technicians at Astrotech's payload processing facility in Titusville, Fla., watch as NASA's Juno spacecraft is tested for center of gravity, weight, and balance on a rotation stand.

After being affixed to a mount at Astrotech's Hazardous Processing Facility in Titusville, Fla., technicians will load Juno with the hydrazine and nitrogen tetroxide propellant necessary for orbiting maneuvers and the attitude control system.

Because of the massive distances that will be between the control center on Earth and Juno when it arrives at Jupiter, the spacecraft cannot be controlled by joystick. Even using radio signals traveling at the speed of light, it will take 45 minutes to send a message, and another 45 minutes to get a response.

Technicians can steer Juno by firing main engines or thrusters, but the commands must be well planned and sent ahead of time.