NASA's Mars Reconnaissance Orbiter will be the largest spacecraft to orbit Mars, weighing 2,180 kilograms (4,796 pounds) at liftoff. This image from early January 2005 shows the spacecraft fitted with five of its six primary science instruments, both solar arrays and its high-gain antenna. The orbiter is undergoing environmental testing at Lockheed Martin Space Systems, Denver, to ensure its performance in simulated launch and space conditions. Technicians in the picture are installing test instrumentation for measuring vibration and acceleration levels during acoustic testing of the spacecraft.