Simulation Part of the preflight testing requirements for the Voyager spacecraft included space simulations. Shown here is one of the Voyagers in a flight simulator. The simulator is vacuum sealed and cooled with liquid nitrogen. Beneath the floor are 37 arc lamps that shine through the floor and onto a mirror on the ceiling. The mirror and lights together are designed to simulate solar thermal radiation. With the simulator, scientists are able to test the spacecraft's performance in realistic situations.