Never has a robotic arm traveled so far and helped deliver so many scientific discoveries as Alliance Spacesystems’ robotic arm for NASA’s Spirit and Opportunity Mars rovers. Called the Instrument Deployment Device, or IDD—the robotic arm is the hardy and versatile appendage that brings the rover’s scientific instruments into contact with Mars rocks and soils. Data returned by those arm-mounted instruments has led to the major finding that liquid water once stood on the surface of Mars. Both arms, designed for the rovers’ original three-month mission lifetimes, have continued operating after more than two years on Mars.

The arm has five rotating joints and an extended reach of more than one meter. Mounted to the rover’s forward structure, the arm was secured during launch, landing and roving by restraint mechanisms, also designed by Alliance Spacesystems, at the arm elbow and the instrument turret at its outboard end. The arm is equipped with numerous Alliance-developed mechanisms: five unique actuators articulate the arm and position scientific instruments; contact sensors detect proximity to targets of interest; and a complex flexprint interconnection system traverses the rotating joints to service the electromechanical devices and instruments.