ESA's LISA Pathfinder.

Space Technology 7's (ST7) Disturbance Reduction System (DRS) will fly onboard the European Space Agency's (ESA) LISA Pathfinder, formerly called SMART-2, in late 2009 or 2010. The spacecraft will be launched in an Earth-escape trajectory and then delivered to its predetermined orbit by the propulsion module, which is supplied with power and driving signals by the spacecraft through an umbilical connection.

Following final orbit acquisition, the propulsion module will separate from the spacecraft. Once in its operational orbit, LISA Pathfinder will fly far above Earth's gravitational field in a low-radiation environment for one year. During this time the DRS will be operational for up to 90 days, during which time it will demonstrate disturbance reduction using ESA's LISA Technology Package Inertial Sensor.

Spacecraft pointing (direction and position) will be aided by startrackers, which identify star patterns in the sky. These modern-day instruments enable spacecraft and earth-orbiting satellites to navigate space much the same way ancient mariners navigated Earth's oceans, by using groups of stars as a reference point. The spacecraft will be powered by a solar array fixed to the body of the spacecraft. The solar array will be pointed to the sun using the data from the star tracker, or, in 'safe mode,' sun sensors mounted outside the craft. A sunshield will protect the DRS and LTP instruments. Commands and telemetry will be relayed through LISA Pathfinder's mission operations center.

LISA Pathfinder cutaway view, with and without solar array.

LISA Pathfinder is a prelude to the Laser Interferometer Space Antenna (LISA) joint ESA and NASA mission (launch date indefinite). LISA will search for and make minute measurements of gravitational waves. Onboard LISA Pathfinder, DRS will demonstrate that a solid body can float freely in space completely undisturbed.