LISA Pathfinder’s science module (the white- and gold-coloured structure) and solar array (the grey panel).
At the heart of the science module lies the LISA Technology Package. This contains inertial sensors, an optical metrology system, the payload computer and a diagnostic system. The inertial sensors and optical metrology system provide signals to the Drag-Free and Attitude Control System, which in turn commands three clusters of cold-gas micronewton thrusters, as well as feeding back to the inertial sensors.
The small appendages seen on the outside of the module are micronewton thrusters, which continually apply miniscule amounts of force to move the spacecraft and keep it centred on the master test mass.
The science module is 231 cm in diameter, 96 cm tall and weighs 450 kg.
The solar array provides the spacecraft with solar power and shields it from the Sun.