LPF's main payload delivers free-falling test-masses and the means to measure their position and attitude.
The main payload onboard LPF is the LISA Technology Package (LTP). The LTP comprises two free-falling test masses, their electrostatic enclosures, the vaccum environment and a high precision optical metrology system for sensing the position and attitude of the test masses. In addition, the LTP contains a diagnostics package which includes thermal and magnetic sensors and actuators.