Point-Ahead Actuation Mechanism stability tests for LISA at the University of Florida

As a laser interferometer in orbit around the Sun, LISA consists of 3 spacecrafts that form an equilateral triangle of side length reaching 2.5 Gm. Due to the sheer size of LISA, light takes 8.3 seconds to travel from one spacecraft to another, so the laser beam transmitted must be projected by one spacecraft point "ahead" to catch the receiving spacecraft. In addition to that, the orbit introduces the point-ahead angle that is out of the constellation plane and is always evolving during the mission. A point-ahead actuation mechanism (PAAM) will not only provide such an angle but maintain sufficient optical power exchange between spacecraft for the lifetime of the LISA mission. Because the PAAM lies in the optical path between spacecraft, its length and angular stability must satisfy stringent performance requirements. The University of Florida (UF) team is experienced in picometer stability tests and is preparing to conduct a series of stability tests on the PAAM. In the presentation we reveal the testing plan for the PAAM, the optical design that integrates it and the lab facilities that will be utilized. Finally, we discuss the effort to mitigate certain limiting noise sources in the reference system that will be deployed for the PAAM tests and future LISA-related tests at UF.