LISA Pathfinder has a main science spacecraft and a separable propulsion module. The propulsion module was jettisoned during the transfer phase since it would be a source of unwanted forces on the science spacecraft during science operations.
The science spacecraft carries two test packages and is covered with a single fixed solar array.
The test packages are:
- LISA Technology Package (LTP) contains two identical proof masses in the form of 46-mm gold:platinum cubes, each suspended in its own vacuum container. They act both as mirrors for the interferometer and as inertial references for the drag-free control system. The LTP interferometer is of the heterodyne Mach-Zender type. It requires as input two light beams derived from the same source but with a frequency difference (a few kHz). These two optical beams are produced in the laser assembly via the Acousto Optical Modulation Unit (AOMU) provided by France, through the responsibility of CNES and APC laboratory (Laboratoire AstroParticule et Cosmologie).
Illustration of the LISA Technology Package. Credit: ESA
- Disturbance Reduction System (DRS) is a NASA-supplied system comprising two clusters of colloidal micro-propulsion thrusters and an electronic unit containing a computer with associated drag-free control software.
FEEP (ESA) and colloidal (NASA) propulsion system layout on the LISA Pathfinder spacecraft,
and pictures of slit and needle FEEP, neutralizer and PCU
LISA Pathfinder was built by an industrial team led by prime contractor ADS (Astrium Defence and Space). Astrium GmbH was responsible for providing the integrated LISA Technology Package (LTP) payload. The subsystems for the LTP were provided by a consortium of European companies, research institutes and ESA.