Inertial Sensor Heads in the LISA Technology Package
The flight model of the LISA Technology Package (LTP), pictured at the Airbus Defence and Space Friedrichshafen facility, in February 2015.
The LTP, provided by European institutes and industry, is one of two payloads, or test packages, that will be carried by the LISA Pathfinder spacecraft; the other package is the Disturbance Reduction System (DRS), provided by NASA.
LISA Pathfinder will use the LTP to test one of the key ideas behind gravitational wave detectors – that free particles follow geodesics in space-time.
On the LTP, two Inertial Sensor Heads (ISH) - the cylindrical containers in this picture – each carry a test mass, which will be free floating once the spacecraft is on orbit. In addition, each ISH also contains: an electrode housing, to electrostatically measure the distance from the mass to the walls of the housing; a launch lock, with two devices to hold the test mass in place during launch, and incorporating a venting gate valve, called the Caging and Venting Mechanism in one of the devices; two Grabbing, Positioning and Release Mechanisms, used to position the test masses; a vacuum enclosure, made of titanium because magnetic components must be avoided; feedthroughs for the UV fibres that are needed for the charge management system, and electrical harnesses.
An industrial team led by the prime contractor, Airbus DS - Stevenage, is building LISA Pathfinder. Airbus DS – Friedrichshafen is the payload architect for the LISA Technology Package (LTP). The optical bench is provided by the University of Glasgow; the inertial sensors and electrode housing by CGS (Milan); the Caging and Venting Mechanism, and the Grabbing, Positioning and Release Mechanisms by RUAG CH, and the mounting hardware and side walls by Airbus DS - Stevenage.