LISA Technology Package - building the Inertial Sensor Head
Assembly of one of the Inertial Sensor Heads for the LISA Technology Package (LTP).
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 is designed to test one of the key ideas behind gravitational wave detectors – that free particles follow geodesics in space-time. The mission can show this more accurately than has been done in the past by tracking two test masses nominally in freefall, using picometre resolution laser interferometry.
On the LTP, two Inertial Sensor Heads (ISH) 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 – seen here being placed in the framework of a ISH – 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 inertial sensors, including the electrode housing, are provided by CGS (Milan).