Technology preparation for the L3 mission: LISA
The successful LISA Pathfinder mission has confirmed the feasibility and maturity of a range of critical functions and technologies needed for ESA's L3 mission LISA, such as drag-free flying of a spacecraft which is required to enable free-falling test masses to follow a purely inertial trajectory.
However, other critical technologies which are still at low maturity, together with anticipated changes in platform size and configuration with respect to LISA Pathfinder, a constellation of three spacecraft, and a much longer mission lifetime present further challenges for the technological preparation of LISA.
In addition, the LISA mission itself presents a unique challenge: due to the high sensitivity of the measurement, the distinction between platform and instrument with regards to interfaces and requirements is highly complex.
| Critical elements and technologies for LISA | |
|---|---|
|
Payload |
Telescope |
|
Optical bench |
|
|
Laser system architecture |
|
|
Phase reference distribution |
|
|
Platform |
Antenna |
|
Micropropulsion |
|
|
Straylight analysis and reduction |
|
|
Constellation acquisition |
|
Optical Bench Manufacturing
 |
| LISA Technology Package optical bench interferometer during calibration. Credit: University of Glasgow and University of Birmingham |
The LISA Pathfinder optical bench was successfully manufactured with Zerodur using hydroxyl catalysis bonding. Due to the required precision the manufacturing process was largely carried out manually. Since LISA will require at least three optical benches, this time-consuming process will need to be accelerated. Options for automation are under investigation.
Laser System Architecture
 |
| LISA Technology Package laser modulator unit. Credit: RUAG, Switzerland |
The LISA mission requires lasers with extremely low frequency and low noise. Such performance has already been demonstrated in a laboratory environment, but the remaining challenge is to demonstrate this performance in a mission relevant environment. Several activities focussing on high power and seed lasers are running or are being planned.