25 Jun 2008 14:44

In the test performed on the evening of Monday 23 June, the spacecraft was shaken vertically along its X-axis in the frequency range 4-100 Hz. For this vibration test, the flight model spacecraft was fastened on an electrodynamic shaker in the ESTEC cleanroom. Starting at 4 Hz, the shaker frequency steadily increased to 100 Hz over a period of about 80 seconds (See Video 1).

Vibration tests will be performed on all three axes of the Herschel spacecraft, with four runs on each axis. These tests are complemented by electrical health verification before and after the runs.

Preceding acoustic tests

Earlier this month, on 5 and 6 June, the spacecraft underwent acoustic tests inside the Large European Acoustic Facility (LEAF) at ESTEC. During these tests, acoustic noise is generated, simulating the noise pressure levels that Herschel will encounter during the launch phase. These images show the spacecraft inside the LEAF during the final test preparations. The tests were successfully completed, after which the spacecraft was transferred to another cleanroom for the current series of vibration tests.

Image 1-3. Three views of the Herschel spacecraft inside the LEAF facility at ESTEC during preparations for the acoustic tests, 5 June 2008

Also visible in these images is some blue wiring. This is a cable harness connecting the telescope to a set of motion sensors (accelerometers) that are used during the vibration tests.