The European telescope is open to the sky

Launched on 14 May 2009, the infrared space observatory has just taken a crucial technical step.

 

The European Space Agency (ESA) announced yesterday that the lid on Herschel’s cryostat had opened correctly on 13 June. What is it that makes this such an important step?

Herschel’s cryostat The lid of this “cold room” is on the top. Crédit : ESA/AOES Medialab

Cold for observing the Universe
This particular ESA satellite is a space telescope which is meant to observe our Universe in the infrared and far infrared light range. However, if the instruments (cameras and spectroscopes) sensitive to these wavelengths are to work efficiently, they have to be chilled so that they are not “blinded” by their own warmth. In Herschel’s case, they are immersed in a cryostat, a type of cold room, at -269°C. The cryostat was sealed prior to the launch, not only to protect the delicate instruments, but also to contain the 2,300 litres of liquid helium, used as the coolant.

Take the cap off!
But, in the same way that a cap protects the lens on a camera, the lid has to be removed from the cryostat so that Herschel’s instruments can observe the sky. Mission controllers, therefore, sent a signal to the telescope which activated small explosives responsible for releasing the spring-operated opening mechanism. An apparently simple solution which had been carefully rehearsed as, in the event of failure, the space observatory cannot be used! The video below shows one of the ground tests.


Herschel will, therefore, soon be making its first observations, but not with any scientific aim in mind; by targeting specific, well-known areas of the sky, the instrument technicians will be able to ensure that they are working correctly and calibrate them. Once this setting stage is completed, the biggest infrared space telescope ever launched will be at the beck and call of the astronomers.

Enjoy Space has a complete feature on Herschel and Planck its launch partner.

Publié on 16 June 2009