Herschel

Not an exclusive, but a nice BBC article on Herschel:

news.bbc.co.uk/1/hi/sci/tech/7864087.stm

Herschel is now in Kourou, awaiting the final testing before integration with the Ariane 5 upper stage in March.

On the Irish angle re. Herschel, Matt Griffin, the head-honcho for my instrument, SPIRE, is a UCD graduate. There's quite a few of us from UCD working on Herschel, as it happens

Interesting article Brian!

Just wonering, what sort of surface accuracy of the mirror?
If I understand it right, the longer the wavelength, the less accurate the surface needs to be polished, yea?

Michael.

Michael, the Herschel mirror has a surface error of 1.5 µm RMS and a surface roughness of less than 30 nm. For the primary and secondary together, we have a total wavefront error of less than 6 µm RMS. Made of Silicon Carbide too (the largest ever such mirror), and has to put up with the thermal and launch stresses. Really cutting edge technology to say the least!

Re. the surface accuracy with increasing wavelength, yep, that's true - as long as the surface accuracy of the reflecting surfaces is many times smaller than the incident radiation wavelength, then we're OK (that's why you can play cricket on a radio telescope dish without damaging it ) . For far-IR, we still need an exacting surface accuracy, given the pretty small wavelengths, as you can see above.

I jumped the gun - Herschel is (at this very moment in time) sitting in an Antonov 124 transport aircraft at Schipol. It'll leave Amsterdam at 5:30pm local time on route to Kourou.

Some photos from Herschel's clean room at Kourou:

www.forum-conquete-spatiale.fr/europe-f1...04-2009-t7410-15.htm

That's one mighty big shaving mirror!
No wonder those guys look so clean!

Seriously though, thanks for keeping us up-to-date on the latest info re the mission. Not too often that one of our own is involved in something like as big like this.

Michael.