Keeping things cold for the Herschel Planck launch! (5/8)


Uploaded by TheOpenUniversity on 03.06.2009

Transcript:
Hi, I'm Tom Bradshaw, head of the cryogenics group,
at Rutherford Appleton Laboratory.
I was responsible for the 4 Kelvin cooling system for the Planck mission,
that's just been launched.
Planck itself is an incredibly complicated cryogenic mission.
You've got several stages of cooling.
Every technique that we know, almost, is used in Planck.
We've got a radius of cooling which gets us down to about 50 Kelvin.
From that, we've got a hydrogen absorption cooling,
supplied by a jet propulsion laboratory,
that gets us down to 18 Kelvin,
And that pre-cools our stage,
which takes the focal plane unit down to 4 Kelvin.
And from then, an open cycle dilution refrigerator,
produced by France that takes that down to 100 milli-Kelvin.
The sort of the cystics and the design that's made there
is rather unusual - it's sort of outside your normal working experience.
For example, the heat load on the focal plane unit at 100 milli-Kelvin,
is only about 80 nanowatts, which is...
You just can't imagine that sort of thing.
Anyway, the launch itself went very well today,
and it's just a relief to get that whole thing off our backs almost,
but, that's just part of the process.
The real point is when the data comes in,
and that's gonna be another exciting moment.