In article ,
wrote:
On 2011-07-15, Quadibloc wrote:
One thing about the JWST that disturbed me was the fact that its
mirrors are coated with gold.

While at the present time, the infrared is a very exciting area for
astronomy, the fact that gold is strongly colored instead of
reflecting all colors equally seemed to me to be precluding the use of
the telescope for astronomy at other wavelengths.

Because the telescope is not serviceable, the instrument package will do
a good enough job of restricting the observations to the infrared.

I imagine that it's also extravagently more difficult to get a
deployable mirror to work nicely at 300nm than at 600nm; the
shortest-wavelength filter on NIRCAM cuts off at about 600nm (that is,
JWST cannot work in the ultra-orange). I think the HgCdTe array is
sensitive to shorter-wavelength light, but as designed the instrument
does not have a 'clear' filter.

Tom