Re: James Webb Space Telescope

Joseph Lazio <jlazio@xxxxxxxxxxxxxxxxx> wrote:
I'm certainly receptive to arguments about a dynamic sky (as I'm
serving on the scientific organizing committee for a meeting
focussed on that). However, I'm not sure that your arguments make
the best case for Hubble.

If I want to study the dynamic sky, why should I prefer Hubble (or a
son-of-Hubble) to a smaller, wide-field instrument that could scan
the sky quickly (see LSST)?

To see smaller, fainter, or more distant objects, of course.

If I want to study Jupiter, why not use the same amount of money to
send an orbiter to Jupiter?

A powerful telescope in Earth orbit can study *all* the planets,
not just the one it's next to. And can also study comets, moons,
asteroids, Kuiper belt objects, stars, pulsars, nebulas, galaxies,
quasars, and GRBs, too.

Besides, if something suddenly happens on Jupiter, it's a lot faster
to aim an existing telescope at it than to design, build, and launch a
probe, and wait for it to arrive at Jupiter.

Moreover, what about the science that Hubble cannot do? The JWST
is being designed, in part, to search out the first stars in the
Universe. That requires an IR-optimized telescope, something Hubble
is not. JWST might still be able to do some of the things that you
describe, yet also (it is hoped) be able to find the first stars.
Isn't that also exciting?

Exciting enough that it shouldn't be thrown away after five years.

Speaking of the beginnings of things and the dynamic sky, just how
precisely can the absolute -- not relative -- microwave background be
measured? Is there any chance that it can be measured so precisely
that two such measurements, perhaps a decade apart, can actually
directly detect the cooling and expansion of the universe? Am I
correct in assuming the cooling is roughly proportional to the
age of the universe, about one part in a billion in a decade?
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.
.

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