Tribute to the Great Hubble Tele

Dat's Me wrote:

I have problems with the concept of calling a telescope that can only see
(whether better or not) - what, a third? - of the spectrum of the one its
replacing, a replacement.

Your premise is false. As David has pointed out, the proposed JWST
will have a much larger spectral range than the HST does. It may be
helpful to think of their ranges in terms of "octaves"
(lg-frequency), making an analogy to our sense of pitch: the visible
spectrum from red to violet covers just about one octave. Hubble can
'see' about 3 1/2 octaves, from about 1 1/2 below to 1 above the ends
of the visible range, but the "replacement" will cover about 5 1/2
octaves, from 5 octaves below red to yellow.

--
Odysseus

On Fri, 06 Feb 2004 09:43:19 -0600, Scott Schwartz wrote:

They really aren't the same thing. It is like owning infrared goggles and
saying they are a good replacement for your 10" scope.

Exactly the point I was making ... JWST is _not_ a suitable replacement, a
replacement should (at least) cover the same spectrum.

On Fri, 06 Feb 2004 00:29:09 -0600, David Knisely wrote:

Dat's Me posted:

Yeah! The only problem is: It operates (almost) exclusivly in the
infrared. While those frequency ranges may be important & interesting,
it is also a very limited range. I'm sure the universe isn't _only_
visible in infrared.

A *limited* range??!! The range is *HUGE*. It runs from 0.6 microns all
the way down to 28 microns. Again, if you look at the current literature,
much of
the universe shows its true characteristics *best* in the infrared and
that
is where much of the cutting edge research is going. Visible light can

Ok. "Limited range" is a poor choice of words. Btw the numbers above
don't mean a lot to me, I went & found a chart to get some idea of
comparative bandwidths of IR,VL & UV:
http://imagine.gsfc.nasa.gov/docs/sc...mspectrum.html

I wasn't counting frequencies rather, I was counting spectra.

You've been arguing the point that Infrared is the best spectrum to view
(to a very large extent, conceded), I on the other hand have been arguing
that it is incorrect to say that JWST (with blood in its eye - only sees
in red to Infrared) can be considered a Hubble 2/replacement. Which is
obviously _not_ the case, considering that Hubble can see in IR (Not as
well as JWST agreed), VL & UV, which by definition means it'll see things
that JWST cannot. EG. The Black Eye Galaxy.

In (and of) itself, the JWST is sure to be a fine telescope but, since
some people have been touting it as the Hubble II, the comparison I made
is fair, the JWST _is_ inferior.

No, the comparison is not at all fair or reasonable. Its like saying that
the Queen Mary is an inferior bicycle! Both vehicles are designed to
transport someone, but comparing the two makes little sense. JWST was

That's a terrible analogy. Staying with the bicycle: The JWST is a
fixed-ratio setup, it can gear up & down in one spectrum. While HST is a
multi-ratio setup, it can not only gear up & down in a spectrum, it can
also change ratio to another spectrum.

transport someone, but comparing the two makes little sense. JWST was
*never* designed to access the visible and ultraviolet wavelengths. HST
was, but can't go as far into the infrared as JWST will. You can compare

Which just adds weight to my argument.

was, but can't go as far into the infrared as JWST will. You can compare
two different instruments designed to access the same spectral region and
judge them against each other, but the comparison between two instruments
with vastly different observing goals to the point of stating that one is
"inferior" is illogical.

Not when one is supposed to be "replacing" the other, at that point, any
such comparison is acceptable and perfectly logical. My opinion stands.

Something to remember though, the Hubble is more likely to attract the
public's attention and keep their attention on space research, because
of the nifty pictures it can provide.

Then you haven't been looking at too many of the beautiful color images in
SKY and TELESCOPE magazine lately, have you? Many are multi-spectral
images taken in the infrared, and show spectacular sights which would be
invisible to any telescope if it looked in the the ultraviolet or visible
portions of the spectrum. JWST would be able to provide similar if not
better "pretty pictures", although its the important science which is the
key reason for its existance.

No I haven't, I do have other things than astronomy in my life and I
certainly couldn't afford to get every (or in some cases any) magazines to
do with everything I have an interest in. Are they available on
http://skyandtelescope.com ? I went looking for "IR images" & "Infrared
images" on their site but, I suspect the few I saw weren't what you were
referring to.

I am truly amazed that NASA/USGov want to toss the Hubble, it seems
incredibly wasteful to me, I doubt it is incapable of being used for
scientific research. Ifthe orbit is such a big problem, why not put a
bit brains behind coming up with a way of giving it a _gentle_ nudge
into a more suitable one.

I too was vastly disappointed in the decision (it was the head of NASA who
made the decision, and it is not at all universally supported in either
the science community or at NASA). If the foam impact issue is
corrected, the risk of the flight to HST for servicing is no more than it
was before Columbia flew its last mission.
As for the orbital problem, the problem isn't altitude (which is easy
to
correct), its inclination. HST currently orbits at about a 28 degree
angle of inclination. It takes a *huge* amount of impulse to change
orbital planes significantly, so much so that we would have to use a
good-sized rocket in orbit to both grab HST and secure it, as well as
man-handling it not so gently into an orbital inclination of 57 degrees,
which is the same as the International Space Station. We don't really

Inclination: That's referring to angle between equatorial & polar?

On Sat, 07 Feb 2004 05:23:20 +0000, Odysseus wrote:

Dat's Me wrote:

I have problems with the concept of calling a telescope that can only
see (whether better or not) - what, a third? - of the spectrum of the
one its replacing, a replacement.

Your premise is false. As David has pointed out, the proposed JWST will
have a much larger spectral range than the HST does. It may be helpful to
think of their ranges in terms of "octaves" (lg-frequency), making an
analogy to our sense of pitch: the visible spectrum from red to violet
covers just about one octave. Hubble can 'see' about 3 1/2 octaves, from
about 1 1/2 below to 1 above the ends of the visible range, but the
"replacement" will cover about 5 1/2 octaves, from 5 octaves below red to
yellow.

Damn! Now David's going to tear up my use of the word spectrum/spectra in
my reply to him. :-)

YOu posted:

The JWST is a
fixed-ratio setup, it can gear up & down in one spectrum.

What are you talking about? What "gearing"? HST is also a fixed-ratio
(f/37). It has two cameras which are needed to access its spectral range.
Again, JWS isn't "fixed" in that it can access any part of the spectral range
it is designed to work under. It covers the red portion of the visible
spectrum, the near infrared, and the far infrared. HST covers the near
ultraviolet, visible, and near infrared.

Which just adds weight to my argument.

No, it shows you argument of calling JWST "inferior" is illogical.

Not when one is supposed to be "replacing" the other, at that point, any
such comparison is acceptable and perfectly logical. My opinion stands.

JWST is a follow-on mission and not as a direct replacement. It was a concept
that was agreed upon as a need being addressed in the astronomical community.
They wanted a big space-based infrared telescope and that is exactly what
they are going to get.

No I haven't, I do have other things than astronomy in my life and I
certainly couldn't afford to get every (or in some cases any) magazines to
do with everything I have an interest in.

Sky and Telescope is probably *the* magazine for general and amateur
Astronomy, and is often carried by local newstands as well as in many public
libraries. They offer discounts for those who subscribe through local
Astronomy clubs.

I went looking for "IR images" & "Infrared
images" on their site but, I suspect the few I saw weren't what you were
referring to.

If you want to see what is coming up, you might check out the article on the
Space Infrared Telescope (the precursor to the JWST) in the February 2003
issue. It has a stunning panoramic image of the entire Milky Way taken in the
Two Micron All-Sky Survey.

Inclination: That's referring to angle between equatorial & polar?

That's referring to the angle between the plane of the satellite's orbit and
the plane of the Earth's equator. Geostationary satellites orbit with a near
zero angle of inclination, while Polar orbiting weather and spy satellites
orbit at an inclination of near 90 degrees. Shuttles launched straight east
from KSC will orbit at about a 27 degree angle of inclination. Clear skies to
you.

--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
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* July 18-23, 2004, Merritt Reservoir *
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Lets give the Hubble to Russia. They can service it. Why let it rot away
in space. It has done so much for Astronomy. More was shown to us then
men walking on Mars,and the moon. It would be a great gesture on
are part. Like France giving us the Statue of Liberty. We could have
ours and their astronauts working together on it Bert

On Sun, 08 Feb 2004 00:42:23 -0600, David Knisely wrote:

YOu posted:

The JWST is a
fixed-ratio setup, it can gear up & down in one spectrum.

What are you talking about? What "gearing"? HST is also a fixed-ratio

You were the one to come up with the bicycle analogy, I just put both
scopes onto the same level - where they belong.

I think anyone who's ever gone from a 3 speed pushbike to something like a
10 (or 15) speed one will understand my analogy. Doesn't matter if not,
you kind of crueled it a bit further down deleted with your near & far infrared.

Not when one is supposed to be "replacing" the other, at that point, any
such comparison is acceptable and perfectly logical. My opinion stands.

JWST is a follow-on mission and not as a direct replacement. It was a

So you agree with me, it should not have been billed as a replacement
scope (as suggested below), rather it is a complementary device?

From the JWST Fast Facts page: "The James Webb Space Telescope (JWST) is an
orbiting infrared observatory that will take the place of the Hubble Space
Telescope at the end of this decade."

concept that was agreed upon as a need being addressed in the astronomical
community.
They wanted a big space-based infrared telescope and that is exactly
what
they are going to get.

Good for them! Irrelevant to topic I thought we were discussing.

No I haven't, I do have other things than astronomy in my life and I
certainly couldn't afford to get every (or in some cases any) magazines
to do with everything I have an interest in.

Sky and Telescope is probably *the* magazine for general and amateur
Astronomy, and is often carried by local newstands as well as in many
public libraries. They offer discounts for those who subscribe through
local Astronomy clubs.

I'm aware of the reputation/popularity of the magazine and the cost is not
beyond my means, my interest in astronomy is simply not strong enough to
make me want to buy it. I enjoy the bits I read in the news (or on tv) and
I read this newsgroup (thinking of subscribing to sci.astronomy) thats
about it.

Its good to see NASA is re-considering doiing (at least) one more
maintenance trip to Hubble.

Dat's Me I can't see why we can't service the Hubble with a Russian
space ship. It is rather embarrassing but I would rather blush than kill
7 more astronauts. It would be cheaper and a hell of a lot safer. Bert

On Mon, 09 Feb 2004 16:13:32 -0500, G=EMC^2 Glazier wrote:

Dat's Me I can't see why we can't service the Hubble with a Russian space
ship. It is rather embarrassing but I would rather blush than kill 7 more
astronauts. It would be cheaper and a hell of a lot safer. Bert

G'day Bert,
To me it doesn't matter who services it (being Australian I have no say
in the matter anyway), my biggest grumble is that seems to be a waste of
good equipment to just dump it. It isn't as though its halfway across the
solar system & out of reach.

I suspect onoe of the benefits of using the shuttle, is the mechanical arm
comes in handy when it comes to moving hardware around. I don't of any
rockets with that facility.

Hi Dat's Me The lack of brain"s of NASA has left us nothing that can
even go into the orbit to service the Hubble. In reality those of the
low lives(brains) of what is left of NASA ( top brains quite) don't
really know what to do? It takes brains to know what to do. Bert