NYT: Death Sentence for the Hubble?

rk wrote:


Sean O'Keefe, the departing administrator of the National Aeronautics and
Space Administration, has yanked the agency's most important scientific
instrument off life support. His refusal to budget any funds to service and
upgrade the Hubble Space Telescope looks like the petulant final act of an
administrator who made a foolish decision and then refused to back down in the
face of withering criticism from experts.



If the repair mission costs as much as building a new telescope, then we
should build a new telescope using updated technology. This time with a
mirror that's ground correctly.
Improved ground based telescope resolution has taken away a lot of
Hubble's necessity.

Pat

Well... If one want a regular serviceable telescop, one might as well
stuck a telescope at the I.S.S., just like Skylab.

It should be noted that a 600 km orbit is not the best orbit for a
space telescope. That's why some space telescopes are put in the
Sun-Earth L1 (for observing the sun) and L2 (for observing outerspace).



As for Hubble.

The problem lies in Hubble's re-entry back to Earth.

There are several ways on what could happen:

- Uncontrolled re-entry back to Earth.

A good way to ruin N.A.S.A.'s reputation.

And I'm affraid that this is what might happen, since that in recent
times, there are people that out there to ruin N.A.S.A.'s reputation
and also the reputation of the government of the U.S.A., either doing
it from the outside or from the inside.

- Controlled re-entry back to Earth.

Might not be so dark as the first option, but would be good enough to
ruin a reputation.

Just like what 'they' did to Mir.

- Bring it back to Earth and then put it in a museum.

A nice retirement for Hubble. I prefer it this way.

- Service the Hubble.

A waste a money, since it's much better to build a newer and much
improved space telescope.

wrote in message
oups.com...
Well... If one want a regular serviceable telescop, one might as well
stuck a telescope at the I.S.S., just like Skylab.

Doesn't work, too many vibrations due to crew movement. What might work,
however, is to have it attached via tether using the gravitational gradient
to keep it in place. Maybe.

On Tue, 15 Feb 2005 12:56:33 -0500, Ami Silberman wrote:

Doesn't work, too many vibrations due to crew movement. What might work,
however, is to have it attached via tether using the gravitational gradient
to keep it in place. Maybe.

Assuming a Hubble-class instrument: Nope.

First: The vibrations will travel down the cable
from ISS to the telescope. There's nothing about
tidal effects to damp down transient vibrations
from crew movement... at least in a time frame
that would do the 'scope any good.

Second: ISS is a dirty place to hang around
outside for for long, if you're high-quality
optics, and is definitely in a low-rent
neiborhood orbit-wise

--
Chuck Stewart
"Anime-style catgirls: Threat? Menace? Or just studying algebra?"

"Pat Flannery" wrote in message
...
could some sort of an
ISS/Earth Lagrange point exist?

The third body has to be of insignificant mass as compared to the other two-
the freeflyer represented a substantial mass compared to Mir, when Mir is
compared to Earth.

In article ,
Pat Flannery wrote:
The Russians had that failed remote operator freeflyer go into orbit
around Mir due to Mir's microgravity field... could some sort of an
ISS/Earth Lagrange point exist?

Not a useful one. But if the free-flyer has a little bit of maneuvering
capability for small corrections, it's easy enough to set up formation
flying, either both spacecraft in the same orbit (e.g. free-flyer 10km
ahead of ISS) or synchronized orbits (free-flyer "orbiting" ISS, in the
same plane as ISS's orbit, in an ellipse with horizontal dimension double
the vertical dimension).
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Scott Hedrick wrote:

The third body has to be of insignificant mass as compared to the other two-
the freeflyer represented a substantial mass compared to Mir, when Mir is
compared to Earth.



I still think the slightly out of phase orbits at the same inclination
that intersect at long intervals (say a year or so) is a good idea.
When the station and telescope are close together, a maintenance mission
with low delta V can be accomplished, while still keeping the station
and shuttle (or whatever replaces it) from interfering with the
telescope most of the time.

Pat

Pat Flannery wrote:
I still think the slightly out of phase orbits at the same inclination
that intersect at long intervals (say a year or so) is a good idea.
When the station and telescope are close together, a maintenance mission
with low delta V can be accomplished, while still keeping the station
and shuttle (or whatever replaces it) from interfering with the
telescope most of the time.

Wouldn't work. ISS, at least, and telescopes are fundamentally
incompatable. ISS has to have a low orbit due to the limitations
of Soyuz / Progress, and launch systems in general. Frequent
reboosts aren't much of a problem because supply and ferry ships
dock frequently. However, a telescope in an orbit with such a
low lifetime would also need frequent reboosts, which would
require a lot of onboard propellant and frequent usage of some
sort of thruster. Things which are not terribly compatable
with high precision optical astronomy equipment, though it's
not completely out of the question.

JRS: In article , dated Tue, 15 Feb
2005 13:56:48, seen in news:sci.space.shuttle, Pat Flannery
posted :

The Russians had that failed remote operator freeflyer go into orbit
around Mir due to Mir's microgravity field... could some sort of an
ISS/Earth Lagrange point exist?


In principle, yes.

But for it to be stable I suspect that one would need to remove the
Moon, very probably the Sun, probably much of the rest of the Solar
System, and perhaps other nearby parts of the Universe,

Or to ballast ISS up to the Teraton range or higher.

Both of those seem rather drastic procedures, though there would be some
economy in partially combining them.


Actually, I rather doubt whether anything can orbit around a likely LEO
man-made object; consider the Roche Limit. The flyer may have remained
near Mir due to having a similar orbit around the Earth - but I don't
recall the facts, if any.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

In article ,
Christopher M. Jones wrote:
...However, a telescope in an orbit with such a
low lifetime would also need frequent reboosts, which would
require a lot of onboard propellant and frequent usage of some
sort of thruster. Things which are not terribly compatable
with high precision optical astronomy equipment...

No, it just means you have to choose propulsion systems carefully,
avoiding orthodox hypergolics and other systems which spew out condensible
garbage that can easily contaminate optics. Xenon Hall-effect thrusters
or an ammonia arcjet would be good choices.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |