save the Hubble

Lynndel Humphreys wrote:


Would it not be just as easy to capture the Hubble and return it safely.
Let's face it if 007 foes can do something similar surely NASA can.


The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.

It will take an act of Congress to save what is
inarguably one of the finest instruments of science
ever invented from premature death due to bone-headed
stupidness on the part of NASA.

JazzMan
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JazzMan writes:

It will take an act of Congress to save what is
inarguably one of the finest instruments of science
ever invented from premature death due to bone-headed
stupidness on the part of NASA.

Congress has no political incentive to do so.

Technogeeks do not have a strong lobbying presence, and
do not represent a significant "swing vote" in elections.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

JazzMan writes:

It will take an act of Congress to save what is
inarguably one of the finest instruments of science
ever invented from premature death due to bone-headed
stupidness on the part of NASA.

Congress has no political incentive to do so.

Technogeeks, astronomers, and space scientists do not have a strong
lobbying presence in Washington D.C., and do not represent a significant
"swing vote" in federal elections.

Also, from a political perspective, it "creates" more patronage jobs
for a district containing an aerospace contractor if the Hubble
is allowed to burn up, so that it must be replaced by a bigger,
more expensive telescope. By contrast, _saving_ the Hubble does not
"create" _any_ political patronage jobs.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

In article ,
JazzMan wrote:
The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.

It won't tumble. It has a low-precision gyro pack intended specifically
to stabilize it for retrieval even if the main gyros are out.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.


Haven't NASA engineers heard of solid state gyros? Such as RLG-s (ring
laser gyro) or FOG (fiber optic gyro). See:
http://www.kvh.com/FiberOpt/

These are commercially available and cheap.

Zoltan

In article ,
Zoltan Szakaly wrote:
The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear out...

Haven't NASA engineers heard of solid state gyros? Such as RLG-s (ring
laser gyro) or FOG (fiber optic gyro).

Remember that Hubble was designed in the 1970s, and that the specs for
those gyros are rather severe. You might be able to meet them with RLGs
now, but the cost of designing and qualifying a new-technology gyro set
would be significant.

Nobody would design a *new* system with those gyros, but for a telescope
that wants regular visits anyway for instrument upgrades, it's hard to
justify the one-time engineering cost of a retrofit of newer technology.

Fiber gyros are nowhere near meeting Hubble's specs, although they are
very useful for less demanding applications.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Zoltan Szakaly) wrote in
om:

The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.

Haven't NASA engineers heard of solid state gyros? Such as RLG-s (ring
laser gyro) or FOG (fiber optic gyro).

Of course they have.

See:
http://www.kvh.com/FiberOpt/

These are commercially available and cheap.

Very good. Now compare the precision of even the best of these gyros with
the ones used on HST.


--
JRF

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check "Organization" (I am not assimilated) and
think one step ahead of IBM.

(Zoltan Szakaly) writes:

The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.

Haven't NASA engineers heard of solid state gyros? Such as RLG-s
(ring laser gyro) or FOG (fiber optic gyro). See:
http://www.kvh.com/FiberOpt/

These are commercially available and cheap.

In this particular context, "gyro" actually means "reaction wheel."

Fiber optic gyros are not practical substitutes for reaction wheels.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

In article ,
(Zoltan Szakaly) wrote:

The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working, and it needs two
to maintain itself and be usable. The gyroscopes wear
out, and the next is expected to fail with a couple
of years. Once it starts tumbling then there's no
way to do anything with it remotely.


Haven't NASA engineers heard of solid state gyros? Such as RLG-s (ring
laser gyro) or FOG (fiber optic gyro). See:
http://www.kvh.com/FiberOpt/

These are commercially available and cheap.

They aren't much use, either, for changing the orientation of the
Hubble, since they don't have enough momentum to do the job, being just
a little mass-deficient.

In article ,
Gordon D. Pusch wrote:
The problem is that Hubble only has, what, 3 of it's
original 6 gyroscopes still working...

In this particular context, "gyro" actually means "reaction wheel."

No, actually, "gyro" means "gyro" here. It's the high-precision sensors
that are giving trouble. The gyrodynes (I think) that actually produce
torque to rotate Hubble have been reliable.

(Reaction wheels, momentum wheels, and gyrodynes aka control moment gyros,
are three different things, despite some similarities, although the
terminology is not entirely standardized. Reaction wheels are wheels
whose initial speed is nominally roughly zero, and whose speed is varied
to exert torque. Momentum wheels nominally run at constant speed and
their purpose is to provide gyroscopic stiffness around the other two
axes, although often some degree of reaction-wheel functionality is added,
with some variation in speed permitted for exerting small torques around
the wheel axis. Gyrodynes run at constant speed, and unlike the other
two, are mounted in gimbals; torques are produced by rotating the gimbals,
pushing against the wheels' gyroscopic stiffness, roughly speaking. If
memory serves, Hubble uses gyrodynes, although they are sometimes called
reaction wheels.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |