Hubble defective, NASA delays repair mission.

Hubble defective, NASA delays repair mission:
http://edition.cnn.com/2008/TECH/spa....ap/index.html
Data transmisison is no longer working, work in progress to switch to the backup system.

"Jan Panteltje" wrote in message
...
Hubble defective, NASA delays repair mission:
http://edition.cnn.com/2008/TECH/spa....ap/index.html
Data transmisison is no longer working, work in progress to switch to the
backup system.

The local water authority operates a dual system; in the event of failure of
one
pump the other carries on whilst repairs are made. The changeover between
systems occurs weekly so that both systems become obsolete and wear out
together. Planned maintenance is carried out on both systems.
Now we learn that NASA has a backup system for Hubble that it hasn't fired
up since the 80s and it will take work to switch over?
"Work has begun to switch the telescope to the backup channel."
If people went without water for a week someone would lose their job.

"Androcles" wrote in message
...

"Jan Panteltje" wrote in message
...
Hubble defective, NASA delays repair mission:
http://edition.cnn.com/2008/TECH/spa....ap/index.html
Data transmisison is no longer working, work in progress to switch to the
backup system.

The local water authority operates a dual system; in the event of failure
of one
pump the other carries on whilst repairs are made. The changeover between
systems occurs weekly so that both systems become obsolete and wear out
together. Planned maintenance is carried out on both systems.
Now we learn that NASA has a backup system for Hubble that it hasn't fired
up since the 80s and it will take work to switch over?
"Work has begun to switch the telescope to the backup channel."
If people went without water for a week someone would lose their job.


There are good reasons why engineers operating Hubble and other spacecraft
do not engage in frequent routine switchovers between primary and backup
systems where they exist: the chance of something going wrong in such a
process (either electro-mechanical or software or human error) is
significantly greater than if it is just left alone as long as it works.
Given that Hubble has operated well beyond its original planned lifetime
indicates that they have done well, on the whole, even if individual
instruments have stopped working.

When they fix the local water pumping station, they don't have to plan for
years and spend $250,000,000 or more to do it, and have a fight in Congress
over the plans. Given the critical nature of the water supply, the
engineering and maintenance approach used there makes sense. And if
something goes really wrong an engineer can be there in minutes, usually.
These considerations do not apply to a satellite in orbit.

And nobody will die if it takes a week to fix Hubble. Caution makes good
sense.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

"Mike Dworetsky" wrote in message
...
"Androcles" wrote in message
...

"Jan Panteltje" wrote in message
...
Hubble defective, NASA delays repair mission:
http://edition.cnn.com/2008/TECH/spa....ap/index.html
Data transmisison is no longer working, work in progress to switch to
the backup system.

The local water authority operates a dual system; in the event of failure
of one
pump the other carries on whilst repairs are made. The changeover between
systems occurs weekly so that both systems become obsolete and wear out
together. Planned maintenance is carried out on both systems.
Now we learn that NASA has a backup system for Hubble that it hasn't
fired
up since the 80s and it will take work to switch over?
"Work has begun to switch the telescope to the backup channel."
If people went without water for a week someone would lose their job.


There are good reasons why engineers operating Hubble and other spacecraft
do not engage in frequent routine switchovers between primary and backup
systems where they exist: the chance of something going wrong in such a
process (either electro-mechanical or software or human error) is
significantly greater than if it is just left alone as long as it works.
Given that Hubble has operated well beyond its original planned lifetime
indicates that they have done well, on the whole, even if individual
instruments have stopped working.

When they fix the local water pumping station, they don't have to plan for
years and spend $250,000,000 or more to do it, and have a fight in
Congress over the plans. Given the critical nature of the water supply,
the engineering and maintenance approach used there makes sense. And if
something goes really wrong an engineer can be there in minutes, usually.
These considerations do not apply to a satellite in orbit.

And nobody will die if it takes a week to fix Hubble. Caution makes good
sense.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

18 years old. In an extremely hostile environment. And they have a redundant
system on board ready to cutover.

Sounds like pretty damn good engineering to me.

"Peter Webb" wrote in message
u...

"Mike Dworetsky" wrote in message
...
"Androcles" wrote in message
...

"Jan Panteltje" wrote in message
...
Hubble defective, NASA delays repair mission:
http://edition.cnn.com/2008/TECH/spa....ap/index.html
Data transmisison is no longer working, work in progress to switch to
the backup system.

The local water authority operates a dual system; in the event of
failure of one
pump the other carries on whilst repairs are made. The changeover
between
systems occurs weekly so that both systems become obsolete and wear out
together. Planned maintenance is carried out on both systems.
Now we learn that NASA has a backup system for Hubble that it hasn't
fired
up since the 80s and it will take work to switch over?
"Work has begun to switch the telescope to the backup channel."
If people went without water for a week someone would lose their job.


There are good reasons why engineers operating Hubble and other
spacecraft do not engage in frequent routine switchovers between primary
and backup systems where they exist: the chance of something going wrong
in such a process (either electro-mechanical or software or human error)
is significantly greater than if it is just left alone as long as it
works. Given that Hubble has operated well beyond its original planned
lifetime indicates that they have done well, on the whole, even if
individual instruments have stopped working.

When they fix the local water pumping station, they don't have to plan
for years and spend $250,000,000 or more to do it, and have a fight in
Congress over the plans. Given the critical nature of the water supply,
the engineering and maintenance approach used there makes sense. And if
something goes really wrong an engineer can be there in minutes, usually.
These considerations do not apply to a satellite in orbit.

And nobody will die if it takes a week to fix Hubble. Caution makes good
sense.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

18 years old. In an extremely hostile environment. And they have a
redundant system on board ready to cutover.

Sounds like pretty damn good engineering to me.



Exactly.

Except for the early optics blunder, of course. The detailed story on that
one is a textbook case of "what can go wrong". The eventual optical fix was
a brilliant bit of work.

Yes, that's a hard environment, particle radiation, UV, hard vacuum,
frequent temperature extremes.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)