HST: why considered "dead" without Shuttle visits?

Hello!

I've read in few articles dealing with the priorities change
in NASA that HST will be let to naturally die as a result of Shuttle
service missions cancellation. Why is it considered such an absolute
requirement to have a manned service mission? If memory serves, a Shuttle
mission cost is around 450-475 M$, how much could it cost to designin
a robotic mission? Take the design of the Shuttle's RMS or maybe even
the complete hardware if spares exist, attach to it another similar "arm"
with different "tool-holding adaptors", also attach few cameras, telemetry
and have some fuel reserve to boost the HST to a higher orbit. Launch
the "thing", attach it the same way Shuttles RMS would attach and boost it
to a higher orbit or perform a repair via telemetry, with the operator
wearing a VR gougles.

How difficult/expensive such a design/mission would be?

************************************************** ****************************
* Arie Kazachin, Israel, e-mail: *
************************************************** ****************************
NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap.

In article ,
Arie Kazachin wrote:
...Why is it considered such an absolute
requirement to have a manned service mission?

Because current operational space robotics hardware cannot even come close
to equaling the manual dexterity of a spacesuited astronaut. Hubble is
complicated, and it wasn't designed for robotic servicing.

Adequately-dextrous robotics are probably possible, but they are an
advanced research topic, not something you can confidently ship up with a
high probability of things working right the first time.

...Take the design of the Shuttle's RMS or maybe even
the complete hardware if spares exist, attach to it another similar "arm"
with different "tool-holding adaptors"...

Uh, the "hand" at the end of the shuttle arm is the size of a garbage can,
and all it can do is grab objects (which in practice have to be of equal
or greater size) which have standard grapple fixtures. It's not something
you can use to disconnect walnut-sized electrical connectors.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Arie Kazachin) wrote in message ...
Hello!

I've read in few articles dealing with the priorities change
in NASA that HST will be let to naturally die as a result of Shuttle
service missions cancellation. Why is it considered such an absolute
requirement to have a manned service mission? If memory serves, a Shuttle
mission cost is around 450-475 M$, how much could it cost to designin
a robotic mission?

As I understand Hubble, it is not meant for maintenance in space, or
at least not optimized for maintenance in space. A great deal of
manual dexterity is required to handle the small screws and tight
spaces inside the Hubble.

I don't know that teleoperated systems deliver adequate performance
yet.

Mike Miller, Materials Engineer

In article ,
Mike Miller wrote:
As I understand Hubble, it is not meant for maintenance in space, or
at least not optimized for maintenance in space. A great deal of
manual dexterity is required to handle the small screws and tight
spaces inside the Hubble.

No, Hubble *was* meant for maintenance in space, although as usual
(repeating a mistake made on Skylab), they cheaped out and decided that
some portions of it wouldn't break and hence wouldn't need to be set up
for maintenance... and of course, some of those *have* needed maintenance.
But it was always planned that things like instrument changes would be
done by spacewalking astronauts, and that was very definitely designed in.

I don't know that teleoperated systems deliver adequate performance yet.

Definitely not. Some of the more ambitious designs have a goal of
equaling the capabilities of a spacesuited astronaut, but they're not
there yet.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

In message - (Henry Spencer)
writes:


[snip]


No, Hubble *was* meant for maintenance in space, although as usual
(repeating a mistake made on Skylab), they cheaped out and decided that
some portions of it wouldn't break and hence wouldn't need to be set up
for maintenance... and of course, some of those *have* needed maintenance.

That reminds me one of the great bits from "The Hitchhiker's Guide to
the Galaxy" trilogy, book 5:

"The major difference between a thing that might go wrong and a thing
that cannot possibly go wrong is that when a thing that cannot possibly
go wrong goes wrong it usually turns out to be impossible to get at
or repair".


:-) :-) :-)



But it was always planned that things like instrument changes would be
done by spacewalking astronauts, and that was very definitely designed in.

I don't know that teleoperated systems deliver adequate performance yet.

Definitely not. Some of the more ambitious designs have a goal of
equaling the capabilities of a spacesuited astronaut, but they're not
there yet.
--

OK, so if currently there is nothing close to being ready for "one launch
solution", maybe a two step approach might be used: first laucn something
that need only to grab the HST (at the same point the Shuttle RMS grabbed it)
and which has fuel reserve to boost the HST to a higher orbit where it can
stay for few good years. Later on, when robotic "hands" will become capable
enough, launch a repair mission (robotic).

Another possibility (assuming HST orbit had been boosted): since NASA intends
to develop a CEV (Crew Exploration Vehicle) capable of carrying a crew far
beyound LEO, a service mission to HST is a good candidate for a test flight
for such a vehicle.


************************************************** ****************************
* Arie Kazachin, Israel, e-mail: *
************************************************** ****************************
NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap.

(Henry Spencer) wrote in message
Definitely not. Some of the more ambitious designs have a goal of
equaling the capabilities of a spacesuited astronaut, but they're not
there yet.

Underwater construction rovers on oil rigs and pipelines etc.. have
largely replaced deep sea divers for most new construction work. Its
not by very dexterous robots but by deliberately avoiding structures
that need very dexterous robots, ie special nuts and bolts with large
clearances and highly specialised manipulators.

One big difference is that there is a lot more experience with
underwater construction and maintenance than equivalent space
activities. Also the rovers don't have the weight constraints (they
are very heavy) and still cost a lot (about $5M). Older rigs still
need to use divers but usually smaller crews with rover aids.

The point i wish to make is that it would be better to meet half way
between highly dexterous robots and structures specifically designed
to be constructed and maintained by robots. IMHO of course.

Greg

(Greg) wrote in
:

(Henry Spencer) wrote in message
Definitely not. Some of the more ambitious designs have a goal of
equaling the capabilities of a spacesuited astronaut, but they're not
there yet.

Underwater construction rovers on oil rigs and pipelines etc.. have
largely replaced deep sea divers for most new construction work. Its
not by very dexterous robots but by deliberately avoiding structures
that need very dexterous robots, ie special nuts and bolts with large
clearances and highly specialised manipulators.

Which HST most definitely does not have.

One big difference is that there is a lot more experience with
underwater construction and maintenance than equivalent space
activities. Also the rovers don't have the weight constraints (they
are very heavy) and still cost a lot (about $5M). Older rigs still
need to use divers but usually smaller crews with rover aids.

The point i wish to make is that it would be better to meet half way
between highly dexterous robots and structures specifically designed
to be constructed and maintained by robots. IMHO of course.

A valid point for future spacecraft, but alas it will do HST no good.


--
JRF

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

(Henry Spencer) wrote in message ...

No, Hubble *was* meant for maintenance in space, although as usual
(repeating a mistake made on Skylab), they cheaped out and decided that
some portions of it wouldn't break and hence wouldn't need to be set up
for maintenance... and of course, some of those *have* needed maintenance.

Being an optimist, I was half correct.

Heh. I learn so much by being wrong on these newsgroups.

Mike Miller, MatE

In article ,
Greg wrote:
Definitely not. Some of the more ambitious designs have a goal of
equaling the capabilities of a spacesuited astronaut, but they're not
there yet.

Underwater construction rovers on oil rigs and pipelines etc.. have
largely replaced deep sea divers for most new construction work. Its
not by very dexterous robots but by deliberately avoiding structures
that need very dexterous robots, ie special nuts and bolts with large
clearances and highly specialised manipulators.

The robotics people have been suggesting for a number of years now that
the spacecraft people do likewise. So far, the spacecraft guys haven't
bought into it -- they have assessed the chances that their stuff will
ever be serviced by a robot as so slight that it's not worth the cost in
mass and design problems. Given their historical preoccupation with
squeezing absolute maximum functionality out of absolute minimum mass,
selling this idea to them will be very difficult. The more dextrous the
robots are -- and thus, the fewer the compromises needed to permit robotic
servicing -- the easier it will be.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Henry Spencer) wrote:
In article ,
Mike Miller wrote:

As I understand Hubble, it is not meant for maintenance in space, or
at least not optimized for maintenance in space. A great deal of
manual dexterity is required to handle the small screws and tight
spaces inside the Hubble.

No, Hubble *was* meant for maintenance in space, although as usual
(repeating a mistake made on Skylab), they cheaped out and decided that
some portions of it wouldn't break and hence wouldn't need to be set up
for maintenance...

It's not cheaping out, it's designing for the real world. It's very
difficult to provide every component with clear access, and large
(spacesuit operable) connectors and fasteners etc... If you had
infinite volume available the problem becomes much simpler, but the
designers/builders of Hubble didn't have infinite volume.

There are many things to cast aspersions at NASA about, but doing so
over simple engineering decisions and cost v. benefit analyses that
don't meet some absurd standard is not helpful to anyone.

and of course, some of those *have* needed maintenance.

Again, welcome to the real world, vice the ivory tower. In the real
world constants aren't and variable won't.

D.
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