Galileo antennae article

From US Space News: http://www.usspacenews.com/

"What Really Happened To Galileo’s High Gain Antenna
A Special “There I Was” Guest Article
August 24, 2006

Back in 1984 the Galileo Orbiter was undergoing test, integration and
final construction
of structures, systems and subsystems in support of the original 1986
launch to Jupiter.
One of the major structures to be tested was the High Gain Antenna
(HGA). Galileo’s
HGA was based on the design used by TDRSS. To support the mission JPL
had two
identical antennas constructed (a flight and flight back-up). The HGA’s
had a
requirement to withstand 3X the amount of vibration a shuttle launch and
Shuttle Centaur
could impart. So one day the backup HGA was taken to the Vibration Test
Facility (VTF).
It was mounted to the test fixture and set in the stand. Then vibration
per requirement
was induced for the total amount of time identified by the systems
engineers (n min. for
launch and n min. for Shuttle Centaur). That antenna came back to the
Spacecraft
Assembly Facility (SAF) badly damaged. The gold wire mesh was torn, the
antenna ribs
sprung and thermal insulation torn lose. The HGA would not fully close.
It hung open by
several rids at the top. Ok, what to do? They lowered the requirement to
1X shuttle
launch and Shuttle Centaur induced vibration and took the flight HGA up
to the VTF.

Then they brought the flight HGA back to the SAF.

It was destroyed. Several ribs had broken at the base, only hanging on
to the antenna
be the gold mesh material. An Instrument was broken lose from the top of
the antenna
and hung suspend by its power/data cable. The gold mesh and thermal
insulation was
torn in several places.
They eventually got the ribs to close. When they did several ribs hung
by retention pins
from the top and the ribs torn lose hung free at the base.
That HGA was never going to fly.

I stood in the SFA and asked “what are we going to do?” and “I guess the
May 86
launch is out”. Well nope. I was told we would refurbish the back-up
antenna and launch
with risk.

Years later (the original May 86 launch was delayed due to the loss of
Challenger and
the cancellation of Shuttle Centaur) I watch the 1989 Atlantis launch of
Galileo and
remembered what was said in the SAF that day back in 1984. I knew the
HGA would not
be opened unit after the last Earth fly-by. So it would be a good bit of
time until anyone
knew if the HGA was OK. When the command was finally given to deploy the
HGA, it
failed.

A NIMS image (Galileo self-image) taken by the S/C showed the HGA had
not deployed.
Because of the necessary addition of the sunshield on the Spun Bus when
the trajectory
and Earth departure stage were changed, a detailed image of the HGA base
was not
possible. Originally Galileo was designed for a direct flight to Jupiter
on a Shuttle
Centaur. After the loss of Challenger, Galileo was switch to the IUS and
a trajectory that
took the spacecraft past Venus and Earth before leaving the inner solar
system for
Jupiter. One interesting point the change in trajectory required the
additional of a cruse
relay antenna. That capability allowed Galileo to send the science it
did back to Earth.

To this day I believe the HGA failed in space just like it did in the
VTF so many years
ago. But we will never know."


Pat

On Wed, 30 Aug 2006 02:58:22 -0500, Pat Flannery
wrote:

A NIMS image (Galileo self-image) taken by the S/C showed the HGA had
not deployed.

....This image anywhere online?

OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

In article ,
Pat Flannery wrote:
...in support of the original 1986 launch to Jupiter.

Well, the *original* original Galileo launch date was 1982, although the
project knew fairly early that this was likely to slip.

"...So it would be a good bit of time until anyone
knew if the HGA was OK..."

Remember that Galileo could be, and was, extensively *photographed* close
up after launch, before and during separation from the shuttle. The sort
of gross damage that he's referring to should have been detectable then, I
would think. But in fact, the antenna looks flawless then.

A NIMS image (Galileo self-image) taken by the S/C showed the HGA had
not deployed.

Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work -- I heard a description
of this last week, by some of the people who were there, including the
guy who built the HGA-deployment command sequence -- and I've never heard
of any self-imaging being possible, let alone being done.

Was there a *name* on this "Guest Article"?
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:


Was there a *name* on this "Guest Article"?


Nope, which had me wondering also.
Here's the contact page: http://www.usspacenews.com/contactus.html

Pat

(Henry Spencer) writes:

In article ,
Pat Flannery wrote:

A NIMS image (Galileo self-image) taken by the S/C showed the HGA had
not deployed.

Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work -- I heard a description
of this last week, by some of the people who were there, including the
guy who built the HGA-deployment command sequence -- and I've never heard
of any self-imaging being possible, let alone being done.

Working strictly from memory, I seem to recall they tried turning the spacecraft
to various odd attitude, where various parts of the antenna would/would not
block the sun sensor. By doing this they were able to build a very crude
picture of the outline of the antenna. This was more of a confirmation step
(I think the unbalanced deployment created a wobble that matched their
idea of what had happened).

Also, the original story seems self-contradictory. If they *could* take a
good picture, and the damage was as obvious as the author suggested, then
there would be no myustery about what happened. You'd need a cover-up
and not just bad judgement in this case, since no one here (a rather
interested community) has seen these pictures if they exist.

Lou Scheffer

On Wed, 30 Aug 2006 14:13:10 GMT, (Henry Spencer)
wrote:

Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work -- I heard a description
of this last week, by some of the people who were there, including the
guy who built the HGA-deployment command sequence -- and I've never heard
of any self-imaging being possible, let alone being done.

....Which is why I asked if this "photo" was online somewhere. The
whole piece had the same tone as about 2/3 of the CT Nutter theories,
and about half of the Lone Nutter ones. Besides, had NASA/JPL been
able to take shots of the HGA all along, they'd have shown them the
day they got them, because even if they showed a failure mode, they'd
been part of the "golly gee whiz gosh wow!" type of photo that even
Joe Punchclock and Ethyl Soapsjunkie want to see.

OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

OM wrote:
On Wed, 30 Aug 2006 14:13:10 GMT, (Henry Spencer)
wrote:

Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work -- I heard a description
of this last week, by some of the people who were there, including the
guy who built the HGA-deployment command sequence -- and I've never heard
of any self-imaging being possible, let alone being done.

...Which is why I asked if this "photo" was online somewhere. The
whole piece had the same tone as about 2/3 of the CT Nutter theories,
and about half of the Lone Nutter ones. Besides, had NASA/JPL been
able to take shots of the HGA all along, they'd have shown them the
day they got them, because even if they showed a failure mode, they'd
been part of the "golly gee whiz gosh wow!" type of photo that even
Joe Punchclock and Ethyl Soapsjunkie want to see.


CT and lone nutter? What does the JFK assassination have to do with an
article about the Galileo HGA?

Eric

OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

In article ,
OM wrote:
Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work...

...Which is why I asked if this "photo" was online somewhere. The
whole piece had the same tone as about 2/3 of the CT Nutter theories...

It wasn't *entirely* ridiculous -- they did manage to damage the original
flight antenna during testing, if dim memory serves -- but it sounded
rather more drastic than the versions I'd heard.

...Besides, had NASA/JPL been
able to take shots of the HGA all along, they'd have shown them the
day they got them, because even if they showed a failure mode, they'd
been part of the "golly gee whiz gosh wow!" type of photo that even
Joe Punchclock and Ethyl Soapsjunkie want to see.

Very true.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

"Henry Spencer" wrote in message
...
In article ,
Pat Flannery wrote:
...in support of the original 1986 launch to Jupiter.

Well, the *original* original Galileo launch date was 1982, although the
project knew fairly early that this was likely to slip.

"...So it would be a good bit of time until anyone
knew if the HGA was OK..."

Remember that Galileo could be, and was, extensively *photographed* close
up after launch, before and during separation from the shuttle. The sort
of gross damage that he's referring to should have been detectable then, I
would think. But in fact, the antenna looks flawless then.

I know an ex-Harris employee who heard stories about the HGA (it was handed
off to JPL before he was hired). The very fact that *anyone* outside of
Harris would deploy and then re-stow one of *their* antennas made the Harris
engineers feel that the customer had automatically "voided the warranty".
These things are very finiky things to stow properly so they will later
deploy properly. And that was on top of the shaker table horror stories,
shipping the thing cross country a few times, and etc.

From what my friend says, the engineers at Harris weren't at all surprised
when the HGA didn't deploy. He also said that many there said that JPL
stood for Just Plain Lucky since they didn't feel that JPL really knew what
they were dealing with.

Was there a *name* on this "Guest Article"?


Of course not, this was "US Space News".

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

"Henry Spencer" wrote in message
...
In article ,
OM wrote:
Here the old bogometer starts beeping. :-) In fact, the HGA's condition
had to be deduced by painstaking detective work...

...Which is why I asked if this "photo" was online somewhere. The
whole piece had the same tone as about 2/3 of the CT Nutter theories...

It wasn't *entirely* ridiculous -- they did manage to damage the original
flight antenna during testing, if dim memory serves -- but it sounded
rather more drastic than the versions I'd heard.

From who? JPL, NASA, or Harris employees? The third had accounts I've
heard from ex-Harris employees (one who used to work me and one other
friend) makes the damage from the vibration testing, which Harris engineers
were against, sound like they stuck it on the shaker table and went to lunch
only to come back to a very damaged antenna.

After some digging, I found NASA Watch has a story that sounds *very* close
to what ex-Harris employees have told me about JPL severely mistreating the
HGA's (there were two that Harris built for Galileo):

Editor' s note: NASA Watch has learned from
that this is not the first time this sort of damage has occurred
at JPL. In 1984, the back-up high gain antenna for Galileo was
on a shake table at JPL and was shaken at 3 times expected Shuttle
launch loads. The antenna was damaged as a result. When the flight
antenna was shaken at just normal Shuttle launch loads it was damaged
and declared scrap. Instead of incurring the cost and schedule hits
that would have been required to redesign the antenna, the project
manager (John Casani) decided to launch "with risk" instead and
installed the back-up antenna on Galileo. Galileo's main antenna
subsequently failed to unfurl properly on its way to Jupiter. The
original flight antenna is now part of a Galileo display at JPL.

On top of that, the ex-Harris employees told me that JPL did the deploy and
re-stow tests on at least one of the HGA's, and that they had never intended
anyone outside of Harris to do this delicate procedure themselves. Their
opinion was that JPL had "voided the warranty" on the HGA by deploying and
re-stowing it themselves. That was on top of the shaker table incidents and
the shipping Galileo across the country several times without checking the
HGA properly after the fact.

My guess is that anything released by JPL or NASA about the HGA wouldn't
directly point blame back at themselves.

At the bottom of the following page there are two drawings of what they
thought it looked like partially deployed:

http://www2.jpl.nasa.gov/galileo/mes...dmess/HGA.html

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)