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The Recon Report--3F

Interview with Frank Madden (Part-I)
Frank Madden had a background similar to both Haig and Levison--in the
Air Force during World War II and later involved with the reconnaissance
balloon programs.  Madden was brought in to work on CORONA after the
first two camera designs and been developed (when this was I'm not
sure--I don't know if anything had been flown at this time).

The initial "C" camera used a reciprocating, or oscillating, setup.  The
film would slide into place at the top of the camera, and then the entire
camera apparatus--including the heavy lenses and the scan arm, which had
the aperture slit which scanned the film--would rotate 70 degrees and
expose the film.  When it reached the end of its scan it would stop and
then rotate back (I believe that while it was sliding back, new film was
sliding into place, but I don't know this for certain yet).  Then it
would rotate again.

Naturally, rotating this entire apparatus and then stopping it at the end
of its travel only to rotate it back again and stop it again created
vibration.  The momentum of the camera was counterbalanced by a momentum
wheel swinging in the other direction.  But the stops at the end of each
movement were a problem.  They would impart a vibration/movement to the
spacecraft which then had to be dampened out by the spacecraft
station-keeping system.
As far as I can tell, the "C'" ("C Prime") camera mostly involved
improvements to the film movement through the camera--slowing it down so
that it didn't break (at this time they were still using the
acetate-based film).  But the vibration was still there.
Madden was brought in to dramatically reduce the vibration.  He came up
with a unique solution (in the interview he said that he worked as a team
and didn't want to take credit for the idea, but it was apparently his):
they would separate the heavy elements of the camera--the lenses--from
the relatively light scan arm.  The lenses would be contained in a
"rotating lens cell" whereas the scan arm would continue to oscillate
back and forth.  The two would be locked into place as the lens cell came
around.
This was coordinated in a relatively simple fashion--the lens cell had a
little inverted "V" stiking up at the top.  This connected with a grooved
"V" recess in the scan arm.  According to Madden, getting the parts to
fit just perfectly took a lot of work.
In addition, Madden eliminated the gears in the camera mechanism and
replaced it with a rubber timing belt.  This ran much more smoothly and
further reduced vibration.  The result was that the C''' camera had
significantly improved resolution due to the lower vibration.

Madden then took the next step and incorporated two C''' cameras together
to create the "MURAL" camera which provided stereoscopic coverage.  He
says that this was an obvious choice--stereoscopic coverage being very
desirable--and was really only a result of improved rocket lift capability.

But the MURAL camera started to show a problem very early on.  The extra
rollers needed to handle the more complicated film path (it had to move
through two cameras instead of only one) created static electricity which
then discharged and exposed the film.  This, for the most part, caused
the film to fog up under a phenomena known as "corona."
Madden said that corona is actually something that is common to almost
all cameras at one time or another.  It was made worse by the MURAL
camera not only because of the increased complexity (and surface area of
the rollers it had to run over), but also apparently by the outgassing of
water from the film, which made it more likely to create static charge in
the first place.

Now how this problem was solved is an interesting story in itself.  Bud
Wheelon, who ran the CIA end of the National Reconnaissance Office in the
early sixties and was the person who initiated the follow-on program to
the CORONA (a program which still remains classified) stated that he had
a group led by Sydney Drell of Stanford University look into the problem
and solve it.

Tom Haig, who wasn't involved with the CORONA program was still aware of
it from the classified briefings that General Bernard Schriever was
holding.  Haig, who didn't know how they solved the problem, thought that
the solution should have been easy:  coat the back of the film with a
conductive material and ground the rollers.

Madden said that the solution was not the result of the Drell group.
They might have been looking into the issue, but the solution, according
to him, was solely the result of the materials lab at Itek and the
contractors who manufactured the rollers.  What they did was to
manufacture the rollers out of a semi-conductive rubber.  This rubber was
coated onto a steel roller and was shaved down precisely to the right
size.  As it was, the problem was never completely eradicated--the corona
problem still showed up at times, usually when the camera was restarted
after a relatively long stop.  The reason was that the film that was
stretched out in the camera outgassed and became more susceptible to the
static buiildup.  So they planned for having the first few frames fogged
up and started photographing earlier when they knew it would happen.

Madden also emphasized an interesting point:  the subcontractors who
manufactured the rollers did not know what they were to be used for.
They therefore could not be told what the problem was that was forcing a
redesign.  Therefore, secrecy effectively limited the lines of
communications.  The probelm was solved.  But it's possible that it could
have been solved easier, faster, or cheaper if the subcontractors
themselves were allowed to bring their expertise to the issue.

____________________________________________________

D-Day


--
Q