Memory - Mirror for Kuiper Airborn Observatory
[ Jolitz Heritage William Jolitz - Early Years Memory - Mirror for Kuiper Airborn Observatory ]
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Working for Gordon Augason

Gordon Auguson, NASA Ames Research Center, SSA branch

"Back in the early 70's NASA had a student internship program, where in the early afternoon a bus would collect up students from Lynbrook, Monte Vista, Homestead, and Sunnyvale high schools. We'd arrive at Ames around 2pm, and leave around 6pm.

One of my assignments was working for Gordon Augason in the Space Science Astrophysics (SSA) branch. He was doing far infrared astronomy with airborne telescopes.

IR Oscillating Secondary Mirrors

Gordon made 2-inch metal mirrors on a lathe which were used as oscillating secondaries for Frank Low's 12-inch Cass (see "National Air and Space Museum Space Artifacts: Lear Jet Infrared Telescope, picture to right), mounted in place of a window in a souped up NASA Lear Jet, that in an unpressurized cabin would make it up to +50K feet. The source signal from the germanium in liquid helium cooled bolometer ("gold" box in picture) was very weak, and the oscillation of the secondary allowed the source to be seen as AC, the noise DC that would be rejected before massive amplification.

So KAO was coming online and who did he have to work on it? Well, he had me and Eric Lee - two freebie high school students who'd made multiple telescope mirrors. He handed us off to Don Moody's optics shop, and we ground and polished a 9-inch aluminum secondary. It was like kids in a candy store, because we had access to professional polishing equipment and computerized optical testing equipment. No more hand grinding. We had to use an immense amount of force required to move the metal, so we used a grinding machine and very viscous syrupy lap that drooped when you used it. We spent more time fixing up the lap than polishing it, because it kept curling off the machine. We had 20 lb weights pressing down on the machine. It squirted off everywhere.


Frank Low's Airborne IR Telescope
Making the Secondary Mirror

Sometimes the strokes used didn't work as expected, so Eric Lee and myself would go backwards from our target. The NC equipment only allowed a thousandth of an inch accuracy +/-, and we wanted to be at least quarter wave and ten micron. So we had to use the polishing equipment and treat it as if it was an optical surface. The cracking problem was the big problem we faced, but we weren't allowed to "kanegen coat" (nickle). We found that aluminum work hardens fast, and gets cracks easy.

Figure and Measure the Mirror

HP9830 Desk Programmable Calculator

Eric came up with thick, syrupy laps for polishing that moved metal quicker so less time for work hardening. I had the mirror measured by a digital sagittal probe and compared it in software with a HP9830A programmable calculator against the desired hyperbola (past metal mirrors were polished and never figured), charting the process to see if our technique with the polishing machine was aspherizing correctly.

Software "Null" Test for Hyperbolic Secondary

Remote Job Entry Terminal

The we'd run over to Bldg 245 (the penthouse) to hook up via an RJE link to the CDC 7600 located at LBL, enter the paper tape of the distances manually, and see how it conformed to the desired curve. Sometimes we'd overshoot, sometimes undershoot, and sometimes get it right - then we'd plan the next day's work. Sometimes we'd have to give up a blank completely because it was too cracked. We worked on this for months.

Orbital Diagram for Astrogram

Meredith Moore

When Meredith Moore, NASA Ames newsletter staff (who also ran the student program), needed an orbital trace for a comet, I took the same program I wrote to match the mirror and matched it with the orbital parameters to create a diagram for the comet's path through the solar system against time. An early example of code reuse. :-)

KAO and the C-141

I don't remember what any of the mirrors we worked on were used for. But it gave us a great amount of involvement in the telescope, and we spent quite a bit of time inside the C-141 (when it banks, you really know it because as a high-wing plane, it swings to the side pendulously). Since the SOFIA is a mid-wing, no such problems.

There was a door you entered in adjacent to the telescope nasmyth focus that gave you access to the science bay, with racks of equipment alternating with aircraft seats, with another door to the rear of the cargo area. I seem to recall a lot of HP 2640 CRT terminals and minicomputers.

Other Surprises with KAO and C-141

Also, the wings drooped down on the ground, flexed up in flight, and bent up even more in a turn - which freaked out some on board for the first time. They couldn't have a hanger big enough for the C-141, so the tail (high T tail)poked out into the rain, with a cutout in the hanger doors through which the plane extended.

I got the flying bug at this point, and left to work for Chuck Jackson over in flight systems navigation (FSN) branch. But that's another story... - William Jolitz"


Hubble prototype ballon born telescope

In preparation for the Hubble, a series of balloon borne scopes were built and launched.

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