SOFIA visit

by

15 October 2011

NASA had an open house for their airborne infrared observatory project, SOFIA. Jacky signed up for (free) tickets, the noon to two PM slot. It was not a blisteringly hot day, but it was hot enough when we arrived at the Ellis street gate, found a place to park and joined the line.

They have a 747 that was built in 1977 (!), originally delivered to Pan Am, then used by United and retired into the hands of NASA for conversion to an observatory.

There were displays and docents of various kinds to talk with as we waited. It was not a surprise to learn that a new pressure bulkhead had to be built inside the aircraft, forward of the telescope. It was a surprise to learn that they had to install heavy steel floors in the forward part of the plane to maintain its balance. You don’t think of having to add ballast to an airplane!

The telescope is a frame with a triple folded reflector. I was told that the primary mirror is a proprietary glass-like substance designed for ultra-low temperature coefficient of expansion, with an aluminized reflective surface. It is of course able to lock onto a given part of the sky, and is also isolated from aircraft vibration and turbulence effects.

When I visited CERN a couple years ago, they mentioned that they necessarily have to discard 99….9% of the data they collect, searching for the interesting needles of theoretical physics in haystacks of noise. At first, I thought the infrared observatory was probably doing the same, but when I thought about it, I decided they are probably able to crunch most of the data they get.

Well, after standing in line for an hour and a half, we did eventually get onto the plane: for about ten minutes. Climb up the gangway, walk back past the telescope and the control consoles, cross to the other side, walk forward and down a gangway on the other side. I’ll spare you the pictures.


Hangar one has long been a landmark of the bay area, having been built in the 1930s (if I recall) for the dirigible USS Macon, which crashed and burned on its maiden voyage. At an air show some years ago, we went into hangar one. There were three hot-air balloons flying around inside, and they were all only down at one end. The sliding doors at the ends are on railroad tracks, which is not surprising, but they are on double rails, not single. That is one big building.

The skin was full of asbestos, and there have been debates for years about what to do with it: leave it in place, tear it down …. Finally, they decided to leave the skeleton in place but simply to remove the skin. The loud cries of outrage were presumably based on no concept whatever of how much skeleton there was. I think it looks better with the skin off than before.

Here we see the state of affairs, with about half the skin removed, and work in progress toward the rear.

What’s especially interesting today is that someone has built a 20-foot model of the USS Macon. Filled with helium, it actually flies, and today was its grand unveiling in hangar two, where it was flown around for press and dignitaries. There is a museum here, where the model will be on display for the ordinary mortals in a couple of weeks. We need to come back.


Jacky had a conference call when we returned home, so I went to the nearby allotment gardens to see whether I could find a mantis. Mantis? Well, it is the season, and I saw three (believe it or not!) on my bike ride home from work Friday, along the highway 237 corridor.

If there was a mantis to be found, it was hiding pretty well. I did find two harvestmen, however, which are fairly unusual to see. What I hadn’t realized before was how different they were from one another. Clearly not spiders, but clearly a family with quite some variety itself.

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