Instrument Troubleshooting
Cosmic ray instruments are complex and it seems there is always something that needs adjusting or fixing or calibrating, and then testing and confirming and re-calibrating. This is what consumed our time while waiting for the wind to die down. And it is a good thing to have had that time to do those last ground tests, because we encountered a troubling condition—an intermittent false trigger.
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Scientific balloon launches have been part of NASA’s mission for over 30 years, but in 1977, they were conducted by NCAR– the National Center for Atmospheric Research. NCAR maintained a balloon launching facility in Texas that had all of the equipment and resources to support experiments like ours. Unfortunately, Texas was too far south for our experiment. Instead, we would be operating from makeshift facilities in Aberdeen, a town of 25,000 in an area of South Dakota that offered low population, but enough infrastructure to meet our technical and launch requirements.
There was a regional airport outside of town, and an airplane hangar was provided to house our laboratory field station. We were not the only researchers, however. Groups from other universities were also trying to measure the properties of cosmic rays. We each had a section of the hangar to set up and prepare our experiments for launch. After packing up our instrument and all the essential support equipment from our 4th-floor lab in the Physics building into a rental truck and driving a day west on Highway 12, we arrived in Aberdeen. It took us several more days to recreate an operational cosmic ray field lab in the airplane hangar.
Continue readingThis is the beginning of a series of posts that describe the launching of a scientific balloon experiment in 1977. The story was reconstructed after encountering some old photos from that event. Reminiscences can run rather long, so I have partitioned it into more manageable segments. I hope you enjoy this snapshot of the scientific and cultural times of the 1970s.
Background
While attending the University of Minnesota, one of my part-time jobs was as a lab assistant in the Physics and Astronomy Department. I worked in a laboratory dedicated to the cosmic ray research group led by professors Phyllis Freier and C J (Jake) Waddington. In the group were lab manager Chuck Gilman and graduate student Bob Scarlett who were preparing an instrument to be launched and held aloft by a balloon to gather data about cosmic rays, a (still) mysterious radiation of high energy particles from deep outer space.
Continue readingI always had a mild interest in astronomy, and it became a strong interest in the 1990s, triggered by a homework assignment given to my ten-year-old son to go out at night and identify some constellations. I took him away from the city lights to a park where we could see the stars emerge from twilight. On that beautiful fall evening, we found the constellations he was looking for, and we also saw Jupiter, the brightest object in the sky. Through binoculars, we were surprised that we could see its moons. This caused me to wonder what else I might be able to see if I were to look a little closer.
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I had to agree that it was an unusual gas station.
It looked like an airport control tower with a cantilevered roof that protected the customers at the gas pumps – protection from rain and sun that is common today but in 1978, and certainly 20 years earlier when built, it was novel. The pumps were fueling the local cars: a mix of old gas guzzlers and newer more fuel-efficient models that were a response to the oil embargos of the 70s.
We were on the way to our business destination—the US Steel mine near Mountain Iron Minnesota, a town slowly being eaten up by the open pit mine as it followed the deposits of diffuse iron known as taconite.
I was the passenger in Steve Haverberg’s VW microbus. Steve was familiar with the area and knew I would enjoy seeing a gas station that had been designed by Frank Lloyd Wright. We needed gas anyway and it was a good time to stop and stretch.
Another vehicle was also on its way to the mine, but had taken a more direct route. It was equipped with a 4-foot long cylindrical probe, to be lowered by cable into a drill hole. A custom-built instrument specialized for detecting iron ore was also in that truck.
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I recently received a Klein bottle as a gift from my life-long friend Rich, who shares the same quirky interests in math and science that I do. We find the same fascination and amusement in mathematical puzzles and their visual incarnations by artists like M C Escher, Buckminster Fuller, and Scott Kim, along with mathematicians John Conway, Roger Penrose, and Benoit Mandelbrot. So it was with tremendous pleasure that I received this gift. I soon discovered that it held not only the novelty of being a mathematical object, but it had been created by a scientist/artist that had inspired me in an earlier time in my life.
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I am not the only one who enjoys encountering unique examples of architecture. I was accompanied in my quest to find the Harvard Biology Building with its intriguing doors, sculpted façades, and anatomically exact statues of rhinoceroses, by my (newly married) wife Poldi. That was the culmination of a scavenger hunt to locate a novel architectural feature that had been captured in an old photograph my grandfather had taken, soon after the building had been inaugurated. We really enjoyed the experience.
Recently, Poldi, while planning a trip that would take us through Vancouver British Columbia, learned of another unique building, built at about the same time. Our destination was Banff, but we had a day before our train’s departure, to explore this famous port city of western Canada. She encountered references to the “Marine Building”, an art deco monument completed in 1930. At the time, it was the tallest building in the city (22 stories), and it was intended to be a grand statement of the value of Vancouver, especially its importance as a major seaport. They thought of it as their version of the mighty Chrysler building in New York City, completed earlier that same year.
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After a long and productive career, my friend and colleague Fred Nourbakhsh is retiring.
I’ve known Fred a long time. I hired him at Management Graphics in 1991 at a time when this small company was growing because it had invented an unexpectedly popular device that was having a major impact in the computer graphics field, including how Hollywood made movies.
I was impressed when I interviewed him because it was clear that he had done his homework. He somehow knew a lot about the company—its size, its products, revenues, history. MGI was a privately held company, so how had Fred learned all this when corporate reports were only sent to shareholders? This was a time long before you could go to the “About” page on a company website; there was no website—there was no web. However he did it, this depth of research is a strong skill in Fred, and it has served him well.
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Even if light pollution were not an issue, we’d rarely see the northern lights because our latitude in Minneapolis is outside the normal auroral oval. But last week, Earth experienced a strong geomagnetic storm and we were suddenly in the middle of it! Here was a chance to see aurora without traveling to Alaska or Manitoba! And it was the perfect opportunity to photograph them with my wide-angle lenses, one of which I call my “Milky Way/aurora lens”, a 2-1/2-pound monster for just this purpose! But we needed to get away from the city lights.
There is a sculpture park, Franconia, that Poldi and I have enjoyed and contributed to for many years, and it was less than an hour from home. We arrived before sunset and sought permission to take photos, even after the normal park closing time. As I was scouting for locations and setting up tripods, a trickle of other visitors arrived with the same purpose: to see the predicted northern lights. As twilight faded, the aurora tourists expanded to dozens of vehicles, all of which had headlights that swept across the sculpture park grounds, interfering with my carefully selected compositions.
I have learned not to react to unexpected lighting situations. Oftentimes, they make for interesting photographic results. One of my favorite examples is when I was shooting reflections on a calm alpine lake and a group of partiers arrived and went skinnydipping, breaking up the smooth lake surface. Rather than close the shutter and move on, I kept it open for the duration of my planned exposure. It created a wonderful blend of reflected and scattered light!
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My idea of creating a vacuum was terribly simplistic. Just run a pump until you reach your desired vacuum, right?. Well… I learned that there is much more to it.
First, there are different degrees of vacuum, categorized by how difficult it is to attain them. The easiest can be obtained by a mechanical pump, a piston, or equivalent, pushing air molecules from the chamber to the outside, essentially a reverse bicycle pump. It is possible to remove 99.9% of the air molecules and a few more, but that still leaves too many for the cool vacuum electron effects like neon signs, nixie tubes, and for audiophiles, amplifier tubes.
The mechanical vacuum pumps can’t reach those levels; more exotic pumps are needed, but they can get close to where radiometers operate, which is my interest. So following the advice of expert friends, I acquired a pump that, in principle, could reach the level of vacuum I needed: 50 microns (a micron of mercury air pressure is 1/760 thousandth, call it a millionth, of standard atmosphere). The pump model I bought is commonly used by the HVAC industry, where air conditioning units need to be evacuated before charging them with refrigeration working fluids (Freon, etc.). They can reach the 50 micron vacuum level internally, but if you connect it to a real world vacuum chamber, there is a myriad of “leaks” that will prevent getting there.
I found this out by trial and error. I found that the hoses, fittings, and gauges from the HVAC world were not cheap, but there is a market to keep them reasonably affordable to the industry’s practitioners. Vacuum-rated hoses, gauges, valves, and fittings (the connectors between vacuum elements that minimize leaks), are hard to make. And they all seem to have their own connection systems. I learned about “flare” fittings, “nominal pipe thread” and tapered thread, acme threads, o-rings, and a bunch of other methods for connecting things and trying not to leak air molecules.
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