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Pat Seitzer and “Space Debris – When Good Satellites Go Bad”

Editor's Note: University of Michigan Research Professor Dr. Patrick Seitzer presents for the Grand Rapids Amateur Astronomical Association at 7 p.m. Thursday, March 16th at Schuler Books. As a supplement, here is an adaptation of an article about this very interesting person and his unique research that appears in the Grand Rapids Press on Sunday, March 12th.


Dr. Patrick Seitzer’s enthusiasm and passion for his current research began fifteen years ago with

an increasingly annoying problem. It had become nearly impossible to take images of celestial objects

through a telescope without recording an intrusive light streak produced by an object in earth orbit passing through the field of view.

That experience and other concerns prompted the University of Michigan Research Professor to

become part of a worldwide team finding and keeping track of a growing amount of orbiting space debris threatening expensive satellites. “With two launches a month at $250 million each, it is in our best interests to keep near-earth space as pollution free as possible,” he told me in a recent phone interview.

Seitzer became fascinated with astronomy as a youngster, and has long enjoyed the opportunities to actually work with telescopes and collect observational data. “My current research takes me all over the world, and permits productive collaborations with all sorts of people,” he said with enthusiasm. “I have been very fortunate.”

Seitzer has been with the University of Michigan for close to 26 years, where he has benefited from the University’s strong astronomy programs, which bring connections and collaborative arrangements with observatories worldwide. “Michigan is everywhere,” he noted.

A University of Michigan presence that goes back a half century is at the Cerro Tololo Inter-American Observatory on a remote mountaintop in northern Chile, where some of the darkest and clearest skies on the planet are found. Amidst the giant domes housing some of today’s largest and most powerful research telescopes is one sheltering a modest instrument with a light collecting aperture only two feet in diameter.

The telescope uses an optical system developed by an optician named Schmidt, and it was initially named after Heber Curtis, a Muskegon native and legendary early 20th century astronomer with strong University of Michigan ties. It was installed in an observatory near Ann Arbor in the 1950’s, where University faculty and astronomy students constantly fought with clouds.

Moved to Cerro Tololo in 1966, the Curtis-Schmidt became one of the first telescopes to observe

starlight from that pristine site. Eventually it became outclassed for cutting edge research by the

behemoths built around it. Still, the instrument was big enough and in a perfect location for Seitzer’s

growing interest in threatening space debris, and “It was available,” Seitzer noted in our conversation.

The venerable telescope used regularly by Seitzer and his colleagues has been re-designated the “Michigan Orbital DEbris Survey Telescope” or MODEST. It is one of two telescopes at Cerro Tololo used in tandem for finding and charting space debris.

MODEST methodically scans along a band in the sky where numerous communication satellites hover, identifying light signatures left by chunks of orbiting matter glinting weakly in sunlight. Then the somewhat larger telescope tracks each object over a longer period to establish its orbital location and how much of a threat it poses to nearby satellites.

That orbiting matter consists of parts from disintegrated satellites, satellites past their useful life, and remnants of rockets that launched them. I asked why it is so important to monitor this stuff? “The less identification and control of this debris, the greater the threat of damage to very expensive satellites,” Seitzer explained.

Those expensive satellites orbit along a narrow band encircling the earth’s equator. They are in what is called “geosynchronous orbit, ” precisely at the right height to circle Earth at the speed the planet rotates, thus remaining essentially fixed over a certain location.

Without a battery of geosynchronous satellites – and the number is growing all the time – there would be no satellite TV or high efficiency global communication we now take for granted. The ever growing clutter orbiting alongside these vital satellites is cause for concern. Seitzer points out that among the current census of more than 20,000 objects in earth orbit, less than 5 percent are working satellites.

Lots of hits have occurred over time, and many have been costly. The Hubble Space Telescope has survived non-fatal impacts, but there are instances where orbiting laboratories and communication satellites have been permanently disabled.

“Not only have we polluted the earth, but we are doing a good job of polluting the space around it as well,” Seitzer said. “The space close to earth is now the largest of all junk yards.” I could detect from our discussion why he is so passionate about the subject.

International guidelines have been developed to curb the proliferation of space debris, and more are coming. It could not be too soon with twice monthly launches of very expensive satellites continuing.

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