Jerry Nelson:
Peering into the universe's secret past

This is no ordinary story of man and machine,
for the Kecks required a whole new approach to
building big telescopes. Instead of one prodigiously
heavy mirror, many smaller mirrors could fit
together and act as a single reflective surface.


Astronomer Jerry Nelson has many pictures of relatives, but not one is a complete family portrait. Such a photo would show him, his wife Jocelyn, his children Alexandra and Leif--and the world's biggest bouncing baby twins, the W. M. Keck Telescopes in Hawaii.

Nelson is indeed the father of the young Keck Telescope and its sibling, Keck II. With mirrors 33 feet across, the Kecks have transformed astronomy from the ground just as the Hubble Space Telescope has opened new vistas from orbit. Astronomers from UC, Caltech, NASA, and the University of Hawaii are using the observatory to push the frontiers of their field, peering further into the universe and revealing more details than they dared dream a decade ago.

But this is no ordinary story of man and machine, for the Kecks required a whole new approach to building big telescopes. Instead of one prodigiously heavy mirror, Nelson reasoned, many smaller mirrors could fit together and act as a single reflective surface. One almost could envision a huge fly's eye, with hexagonal mirrors instead of segmented lenses, staring into the cosmos.

Now that we know this trick works, it makes sense. But when Nelson first conceived it twenty years ago, it was a tough sell.

"In the astronomical community, there was a fair amount of skepticism," Nelson says. "And from some quarters of the UC system, there was open hostility. I'm not sure we would try to make the same leap today, because we no longer take as many risks."

Nelson is not really an astronomer, he will tell you. Rather, he's a physicist and a putterer who likes to build stuff and solve problems. Those qualities came
in handy as he and his colleagues at Lawrence Berkeley National Laboratory--most notably physicist Terry Mast--set out in the 1980s to realize his concept. Their main hurdles were figuring out how to keep the mirrors perfectly aligned and how to polish each segment so that the whole assembly curved in the exact shape needed to focus light to a pinpoint.

The payoff was the first photo of a galaxy in 1990, with 9 of the 36 mirror segments installed in Keck I. "That was tremendously exciting," Nelson says. "Part of me always knew it would work, but seeing that first image was just fabulous."

Nelson is still improving the quality of images at Keck I and now at Keck II, whose eye opened last year. With a second telescope, new challenges loom. For
instance, Nelson is helping to design an "adaptive optics" system for Keck II to erase the blurring effects of earth's blanket of air. Ultimately, astronomers hope to combine the light from Keck I and Keck II to create ultrasharp resolution--perhaps powerful enough to detect earthlike planets around other stars.

In 1994 Nelson came to UCSC, mainly to work with the crack instrument teams at the UCO/Lick Observatory shops on campus. And as the Kecks blaze new paths in astronomy, accolades from once-dubious colleagues are pouring in. Most recently, Nelson earned a berth in the National Academy of Sciences, joining six other astronomers from UCSC's stellar department.

"The honors are nice, but the fantastic science being done at Keck is infinitely more important," he says. "We did the job right, and the telescopes are having an impact. That's what means the most to me."

Robert Irion