After many years of working on developing instrumentation for ground-based astronomy, Bruce Bigelow—a senior research engineer at the Physics Department—is involved with his first space-based project.
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The process that led to this point began many years ago. In 1998, two groups used Type Ia supernovae to measure the expansion rate of the universe and found that it was accelerating. In its December 1998 issue, Science Magazine declared this discovery as the breakthrough of the year.
Five years later, in its December 2003 issue, Science Magazine proclaimed an image taken by the WMAP (Wilkinson Microwave Anisotropy Probe) satellite as the breakthrough of the year. The satellite had produced an unprecedented snapshot of the universe in its infancy, when it was only 400,000 years old.
The image confirmed the existence of dark energy, which was suggested by the breakthrough of 1998. Dark Energy is the mysterious force that is causing the expansion of universe to accelerate, in keeping with one version of Einstein’s General Theory of Relativity.
The discovery of proof of the existence of dark energy is only the proverbial tip of the iceberg and has led to still more questions. What is the nature of Dark Energy, how does it evolve and what will this mean as the universe expands further?
To learn the answers, research is underway for the design of the SuperNova Acceleration Probe (SNAP) telescope in a joint effort by U-M, the Lawrence Berkeley National Laboratory and a dozen other institutions. This work is being funded by the Department of Energy (DoE), but NASA has plans to partner with the DoE in the future.
Bigelow is one of the people involved in this far-reaching project.
“Compared to the Hubble telescope, the SNAP telescope is designed to look at much bigger chunks of sky all at once,” Bigelow says. “It can look at thousands of distant supernovae and map tens of square degrees of sky (the full moon is 0.5 degrees in diameter and covers 0.2 square degrees of sky). It will help to provide a detailed history of the expansion of the universe for the last 10 billion years, and the behavior and evolution of dark energy.”
The findings also will enable scientists to determine how the universe will expand well into the future, he says.
In order to get stable images of the highest resolution, SNAP will be based in space. SNAP will be put in an orbit well beyond that of the moon.
“At this orbit you can’t fly the space shuttle out to fix it, unlike the Hubble,” Bigelow says. This means that SNAP will have to work the first time because it will not get a second chance.
Bigelow is concentrating on engineering development of the telescope structure, and design of the focal plane detector array, with particular emphasis on how to assemble 72 detectors (a detector is to a telescope as film is to camera) in a focal plane that is two feet square and perfectly flat.
“I basically do computer modeling to figure out how to hold the different parts of the telescope together with as little mass as possible,” he says, “while still maintaining its integrity.”
