The University of Arizona

Astronomer Frank J. Low, 1933-2009

By Jeff Harrison, University Communications | June 22, 2009

Low's innovations in infrared instrumentation opened a previously unseen universe, including views to the very beginning of time.

Frank J. Low
Frank J. Low

University of Arizona Regents' Professor Emeritus Frank J. Low died on June 11 in Tucson after a long illness. He was 75.

Low's brilliant career in astronomy at the UA spanned more than three decades. He devised instruments to detect the faint signals of infrared light in the darkest regions of space, a technology that literally opened the universe for astronomers to explore phenomena that were previously invisible.

Born in 1933 in Mobile, Ala., Low graduated with a bachelor's degree in physics from Yale University and earned a doctorate at Rice University in 1959.

As a young physicist at Texas Instruments, Low invented the gallium-doped germanium bolometer that initiated the era of thermal infrared astronomy.

Low, who was also was a member of the National Academy of Sciences, joined the National Radio Astronomy Observatory in West Virginia to further develop the bolometer and other related instruments. He also briefly worked on the faculty at Rice University before coming to the UA in 1965. In 1967 he started Infrared Laboratories, Inc., a Tucson-based firm that supplied infrared detectors and cryostats to the scientific community.

At the UA's Lunar and Planetary Laboratory, Low teamed up with Harold Johnson, who helped Low adapt his bolometer technology to astronomy. Rodger I. Thompson, an associate professor of astronomy at Steward Observatory, said Low specifically worked on detecting infrared radiation at very long wavelengths.

"The problem is that infrared photons have very little energy," Thompson said.

Low's bolometer "could absorb photons and detect temperature changes as little as a thousandth of a degree," he added. This breakthrough allowed astronomers to see across enormous distances and peer through clouds of interstellar dust to find stars in their earliest stages of creation.

In the 1960s, Low became the first astronomer to use aircraft as a platform for telescopes. After some initial experiments with a small telescope on a U.S. Navy bomber, Low installed a 12-inch telescope on a Learjet.

Despite the telescope's relatively small size, by flying above most of the infrared-absorbing water vapor in Earth's atmosphere it made significant observations of Jupiter, Saturn and Venus as well as star-forming regions and distant galaxies.

With the Learjet observatory, Low and his group discovered that Jupiter and Saturn emit substantially more energy than they absorb from the sun, due to stored heat from the time of their formation. They also discovered the large far-infrared outputs of star-forming regions and galaxies, now known to be a powerful tracer of young, hot stars.

The Learjet project was so successful that it led to the Gerard P. Kuiper Airborne Observatory, with a 36-inch telescope in a converted Lockheed C-141 military cargo plane. The Kuiper's successor is the Stratospheric Observatory for Infrared Astronomy, or SOFIA, a modified Boeing 747SP that will house a 2.5-meter telescope.

UA astronomer Erick Young, who worked closely with Low on other projects, is now the director of SOFIA. He reports that it will start its mission this winter, covering the short-to-mid-range infrared wavelengths.

Young described Low as "a giant in the field of infrared astronomy," and said that working with him was "an amazing experience. "He had the ability to cut through the fog to see obvious solutions to difficult problems, both technical and scientific."

Low's work hugely impacted space telescopes, starting with IRAS, the Infrared Astronomy Satellite that was a collaboration among American, British and Dutch scientists. Launched in 1983 and free of any atmospheric interference, IRAS surveyed the cosmos and yielded new discoveries ranging from features of our own solar system to the most distant objects in the universe. Low's super-cooled amplifiers significantly improved the sensitivity of the IRAS mission, and data collected from it are still being used extensively by the astronomical community.

Low also was the facility scientist on the Space Infrared Telescope Facility, or SIRTF, designed to pinpoint and study in detail items found in the IRAS survey. SIRTF, later renamed the Spitzer Space Telescope, has been one of NASA's most successful astronomy programs.

Low's most important contribution to the SERTF project was proposing a cost-effective way to cool the telescope. Rather than insulate and cool the entire telescope prior to launch, Low instead suggested launching it warm. By exposing parts of the satellite to the near-zero temperatures of space, it was possible to approach the necessary operating temperature without using any internal cooling.

Rodger Thompson, who led the development of NICMOS, the Near Infrared Camera and Multi-object Spectrometer that was mounted on the Hubble Space Telescope, said Low advised on that project as well.

"He was there to tell me when I was wrong," Thompson said. "But he was an expert on cryogenic operations, an important part of NICMOS," he said.

The 6.5-meter James Webb Space Telescope, scheduled for launch in 2014, builds on Low's infrared telescope designs. It will search for the first galaxies that formed in the early universe and peer through dust clouds to see stars forming their own planetary systems.

Low's previous honors included the 2006 Bruce Gold Medal, given by the Astronomical Society of the Pacific for lifetime contributions to astronomy; the American Academy of Arts and Sciences' Rumford Prize for research on heat and light;  the Helen Warner Prize for significant contributions in astronomy; and the Joseph Webber Award for the design, invention or significant improvement of instrumentation leading to advances in astronomy. The Warner and Webber awards were both given by the American Astronomical Society.

Low is survived by Edith Low, his wife, as well as two daughters, Valerie Rossiter of Tucson and Beverly Fjeldstad of Oslo, Norway; a son, Eric Low of Rogers, Ark.; a sister, Sallie Beckner of Washington, and six grandchildren.

Low's family requests donations be made to Casa de los Ninos, 1101 N. 4th Ave., Tucson, AZ 85705, or the Community Food Bank, P.O.Box 26727, Tucson, AZ 85726 .