UC Berkeley professor emeritus of astronomy Stuart Bowyer, who died Sept. 23, will be remembered for his contributions to the field of X-ray astronomy and his pioneering observations in extreme ultraviolet wavelengths, or EUV.

Bowyer died at age 86 from COVID-19-related complications, according to Berkeley News. In addition to his work with EUV and X-ray astronomy, the study of objects in space that release radiation at X-ray wavelengths, Bowyer was also known for his bold personality.

“He was a larger than life guy,” said Dan Werthimer, Berkeley SETI Research Center chief technologist. “He lived life with gusto in both his academic and personal life.”

Werthimer added that Bowyer led the use of EUV light in astronomy, which studies objects that emit EUV radiation, wavelengths between X-rays and ultraviolet. Bowyer made the first maps of the universe in EUV light.

Many astronomers initially doubted Bowyer’s plan to study EUV radiation, according to Berkeley News. EUV is absorbed by gasses in the atmosphere, which prevents observations of the phenomenon on Earth.

“Astronomers thought if you put a telescope up in space with EUV light it would just be black,” Werthimer said. “They thought it was a waste of money but Stu persisted and it led to all kinds of discoveries.”

In 1975, Bowyer proved the viability of using EUV, according to Berkeley News. Bowyer and his team placed detectors on the Apollo-Soyuz space mission that were able to detect EUV emitted from other stars.

NASA approved Bowyer as the principal investigator for the first mission dedicated to EUV astronomy in the early 80s, the Extreme Ultraviolet Explorer mission, according to Berkeley News. The mission was launched into Earth’s orbit on June 7, 1992, and operated for the next nine years, where it cataloged over 800 EUV sources in the Milky Way.

Bowyer was also known for his involvement with the Berkeley SETI Research Center, where he launched the Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations, or SERENDIP, project in 1977, according to Berkeley News. The project simultaneously scanned 100 radio frequencies to search for extraterrestrial intelligence.

While at the Berkeley SETI Research Center, Bowyer pioneered the idea of commensal, also known as piggyback search for extraterrestrial intelligence, or SETI, Werthimer said.

Instead of competing for dedicated telescope time to search for extraterrestrials, Bowyer and his team piggybacked on other astronomers’ telescope time by connecting their detectors while astronomers conducted their own experiments, according to Berkeley News. This system allowed the team to use a telescope 24-hours a day.

“Stu did nothing by halves,” said chair emeritus for SETI Research Jill Tarter in an email. “Working with him led to some unpredictable outcomes, but it was never boring.”