Dr. Peter Backus

December 18, 2004

Observing Programs Manager

Peter R. Backus received a B.S. in Physics from Rensselaer Polytechnic Institute in 1974, and a Ph.D. in Astronomy from the University of Massachusetts in 1981. His graduate and post-doctoral research studied the evolution and emission mechanism of pulsars. In 1982, he began working with NASA’s Search for Extraterrestrial Intelligence (SETI) Office as a National Research Council post-doctoral fellow, and in 1985, joined the newly-formed SETI Institute. He became Co-Principal Investigator on a cooperative agreement with NASA in 1988, leading research and development of both software and hardware for the NASA SETI Program.

After the termination of NASA’s SETI Program in 1993, Dr. Backus held several management roles in Project Phoenix, the privately-funded continuation of the NASA program. From 1995 through March 2004, he conducted SETI observations with his Project Phoenix colleagues in Australia, West Virginia, and Puerto Rico. He is now planning for operations at the Allen Telescope Array (ATA), currently under construction in northern California. As part of NASA’s Astrobiology Institute, he is developing a list of about one million “target” stars for SETI on the ATA.


SETI programs that listen for signals from individual stars have typically favored targets like our Sun.  "For decades, the conventional wisdom said that SETI programs should shun low mass stars," explains astronomer Peter Backus, who is examining that assumption anew as part of the SETI Institute's NAI research.  "These stars are much cooler than the Sun, and in order for a planet to have liquid water, it would  have to orbit very close to the star."

But the closeness required for liquid water on planets circling such low mass M stars comes at a price.  As Backus explains, "Such close proximity to the star would cause tides in the body of the planet and lock its rotation so that one side always faced the star just as the Moon is locked to the Earth."  And that would have implications for the planet as a whole.  "Early work suggested that the atmosphere of such a planet would freeze out on the night side," says Backus, "leaving the day side fully exposed to the star's radiation.  For M stars this is a particular problem since some exhibit gigantic flares, much larger than any produced by our Sun."

But perhaps, suggests Backus, those earlier assumptions were wrong.  "Recently, as we've learned more about the planets in our solar system, improved the computer modeling of atmospheres, and discovered terrestrial life in extreme environments, the possibility of habitable planets orbiting M stars is receiving renewed interest," says Backus, who is the SETI Institute's Observing Programs Manager.  "To explore this issue, the SETI Institute NAI Team will be hosting a series of workshops. About two dozen experts from several branches of astrobiology will come together to study whether these tiny stars with extremely long lifetimes may be suitable hosts for planets with life."

- SETI Institute Explorer, Special Edition 2005


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