In 1960 the first such program, Project Ozma, led by American astronomer Frank Drake at the National Radio Astronomy Observatory in Green Bank, W.Va., focused on the nearby stars Epsilon Eridani and Tau Ceti. Since then other searches, most of limited duration and concentrating on stars similar to the sun, have been conducted without success. In 1992 the High Resolution Microwave Survey (HRMS) was initiated. Using radio telescopes around the world in a planned ten-year search, HRMS envisioned a two-pronged approach. One group was to focus on solar-type stars within 100 light-years of Earth; the other was to conduct an all-sky survey. HRMS was halted by a funding cutback in 1993, but privately raised funds were used by the SETI Institute from 1995 to 2004 to conduct a search of nearby solar-type stars. Project Phoenix, as it was called, monitored only microwave frequencies because there are few natural sources of emissions in that range and researchers hoped that extraterrestrials would recognize that range as a quiet region of the electromagnetic spectrum suited to sending a message. The Allen Telescope Array, which uses a large number of small radio antenna dishes began operations in 2007 with 42 dishes (with an ultimate total of 350 planned). Located in the Cascade Mts. at Hat Creek, Calif., this joint project of the SETI Institute and the Univ. of California, Berkeley, is a broad sky survey over a wide portion of the radio spectrum in a search for evidence of extraterrestrial life; other astronomical research also is conducted. Mothballed during much of 2011 due to funding shortfalls, the array is now also used by the U.S. air force to track objects in orbit.
The Breakthrough Listen project, which began in 2016, uses the Green Bank Radio Telescope in West Virginia and the Parkes Radio Telescope in New South Wales, Australia, to search for extraterrestrial communications. A project of the Breakthrough Initiatives program, it is based at the SETI Research Center of the Univ. of California, Berkeley. The 10-year project also has partnerships with other radio observatories and with NASA.
In addition to the listening efforts of the radio astronomers, other forms of contact have been attempted. Various coded messages have been broadcast in the hope that an extraterrestrial civilization might also have a SETI program. Gambling on a chance encounter with an extraterrestrial civilization, the U.S. space probes
See also E. Ashpole,
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