ARECIBO, P.R. ---- The prominent Norwegian-born astronomer Tor Hagfors will deliver a lecture during next weekend's 40th anniversary celebrations at Arecibo Observatory, home of the world's largest and most-sensitive single-dish radio telescope.

Hagfors, who will give the William E. and Elva F. Gordon Distinguished Lecture on Nov. 3, is an internationally known pioneer in studies of the interaction of electromagnetic waves with ionized plasmas and solid surfaces.

Hagfors was director of the observatory's managing organization, the National Astronomy and Ionosphere Center (NAIC) at Cornell University, Ithaca, N.Y., from 1982 to 1992. He is now professor emeritus of electrical engineering and astronomy at Cornell and scientific member emeritus of the Max-Planck-Institut für Aeronomie in Germany. NAIC, manages the observatory for the National Science Foundation.

While NAIC director and a Cornell professor, Hagfors initiated the engineering studies and developed the proposals that led to the second upgrading of the Arecibo telescope in the mid-1990s. He first joined NAIC as director of operations from 1971 to 1973. He then returned to his native Norway as founding director of the European Incoherent Scatter Association (EISCAT), during which he was responsible for the construction and early operation of the EISCAT facility in Scandinavia.

While at Cornell, Hagfors continued his ionospheric research with several graduate students and, using the radar facilities of the Arecibo Observatory, investigated the properties of Langmuir waves (produced by energetic electrons streaming into the solar wind). After moving to Germany in 1992 to become director of the Max Planck Institute, he became involved in space missions to study the Martian surface and the internal structure of comets. In recognition of his research achievements, and in celebration of his 68th birthday, the asteroid 1985 VD1 was named "Hagfors" in his honor. Hagfors also has served as director of the Jicamarca Radio Observatory in Peru and has been on the faculty at the University of Trondheim and the University of Oslo, both in Norway.

He was one of several people who independently developed the theory for incoherent scattering from magnetized plasmas, and he established many of the fundamental principles that would be needed for radar astronomical observations of the moon and planets. His Hagfors scattering law, describing the scattering of radar waves from planetary surfaces, is still widely used. His early radar studies of the properties of the lunar surface were an important contribution in preparation for the Apollo moon landings.

The Gordon Lecture is endowed by Arecibo pioneer, engineer Tom Talpey, and his wife, Elizabeth. Talpey was a member of the engineering team led by William Gordon that spent three years in Puerto Rico in the early 1960s building Arecibo Observatory, which received its Þrst radio signals in 1963.

Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.

o NAIC: http://www.naic.edu/

o Cornell News Service Arecibo site: http://www.news.cornell.edu/releases/Arecibo40

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