Arecibo was product of Cold War competition, says pioneering scientist

Ionosphere researcher Tor Hagfors, former director of the National Astronomy and Ionosphere Center (NAIC) at Cornell, which manages the Arecibo Observatory in Puerto Rico for the National Science Foundation, poses at the observatory, Nov. 3. Robert Barker/University Photography

By Linda Grace-Kobas

ARECIBO, Puerto Rico -- Although the giant Arecibo telescope is recognized today as the world's largest and most sensitive single-dish instrument for radio astronomy, it actually was built for research into the Earth's upper atmosphere. Its use for radio astronomy was "an afterthought," resulting from the realization that the huge dish could also detect faint signals from outer space, according to a former leader of the Arecibo Observatory.

Presenting the second Gordon lecture Nov. 3 at the observatory's 40th anniversary celebrations, noted ionosphere researcher Tor Hagfors commented that, as a result of the launching of Sputnik by the Soviet Union, it was "relatively easy" to persuade the U.S. government to plan and build the gigantic 305-meter (1,000-foot) diameter reflector dish in a remote, hilly region of Puerto Rico in only five years by putting it in the context of concern about the Soviet "leadership" in space.

Americans, he said, had been shocked when the Soviet Union launched Sputnik in 1957. A year later, Cornell engineering professor William (Bill) Gordon published a paper that described a technology for measuring the density and temperature of the earth's ionosphere. In it he postulated the incoherent scatter mechanism -- a powerful ground-based technique using radar to study the ionosphere and its interactions with the magnetosphere, the outermost region of the atmosphere, and the solar wind. In 1963 his telescope was inaugurated as the Arecibo Ionospheric Observatory.

Although the telescope continues to be an important instrument for using radar for ionospheric research, "no other telescope can compete with Arecibo," in radio research, Hagfors said. Its accomplishments in these areas include the discovery of the first planet beyond our solar system; the discovery of "superclusters" of galaxies that are the largest physical structures in the universe; the discovery of many hundreds of pulsars (fast-spinning neutron stars) and the precise measurements of their rotation rates; radar imaging of the planets and other solar system objects, including the first measurement of the rotation rate of Mercury. The lesson of Arecibo, Hagfors said, is to "think big and be prepared for the unexpected."

Hagfors, a Norwegian scientist, established many of the fundamental principles for the analysis of radar astronomical observations of the moon and planets. During the 1980s he was director of the National Astronomy and Ionosphere Center (NAIC) at Cornell, which manages the observatory for the National Science Foundation, and professor of astronomy and electrical engineering. During this time he initiated the engineering studies and developed proposals that led to the second upgrading of the Arecibo telescope in the 1990s.

His other "very happy times," he said, at Arecibo included serving as director of operations from 1971 to 1973. Hagfors previously had been director of another incoherent scatter radar telescope, the Jicamarca Radio Observatory in Peru. He left NAIC and Cornell in 1992 to become a director of the Max-Planck-Institut für Aeronomie in Germany.

Hagfors is the recipient of prestigious awards, including the Humboldt Society's Senior Scientist Award and the Sir Granville Beynon Medal. To recognize his research achievements and his 68th birthday, the asteroid 1985 VD1 was named "Hagfors" in his honor.

The Gordon lecture, endowed by Arecibo Observatory engineering pioneer Thomas Talpey and his wife, Elizabeth, is named in honor of Bill Gordon, known as "the father of the Arecibo telescope." Hagfors' topic was "Arecibo and the Spawning of New Science and New Observatories."

After the lecture, there was a good-natured exchange between Hagfors and Gordon over the latter's 1958 calculation of how big the dish needed to be for ionosphere studies. Hagfors suggested a much smaller dish would have been sufficient for that purpose. Gordon, unfazed, defended his original calculation. Besides, he added, if it were not for that gigantic dish, "where would pulsars be today?"