Giant Radio Dish Planned for N.E.

A Harvard-M.I.T. committee has submitted plans to the Federal government proposing the construction in New England of the world's largest steerable radio telescope. The 300 to 500-foot instrument would be operated by a group of New England colleges including Harvard and M.I.T.

The world's largest such telescopes--up to 250 feet--are now all located in foreign countries. The largest completely movable telescope in the U.S. measures only 140 feet.

Arthur E. Lilley, professor of Astronomy and member of the planning committee, said that the proposed telescope fills a need the U.S. has for a large "dish" of the size maintained by England and Australia.

"Such fantastic advances are being made in radio astronomy every day," he said, "that it is regretable the United States has no very large telescope. A telescope of the size we propose would be the largest in the world for some time to come."

The joint committee, designated CAMROC, the Cambridge Radio Observatory Committee, is sponsored by Harvard and the Smithsonian Astrophysical Observatory, and M.I.T. and the M.I.T. Lincoln Laboratory. Co-chairmen Edward M. Purcell, Gerhard Gade University Professor, and Jerome B. Wiesner, dean of the School of Science at M.I.T., head the group of ten scientists and engineers.

The committee has submitted plans for an engineering design study on the telescope's feasibility to the National Science Foundation, which is now considering the proposal.

CAMROC predicted in its report that the design study could be completed by June 1967. Lilley himself speculated that if the study were finished then, the telescope could be built by the early 1970's.

After the study has been completed, Purcell said, Harvard and M.I.T. will invite other colleges in the Northeast to join a regional radio observatory built around the giant telescope. Any other action on the plan will be decided by the administrations of Harvard. M.I.T., and the Smithsonian.

The CAMROC report listed the major considerations of design and cost that must be decided:

* Location--CAMROC proposed the telescope as a regional project, but suggested no specific location in New England. While the telescope must be positioned away from the radio disturbances of urban centers, it must also be accessible to the member colleges who will operate it. One plan considered would place the dish itself in an secluded location and put the control center in Cambridge.

* Radome--A telescope covered with a protective shell, a radome, might be cheaper to build and would be safe from weather damage, but no radome of the necessary size has ever been engineered. The design study will research the feasibility of a 350-550 foot shell.

* Dish engineering--The study will contemplate novel designs for the antenna beyond the usual paraboloid construction.

* Cost--The study will have to determine the cost curve of such a large telescope as a function of its possible size and performance. The 140-foot steerable telescope at the National Radio Astronomy Observatory in Greenbank, W. Va., the largest in the country, cost over $10 million. Co-chairman Purcell estimated that the 300-500 foot instrument would cost a few times that amount.

Harvard now owns a 60-foot radio telescope operating at Agassiz Station in Harvard. The telescope, built in 1956, has done important work on radio emissions from hydrogen in space that led to a new map of the galaxy drawn from radio data. By now, however, the telescope is one of the smallest in the country still doing original research.

In 1964, Purcell said, Harvard and M.I.T. decided that the next logical step in their research was to build a large movable dish comparable to the biggest in the world. Such a dish, he said, would extend U.S. capabilities in the field to keep up with the most advanced work being done.

Subsequently, CAMROC members were chosen in June 1965 after an exchange of letters between President Pusey and President Stratton of M.I.T. The committee began meetings this fall, and finished its report in December