Arecibo Facts and Accomplishments

Arecibo Observatory was built in 1963 by the U.S. Air Force under the initiative of Professor William Gordon and his colleagues at Cornell. It was primarily intended for radar studies of the Earth's ionosphere, but it was realized that the telescope would be a very significant new instrument for the then relatively new fields of radio and radar astronomy. In addition to its astronomical observations, it is still used for atmospheric and ionospheric studies. It has been managed by Cornell since its construction, first for the Air Force and, after 1970, for the National Science Foundation.
With a fixed spherical reflector dish and a steerable feed system, the observatory was upgraded in the 1970s shortly after Cornell began operating it for the NSF. An improved surface and high-power solar system radar were added. This upgrade was funded by the NSF, with NASA contributing the funds for the radar transmitter.
The reflector dish is 1,000 feet in diameter (305 meters), as big as 26 football fields. Its surface is made of 38,800 reflective aluminum panels. The ground
screen is 50 feet high surrounding the perimeter of the primary antenna, the reflector dish. It has an area of about 16,000 square meters, the size of five football fields. The screen reduces radio noise emitted by the ground that gets into the receiver systems.

The first planets outside the solar system were discovered around a pulsar.
One of its first accomplishments: Establishing the rotation rate of Mercury, which turned out to be 59 days rather than the previously suspected 88 days (1965).
The first pulsar in a binary system was discovered, leading to important confirmation of Einstein's theory of general relativity and a Nobel Prize for Russell Hulse and Joseph Taylor of Princeton University.
Investigation of ice in craters at the polar regions of the planet Mercury with the radar system.
Provided much of our pre-Magellan mission knowledge of the surface of Venus via 1.5 km (1 mile) resolution imagery of the surface through the planet's cloud cover using the radar system.