SPECIAL FOCUS: Observatories and Earthstations
A Giant Ear Built Onto the Earth
Certain
places on the earth have a special, unearthly function: these
places are built to escape terrestrial limitations, to gaze
upward and outward, to either interact with space probes and
satellites, or to search for meaning beyond this world. In the
interest of improving our understanding of the earth/sky interface,
the Center has established a special focus area relating to
observatories and earthstations. Here are two reports on compelling
and superlative places within this constellation of remarkable
constructions.
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Viewing platform above the big dish at Arecibo.
CLUI Photo.
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Located in the jungle of northern Puerto Rico, the famous Arecibo
Radio Telescope is the largest single dish on earth. The observatory
consists of an immovable 1000 foot wide, 18 acre parabolic bowl
built in a natural depression, and pointing at the zenith, forming
a radiowave collection dish - an "ear" that constantly
listens to whatever might be out there.
Although it is most well known for its central
role in the Search for Extraterrestrial Intelligence (SETI)
project, its conception was military, and aspects of its original
use remain mysterious. The telescope project was funded in 1960
by the Advanced Research Project Agency (ARPA), and was built
in 1963 by Cornell University, under contract with the Air Force’s
Cambridge Research Laboratory, following the initiative of Cornell
professor William Gordon from the Department of Electrical Engineering.
The Air Force intended to use it for a variety of defense-related
purposes, including scanning of the Earth's ionosphere to detect
rocket launches.
By 1970, its military usefulness apparently waning,
ARPA was ready to pull the plug on the facility. Some astronomers
recognized that the telescope could be reengineered to become
a very significant instrument for the then relatively new fields
of radio and radar astronomy. Among the scientists interested
in the site was Frank Drake, one of the founders of the SETI
program, who successfully proposed a project to the National
Science Foundation to replace the military’s wire mesh
dish with a smoother surface of 38,788 shaped aluminum panels,
enabling it to detect signals of higher frequency. Thus the
non-military, extraterrestrial-searching Arecibo was born. Federal
funding for SETI (from NASA) later stopped however, and the
dish is only sometimes used for this function today. Despite
the high cost of operating the remote facility, it is still
managed by Cornell, used primarily for atmospheric and ionospheric
studies. "Sometimes, up to three days a week, the radio
telescope is shut down because technicians essentially have
to beat back the jungle," says Mike Nolan, a planetary
radar scientist at the site.
Recent upgrades are improving the capabilities
of the observatory, including new mirrors and receivers at the
focal point of the dish, contained in a six-story structure
suspended 450 feet above the bottom of the bowl.Tourism is encouraged
at Arecibo, spurred on by its appearances in films such as
Contact, an adaptation of the Carl Sagan book about his
search for ET, where the telescope played itself in a starring
role.
Observatories and
Earthstations: Kitt Peak, Arizona
