FUTURE OF RADIO ASTRONOMYRadio astronomy is pursued at a large number of institutions, including many universities, and at
two U.S. centers sponsored by the National Science Foundation: the National
Astronomy and Ionosphere Center, which operates the Arecibo Observatory, and the National Radio Astronomy Observatory, which operates the Very Large Array near Socorro, N.Mex., and
telescopes at Kitt Peak, Ariz., and Green Bank, W.Va. (where the 91.4-m/300-ft telescope that collapsed in 1988 is being replaced by a more advanced one).The VLBI Project, funded by the National Aeronautics and Space Administration (NASA) and run by the Jet Propulsion Laboratory, has its operations center in Socorro, N.Mex., along with that of the Very Large Array. Completed in the early 1990s, the project's installation now stretches across the United States and its territories. Called the Very Long Baseline Array (VLBA), it consists of ten parabolic antennas, each 25 m (82 ft) in diameter, located in the states of Hawaii, Washington, California, Arizona, New Mexico (two antennas), Texas, Iowa, and Massachusetts, and on St. Croix in the Virgin Islands. It has a resolution 1,000 times that of any currently existing optical or radio telescope. (Canada plans a similar installation, the Canadian Long-Baseline Array of eight 32-m (105-ft) telescopes arranged in a line across the southern part of the country, and Australia is also planning a continent-wide array of radio telescopes.) The VLBI Project, in addition, supports two international efforts: the RadioAstron mission under development by the Astro Space Center of the Lebedev Physical Institute in Russia, and the VSOP (VLBI Space Observatory Program) being developed by Japan's Institute of Space and Astronautical Science. In 1997, as part of the latter program, Japan successfully launched a radio-telescope satellite that now forms part of the VLBI array. More launches are being planned by the project's members.Radio telescopes are also being constructed to explore the last remaining untapped region of the electromagnetic spectrum: the submillimeter region that lies between the very shortest radio wavelengths and the very longest wavelengths of infrared radiation. Because waves in this region of the spectrum are strongly absorbed by atmospheric water vapor, the submillimeter radio antennas to receive them must be built in arid regions, preferably at high altitudes. Such installations exist or are being planned by British, Dutch, German, U.S., and other radio astronomers at sites such as Mauna Kea in Hawaii.