Astronomers' 'Impossible Dream'

While admitting the adage that ''hope springs eternal,'' one can only wonder at the optimism of astronomers in drawing up their wish list of priorities for the 1980s.

The report of the Astronomy Survey Committee of the US National Academy of Sciences reads like the scenario for a quixotic ''impossible dream.''

In the face of the most drastic curtailment of federal support for the sciences in several decades, the committee has come up with a program that would cost 1.91 billion 1980 dollars, mostly for new facilities. It would add 30 percent to the National Science Foundation astronomy budget. What is more, tucked away in the program details is $20 million for a search for extraterrestrial intelligence - the bete noire of Sen. William Proxmire (D) of Wisconsin, who has ruthlessly exorcised it from the National Aeronautics and Space Administration budget.

Working under the chairmanship of George Field, director of the Harvard-Smithsonian Center for Astrophysics, the committee has laid out a program that would be ambitious in the best of budgetary times. It assumes that several new facilities already authorized, such as the orbiting Space Telescope, will be put in place, and goes on from there.

Chief among the new items requested is the $500 million Advanced X-ray Astrophysics Facility satellite to study X-ray emissions from outer space. Also requested is a Very Long Baseline radiotelescope array to measure fine details of distant radio sources, a giant New Technology Telescope measuring some 591 inches in diameter (compared with 200 inches for the Mt. Palomar instrument), and a 394-inch radiotelescope for studies in the submillimeter wavelength radio range.

The committee also asks more support for so-called ''prerequisites.'' These include theoretical studies and data analysis, new laboratory equipment, new instrument design, and even declassification of some secret military infrared sensors.

In requesting all this, the committee makes clear that it is after big game. It outlines why it thinks the time is right for a major assault on some of the largest and most basic mysteries in astronomy -large-scale structure of the universe; evolution of galaxies, stars, and planets; the true nature of the violently explosive events that seem prevalent in many parts of the universe; and the inner secrets of the activity of the stars.

It's a wonderful dream. But to be realistic one has to remember that a similar report a decade ago had a similar vision. Only one of the facilities it envisioned - the Very Large Array radiotelescope observatory in New Mexico - was actually built. Now the fiscal outlook is much grimmer. The best hope the committee can offer is that the administration's economic program will work and that new funding will be possible.

At the least, the report shows how far astronomy has progressed and what it is now capable of doing. It is indeed a lovely dream.