Next year, the blackness of outer space will get a lot blacker -- for those of us here on Earth, that is. For nearly 20 years, pictures relayed by the US manned and unmanned space probes have been flashing back to Earth and across millions of television screens -- dramatic shots of man's first walk on the moon, eerie pictures of a rocky Martian landscape, and stunning photos of Jupiter's famed, swirling Red Spot.
But when Voyager II reaches Saturn in August 1981, two years after its encounter with Jupiter, it will signal a "last picture show" of sorts for a space-watching world. For there will ensue a five-year hiatus before scientists get another glimpse of the solar system from US probes.
"Starting in 1963, there has never been more than 12 months when the United States has not been producing new images of new places," says Bruce Murray, director of the NASA-Jet Propulsion Laboratory (JPL), which controls the country's unmanned space shots.
"More than half the people in the United States have never known . . . a time when that exploring wasn't going on," Dr. Murray continues. "Now they're going to know."
Caught in Capitol Hill's budget-cutting drive -- and capturing less of a nation's fancy than it did during the race to the moon -- America's planetary exploration program, Dr. Murray says, is "on the ropes."
Recent space flights such as the Voyager and Viking missions to Jupiter and Mars, respectively, have been a part of a period of "unprecedented exploration," says the JPL director.
But they are the culmination of a slew of projects begun in the late '60s -- a continuous chain of events that was broken in the late 1970s when, for the first time in years, no new planetary exploration projects were funded.
Traditionally Congress has been generous in funding the National Aeronautics and Space Administration (NASA), which owns JPL and includes the laboratory in its budget. But the lion's share of recent NASA budgets has gone to the space shuttle program. The shuttle, which has suffered a two-year delay, was supposed to have been launched last year.
As a result, Dr. Murray explains, JPL -- which last year spent $250 million on flight projects -- is down to its last two scheduled missions.
They are the Galileo flight to Jupiter, which was originally expected to arrive and start relaying pictures in 1984; and a joint American-European venture planned for 1983, which will send two spacecraft around the sun's poles. Because both missions are to be launched from the space shuttle, they have been set back two years, to 1986 and 1985. And because of last-minute congressional budget-cutting, the so-called "solar polar" mission may yet be cut from JPL's agenda.
But planetary scientists such as Dr. Murray worry that the current political pressure to cut back spending may mean a loss of perspective on the long-range importance of planetary exploration. And they chafe over the fact that they have the knowledge and skills to develop technology to travel throughout the solar system. It is a tantalizing prospect that, because of a lack of money, dangles just out of their reach.
The impact of a decline in space exploration, Dr. Murray warns, is twofold. First, he says, a lack of new planetary projects will cause many scientists to leave the field for other areas, such as the booming defense industry -- an exodus he says has already begun.
But more important, he says, there will be an intangible impact on the nation at large. It will be a loss of a feeling of "participation in the future, of leading the world in something positive, doing something with our technology that we can be proud of."
Dr. Murray acknowledges the earnestness of the national trend toward tightening purse strings. But he refuses to believe that Americans have lost their interest in planetary exploration.
"The problem is not that the American people have turned so inward that they no longer care. I think it's almost the reverse," he claims. "They desperately yearn for somebody to tell them how to be great, how to have a future, how to do something they can be proud of."
The planetary program "is like the 'National Geographic' in space," he says. "There's a basic interest in the United States, and in other countries as well, in exploration: What's the new frontier, what's it like out there, what's the next place? It's not well represented in a lobbying sense, but it's there, very strongly."
While Dr. Murray and other planetary scientists puzzle over how to spur that latent concern into vocal interest, he outlines these frontiers in space, which space scientists now are ready to tackle:
* A search for extraterrestial intelligence. Although such a proposal has been turned down twice, JPL is trying for funding once again because, says Dr. Murray, "we have the technology now to do a million-fold better search than has ever been done before."
The seven-year project would involve a search through millions of radio frequencies across hundreds of light years for a signal being transmitted from somewhere in outer space.
Time is running out for such a mission, says Dr. Murray, because the increasing number of satellites being launched into Earth's orbit is creating "radio frequency pollution" that makes it almost impossible to "hear" any faint signals which might be picked up in space.
* An exploration of Venus. Because Venus, Earth's nearest neighbor, is covered by dense clouds, conventional space sensors have been unable to make pictures of the planet's surface. But with the help of newly developed "imaging radar," JPL scientists say they will be able to explore the hidden surface of the planet that has been called "Earth's twin." Such information, they claim, will prove invaluable in understanding Earth.
* A comet mission. Under a proposal now being written, a set of sensors would be launched in a probe directly into the center of Halley's Comet, providing data on a phenomenon that scientists know little about.