We are at a critical juncture in solar system exploration. On the drawing boards are dozens of promising ideas, many which could be realized in the coming decades. There is plenty of incentive for human expansion into the solar system, yet there is no long-term commitment and no consensus on how or when it will occur.

This past May, at the fiftieth anniversary celebration of the American Institute of Aeronautics and Astronautics (AIAA) held in Baltimore, Maryland, a panel addressed these issues. Members of The Planetary Society and the National Space Institute filled out the audience, along with some familiar faces author James Michener and Apollo 11 astronaut Michael Collins. The panel's charter was broad: to address what humans and machines could do in space over the next 50 years.

Louis Friedman, The Planetary Society's Executive Director, chaired the panel, which included Benjamin Finney of the University of Hawaii, Tom Rogers of the National Academy of Sciences's Space Applications Board, Carol Stoker of the University of Colorado, Ben Bova of Ornni Magazine and myself.

In his opening remarks, Friedman stressed a "continuing partnership between the role of humans and the role of machines in exploring the solar system!'

He said that, while he has been struck by the continuing debate on manned versus unmanned space exploration, there will be significant roles for both. This view was later echoed by other panel members.

The panelists spoke in the temporal order of their topics, from historical analogues to the far future. Ben Finney began with a richly-illustrated discussion of early human expansion across the oceans. Citing numerous examples of some nations willing to risk long voyages while others bowed out, he warned that the United States risks losing its leadership in solar system exploration. History has repeatedly shown that abrogating such leadership can have enormous long-term societal consequences.

Finney gave the example of the rise of the Portuguese and the fall of the Chinese in maritime activity during the fifteenth century. Turning inward, the bureaucratic leaders of China had all but stopped their people's seafaring. By the year 1500, it became a capital offense in China to build a sea-going junk with more than two masts.

"Had the Chinese kept going;' said Finney, "had they rounded the Cape of Good Hope, sailed north, then anchored off Lisbon, explored the Thames or cruised the Mediterranean, all of which they were technically capable of doing, how differently the modern world might have turned out!'

European countries one by one first Portugal, then Spain, then Holland, then England rose and fell in maritime leadership. In each case the retreat had negative economic effects lasting for centuries. In this light, Finney expressed concern about NASA's stagnant budget. "Does this mean our space program is in danger of going the way of the Ming Dynasty navy?" he asked.

"I do not think so, although the specter might be useful for badgering your congressman, or the President, when he says we cannot afford to spend more on space!' Finney speculated that Japan may take over our lead in space exploration if there is not a turnabout in U.S. policy.

The other lesson to be learned from oceanic exploration, according to Finney, is that new forms of political and economic organization are required. What forms will they take?

Currently they are impossible to predict, but he described the Polynesian voyages in the Pacific as the most pertinent analogue: for millennia, these Stone Age explorers had reached new lands previously unsettled, from which their descendants would eventually push on and colonize still more lands. Speculating on our future, Finney concluded that, "Employing new technologies, new forms of social organization, these space-adapted people will be the Polynesians of humanity's odyssey among the stars!'