Questions, questions, questions …
Human beings don’t accept things as they find them. They ask questions, and they search for answers. What am I? Where am I? What is my past? What is my future? From earliest childhood, people want to know things. Why is the sky blue? What makes the Sun shine? What is the Moon made of? What are the stars?

Curiosity drives us to explore our surroundings. We want to see the unseen and to learn what lies over the next hill. People have always been bothered by blank areas on the map or in the mind, and they have studied and worked and striven and sometimes died to fill them in. Over the centuries, the urge to explore has taken human beings into unknown and unreachable places: to the New World, the South Pole, Mount Everest, and the Moon. The same urge has carried the human mind outward into the realm of the galaxies and into the microscopic domain of subatomic particles.

These explorations have always been profitable. They have produced tangible riches: gold, new lands, beneficial trade, and profitable technological advances. More important is the knowledge gleaned: a better understanding of our world, its mechanisms and processes, and the basic natural laws that govern them. It is knowledge, much more than riches, that makes modern civilization possible.

When we think of exploration, we think of individuals: Marco Polo, Columbus, Lewis and Clark, Lindbergh, Neil Armstrong. But great explorations have also been an important part of the character of nations. To search for something new is an expression of a nation’s confidence and enthusiasm, of its ability to organize and its willingness to innovate. It is no coincidence that the New World was discovered at the height of the Renaissance, nor that the colonization of North America accompanied the rise of Elizabethan England. In our own time, the Apollo Program manned landings and exploration of the Moon were the American response to the challenge of competition in the new ocean of space.

The exploration of space may be only the latest episode in the long human history of wondering and seeking, but the sudden explosions of travel, new sights, and scientific discovery exceed anything that preceded them. New worlds have been discovered, not one by one, but by the dozen. Human beings have explored and sampled the Moon. Robot laboratories have dug into and analyzed the surface of Mars. The video eyes of our spacecraft are providing close-up views of planets never seen by the ancients, and more than a dozen moons have emerged in our consciousness from tiny points of light to unique, mysterious, and changing worlds.

Great as these steps have been, they have occurred in a remarkably short time. Only a single generation separates the flight of Sputnik I from the first spacecraft pictures of Saturn’s moons; the first geologist to explore the Antarctic is still around to talk with the first geologist to go to the Moon! Thanks to modern communications, all of us have shared in these voyages to an extent never possible before. Less than 100 people witnessed Columbus’ landfall in the New World; half a billion watched on television as Armstrong and Aldrin stepped onto the Moon.

We have flown into space, but from this high vantage point we still feel as curious as an earthbound child. How did the universe form? How will it end? How was the solar system created? What are the other planets really like? What lies in deep space beyond the Sun? How did life originate? Is there other life out there? In the last generation, we have come a long way toward the answers. But we still have farther to reach, more questions to ask, and much more to learn. Like earlier explorers, we have painfully struggled to a high plateau from which we see new mountains and valleys beyond. The answers to our questions, the benefits from the new knowledge, still lie ahead out of sight, but no longer out of reach.

Outward bound to the stars.

In this artist view of Pioneer 10, launched from Earth in 1972, the spacecraft makes a close passage of the Moon as it follows a path toward the giant planet Jupiter. The blue, cloud-covered Earth is in the background. This view shows the Moon’s heavily cratered far side, highlighted by the dark crater Tsiolkovsky. Pioneer 10 will never return. After its encounter with Jupiter in 1973, Pioneer 10 was moving fast enough to escape from the solar system entirely. It is the first human artifact sent out to roam among the stars, a calling card announcing our existence to any other intelligences in the universe.