We live in troubled times. We are at war, and we have suffered from extraordinary natural catastrophes. There is a clamor in the land to stop spending on activities that are not of immediate short-term benefit. Space exploration is one area under scrutiny. While i n times like these, it is a natural instinct to pull back and spend scarce resources on our immediate needs . I t is also shortsighted.

Since the earliest times, humans have wondered about our cosmic neighborhood. We have gazed in awe at the planets and stars. We have wondered about our origins and our destiny. The heavens beckon us. Even the seven days of our week are named for the seven ancient “planetes,” or wanderers, visible to the ancient Greeks: the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn.

Once the abode of gods, the heavens have slowly yielded their secrets to rational thought. By 300 BC the ancient Greeks, using nothing more than the naked eye, had determined that the Sun was much farther away from Earth than the Moon. By 140 AD Ptolemy had determined the distance to the Moon and bequeathed us the Earth-centered Ptolemaic system of motion of the planets.

But it was technology that enabled great leaps forward. With the invention of the telescope, Galileo discovered sunspots , craters on the Moon, the Galilean moons of Jupiter and that planet’s Great Red Spot. As a result of his discoveries, Galileo got into trouble with the church for supporting the view that the Sun, not Earth, was the center of the solar system.

The invention of spaceflight led to the golden age of cosmic exploration. In 1957 with Sputnik, we took the first tentative steps towards projecting ourselves into space, first robotically, then with humans. A destiny among the stars seemed to be within reach. In the ensuing 48 years, robotic spacecraft have explored to the far reaches of the solar system and beyond, revealing exotic new worlds to the wonderment of human eyes. We have landed robots on the Moon, Mars, Venus, Saturn’s moon Titan and an asteroid.

Powerful space telescopes have probed outwards into the universe and back in time to within a few billion years of the big bang. We have even detected the microwave residue of the big bang, almost 14 billion years later. Earth-orbiting spacecraft have predicted weather, surveyed natural resources, monitored crops, probed the oceans, provided us with navigation tools, television and communications, and have contributed to our national defense. Because of space exploration, we are the first species in the 4.5 billion-year history of our planet that can protect the planet against cosmic catastrophes like the impact of a near 32-kilometer wide asteroid 65 million years ago that wiped out the dinosaurs and most species on the planet.

Americans are an exploring people, the frontier is a concept deeply embedded in our national consciousness, and we are excited and proud to see Americans performing extraordinary feats in space. We have landed humans on the Moon and built an Earth-orbiting space station. Deep inside, we believe that our destiny lies among the stars, as popular culture reveals with the popularity of “Star Trek” and “Star Wars.”

The U.S. space program has enriched us emotionally and intellectually; has made our lives better, more convenient and safer; and continues to engage us culturally. But is it worth the cost at a time of massive budget deficits and a shaky economy, when so much needs to be done at home?

NASA consumes less than 1 percent of the federal budget, down from about 4 percent at the time of Apollo. Most of that money is spent employing people here in the United States. Investing in NASA is investing in the nation.

Every great society in history has spent some fraction of its national treasure on the arts, exploration and discovery. The ancient Greek city-states, the Roman Empire, the Islamic Caliphates, the Medicis, the British Empire and now the United States have placed high value on expanding human knowledge and culture without demonstrable, immediate, tangible benefit, only to be richly rewarded by application of unanticipated discoveries.

In the 15th century, the Chinese Emperor Ming Chengzu made the fateful decision to stop exploring the oceans and burn his ships. Had he not done so, the great European voyages of discovery would perhaps never have been taken, and the world would be a very different place. A retreat by the United States from the exploration and development of space, from the expansion of human presence into the solar system, would be as shortsighted.

Should the United States retreat from space just as India, Japan and particularly China are expanding into space? Do we really want to watch China plant its flag on the Moon when we no longer have the capability to fly to the Moon? Americans always have explored, and space really is the final frontier. To retreat from the adventure of human spaceflight runs counter to the dynamic of American culture. The popular bumper sticker about the Stars and Stripes, “These Colors Don’t Run,” pervades all aspects of our society. Let us join the Chinese and others and lead as we go back to the Moon, on to Mars and perhaps beyond with astronauts. To do otherwise would be counter to the American spirit.

Peter Likins is president of the University of Arizona, Tucson. Michael J. Drake is director of the Lunar and Planetary Laboratory at the University of Arizona.