Can America conquer the eighth continent? We put a man on the moon almost 40 years ago. Now it is time to establish a lunar infrastructure that will challenge us to improve the reliability of space transportation as preparations are made for journeys to other worlds

ON MAY 10, 1869, a golden spike joined two railways at Promontory Point, Utah, and the first transcontinental railroad was completed. On Jan. 14, 2004, Pres. George W. Bush announced a new vision for our nation's space exploration program and committed the U.S. to a long-term human initiative to explore the solar system, starting with a return to the moon.

There is no doubt that the railroad changed the world, opening up frontiers to discovery, settlement, and commerce. The railroad was the backbone for the Industrial Revolution that provided the largest increase in life expectancy and improvement in quality of life in history. Just as the Industrial Revolution brought about unprecedented improvements in quality of life, so, too, can the new age of space exploration and development, but this time with a positive impact on the environment. To begin a period of sustainable space exploration, the public and private sectors must seize the opportunity.

Since the Vision for Space Exploration was announced, there has been an ongoing debate about the importance of returning to the moon. The reasons for making this the next step include fulfilling a compelling human need to explore: gaining a foothold to prepare for journeys to other worlds; easing the world's energy problems; protecting the planet from disasters: creating moon-based commercial enterprises that will improve life on Earth; conducting scientific research; inspiring young people toward higher education; and utilizing space resources to help spread prosperity throughout the world.

We should not return to the moon for any one of these reasons, but for all of them and more. By first establishing the basic infrastructure for a transportation system between the Earth and the moon and a sustainable, semiautonomous, permanent human settlement, we will open the door to significant benefits for all. Of course, any permanent lunar base must be economically and politically sustainable and therefore has to provide tangible benefits and a return on investment.

Exploration. Great nations accomplish extraordinary endeavors that help to maintain their leadership in the world. American history is built on a desire to open new frontiers and seek new discoveries. "Mankind is drawn to the heavens for the same reason we were once drown into unknown lands and across the open sea," Pres. Bush commented. "We choose to explore space because doing so improves our lives and lifts our national spirit."

Gaining a foothold. Establishing a lunar infrastructure will challenge us to improve the reliability of space transportation and allow us to demonstrate exploration systems and concepts without leaving the relative safety of near-Earth space. Testing systems and concepts at a location that is a three-day journey from our planet is a logical step before we make the leap of a six-month trip to Mars. Establishing a permanently occupied lunar base also will open the way for detailed study and use of lunar resources, which likely are significantly more economical than lifting all required exploration resources from the Earth's surface.

Energy needs. Today, about 1,600,000,000 people do not have access to electricity. The World Bank estimates that 1,100,000,000 individuals live in extreme poverty, leading to 8,000,000 premature deaths every year. In developed countries, higher quality of life is achieved only through a high rate of energy use. Increased energy supply is needed for economic and social development, improved quality of life, and to grow enough food to provide for the citizens of the developing world. Unless something is done soon, the world will be laced with a crisis of enormous proportions. The United Nations estimates that the global population will be approximately 9,100,000,000 by 2050, with virtually all growth in the 50 poorest countries. The choices that the global society makes to provide for future energy needs will have a profound effect on humanity and the environment.

The moon can supplement Earth-based renewable energy systems to meet future energy demand. Ample energy from the Sun reaches the moon and is not interrupted by weather, pollution, or volcanic ash. Solar energy farms on the moon can "beam" limitless clean energy down to where it is needed on Earth or to satellites for relay to our planet. There also are other potential sources of energy, including platinum for fuel cells and an isotope called helium-3, which could be used in fusion reactors of the future. Moreover, supplying energy from the moon will enable us to help provide the Earth's energy needs without destroying our environment.

Protection from disasters. There is a real risk to Earth's inhabitants from asteroid impacts and super-volcano eruptions. If a large object the size of Comet Shoemaker-Levy 9, that recently slammed into Jupiter, were to hit Earth, civilization could be destroyed. Even much smaller asteroids can cause tremendous damage and loss of life. The moon is a superb location for early detection systems.