Astronaut Eugene Cernan is not a name that usually comes up in discussions of the U.S. space program. In fact, he has not been part of NASA since 1976. However, his unique place in space exploration history is a stark example of the lack of enthusiasm we now have for space travel. So what is Cernan’s fame? He is the last person to have set foot on the moon.

The successful launch of Sputnik in 1957 stunned the United States. It galvanized public support and had politicians clamoring for a U.S. response. The result was the Apollo program, which had the ambitious goal of putting an American on the moon before 1970. It succeeded in 1969. This was probably the apex of the space program.

NASA’s budget reached its peak in 1966 at $27 million (in mid-1990s dollars) and has been declining since. The Shuttle program, Apollo’s successor, has been both costly and fatal. The repeated delays and problems with the shuttles have led the United States to rely on the Russian Soyuz rockets to carry astronauts to the International Space Station. This will become more prominent in 2010 when the shuttles are retired. The next generation of U.S. manned spacecraft will be available in 2015 at the earliest.

In 2006, NASA declared its intent to return to the moon by 2020. The response was distinctly less positive then the response to President Kennedy’s 1961 speech on the same topic. The critics were quick to point out that manned space travel is both expensive and risky. Our robotic missions have explored everything from the surface of Mars to the edges of our solar system, but the Challenger and Columbia disasters show that space flight is still quite dangerous.

Does that mean that we have lost the urge for interplanetary travel? Although NASA has taken some heat, the organization is following an emerging international trend. Both Japan and China have set a goal of reaching the moon by 2020, Europe and Russia are planning to arrive sometime around 2025 and India wants to get there by 2030.

This interest has even spread to the private sector. The X Prize Foundation offered a $10 million prize to the first successful private venture into space and has now created a lunar equivalent. The Google Lunar X Prize is a $30 million competition, with the goal of safely landing a robot on the moon that can both move around and send data back to Earth before 2015.

The urge for space travel has even created a market for tourism. Space Adventures is offering private flights to the International Space Station for $20 million through the Russian Space Agency. They are also planning on offering trips to the moon for around $100 million.

These international and private space ventures have only highlighted the United States’ lackluster efforts. A 2006 Gallup poll showed that nearly half of Americans did not think the Shuttle program had been worth the cost. In fact, space travel rarely makes it onto the list of America’s priorities. After Iraq, healthcare and the economy, who cares about the moon?

This overlooks the fact that the moon landing was one of the greatest achievements in history — so uniquely American that no one has been able to copy it. But if we give up our efforts, then it will only be a matter of time before we get another Sputnik shock.