In April, President Obama flew to Kennedy Space Center in Cape Canaveral, FL, to reveal details of his new strategy for NASA and the future of U.S. spaceflight. Sitting next to the president on Air Force One was Buzz Aldrin, who in July 1969 became the second man to walk on the moon. The seating arrangement was appropriate, since both men share a common goal for the nation's space program: reaching Mars by the mid-2030s.

Like Obama, Aldrin opposes the strategy set by President Bush in 2004 to return humans to the lunar surface by 2020. The cornerstone of Bush's plan for NASA was the Constellation program, which included building two new rockets--Ares I to ferry humans into orbit and Ares V to transport heavy cargo--and a manned exploration vehicle called Orion. But the program fell behind schedule and was over budget (see "The Future of Human Spaceflight," January/February 2010). In January, Obama released a new budget proposal that increased NASA's budget by $6 billion over the next five years but terminated the Constellation program.

Technology Review reporter Brittany Sauser recently asked Aldrin about his ideas for the future of U.S. human spaceflight.

TR: Why not go back to the moon?

Buzz Aldrin: We explored the moon 40 years ago, and now it should be developed by robots for scientific, commercial, and security reasons. Basically, I don't see a financial return to justify the cost of sending U.S. humans and rockets back to the moon; it's a waste of decades and hundreds of billions of dollars.

TR: What should NASA focus on instead?

BA: The objective should be a permanent presence on Mars by 2035. That's 66 years after Neil Armstrong and I first landed on the moon, and our landing was 66 years after the Wright brothers' first flight. Mars is clearly the best permanent-­residence location other than Earth, and we can go there in case somebody or something blows up Earth. We will have a place that ensures the survival of the human race. That means humans who go there commit to staying--one-way tickets will be technically easier and less expensive and get us there sooner.

TR: But that will take years. What should NASA's transition strategy be?

BA: Ares 1 and Ares V should be canceled, and in their place we [should] build an evolutionary shuttle-replacement launch system that could be called something like Ares III [and would transport both people and heavy cargo]. Orion should continue to be developed as an emergency vehicle for the space station, as the president stated. Meanwhile, I also very strongly suggest that instead of retiring the shuttles [in late 2010] and buying rides with the Russians for five, six, or seven years to get to our $100 billion space station, a highly undesirable situation, we stretch out the flights of the five remaining shuttle orbiters to 2015.