In announcing his space initiative last week, President Bush talked of bold missions and fulfilling commitments. He did not, however, answer an overarching question: Why do people, Americans, need to travel to the moon, Mars and beyond?

The president spoke of the need to “see and examine and touch for ourselves” rather than rely on images from landers and samples from probes and said that “desire to explore and understand is part of our character.” But, given the current budget deficit and competing demands for federal funds, the president’s justification is not enough. Especially since these new missions will be accomplished without a significant boost in NASA’s budget.

The need to answer the question of why Americans will return to the moon and go to Mars was highlighted the day the president made his speech when children visiting the National Air and Space Museum in Washington, D.C., were asked why they believed travel to Mars was important. Several youngsters talked of the need to have someplace to go when “the Earth dies.” Not all their answers were so sinister sounding. One very young girl hoped to find purple and yellow flowers on the red planet and others spoke of the importance of scientific experiments conducted in space.

Such conflicting views of the importance of and need for space travel persist in adults, too. A poll released earlier this week found Americans evenly split on Bush’s proposal, mirroring opinion 35 years ago when President John F. Kennedy pledged to land a man on the moon. Half of those polled said it would be better to spend the money on programs such as health care and education rather than on space research.

Unlike President Kennedy who acknowledged the huge expense of his space program, President Bush hopes to reinvigorate America’s space program on the cheap. This was the downfall of the Mars ambitions of another former president, his father. In 1989, George H.W. Bush pledged that America would return to the moon and one day head to Mars. This endeavor languished because of its price, estimated to be at least $400 billion.

This President Bush’s space plan includes important improvements in the space program, such as the replacement of the space shuttle fleet and completion of the International Space Station by 2010, that should go forward. Beyond this, however, there needs to be a national conversation about America’s space ambitions and where they fit with other priorities. The Senate Commerce Committee, which has jurisdiction over NASA, is expected to hold hearings on the president’s proposal where the big question – why – as well as the smaller, but important questions of cost, timing, international cooperation and feasibility, must be answered.

Students in Bangor who talked last week to an American and Russian astronaut currently on the space station were inspired and awed by the experience. However, the pictures now being beamed back from the unmanned Mars Rover are also exhilarating. President Bush has laid out his vision for reinvigorating America’s space ambitions. Now, the conversation must turn to whether the goals the president seeks to achieve are appropriate, achievable and affordable given other programs that are short on funds.