You can't cancel an enormous federal program without hitting pushback, and President Obama is hitting plenty of it over his proposal to end NASA's Constellation program. In January his budget proposal put forth no funding for Constellation, the space shuttle successor program that included the Ares rockets, Orion crew capsule, and plans to send astronauts back to the moon by 2020. Instead, NASA would become more reliant on private companies to ferry its astronauts to the space station, and would explore new ideas for visiting Mars or nearby asteroids. But the proposal has already ruffled lots of feathers, prompting the President to say he will hold a conference to further outline his plan. First, many high-profile space experts balked at the proposal. Former astronaut Tom Jones said Obama was surrendering human spaceflight, and Apollo 17 astronaut Harrison Schmitt, one of the last men to walk on the moon, was equally displeased.