NASA will test the powerful first stage of its new Ares moon rocket Thursday, a milestone in a program that already has spent $7 billion for a rocket that astronauts may never use. When that first stage is tested, it will be mounted horizontally. The engine will fire, shake and make a lot of noise. But by design, it will not leave the ground. The same could be said for NASA's plans to go to the moon, Mars or beyond Earth orbit. It's not so much a physical challenge for engineers as it is a financial challenge for budgeteers.