Answering a question in a Twitter town hall meeting Thursday, President Obama suggested spaceflight is stuck in the Apollo-era mode and said NASA needs a technological breakthrough to allow faster, longer spaceflight with a goal of getting astronauts to Mars. "Frankly, I have been pushing NASA to revamp its vision," Obama said. "The shuttle did some extraordinary work in low orbit: experiments, the International Space Station, moving cargo. It was an extraordinary accomplishment and we're very proud of the work that it did. But now what we need is that next technological breakthrough. "We’re still using the same models for...