NASA chief Charles Bolden told senators Wednesday that sending astronauts to Mars is still the ultimate goal for U.S. human spaceflight, as he defended the agency's new space plan against criticism in a heated budget hearing. "Mars is what I believe to be the ultimate destination for human exploration in our solar system," Bolden told the Senate's Commerce, Science and Transportation subcommittee. But NASA will likely not have the technology to send astronauts to Mars for at least the next 10 years, he said. "There are too many capabilities that we don't have in our kit bag," Bolden said. That's...