President Kennedy laid down a straightforward if daunting challenge: the Moon. President George W Bush, perhaps looking for a Kennedy moment, set that challenge again. From President Barack Obama, a more nuanced directive is no surprise. But while Obama would forego a headline destination in favour of having NASA develop exotic technologies to enable human exploration of deep space while the private sector takes on the low- Earth orbit transport challenge, one former NASA astronaut thinks he can achieve both goals - and before any crew is carried aloft in a private rocket. THERE AND BACK Franklin Chang Diaz believes...