A trip to Phobos comes with extras (Image: NASA/JPL)

FORGET the risk of exploding rockets or getting sideswiped by a wayward bit of space junk. Radiation may be the biggest hurdle to human exploration beyond low-Earth orbit and could put a damper on a recently proposed mission to Mars orbit.

A panel tasked by the White House with reviewing NASA’s human space flight activities (New Scientist, 22 August, p 8) suggests sending astronauts to one of Mars’s moons, Phobos or Deimos, among other possibilities raised in its report released last week (http://tinyurl.com/mbajav).

From such a perch, astronauts could use …