IN THE past few months, the wheels started to fall off NASA’s Mars Sample Return (MSR) mission. The project aims to bring 500 grams of Martian rock and soil to Earth in 2033 to look for signs of existing or extinct life forms, but a litany of budget overruns and technology blunders have put its viability in doubt.
Not that MSR needs such problems to arouse controversy, as it is a troublesome concept all round. The reason why? There is a non-zero risk that it could deliver to Earth extraterrestrial organisms that microbiologists simply don’t understand or know how to …