An apparent lack of rigor in maintaining cleanliness on the Curiosity rover while it was being assembled may one day force a hiatus in its use to explore Mars, if its instruments detect the possibility that life-supporting water exists nearby.

NASA's planetary protection officer, the scientist in charge of ensuring U.S. terrestrial probes do not contaminate celestial bodies, certified Curiosity for landing only because it was targeted on an equatorial crater that is unlikely to harbor subsurface water. Had planetary scientists chosen another landing site, mishandling of the rover's wheels and drill bits on Earth might have forced a two-year slip in launching until the next planetary window.

NASA officials, including Planetary Protection Officer Catharine Conley, stress that Curiosity is “fully compliant” with international protocols dating back to the Viking missions. Those standards were designed to ensure that any life found on Mars originated there, and did not arrive on the lander that found it or an earlier robotic visitor from Earth.

However, if Curiosity turns up evidence of contemporary water or ice as it explores Gale Crater, it may be commanded to back off from the potentially life-sustaining area while astrobiologists and planetary scientists ponder whether the rover could “forward contaminate” Mars.