Should NASA bring back Mars soil or rock to Earth? While the space agency hopes to accomplish that feat within the decade, the International Committee Against Mars Sample Return (ICAMSR) warns it could infect Earth with an interplanetary plague. NASA unveiled in October a wish list of unmanned missions to Mars in the early 21st century, culminating in several roundtrip flights that would bring home multi-kilogram chunks of the red planet. Terrestrial scientists would poke and prod the samples for evidence of past or present microbial life.