NASA's Planetary Protection Office is charged with two primary responsibilities: to ensure that outbound spacecraft do not contaminate the cosmos with organisms from Earth, and to protect the Earth from extraterrestrial microbes that could cause disease. The latter directive is especially important given that NASA hopes to one day retrieve rock samples from the surface of Mars. NASA official, John D. Rummel, envisions building a P-4 level containment facility, similar to what the CDC uses to study Earth's most dangerous viruses, for the analysis of Martian samples. Read more at Slate Magazine(1) and NASA's Planetary Protection website(2).
Image credit: NASA/JPL