Exploring Meteorite Mysteries slide set,

One of the difficulties in searching for fossil life in Martian meteorites is deciding whether the meteorites have been contaminated since arriving on Earth. Lloyd Burckle (Lamont-Doherty Earth Observatory) and Jeremy Delaney (Rutgers University) have found dramatic new evidence for contamination in Antarctic meteorites. They removed dust from cracks in metamorphosed ordinary chondrites, which are meteorites that were heated to several hundred degrees Celsius in asteroids and are completely devoid of life. The dust contained identifiable microorganisms 5 to 40 micrometers across, from both ocean and land environments. Burckle and Delaney suggest that the fossils were transported to Antarctica by wind, along with dust, and eventually deposited in small cracks in the meteorites. They conclude that contamination with micrometer-sized organisms might be a ubiquitous process in Antarctica. This presents a big problem for scientists searching for fossil extraterrestrial life in an Antarctic meteorite