Before revision: Archaeal diversity analysis of spacecraft assembly clean rooms, he ISME Journal (2008) 2, 115–119; On a contaminated planet, it might be difficult to distinguish the DNA of extraterrestrial life from the DNA of life brought to the planet by the exploring.
After revision: On a contaminated planet, it might be difficult to distinguish the DNA of extraterrestrial life from the DNA of life brought to the planet by the exploring.