The discovery on Mars of the perchlorate ion, ClO4, "probably comes down as a positive rather than a negative" says principal investigator Peter Smith. However, other scientists were less optimistic about the potential. Michael Hect of NASA's Jet Propulsion Laboratory described the finding as "neither good nor bad for life".
Perchlorate ions form salts with elements such as sodium and magnesium, as well as the ammonium ion among others. Some perchlorate salts are in fact, not only compatible with life, but certain bacteria strains can use them as an energy source.