Evidence for the extraterrestrial origin of polycyclic aromatic hydrocarbons in the Martian meteorite ALH84001

Abstract

Possible sources of terrestrial contamination are considered for the observation of polycyclic aromatic hydrocarbons (PAHs) in the Martian meteorite ALH84001. Contamination is concluded to be negligible.

Truncated hexa-octahedral magnetite crystals in ALH84001: Presumptive biosignatures

“…As such, these crystals are interpreted as Martian magnetofossils and they constitute evidence of the oldest life yet found. In support of this, we note that early Mars likely had free-standing bodies of liquid water (13,14), and both organic (15) and inorganic carbon and energy (e.g., atmospheric CO 2 13 ) sources. Furthermore, early Mars also likely possessed a substantial planetary magnetic field (16), which would have been sufficient to support the evolution and growth of magnetotactic bacteria.…”

“…Consequently, the lack of detectable organic compounds at the two Viking sites (Chryse Planitia & Utopia Planitia) may be a surface-limited feature, and organic carbon could exist at deeper levels. Indigenous aromatic organic compounds have been detected in the two Martian meteorites-ALH84001 (15) and Nakhla (S.J.C., unpublished data).…”

Magnetofossils from Ancient Mars: a Robust Biosignature in the Martian Meteorite ALH84001

“…It is not known whether organic compounds are present in soil below the surface. Indigenous organic compounds have been detected in some Martian meteorites (34,64), including ALH84001 (19). Thus, Mars appears to have had and may still have relatively large reservoirs of liquid water in which microbes could have existed and may continue to exist.…”

Origins of magnetite nanocrystals in Martian meteorite ALH84001

“…Absence of graphite within carbonate disks, e.g., McKay et al (1996), Flynn et al (1998), Flynn et al (1999), Clemett et al (1998) and this study.…”