Astrobiology is the search for the origin and distribution of life in the universe. A microbiologist by training, his principal interest is in developing protocols, instrumentation, and procedures for life detection in samples from the early Earth and elsewhere in the Solar System.

    The main focus behind Andrew Steele's research has been the development of scientific and measurement criteria for the unambiguous detection of life in early Earth and Mars samples, future robotic and sample return missions to Mars, and missions to Europa and Enceladus.

    The scientific underpinning of this work has revolved around establishing a “null hypothesis” to life detection that relies on accurately cataloging non-biological morphological and organic chemical input to a particular sample. His laboratory work has concentrated on samples as diverse as Apex chert, Strelley pool chert, Isua, Akilia, Gunflint samples, as well as mantle xenoliths, fossil lagerstatten (Enspel, Messel), Martian meteorites, Apollo return samples, ordinary and carbonaceous chondrites, Stardust, ureilites, and inclusions in diamonds.

    He uses light microscopy with high resolution scanning confocal Raman spectroscopy to initially survey samples of interest.

    The search for life cannot be accomplished with confidence in one particular measurement, and as such multiple analysis techniques must be used on the same sample to give a convincing answer. Steele has developed the capability to use and interpret data from a wide range of instrumental techniques, including; Atomic Force Microscopy, Scanning and Transmission Electron Microscopy, FTIR spectroscopy, Isotope Ratio Mass Spectroscopy, Time of Flight Secondary Ion Mass Spectrometry, Gas Chromatography-Mass Spectrometry, Electron and Ion Microprobes, X-ray elemental and Diffraction analysis (EDX and XRD), microbial culturing and aseptic technique, biomolecule extraction, DNA amplification, Lab-on-a-chip microfluidic capillary electrophoresis and metabolism, and endotoxin analysis.

    He has been instrumental in developing several of the latter techniques for robust use in field conditions and was a part of a team using non-culture-based methods on the International Space Station.

    His laboratory work with a range of co-investigators has led to some significant discoveries, including; lunar graphite, new carbon allotropes in meteorites, the detection of 4 abiogenic organic carbon synthesis mechanisms on Mars, as well as water in lunar and Martian rocks. This year I have also been part of the COSAC instrument team onboard the Philae lander on the ESA Rosetta mission. By following the trail of abiotic carbon, he has become very interested in the terrestrial and Martian deep carbon cycles. His current work focuses on what appears to be an explanation for reduced carbon species within the terrestrial and Martian mantles, following the unambiguous discovery of organic carbon in Martian meteorites.

    He is also a co-investigator on the Sample Analysis at Mars (SAM) instrument onboard the Curiosity Mission and the SHERLOC instrument on Perseverance (Mars 2020) Mission.

    In an effort to continue setting an abiotic baseline for the detection of life, Steele and collaborators have been undertaking high pressure and temperature experiments into organic carbon produced during the cooling of silicate melts. He is currently funded to undertake these experiments through a NASA grant, and we will continue to vary temperature, composition, and oxygen fugacity parameters to characterise possible organic synthesis reactions in these systems.

    Finally, he is exploring a further line of research that I have recently begun, to probe the reactions that could lead to the transition of abiotic chemistry to prebiotic chemistry and then life. At this time, this work has involved bioinformatics research into the nature of protein-nucleic acid interactions that could have led to the first proto-life molecular constructs that led to information exchange and storage under the conditions that formed life on earth. It is Steele's goal to transport this in-silico work into several laboratory experiments that would shed light on the origin of protein / nucleic acid interactions.




    Recent Publications