School of Natural and Environmental Sciences

Event items

Early Earth biosignatures and the search for life on Mars

Earth, Ocean and Planetary Sciences Seminar Group - Dr Frances Westall, CNRS-Centre de Biophysique Moléculaire, Orléans, France

Date/Time: Thursday 29 November 2018, 13:00 - 14:00

Venue: Ridley Building 2, Room 1.58


What kind of life can we expect on Mars?

Given its apparent “punctuated” habitability (Westall et al., 2013, 2015) over the course of its history and likely lack of connectivity of its habitats (Cockell et al., 2013), life forms on Mars are likely to have been, at a minimum, even more primitive that the simplest life forms on Earth (protocells).

At a maximum, they are not likely to be more evolved than anaerobic prokaryotes (organotrophs and lithotrophs), although it must be honestly stated that we really do not understand the early evolution of Mars and its habitability.

These kinds of lithotrophic and organotrophic anaerobes were common on the early Earth, a good analogue for early Mars – on the microbiological scale.

These organisms were preserved as morphological fossils, organic traces and by-products of their activities.

Among the latter are biofilms formed in the vicinity of nutrient-rich hydrothermal effluent, as well as microbial polymer (EPS, extracellular polymeric substances)-filled tunnels in volcanic shards.

These are kinds of biosignatures for which the European/Russian ExoMars 2020 mission will be searching, the emphasis in this mission, however, being analysis of organo-chemical biosignatures.

  • Vago, JL., Westall, F., Pasteur Teams, Landing Site Selection Working Group, and Other Contributors 2017. Habitability on Early Mars and the Search for Biosignatures with the ExoMars Rover. Astrobiology, 17, 471-510.
  • Westall, F., et al.  2015, Biosignatures on Mars: what, where and how? Implications for the search for Martian life. Astrobiology, vol 15, pp 998-1029
  • Westall, F., et al., 2013. Habitability on Mars from a microbial point of view. Astrobiology, 13, 887-897.
  • Westall, F., et al., 2011. Early life on Earth & Mars: a case study from ~3.5 Ga-old rocks from the Pilbara, Australia. Planetary & Space Science, 59, 1093–1106
  • Foucher, F., Westall, F., Bény, J.M., Brandstätter, F. & Demets, R., 2009. STONE 6 Experiment : An investigation of the survival of microfossils during atmospheric entry. Origins of Life and Evolution of Biospheres, 39, 360-361