Life on Mars

Alfred Russel Wallace (the co-proposer of the concept of evolution by natural selection) was one of the first to seriously consider the possibility of life on Mars. In 1907 he published a small booklet, Is Mars Habitable? in response to American astronomer Percival Lowell's suggestion that marks on the surface Mars were canals built by intelligent Martians. After surveying all the evidence available at that time, Wallace concluded that: "Mars ... is absolutely UNINHABITABLE".

Today, data from both the ESA's Mars Express mission and NASA's Mars Exploration Rover missions suggest that conditions on Mars could support microbial life.

One of the scientific reports published as the Mars Express mission was being planned was Exobiology in the solar system and the search for life on Mars by Andrew Wilson [Ed.] (1999) European Space Agency Publications Division. ISBN: 92 9092520 5. This can be downloaded from the ESA's web site as a PDF file:

This report identified the conditions necessary to support microbial life, locations on the red planet most likely to support life, and the tell-tale chemical signs that might reveal its presence.

Potential practical work could include a microbial fuel cell, used to detect microorganisms that are able to oxidise organic compounds with the direct transfer of electrons to an electrode [1], or a colour-change method [2] such as those used in food freshness indicators?

1. Lovley, D. R. (2006) Bug juice: harvesting electricity with microorganisms Nature Reviews Microbiology 4, 497-508. | DOI:10.1038/nrmicro1442
2. See: (European Patent No. 99941753). These detect gases containing sulphides or amines.

Astrobiology and exobiology resources

The Astrobiology Web

NASA Astrobiology Institute

NASA Exobiology site

NASA 'Life on Mars' site

The Viking labelled release experiment (Controversial interpretation of the Viking data)

Marsbugs (Electronic Astrobiology Newsletter)

Important note: Martians once advertised instant potatoes in the UK -- so obviously there was life on Mars in the 1970s.