Analysis of soil from the red planet found that its surface had been dry for such a long time that any life would have to be lurking deep underground.
Researchers deduced that there had been water present during a warmer period lasting up to 5,000 years in the distant past, but this would have been too little time for life to establish itself on the surface.
The findings published in the Geophysical Research Letters journal were based on soil collected during the 2008 Nasa Phoenix mission to Mars.
Experts spent three years painstakingly scrutinising individual particles of soil to determine whether or not the planet was habitable.
The analysis, by Imperial College London researchers, showed that soil on Mars is formed under similarly arid conditions to the Moon.