Australian scientists, who have made an overall study of temperature and pressure conditions of Mars, say that a greater percentage of the Red Planet is habitable than Earth.
Scientists from the Australian National University say that 3% of Mars could sustain life, while just one per cent of Earthâ€™s volume contains life â€“ from the core to upper atmosphere.
However, the researchers say that most Earth-like organisms would need to retreat underground to survive on Mars.
Astrobiologist Charley Lineweaver told AFP: â€śWhat we tried to do, simply, was take almost all of the information we could and put it together and say <<is the big picture consistent with there being life on Mars?>>â€ť And the simple answer is yes… There are large regions of Mars that are compatible with terrestrial life.â€ť
Life could exist on Mars, scientists say, largely because there is a huge amount of water there in the form of ice, found at the polar regions.
But the pressure on the planet is so low that water would vaporize on the surface.
Below ground, however, there is sufficient pressure for water to be kept in a liquid state, which would enable microbes to thrive.
And while the surface temperature is not ideal for life, being an extremely chilly -65C, below ground it would be much warmer thanks to heat from the planetâ€™s core.
Charley Lineweaver added that his study, which analyzed decades of data, was â€śthe best estimate yet published of how habitable Mars is to terrestrial microbesâ€ť.
His findings were published today in Astrobiology.
Scientists will learn a great deal more about Marsâ€™s ability to sustain life when the rover Curiosity lands on the surface next August.
NASAâ€™s earlier Viking rovers concluded 35 years ago that there was no sign of life, but scientists hope Curiosityâ€™s more sophisticated equipment will reveal more.
It will be â€śthe largest and most complex piece of equipment ever placed on the surface of another planetâ€ť, said Doug McCuistion, director of NASAâ€™s Mars exploration programme.
Curiosity rover is expected to land on Mars on August 5, 2012, after travelling nearly 354 million miles from our planet.
One of the chief tasks of the $2.5billion mission will be to discover the source of the methane gas scientists have detected in the Martian air.
It will also fire a laser beam with the energy of a million lightbulbs at the surface of the red planet to see whether or not it could have supported life.
The international team of space explorers that launched the Mars Science Laboratory is relying on the instrument to look for biological signs on the distant world.
The ChemCam will fire a powerful laser pulse, vaporising some Mars dust and examining the spectrum of light shining through it.
The robust system is one of 10 instruments mounted on the mission’s rover vehicle.
When ChemCam fires its extremely powerful laser pulse, it will vaporize an area the size of a pinhead.
The system’s telescope will peer at the flash of glowing plasma created by the vaporized material and record the colours of light contained within it.
These spectral colours will then be interpreted by a spectrometer, enabling scientists to determine the elemental composition of the vaporized material.