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Australian scientists who modeled conditions on Mars to examine how much of the red planet was habitable said on Monday that "large regions" could sustain life.

Charley Lineweaver's team, from the Australian National University, compared models of temperature and pressure conditions on Earth with those on Mars to estimate how much of the distant planet was livable for Earth-like organisms.

While just 1 percent of Earth's volume - from core to upper atmosphere - was occupied by life, Lineweaver said their world-first modeling showed 3 percent of Mars was habitable, though most of it was underground.

The astrobiologist explained that the group simply tried to take all of the information possible and put it together and asked the question: 'is the big picture consistent with there being life on Mars?'

The simple answer is yes. The scientists found that there are large regions of Mars that are compatible with terrestrial life.

Where previous studies had taken a "piecemeal" approach by examining particular sites on Mars for signs of life, Lineweaver said his research was a "comprehensive compilation" of the entire planet using decades of data.

Frozen water has been found at the poles on Mars and the ANU study examined how much of the planet could sustain water "that could be habitable by Earth-like standards by Earth-like microbes".

The low-pressure environment of Mars means water cannot exist as a liquid and will vaporize on the surface, but Lineweaver said the conditions are right underground, where the weight of the soil gives the added pressure required.

It would also be warm enough, at certain depths, for bacteria and other micro-organisms to thrive due to heat from the planet's core.

The average surface temperature on Mars, Earth's nearest neighbor, is minus 63 C.

Lineweaver said his study was "the best estimate yet published of how habitable Mars is to terrestrial microbes" and a significant finding given mankind had evolved from microbial life.

The scientist said that his study was no not important to figuring out the laws of physics or to talk to intelligent aliens. But it’s important for those interested in the origin of life and how likely life is to get started on other planets."

NASA's Curiosity Rover, the largest, most sophisticated robotic explorer ever built, is en route to Mars and due to land in August 2012.

It has a laser beam for zapping rocks and a tool kit to analyze their contents as well as a robotic arm, drill, cameras and sensors to enable it to report back on the Martian weather and atmospheric radiation.

Questions:

1. What percentage of Mars is habitable?

2. What does the low-pressure environment of Mars mean for water?

3. When is NASA's Curiosity Rover due to land on Mars?

Answers:

1. 3 percent.

2. It cannot exist as a liquid and will vaporize on the surface.

3. August 2012.

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About the broadcaster:

Emily Cheng is an editor at China Daily. She was born in Sydney, Australia and graduated from the University of Sydney with a degree in Media, English Literature and Politics. She has worked in the media industry since starting university and this is the third time she has settled abroad - she interned with a magazine in Hong Kong 2007 and studied at the University of Leeds in 2009.