Martian lifeforms could be hiding under the surface of the Red Planet's atmosphere, according to ground-breaking research led by a New Zealand scientist.
Canterbury University geologist Dr Christopher Oze believes evidence of life forms could be found on earth's closest neighbour by measuring its ratio of hydrogen to methane.
He has teamed up with colleagues in the United States over the last three years to perform a series of experiments to examine the dynamics hydrogen and methane production in hydrothermal systems.
The research made scientists realise that life could be possible on other planets.
"Life forms on Mars may be under the surface of the planet, where no probe can currently go right now," Dr Oze said.
"But methane and hydrogen formed in specific hydrothermal systems are eventually released at the surface so all that needs to be done is for an analysis to be made at a vent to measure the gas that is released.
"What's really nice about this is that it is an incredibly simple method - all you need to do is measure the methane and hydrogen levels on Mars, something that can easily be done now."
The team's experiments, which excluded living things, involved measuring the rates of methane production during a process called olivine hydrolysis or serpentinization, which occurs in the deep sub-surface of Earth and Mars.
Dr Oze said olivine is an abundant mineral found on both planets.
By using water to convert it to serpentine, the team measured how quickly methane was produced. This was then compared to measurements taken in the field where living organisms were present.
"From these experiments the hydrogen to methane ratio over time divided hydrothermal systems that did not involve living matter from those in which biota was present," Dr Oze said.
"This really gave us an 'aha' moment where we realised this method could be used to look at life on other planets.
"From our calculations low hydrogen-methane levels could indicate that there might be life, if it's similar to that on Earth."