Europe's ExoMars rover, is scheduled to land on the Red Planet in March 2021.
Dubbed 'Rosalind' in honor of the British chemist Rosalind Franklin, the rover will drill six-and-a half feet down into the ground to take samples.
The Martian cores are then fed through an aperture on the rover into a mobile laboratory where they are crushed up and examined for organic matter.
Confirmation of life could come within just weeks or months of landing.
Likewise NASA's rover Mars2020 will drill into rock formations on the surface and then leave the samples in test-tubes which will later be collected and sent back to Earth for examination, the first time that material from Mars will ever have been brought back.
Crucially, scientists will be looking for the 300 minerals which can only be made by life.
The rovers will be hunting near the site of an ancient Martian ocean, where life may have lived billions of years ago, when the Red Planet was 'blue' like Earth.
"I'm excited about these missions because they have the opportunity to find life, they really do, and I want them to," he added.
"We've never drilled that deep down. When environments get extreme life moves into the rocks.
"When we first started the field of astrobiology in the 90s we started looking for extreme life. We go down in mines two miles deep into the Earth and if they were weeping with water they were full of life.
"We have gone in nuclear cesspools, places where you'd think nothing could survive, and they are full of life. And the bottom line is where there is water there is life.
"In fact, because the crust has so much water in it, we now know that there is more life below our feet than on the surface of this Earth including life in the ocean."
Dr Green, who has worked at NASA for 38
years, believes that as well as small
organisms on other planets, there may be
'weird life' on
Saturn's moon Titan, and
even civilizations in the non-so-distant
reaches of the galaxy.
Recent research has also found that areas in Solar Systems that scientists considered uninhabitable may have once held liquid water.
Planets that are neither too hot or too cold for liquid water are said to be in the 'Goldilocks Zone', but this month computer modeling showed that Venus could have held water for billions of years, despite being so close to the Sun.
Venus may have been warm and wet
for billions of years, long enough
for life to become established
Credit: NASA
The Moon is also now known to have a water cycle.
"This concept of what a 'Goldilocks Zone' looks like has to be modified," added Dr Green.
"Venus was a blue planet for a significant amount of time. There is no reason to think that there isn't civilizations elsewhere, because we are finding exoplanets all over the place.
"We now know from Kepler observations that there are more planets in the galaxy than there are stars."
He added:
"If we were going anywhere to look for life that is not like us we would go to Titan.
"On Titan you substitute methane for the water, so you will have a different type of life, a new set of chemicals that would compose a new type of DNA. It really would be weird."
The NASA and ESA missions will take off in the same month as other Mars projects from the United Arab Emirates (UAE) and China.
"They're all going at the same time, because it's when the window opens," said Dr Green.
"It's like rush hour to Mars, but that's when the alignment of the planets is just right and we can get there as fast as possible, not chase Mars around the Sun."
NASA's rover will enter the atmosphere at 4 miles per second, and to slow down, the lander must flip onto its side and travel vertically to pick up enough drag that it will not crash to the surface.
The lander will then hover and place the rover gently onto the surface using a sky crane.
"We have a little wiggle room but it's still like hitting a golf ball in New York and having it land a hole in one in LA," he added.
"NASA can do that. We do the impossible, and we do it everyday. So does ESA. Our space agencies do incredible stuff. They perform miracles all the time."