The discovery of the oldest fossil on Earth at Nuvvuagittuq Supracrustal rock formations in Canada's Quebec has shown that microscopic bacteria smaller than the human hair flourished 4.2 billion years ago.
The excavation also confirmed that the organisms thrived in hot conditions of the oceans in almost 60 degrees Celsius during early Earth.
It then follows that if life existed on Earth at hot vents, similar organisms would have existed on Mars as well where the existence of oceans and atmosphere had been confirmed.
Fossils On Mars
The team of scholars from University College London who made the Quebec discovery believes that similar fossils might be there on the Mars as well and tracing vestiges of hydrothermal vents will be the right way to confirm alien life.
"We found the filaments and tubes inside centimetre-sized structures called concretions or nodules," said Dr. Dominic Papineau of UCL Earth Sciences and the London Centre for Nanotechnology, referring to the microfossils found in Quebec.
The research has been published in the journal Nature.
Martian Origin Of life
Traces of life on Mars will strengthen the belief that life had a Martian origin under the concept panspermia.
"Early Mars and early Earth are very similar places, so we may expect to find life on both planets at this time," added Matthew Dodd, the lead author and a doctoral student of the study cofunded by NASA.
According to astronomer Royal Sir Martin Rees, life evolved on both Earth and Mars at the same time.
"It's indeed possible that life started on Mars as well as the Earth, but then fizzled out — maybe leaving some traces that we will discover from future probes," Rees added.
This fossil lead from Earth has shifted the focus to Mars, where decades of exploration to confirm life had been going on with NASA at the lead with its orbiters and rovers.
However, one scientist has suggested a new approach.
Scientists Gibert Levin says way back in 1976, NASA detected microbial life on Mars. He was part of the Viking lander team, which conducted biological experiments and got mixed results.
Positive results came for metabolism detection, while organic molecules drew a negative reaction. That time, scientists held the view that biological signs were the result of natural processes.
Levin offers the hypothesis that unreliable organic molecule detection failed, but metabolism detection has been successful.
The challenges of searching for life on Mars with indirect experiments are also evident in the exercise.
"We're not looking for skeletons. We're looking for fossil microbes — if [Mars] life did indeed go extinct," said Ellen Stofan, then NASA's chief scientist, in 2016.
Rovers such as Sojourner, Spirit, Opportunity, and Curiosity made many discoveries in 27 years and unraveled signs of the ocean, flowing water, and organic molecules.
Though the experiments enhanced the understanding of Mars as a planet with warm and wet conditions suitable for life, they were short of clear evidence of microbes than Viking offered in the 1970s.
Deep Drilling Required
"The biggest advantage of future astronauts in terms of astrobiology is the ability to do deep drilling. The future of life search on Mars has to be with samples from deep underground," explains Chris McKay, a planetary scientist at NASA Ames Research Center.
That must be backed by on-site analysis rather than flying samples back to Earth.
McKay outlines a five-point action plan for making clinching evidence on the existence of Martian life.
• Dig deep for organic-rich samples
• Search samples for amino acids
• Try imaging with a microscope.
• Incubate samples for Viking-like experiment
• Bring samples to Earth for detailed study
Again, the bottom line is getting boots on the ground as a game changer, as humans have an edge over robots in the matter of exploration.