New analysis of infamous NASA meteorite finds no evidence of life on Mars: Decades-long study debunks excited 1996 claim from the likes of Bill Clinton that it could prove existence of life on Red Planet

• NASA scientists in 1996 claimed a meteorite showed evidence of life on Mars
• Bill Clinton arranged a televised press conference hailing the 'awe-inspiring' find
• Other scientists were sceptical and modern techniques have proved them right 
• The new study says that evidence of organic material was made by water 

A meteorite that caused a global frenzy in the 1990s after it was dubiously claimed by many including President Bill Clinton that it could show evidence of life on Mars has been proven to be nothing more than a lump of rock and water.

The four billion-year-old piece of rock, discovered in 1984 in Antarctica, made headlines worldwide after a group of NASA-led scientists said in 1996 it contained microscopic fossils of bacteria.

Their claims prompted Clinton to arrange an immediate televised press conference about the discovery, which he said could be 'one of the most stunning insights into our universe that science has ever uncovered'. 

He said: 'Its implications are as far-reaching and awe-inspiring as can be imagined. 

'Even as it promises answers to some of our oldest questions, it poses still others even more fundamental.'

The president used the claims to justify further funding for America's space programme.

But even at the time, scientists were sceptical of the NASA-led findings and questioned the hype around the apparent discovery.

And they have now been vindicated after researchers spent decades studying the 4lb rock in detail.  

Experts from the Carnegie Institution for Science in Washington, DC, examined tiny samples of the meteorite, finding that the carbon-rich compounds are actually the result of salty, briny water flowing over the rock for a prolonged period of time.

The rock would have been formed during Mars' wet and early past, with two impacts occurring near the rock that heated the planet around its surface, the team found.

A third impact bounced the rock off the Red Planet, sending it into space millions of years ago, eventually landing on the Earth, and discovered in Antarctica in 1984. 

The science community has long questioned the original NASA findings, suggesting something other than signs of life created the organic compounds.

For this new study a team analysed the minerals in the meteorite using new techniques, discovering they were associated with serpentine-like minerals.

This is a dark green mineral that can sometimes be spotted like a snake skin, and is associated with once-wet environments, as the early Mars would have been when it first formed.  

The researchers suggest that billions of years ago Martian groundwater, moving through the cracks in the rock, formed the tiny globs of carbon. 

They are what made some scientists in the 1990s think that there was evidence of ancient Martian primitive life contained within the Antarctica meteorite.

The same process, of water moving through cracks, can happen on Earth and could help explain the presence of methane in Mars' atmosphere, they said.

One of the processes that may have been at play on a young Mars is serpentinization, which happens when iron or magnesium-rich volcanic rocks interact with circulating water.

This changes their mineral nature and produces hydrogen in the rock.

Another method that may have led to the findings is carbonisation, which is the result of rocks reacting with acidic water that contains dissolved carbon dioxide. 

The organic compounds found by the 1996 NASA team were likely produced when volcanic rock on Mars interacted with briny water, flowing over the rock. 

According to study lead author, Andrew Steele, advances in technology made his team's new findings possible.

He commended the measurements by the original researchers and noted that their life-claiming hypothesis 'was a reasonable interpretation' at the time. 

He said he and his team - which includes US, German and British scientists - took care to present their results 'for what they are, which is a very exciting discovery about Mars and not a study to disprove' the original premise.

This finding 'is huge for our understanding of how life started on this planet,' explained Steele, as well as whether life may have started on an early Mars.

He added that it helps refine the techniques we need to find life elsewhere on Mars, or Enceladus and Europa.'

There are already rovers on Mars looking for signs of life - with vehicles sent from NASA and China, with another due to arrive from Europe next year.

Future missions are expected to visit the ice-moons of Jupiter and Saturn, as they are thought to contain massive, moon-sized oceans under the surface ice, which may host living bacteria. 

The only way to prove whether Mars ever had or still has microbial life, according to Steele, is to bring samples to Earth for analysis. 

NASA's Perseverance Mars rover already has collected six samples for return to Earth, with about three dozen samples expected to be produced.

They will be collected from the surface of the Red Planet by a joint NASA and European Space Agency mission, and returned to Earth by 2030.  

China and Japan are also planning to visit the Red Planet in the coming decades, and bring samples of Martian rock back to the Earth for study. 

The small piece of rock, found in Antarctica on December 27, 1984, by a team of American meteorite hunters, is one of the most studied in the world. 

Studies have shown that it was blasted off the surface of Mars by an asteroid impact about 17 million years ago, causing it to float through space on its way to the Earth.

It eventually plummeted to Earth, landing in the Allan Hills of Antarctica about 13,000 years ago, where it sat, untouched,

The small gray-green fragment got its name - Allan Hills 84001 - from the hills where it was found on the frozen continent. 

Two scientists who took part in the original study took issue with these latest findings, calling them 'disappointing.' 

In a shared email, Kathie Thomas-Keprta and Simon Clemett, astromaterial researchers at NASA's Johnson Space Center in Houston, said they stand by their 1996 observations.

'While the data presented incrementally adds to our knowledge of (the meteorite), the interpretation is hardly novel, nor is it supported by the research,' they wrote.

'Unsupported speculation does nothing to resolve the conundrum surrounding the origin of organic matter' in the meteorite.' 

'I think the debate on this meteorite polarised the community many years ago but I think a lot of that polarization has eased over the years,' Steele told Space.com. 

'I hope this paper inspires the debate again in a positive way.' 

The findings appear in the journal Science.