A four billion-year-old meteorite from Mars that caused a splash here on Earth decades ago contains no evidence of ancient, primitive Martian life after all, scientists have said.

Tiny samples from the meteorite show the carbon-rich compounds are actually the result of water – most likely salty or briny water – flowing over the rock for a prolonged period, Steele said.

But two scientists who took part in the original study took issue with these latest findings, calling them “disappointing”.

He said he and his team – which includes Nasa, 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 and helps refine the techniques we need to find life elsewhere on Mars, or Enceladus and Europa,” Steele said in an email, referring to Saturn and Jupiter’s moons with subsurface oceans.

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.