Is there life on Mars? A question everyone from Carl Sagan to HG Wells to Bowie has sought the answer to – and we may finally be close to getting an answer, but the world is not ready for it, according to NASA’s chief scientist.

Next year, two planned missions to send rovers to Mars will drill deep into the surface in the search for extraterrestrial life, which means we could find out the answer in the next couple of years. If we are successful it will be “revolutionary,” but we’re not prepared for this momentous occasion, Dr Jim Green, director of NASA's Planetary Science Division, warned.

“I’ve been worried about that because I think we’re close to finding it and making some announcements,” Dr Green said in an interview with The Sunday Telegraph. “It will start a whole new line of thinking. I don’t think we’re prepared for the results.”

In 2020, Earth and Mars will be at a close approach, opening a prime window for mission launches, something that five space agencies are taking advantage of. China and the United Arabic Emirates are preparing for their first trips, launching an orbiter and rover, and an orbiter, respectively.

NASA and the European Space Agency (ESA) in partnership with Russia’s Roscosmos are both sending rovers to drill for samples, hoping to find organic matter. NASA’s Mars 2020 rover will drill into rock formations to collect samples and send them back to Earth – the first time material from Mars will visit our planet. ESA’s Rosalind Franklin rover will also drill for samples, crushing up and analyzing them in Roscosmos' stationary surface laboratory while there.

Dr Green thinks both could be successful, and if they are it would be akin to Copernicus stating in the 1500s that Earth goes around the Sun, not the other way around, and how after that we had to reconsider everything we knew. Which is why he thinks Earth is not prepared for what happens if we do.

“What happens next is a whole new set of scientific questions. Is that life like us? How are we related? Can life move from planet to planet or do we have a spark and just the right environment and that spark generates life – like us or not like us – based on the chemical environment that it is in?” he said.

NASA’s Mars 2020 rover is due to land on the Red Planet's surface on February 18, 2021, with ESA’s Rosalind Franklin rover arriving one month later in March 2021. Both are searching in the vicinity of an ancient lake or ocean bed that once held water – so crucial for life – and may now be rich in clay. NASA's chosen landing site is the Jezero Crater delta, a 49-kilometer-wide (30-mile) crater once thought to have been flooded with water, and now a clay-rich delta. The ExoMars mission hasn't finalized its landing site yet but it announced last year its preferred site is Oxia Planum, a site rich in iron-magnesium clay, a sign water was once present.

Mars is not the only place with the potential to have once held water, including places scientists hadn't thought possible before. It was recently revealed that Venus, Earth's hellish twin, may have once had water 3 billion years ago before its atmosphere became incredibly dense and hot 700 million years ago. 

“There is no reason to think that there isn’t civilisations elsewhere, because we are finding exoplanets all over the place," Dr Green said. “This concept of what a ‘Goldilocks Zone’ looks like has to be modified.”