The exploration of Mars is being unnecessarily hindered by fears that we could contaminate the planet, a report has suggested.
Current missions to the planet have to be carefully managed to avoid sending microbes to the Red Planet from Earth. The worry is they could either damage evidence of former life on Mars, or even "infect" the planet with new organisms.
But a new report published in Nature Geoscience argues that these policies need to be reassessed in order to speed up our search for life on our nearest neighbour.
Alberto G. Fairén (Cornell University) and Dirk Schulze-Makuch (Washington State University) argue in "The Overprotection of Mars" that missions to the most interesting places on Mars are unable to launch due to overly "detailed and expensive sterilization requirements" imposed by the Committee on Space Research and other bodies.
Either life from Earth cannot survive there, in which case we don't need to worry, the report argues, or it can - in which case it's probably there already.
"If Earth life cannot thrive on Mars, we don't need any special cleaning protocol for our spacecraft; and if Earth life actually can survive on Mars, it most likely already does, after four billion years of meteoritic transport and four decades of spacecraft investigations not always following sterilisation procedures," said Farien in the report.
"Planetary protection policies are at least partly responsible for the lack of life-hunting Mars missions since Viking, as they impose very stringent requirements for sterilization of the spacecrafts which, in my opinion, are not necessary."
The report adds that Nasa's stated goal of sending a human to Mars in the 2030s will render all of the policies moot in any event.
"NASA's program of human exploration of the Solar System includes sending humans to Mars in the 2030's, and it won't be a surprise if other nations also try to put a human on Mars even earlier. You can't sterilize humans, and as soon as an astronaut steps on Mars, you will have Earth bacteria on Mars. Are all these complicated procedures valid just for the next two decades? What happens next?"
In a response, Nasa's Catharine A. Conley writes that such protections "are essential for any valid plan to search for any extant or extinct life on Mars".
"Preventing the contamination of the Mars environment is the best way to ensure we have a chance to understand our own origins and the potential for life on Mars, now and in the future," she said.