The U.S. space agency, NASA, is planning to send another rover to Mars in 2020.
A NASA-appointed team of 19 scientists and engineers says the next Mars rover should seek out signs of past life on the Red Planet and collect samples for possible future return to Earth.
One member of the Mars 2020 Science Definition Team, Lindy Elkins-Tanton of the Carnegie Institution in Washington, studies the evolution of planets. She told reporters during a NASA teleconference that questions are what drive scientific discoveries.
"And one of the very biggest questions for all of humankind is, 'are we alone?' and that is the question we're hoping to make really big advances with with this Mars 2020 mission," she said.
Scientists already scored a major victory when NASA's Curiosity rover, which landed on the Red Planet last August, provided evidence that ancient Mars had an environment that could have supported living microbes.
The team says the next step is to actually seek out biosignatures, preserved features in ancient rocks and soil that could have formed biologically.
Jack Mustard is the chair of the Science Definition Team and a professor of geological sciences at Brown University in Rhode Island. He says team members did discuss whether to look for existing life on Mars.
"But the feeling was, on the basis of the scientific evidence we have today, that the most logical steps forward were to look for the ancient signs of life that would be preserved within the rock record," he explained, adding that evidence suggests that habitable environments on Mars were common in the ancient past.
The next rover will look similar to the car-sized, six-wheeled Curiosity rover, in part because using an existing design will reduce costs. The 2020 rover would be able to drill into and sample Martian rock, just as Curiosity does now. But the team says a major objective for the next rover is to package as many as 31 samples that could be returned to Earth during a later mission.
John Grunsfeld, a former astronaut and NASA's associate administrator for science in Washington, noted that while the 2020 rover mission concept allows for the selection, gathering and caching of samples, it does not include their eventual return.
"I wouldn't rule out that perhaps human explorers will go and retrieve the cache, you know, in 20-plus years from now, as explorers set foot on Mars," he said. "That's an eventual goal: to put astrobiologists and planetary scientists on the surface of Mars."
The team also says the 2020 rover should help advance NASA's plans for human exploration of the Red Planet in the 2030s. The 2020 mission could help scientists understand any hazards posed by Martian dust or demonstrate ways to collect carbon dioxide that could be used as a resource for making oxygen or rocket fuel.
The Mars 2020 Science Definition Team is made up of experts from universities, research institutions and NASA. They spent much of 2013 preparing guidelines for the Mars 2020 mission and released a 154-page report on Tuesday.