How the Next Generation of Mars Rovers will Search for Signs of Life

Humankind has long dreamed of setting foot on another planet, and the orange glow of nearby Mars has caught our eye. While we aren’t quite there yet, we’re getting close: In the past 36 years, NASA has sent three landers and four rovers to the red planet, all in the service of eventually getting humans to Mars. In the summer of 2020, we’ll send the most advanced robotic emissary yet armed with a whole new suite of tools. The Mars 2020 rover hasn't even been christened yet, but it already has a big goal: to find signs of life.

The new rover will have some big space shoes to fill. In 2012, the Mars Science Laboratory (MSL), more commonly known as Curiosity, survived seven minutes of terror before coming to a gentle touchdown on the surface of the red planet. Since then, Curiosity has astonished scientists around the world with its ongoing discoveries about Mars. Scientists may have already known that there was once water on Mars, as its polar caps are covered in frozen water-ice and there are clear river-like channels on the surface. But Curiosity was the first to confirm that Mars had once been covered in water, meaning that Mars was once a habitable place some 3 billion years ago. 

Curiosity also discovered an abnormal source of methane gas in the atmosphere, which is usually released by living organisms. “With Curiosity, we got extremely good evidence that there was once an abundance of liquid water there,” says Ken Williford, Mars 2020 Deputy Project Scientist at NASA’s Jet Propulsion Laboratory.  “Not only that, but there were elemental ingredients for life. Curiosity found evidence not just for water but water with interesting chemistry. All of this is good evidence that early Mars was habitable. We just now have to figure out, exactly how long ago did those habitable conditions exist?”

The new rover will feature a similar suite of instruments, and will look almost identical to its predecessor. But instead of looking for water, the Mars 2020 rover will be the first with an explicit mission to hunt for evidence of life. “We are really the first NASA mission since Viking to have stated an objective to seek the evidence of life directly,” Williford says. “The MER (Mars Exploration Rovers) took the critical first steps of following the water, Curiosity took the next step and searched for evidence of habitability. Now Mars 2020 will take it one step further, by directly looking for evidence of ancient life on the Martian surface.”

“Ancient” is the key word here. After decades of studying our own solar system and exoplanets around other stars, most scientists agree that our planet is a galactic anomaly. Earth has an abundance of fresh water, plenty of oxygen and lush plant life to help regulate our atmosphere. On the other hand the surface fo Mars is a cold, barren landscape and countless ways of killing any life forms, from freezing to suffocating to irradiating to starving. “One thing we’ve learned is that the surface of Mars today is incredibly inhospitable to life as we know it,” says Williford. Scientists will use Mars 2020’s seven instruments to search for fossilized microbes that may at one time have lived and even flourished during the red planet's heyday.

In many ways, Mars 2020 will explore the surface just as MSL did. “We’ll ultimately drive around like we’ve done with Curiosity,” explains Williford. “We’ll use the Mastcam-Z camera to survey the surface of Mars just like a geologist would do, and when we see something interesting and worth examining, we can then direct the rover to drive closer, at that point then we can break out the instruments we need to do our research.”

Mars 2020 will then use several of its high tech features to examine its surroundings. A few tools in particular that will headline the search for fossilized life: PIXL (Planetary Instrument X-Ray Lithochemistry), RIMFAX (Radar Imager for Mars’ subsurFace eXperiment), and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals).  PIXL can identify chemicals the size of a grain of table salt, a tool vital when searching for near microscopic fossils. “RIMFAX is a completely new technology for the surface of Mars,” says Williford. Its ground penetrating radar will allow scientists to trace out bedrock layers that the rover would otherwise not be able to see. And SHERLOC’s spectrometer technology can identify organics and possible bio signatures in the geology on Mars.

The team is looking for evidence of microscopic life by looking at macroscopic features; specifically, they’re looking for stromatolites. These features, also found on Earth, are layered structures in rocks that are essentially microbial mass. “If we found a stromatolite, we could use our chemistry instruments to understand its makeup of elements and mineralogy,” says Williford. “This will help indicate that life may have been present to produce those minerals.”

Mars 2020 is more forward-looking than any previous expedition. The rover will collect actual rock and soil samples along the way, and place them into stored tubes where they will be sealed and left strategically on the surface for future astronauts to collect. “The scientific community agrees that if we want to get serious about the search for ancient life on Mars, and find what we could call conclusive evidence of ancient life, it will almost certainly require us to return samples from the surface so that we can analyze them back on Earth using our full arsenal of scientific techniques,” says Williford.

There is one special addition to Mars 2020 that’s never been done before: a set of microphones. For the first time audio of a rover’s entry, descent and landing process will be recorded. By having access to audio of Martian operations, it will let the science teams listen to the sounds of their instruments on board, allowing them to diagnose any problems. Even cooler from an Earthling’s perspective, the rover will send back recordings of Martian winds and weather changes, letting us hear sounds created on another world, far away from our own, for the first time.

The 2020 rover is just one of many future NASA missions with the goal of finding evidence of past life in our solar system. It may be still be years before we find evidence of life, but if we do find it, the consequences would be vast. “It’s one of the biggest scientific questions that has ever existed in human history,” says Williford. “That is: has life ever existed outside of Earth? To find conclusive evidence that life emerged and existed elsewhere would fundamentally change our understanding of the universe."