One year ago this week people around the world held their breaths as Nasa’s Curiosity rover began its landing sequence. The complicated sky crane, which lowered the rover from a tether before gently hovering closer and closer to the surface, worked. Curiosity reached Mars healthy, and we were all happy.
Since landing, Curiosity has sent more than 190 gigabits of data to Earth, returned more than 70,000 pictures, and fired its laser more than 75,000 times. What’s more, just a year into the mission and Curiosity has already achieved its main science goal.
Curiosity never set out to look for life, although that’s the ultimate goal in exploring Mars. After Nasa’s Viking landers failed to find sure signs of life in 1976, the agency took a step back. It has since, along with the European Space Agency, launched a series of missions designed to understand the Martian environment. It stands to reason that knowing as much as we can about ancient Mars will help us determine whether or not there was ever life on our planetary neighbour.
Curiosity was the latest step in this detailed Martian survey. Specifically, it was designed to look at Mars chemically to see whether there is any evidence that the planet was once habitable. It may seem like an esoteric mission goal, but it’s an important one.
And it’s a goal Curiosity has already accomplished. Not only has the rover found compelling evidence of deep, fast-moving water on the surface of ancient Mars, it’s determined that Mars could have played host at least to microbes in the past. The rover, which is basically a roving chemistry laboratory, drilled into a rock and analyzed the dust. It found traces of sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon. It also found that 20% of the sample was clay minerals, something you find on Earth only when fresh water interacts with igneous materials. There was calcium sulfate in the sample, too, suggesting the water that was once there was neutral or slightly alkaline.
In short, the remnants of Mars’ old environment found by Curiosity suggest the planet could have played host to living organisms.
The next step is to look for evidence of that past microbial life directly, and that’s what Nasa is planning to do with another Curiosity-type mission. In 2020, the space agency is going to launch a similar rover with the necessary onboard instruments to visually, mineralogically, and chemically analyse the Martian environment right down to the microscopic level. It will look for biosignatures or forms left in rocks that could only be explained by the presence of life. We’re talking microbes, not little green men.
Not only will it look for evidence of past life, this new rover will collect a series of small samples and store them. A later mission could then retrieve the samples and bring them back to Earth. It will be much easier to look for traces of life with those returned samples. Rather than have a rover whose instruments get more out of date every day on Mars, scientists will be able to test and retest samples with the latest technology here on Earth.
Up next for Curiosity is a bit of a road trip. It landed, as planned, in Gale Crater near its primary target of Mount Sharp. An up close study of the mountain’s exposed layers promises to tell the billions-year-old geological story of Mars’ life, so that’s where the little rover that can is rolling off to next.