We may be coming up on the two year anniversary of NASA’s Curiosity rover landing on Mars, but we’ve just passed Curiosity’s first Marsiversary. June 24 marked one Martian year—687 Earth days—that the rover has been active on the surface of our planetary neighbour, and it’s been a great Mars-year.
Curiosity was designed for a bit of a strange purpose. Rather than look for life directly, this mission was designed to look at the Martian environment to determine whether Mars could ever have hosted life.
The rover accomplished that major mission goal not long after landing. After finding an ancient riverbed, Curiosity traveled to an area called Yellowknife Bay, where it found and drilled into two mudstone slabs. Analysis revealed the site was once a lakebed with water, the essential elemental ingredients for life, and the same chemical energy some microbes on Earth use. If anything ever lived on Mars, Curiosity roved right into what might have been its home.
In the months since accomplishing its primary goal, Curiosity has made some other really important discoveries and gathered some really important data points that will help shape future missions.
During its coast to Mars and since its arrival on the surface, Curiosity has measured radiation levels. Understanding the radiation environment will held scientists designing adequate protection future human astronauts on manned missions to the red planet.
Curiosity's celebratory Marsiversary selfie. Image: NASA
The rover has also measured the variation of elements in the Martian atmosphere, specifically the ratio of heavy to light elements. Curiosity determined that much of Mars' early atmosphere disappeared by processes favoring loss of lighter atoms. The lighter atoms were lost to space. Other measurements found that the atmosphere holds very little, if any, methane, a gas that is typically produced biologically on Earth.
Curiosity was also the first rover to determine the age of a rock on Mars and how long it’s been exposed to radiation. Assessing the degradation of organic compounds in rocks and soil has given the science team a better understanding of when water flowed on Mars.
Earlier this (Earth) year, Curiosity drilled and collected a sample from a sandstone site called Windjana. "Windjana has more magnetite than previous samples we've analyzed," said David Blake, principal investigator behind Curiosity's Chemistry and Mineralogy (CheMin) instrument at NASA’s Ames Research Center. "A key question is whether this magnetite is a component of the original basalt or resulted from later processes, such as would happen in water-soaked basaltic sediments. The answer is important to our understanding of habitability and the nature of the early-Mars environment.”
Curiosity still has the Windjana sample on board for follow-up analysis, but preliminary analysis indicated this sandstone contains a more diverse mix of clay minerals than any rocks Curiosity has yet investigated.
Most notably, this sample is unexpectedly rich in orthoclase, a potassium-rich feldspar that is among the most abundant minerals in the Earth's crust, but has never been definitively found on Mars. This suggests this area of Mars has gone through complex geological processing, something like multiple episodes of melting.
"It's too early for conclusions, but we expect the results to help us connect what we learned at Yellowknife Bay to what we'll learn at Mount Sharp," said John Grotzinger, a Curiosity project scientist at the California Institute of Technology. "Windjana is still within an area where a river flowed. We see signs of a complex history of interaction between water and rock.”
The first Mars-year has also led to some hardware issues, namely wheel damage from some unexpectedly hard rocks. This has slowed the rover’s process slightly and forced a change in route to the base of Mount Sharp, which has been Curiosity’s target all along. Scientists suspect the base of this mountain inside a crater will have exposed geological layering that will answer questions about Mars’ ancient environment.
Because Curiosity reached its main goal so early after landing, the bar has been raised for the next phase of the mission. Now the question at Mount Sharp won’t just be whether ancient Mars could have supported life, but also how the Martian environment evolved and what conditions have preserved the traces that might tell us whether life ever existed on the red planet’s surface.
Curiosity is currently a little less than 2.5 miles from reaching Mount Sharp. It will get there in the coming months by crossing some sandy patches and some rockier ground, hopefully limiting further wheel damage. "We are getting in some long drives using what we have learned," said Jim Erickson, the Curiosity project manager at NASA's Jet Propulsion Laboratory. "When you're exploring another planet, you expect surprises. The sharp, embedded rocks were a bad surprise. Yellowknife Bay was a good surprise.”
This first Marsversary also marks the end of Curiosity’s primary mission, but the rover obviously isn’t stopping anytime soon. And if this first Mars-year is any indication, we should see a some pretty incredible things during Curiosity’s second year on Mars.