“The overall highlight, I think, even a year later, still is planning successfully and seeing Gale Crater for the first time,” Vasavada said. He added: “We landed much more smoothly than we ever rehearsed it.”
2. Life on Mars could have existed. This was the major science highlight of Curiosity’s inaugural Martian year, Vasavada said. Although this discovery builds upon previous ideas, Curiosity provided enough confirmation for scientists to finally come out and say it: The environment Curiosity has been exploring was once habitable.
“We now know Mars offered favorable conditions for microbial life billions of years ago,” said the mission’s project scientist, John Grotzinger of the California Institute of Technology.
Curiosity became the first robot to drill on another planet, and the powder on the drill bit gave the scientists sufficient evidence to say that life could have survived in that area. The drill material had chemicals important for life in it, including sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon. Also excitingly for scientists, the sample contained a type of clay that forms in the presence of water.
The rover’s Mast Camera (Mastcam) additionally spotted evidence of water-bearing minerals in the Yellowknife Bay area where Curiosity first drilled. Scientists detected minerals using the camera’s infrared-imaging capability.
This area that Curiosity has been exploring is part of an alluvial fan, a formation of debris left by a river that once flowed into the crater, scientists say.
“We investigated the fan and found evidence that there was very likely an intermittent lake that had freshwater at one point,” Vasavada said.
3. Mars is red on top, gray below. That material in the drill bit that the rover used to probe rock wasn’t the same orange color that’s so familiar to us from the rover’s photography. Instead, it was gray, scientists said in February.
“You can probably bet that when things turn orange, it’s because there’s a rusting process of some kind going on that oxidizes the iron in the rock,” Joel Hurowitz, sampling system scientist for Curiosity at NASA’s Jet Propulsion Laboratory, said at the time.
4. The planet’s atmosphere was destroyed a long time ago. Using instruments on board Curiosity, scientists determined that the Martian atmosphere hasn’t changed much in the last 4 billion years, and during that whole time it has been thin, as well as inhospitable to life as we know it.
Initially, however, after the planet formed 4.5 billion years ago, the planet’s atmosphere was 100 times denser than the Earth’s atmosphere, scientists say. Their results were published in the journal Science in July.
We could learn even more about the atmosphere from NASA’s Mars Atmosphere and Volatile Evolution Mission orbiter, which is expected to launch in November. This spacecraft will have techniques to measure the current rate of loss of the atmosphere.
5. Radiation makes the trip to Mars dangerous for humans. Curiosity spent 253 days getting to Mars in 2012. During that time, the mission (officially called Mars Science Laboratory) was collecting data about radiation on the journey to the Red Planet using the Radiation Assessment Detector device.