Three years ago today, the Curiosity rover touched down on Mars. After a nerve-wracking descent sequence nicknamed the "seven minutes of terror," the vehicle landed in Gale Crater at 1:17 AM Eastern Time on August 6, 2012.
Take a second to remember the sheer excitement of that moment by watching this footage of mission control's reaction (be prepared for happy sobs).
The Curiosity team reacts to the rover's landing. Credit: Associated Press/YouTube
Deploying a car-sized payload of scientific instruments to the Martian surface isn't easy, and one can only imagine how elated the team must have felt when Curiosity radioed back its first status report from Mars.
Fortunately, the clean landing was only the first of many successful endeavors achieved by Curiosity. The rover is by far the biggest and most sophisticated lander ever sent to Mars, decked out in instruments designed to determine, among other things, if Mars ever could have hosted life.
To recap, Curiosity wasted no time solving that particular problem. In a reddit AMA conducted yesterday, the researchers said that "the discovery that that Yellowknife Bay was once a habitable environment" was the most surprising find of all three years. "We learned that with the first drill hole on Mars!" the team said.
Yellowknife Bay is a region inside of Gale Crater with many geological signatures of an ancient freshwater lakebed. Within its first months on Mars, Curiosity confirmed that the area was shaped by freshwater flows, but also that it was rich in the chemical building blocks of life—sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon, among other elements.
"A fundamental question for this mission is whether Mars could have supported a habitable environment," said Michael Meyer, lead scientist for NASA's Mars Exploration Program, said in a March 2013 statement. "From what we know now, the answer is yes."
Of course, this revelation doesn't mean life definitely thrived in Yellowknife Bay, just that the conditions were right for it. To that point, Curiosity isn't even equipped to directly detect lifeforms on Mars—that's a job for future Mars landers, like the European Space Agency's ExoMars mission.
But regardless, the discovery that Mars once boasted habitable conditions is a rare beacon of hope in the search for alien life. Curiosity has demonstrated that once upon a time, around three billion years ago, Gale Crater was home to a massive reservoir of freshwater and rich organic materials. Life may have emerged in these waters just as it begun to thrive, around the same period, on our own planet.
As big as this discovery was, it was just Curiosity's warm-up round. The researchers have compiled a convenient list of what they consider to be the rover's other major accomplishments on Mars, but you can also go for the tl;dr version as summed up by NASA publicist Carolina Martinez.
Curiosity atmospheric scientist Michael Mischna also added that he was excited by the fact that "just below the surface, Red Mars is actually Gray Mars!" while geologist Fred Calef said that the most exciting discovery for him was that almost "all the rocks we've driven over are water deposited."
"From orbit, the morphology (i.e. 'shape') of the landforms indicated water was involved, but the amount, to me, was surprising," Calef commented.
In terms of the rover's future, the team assured redditors (and the attendant lurkers) that new discoveries are on the way, as it ascends Mount Sharp.
"We're really excited to study the variety of minerals exposed in the layers of Mount Sharp, including hematite, clay, and sulfate that may indicate environmental changes on the surface of Mars over time," said planetary scientist Katie Stack.
"Curiosity has already survived longer than its nominal mission of one Mars year," said Mischna further in the thread. "We've just surpassed 11 km on the surface [...] We expect to be able to traverse many more kilometers in the future."
On that note, be sure to send some good vibes over to Mars today. Happy third Martian anniversary, Curiosity, and here's to many more.