Some 3.5 billion years ago, the Red planet was home to a lake that persisted long enough to sustain microbial life, scientists announced Monday.
Curiosity detected stacks of rocks containing sediments that had been deposited by water. The rocks, found researchers, are inclined toward the crater's center, culminating in a three-mile-high mound called Mount Sharp.
These latest observations could mean Mars' warm, wet period occurred about 3.5 billion years ago, more recently than scientists had thought.
In addition, Martian lakes could have lasted longer than previously suspected. Scientists are uncertain whether this wet period was continuous or interrupted by dry spells.
"This lake was large enough, it could have lasted millions of years — sufficient time for life to get started and thrive, sufficient time for lake sediment to build up to form Mount Sharp," Michael Meyer, lead scientist of NASA's Mars exploration program, told the Associated Press.
Meyer acknowledged that even here on Earth, "we don't have a very good handle" on how long it takes life to originate and how long a conducive environment needs to be in place beforehand. So addressing the possibility of whether life once existed on other planets is made all the more complicated.
Curiosity arrived on the Red Planet on August 6, 2012, touching down in the 96-mile-wide Gale Crater.
Shortly after landing, the rover found that Mars once had the chemical ingredients and the environmental conditions needed to support microbial life, fulfilling the primary goal of its mission. It then began its slow drive toward Mount Sharp, collecting more data along the way. The rover has traveled about five miles on Mars so far.
"All that driving we did ... just didn't get us to Mount Sharp. It gave us the context to appreciate Mount Sharp," Grotzinger told Reuters.
This report uses material from the Associated Press and Reuters.