Alien waves on ancient shores: Curiosity confirms lake flourished at Gale Crater
The team working with NASA’s Mars Science Laboratory (MSL) Curiosity rover has found the best evidence to date that, billions of years ago, Mars once had lakes that lasted for extended periods of time. This is just the latest discovery concerning the Red Planet’s past.
Curiosity landed in Gale crater more than three years ago, in August of 2012. Since that time the one-ton rover has determined that water helped build sedimentary deposits in the region where the robotic geologist is currently exploring. The data suggests that the base of Mount Sharp, which is found in the center of Gale Crater, was formed from these deposits.
“Observations from the rover suggest that a series of long-lived streams and lakes existed at some point between about 3.8 to 3.3 billion years ago, delivering sediment that slowly built up the lower layers of Mount Sharp,” said Ashwin Vasavada, Mars Science Laboratory project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and co-author of the new Science article that was published on Friday, Oct. 9.
These findings continue expanding the body of evidence that suggests there were ancient lakes and seas across the Red Planet. In September, NASA scientists working with Lujendra Ojha of the Georgia Institute of Technology (Georgia Tech) confirmed the existence of flowing water on Mars using the Mars Reconnaissance Orbiter (MRO).
Michael Meyer, lead scientist for NASA’s Mars Exploration Program at NASA Headquarters in Washington was quoted in the NASA-issued release as saying, “What we thought we knew about water on Mars is constantly being put to the test. It’s clear that the Mars of billions of years ago more closely resembled Earth than it does today. Our challenge is to figure out how this more clement Mars was even possible, and what happened to that wetter Mars.”
Before Curiosity began exploring Mars in 2012, many scientists speculated that Gale Crater had been filled with dry sediments such as sand and dust blown in by the Martian winds. Some had speculated that the sediments may have been formed by ancient lakes. The new results indicate that the latter scenario is indeed correct and that Mars had abundant water sources. The current studies indicate that water had flowed within the crater for somewhat less than 500 million years.
“During the traverse of Gale, we have noticed patterns in the geology where we saw evidence of ancient fast-moving streams with coarser gravel, as well as places where streams appear to have emptied out into bodies of standing water,” Vasavada said. “The prediction was that we should start seeing water-deposited, fine-grained rocks closer to Mount Sharp. Now that we’ve arrived, we’re seeing finely laminated mudstones in abundance that look like lake deposits.”
The evidence also suggests that the waters were not static over the proposed timeframe. Periodic receding and expansion of the waters formed the sediments that Curiosity is finding today.
“Paradoxically, where there is a mountain today there was once a basin, and it was sometimes filled with water,” said John Grotzinger, the former project scientist for Mars Science Laboratory at the California Institute of Technology in Pasadena, and lead author of the new report. “We see evidence of about 250 feet (75 meters) of sedimentary fill, and based on mapping data from NASA’s Mars Reconnaissance Orbiter and images from Curiosity’s camera, it appears that the water-transported sedimentary deposition could have extended at least 500 to 650 feet (150 to 200 meters) above the crater floor.”
The data also suggests that there may be indications of water interaction further up on Mount Sharp, perhaps up to 2,600 feet (800 meters) above the crater floor. Beyond that altitude, the indicators for water disappear lending to speculation that the higher elevations of the peak were formed by dry, wind-driven deposits.
While the evidence for liquid water in Gale crater continues to grow, there still remains the question of where the sediment-carrying water came from in the first place. Some scientists think the water may have come from rain and snowfall along the rim of Gale crater. Others speculate that perhaps there was an ocean to the north of the crater. Neither theory explains how the water remained liquid for so long if Mars had its current climate conditions. For water to flow on Mars, there had to have been a thicker atmosphere and a warmer climate. If those conditions existed before, what happened to change them to the dry arid planet we see today?
“We have tended to think of Mars as being simple,” Grotzinger stated. “We once thought of the Earth as being simple too. But the more you look into it, questions come up because you’re beginning to fathom the real complexity of what we see on Mars. This is a good time to go back to re-evaluate all our assumptions. Something is missing somewhere.”
Joe Latrell is a life-long avid space enthusiast having created his own rocket company in Roswell, NM in addition to other consumer space endeavors. He continues to design, build and launch his own rockets and has a passion to see the next generation excited about the opportunities of space exploration. Joe lends his experiences from the corporate and small business arenas to organizations such as Teachers In Space, Inc. He is also actively engaged in his church investing his many skills to assist this and other non-profit endeavors.