| Online: | |
| Visits: | |
| Stories: |
Martian lake crater prime target for NASA’s 2020 rover
Eric Hopton for redOrbit.com – Your Universe Online
An ancient Martian lake system in the Jezero Crater, near the planet’s equator, is high on a list of possible landing sites for NASA’s Mars 2020 rover. The site shows clear signs of water and may therefore hold significant clues to the presence of ancient life on Mars. Researchers from Brown University have completed a new analysis of the Jezero area which found that water filled the crater at least twice in separate periods of water activity. This makes Jezero a prime target in the search for life on the Red Planet.
Current and former graduate students at Brown University have combined data from two NASA’s instruments for the study. Images were captured from the CTX Context Camera and combined with mineralogical data from the CRISM orbiting spectrometer. The result is a detailed geological and mineralogical map of the entire Jezero Crater paleolake system. We now have an impressive recreation of Martian geology nearly 4 billion years ago. The study has been published in the Journal of Geophysical Research: Planets.
“We can say that this one really well-exposed location makes a strong case for at least two periods of water-related activity in Mars’ history,” said Tim Goudge, a graduate student at Brown who led the work. “That tells us something really interesting about how early Mars operated.”
Minerals formed in the watershed
Back in 2005, Caleb Fassett, a former Brown graduate student now a professor at Mount Holyoke College, first identified the ancient lake at the Jezero crater. Fassett believes that two channels on the northern and western sides of the crater supplied it with water. Eventually the water flowed over the top of the crater wall on its southern side through a third large channel. The crater probably dried out some 3.5 to 3.8 billion years ago.
[STORY: Did Jupiter wipe out an entire generation of planets?]
The study has now shown that the crater’s inlet channels deposited clay mineral sediments from the surrounding watershed. Each of the fan deposits has its own distinct mineral signature that matches the signature of the watershed from which it was sourced. “That’s a good indication that the minerals formed in the watershed and were then transported into the lake,” Goudge said.
The minerals’ formation and their transportation seem to have been separated by a fair amount of time. Mapping of the watershed showed a younger layer of rock that sits on top of the hydrated minerals. The crater’s inlet channels cut through that layer of younger rock. That means the water that carved the channels must have flowed well after the mineral layer had formed.
“What it implies is that there were actually two periods of water-related activity,” Goudge said. “The earlier episode formed the alteration minerals in the watershed, then some time later you had the surface water activity that transported the minerals into the lake. At this site, those two events appear not to have been genetically related.”
Top five landing sites
All this makes the Jezero crater attractive for future research. As Goudge says, “River and lake deposits on Earth are some of the best preservers of biologic signatures. At Jezero, you’re gathering all this material from this huge watershed and dumping into one place. So if there perhaps was any biologic or organic material in the watershed, you might have transported some of that to the basin.”
[STORY: Fatty acids may have been found on Mars]
Jezero’s water does not seem to have significantly changed the chemistry of the rocks in the crater. This is a strong indicator that the water had a nearly neutral pH, which would also make it potentially an even more habitable environment.
In the NASA selection process for exploration sites for the 2020 rover, Jezero is currently one of the top five landing site candidates. Goudge and his colleagues are rooting for Jezero to make the final cut.
“We think Jezero has a really interesting story to tell,” Goudge said. “It would be a fun place to get to drive around in.”
—–
Follow redOrbit on Twitter, Facebook, Google+, Instagram and Pinterest.
redOrbit.com
offers Science, Space, Technology, Health news, videos, images and
reference information. For the latest science news, space news,
technology news, health news visit redOrbit.com frequently. Learn
something new every day.”
Source: http://www.redorbit.com/news/space/1113360526/mars-lake-crater-032715/
