Curiosity Follows the Water on Mars to Ancient Lake in Gale Crater

Summary: NASA's Curiosity follows the water on Mars to an ancient lake in Gale Crater, according to Mars Science Laboratory team's Oct. 9 report in Science.

Higher regions of Mount Sharp showing changing mineralogy (long ridge of hematite, undulating clay-rich plain, sulfate-rich rounded buttes); composite image obtained Wednesday, Sep. 9, 2015, by Curiosity; image addition date 2015-10-02; image credit NASA/JPL-Caltech/MSSS: "PIA19912 Mount Sharp Comes In Sharply," May be used for any purpose without prior permission, via NASA JPL Photojournal

MSL (Mars Science Laboratory) rover Curiosity’s successful follow-the-water exploration in Gale Crater finds Mount Sharp’s lower layers formed by sediment from lakes filling the crater over 3 billion years ago, according to a report by the MSL team published in Science on Oct. 9, 2015.

Located in the Southern Hemisphere near the Martian equator, Gale Carter presents ideal terrain for an ancient scenario of life-supporting, wet Mars. Alluvial fans, deltas, clay and sulfate byproducts of water, and layers of sediment all suggest the presence of water. Finely laminated, or layered, mudstone indicate standing water. Deposits from fast-moving streams and standing lake water seem to have built up Mount Sharp’s lower layers by filling in the underlying basin. The process of mountain building is thought to have taken place over a period of less than 500 million years.

Ashwin Vasavada, co-author and MSL project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, sums up Curiosity’s successful diggings: “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.”

Curiosity has been drilling for samples and gathering information on Mount Sharp since the car-sized rover’s arrival on Sept. 11, 2014, at Pahrump Hills, an outcrop serving as one of the mountain’s entryways. The sophisticated, car-sized rover’s original two-year mission began with its landing on Aolis Palus, the plain on Mount Sharp’s northern foothills, at 10:32 p.m. Pacific Daylight Time on Aug. 5, 2012.

On Dec. 4, 2012, NASA announced an indefinite extension to Curiosity’s mission of searching for evidence of microbial life on Mars. A radioisotope thermoelectric generator (RTG) powers the $2.5 billion rover through heat conversion of plutonium-238’s radioactive decay into electricity.

John Grunsfled, NASA’s associate administer for science, gives an informed guess on Curiosity’s lifespan: “I never get a straight answer on this, but I think it has 55 years of positive power margin.”

Mount Sharp, known officially as Aeolis Mons, rises as Gale Crater’s central peak to a height of 3.4 miles (5.5 kilometers) above the crater’s northern floor and 2.8 miles (4.5 kilometers) above the southern floor. With a sprawling diameter of 55+ miles (88+ kilometers), Mount Sharp dominates the crater’s 96-mile-diameter (154-kilometer-diameter) and roughly covers an area equal to that of the combined states of Connecticut and Rhode Island.

Water deposits appear to have formed the mountain’s lower layers, from the base up to one-half mile (800 meters). Dry, wind-driven deposits seem to be responsible for the bulk of Mount Sharp.

As with the big questions of the source for the water that sculpted the crater’s terrain and the triggers for the planet’s apparent change from anciently wet Mars to today’s dry Mars, Curiosity’s diggings show Mars as a big question mark.

“We have tended to think of Mars as being simple. We once thought of the Earth as being simple too," John Grotzinger, former MSL project scientist and the report’s lead author, notes. "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 reevaluate all our assumptions. Something is missing somewhere.”

Curiosity's selfie of drilling in cross-bedded sandstone Tuesday, Oct. 6, 2015, at Big Sky site for mission's "fifth taste of Mount Sharp"; image addition date 2015-10-13; image credit NASA/JPL-Caltech/MSSS: "PIA19920 Curiosity Self-Portrait at 'Big Sky' Drilling Site," May be used for any purpose without prior permission, via NASA JPL Photojournal

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Higher regions of Mount Sharp showing changing mineralogy (long ridge of hematite, undulating clay-rich plain, sulfate-rich rounded buttes); composite image obtained Wednesday, Sep. 9, 2015, by Curiosity; image addition date 2015-10-02; image credit NASA/JPL-Caltech/MSSS: "PIA19912 Mount Sharp Comes In Sharply," May be used for any purpose without prior permission, via NASA JPL Photojournal @ http://photojournal.jpl.nasa.gov/catalog/PIA19912; via NASA Science @ https://science.nasa.gov/resource/mount-sharp-comes-in-sharply/

Curiosity's selfie of drilling in cross-bedded sandstone Tuesday, Oct. 6, 2015, at Big Sky site for mission's "fifth taste of Mount Sharp"; image addition date 2015-10-13; image credit NASA/JPL-Caltech/MSSS: "PIA19920 Curiosity Self-Portrait at 'Big Sky' Drilling Site," May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA19920;
Generally not subject to copyright in the United States, via NASA Science Mars Exploration @ https://science.nasa.gov/resource/curiosity-self-portrait-at-big-sky-drilling-site/; (NASA Science Mars Exploration image gallery URL @ http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=7507)

For further information:

Clavin, Whitney. "NASA's Curiosity Rover Team Confirms Ancient Lakes on Mars." NASA > Mars. Oct. 8, 2015.
Available @ https://www.nasa.gov/feature/jpl/nasas-curiosity-rover-team-confirms-ancient-lakes-on-mars

Grotzinger, J.P., et al. "Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale Crater, Mars." Science, vol. 350, issue 6257 (Oct. 9, 2015). DOI: 10.1126/science.aac7575
Available @ http://www.sciencemag.org/content/350/6257/aac7575

Klotz, Irene/Reuters. "NASA Mars rover finds clear evidence for ancient lakes." Review Journal. Oct. 8, 2015.
Available @ http://www.reviewjournal.com/news/nation-and-world/nasa-mars-rover-finds-clear-evidence-ancient-lakes

Watery Mars: NASA Confirms Seasonal Presence of Surface Water on Mars

Summary: A watery Mars emerges as NASA confirms the seasonal presence of surface water, according to NASA's Sept. 28 press release.

Processed, false-color view of dark, football-field length streaks, known as recurring slope lineae (RSL), at Hale Crater, Mars; imaging and topographical information via High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO); image addition date 2015-09-28; image credit NASA/JPL-Caltech/Univ. of Arizona: "PIA19916 Recurring 'Lineae' on Slopes at Hale Crater, Mars," May be used for any purpose without prior permission, via NASA JPL Photojournal

The National Aeronautics and Space Administration announced Monday, Sept. 28, 2015, at 11:30 a.m. Eastern Daylight Time on NASA TV that a four-year scrutiny of the Red Planet has yielded key evidence of the chemical identity of dark streaks occurring as seasonal events on Mars.

Wavelength analysis has identified perchlorate salts as ubiquitous in recurring slope lineae (RSL) occurring on steep sites on Mars.

RSL were discovered in 2011 via images captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO). The multipurpose spacecraft has been conducting exploration and reconnaissance missions since attaining its final science orbit of Mars in November 2006.

Recurring slope lineae appear at different latitudes and times as seasonal dark streaks on steep slopes. RSL present an annual, temperature-dependent cycle of emergence in spring and peak growth in downslope directions in summer, with fading and disappearance during the cold season. The surface temperatures conducive to the dark streak flows range from 250 to 300 Kelvin (minus 23 degrees to 27 degrees Celsius; minus 10 degrees to 81 degrees Fahrenheit).

Included among MRO's host of onboard scientific apparatuses is Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), an infrared-visible light spectrometer that searches for chemical and mineralogical evidence of past and present water on Mars. CRISM breaks sunlight reflected from Mars’ surface into a measurable spectrum of 544 colors. As a reflectance spectrometer, CRISM builds a profile of surface composition by measuring amounts of reflected light at different wavelengths to identify absorption signatures of specific chemicals and minerals.

A scientific team led by Lujendra Ojha, Ph.D. candidate in Georgia Institute of Technology's School of Earth and Atmospheric Sciences, analyzed CRISM wavelength data from four RSL locations. Coprates Chasma is located in the central portion of the equatorial Valles Marineris canyon system complex. Hale Crater lies in the southern highlands. Horowitz Crater is sited at 32 degrees south latitude. Palikir Crateris found inside Newton Crater in southern hemisphere's massively cratered Terra Sirenum.

CRISM's sweep of the four RSL locations detected wavelengths that absorption analysis associates with perchlorates. Perchlorates are salts which dissolve readily in water.

Lujendra Ojha's team identified the hydrated salts at all four locations as magnesium chlorate, magnesium perchlorate and sodium perchlorate.

NASA astrophysicist Tom Greene has shared that seemingly dry, arid Mars anciently welcomed a huge ocean, with a depth of at least 1 mile and a spread equal to two-thirds of Earth's Northern Hemisphere. But Mars seemingly lost its surface water because of an enigmatic climate change.

The dramatic confirmation of seasonal flows of briny water via NASA TV and the publication of Lujendra Ojha's findings, both presented Monday, Sept. 28, 2015, increase Mars' mystique and enliven the dialogue and research on deciphering mysteries of life on Earth and life's possibilities elsewhere.

Dark narrow streaks, called "recurring slope lineae," with a hypothesized formation from briny liquid water flow, emanate from the walls of Garni Crater on Mars; image created by "draping an orthorectified (RED) image (ESP_031059_1685) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona)," with vertical exaggeration of 1.5 in comparison with horizontal dimensions; image addition date 2015-09-28; image credit NASA/JPL-Caltech/Univ. of Arizona: "PIA19917 Dark, Recurring Streaks on Walls of Garni Crater," May be used for any purpose without prior permission, via NASA JPL Photojournal

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Processed, false-color view of dark, football-field length streaks, known as recurring slope lineae (RSL), at Hale Crater, Mars; imaging and topographical information via High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO); image addition date 2015-09-28; image credit NASA/JPL-Caltech/Univ. of Arizona: "PIA19916 Recurring 'Lineae' on Slopes at Hale Crater, Mars," May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA19916;
"Recurring 'Lineae' on Slopes at Hale Crater, Mars," NASA image, Sep. 28, 2015, May be used for any purpose without prior permission, via NASA JPL @ http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA19916

Dark narrow streaks, called "recurring slope lineae," with a hypothesized formation from briny liquid water flow, emanate from the walls of Garni Crater on Mars; image created by "draping an orthorectified (RED) image (ESP_031059_1685) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona)," with vertical exaggeration of 1.5 in comparison with horizontal dimensions; image addition date 2015-09-28; image credit NASA/JPL-Caltech/Univ. of Arizona: "PIA19917 Dark, Recurring Streaks on Walls of Garni Crater," May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA19917;
"NASA Confirms Evidence That Liquid Water Flows on Today’s Mars," NASA release, Sep. 28, 2015, Generally not subject to copyright in the United States, via NASA @ https://www.nasa.gov/news-release/nasa-confirms-evidence-that-liquid-water-flows-on-todays-mars/

For further information:

Brown, Dwayne; Laurie Cantillo; Guy Webster. "NASA Confirms Evidence That Liquid Water Flows on Today's Mars." NASA > Press Release > MRO. Sept. 28, 2015.
Available @ https://www.nasa.gov/press-release/nasa-confirms-evidence-that-liquid-water-flows-on-today-s-mars

JPLraw. "Animation of Site of Seasonal Flows in Hale Crater, Mars." YouTube. Sept. 28, 2015.
Available @ https://www.youtube.com/watch?v=MDb3UZPoTpc&feature=youtu.be

Ojha, Lujendra, Mary Beth Wilhelm, Scott L. Murchie, Alfred S. McEwen, James J. Wray, Jennifer Hanley, Marion Massé, and Matt Chojnacki. “Spectral evidence for hydrated salts in recurring slope lineae on Mars.” Nature Geoscience > Letter. Published online Sept. 28, 2015.
Available via Nature Publishing Group @ http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2546.html