The study by the University of Colorado at Boulder is the first to integrate multiple data sets of river deltas, valley networks and topography from a cadre of NASA and European Space Agency orbiting missions of Mars dating back to 2001, the researchers claim.
15 reasons why Mars is one hot, hot, hot planet The river deltas on Mars are of interest to researchers because deltas on Earth rapidly bury organic carbon and other biomarkers of life and are a prime target for future exploration. Most astrobiologists believe any present indications of life on Mars will be discovered in the form of subterranean microorganisms, researchers stated. CU researchers said long-lived oceans may have provided an environment for microbial life to take hold on Mars.
The study implies that ancient Mars probably had an Earth-like water cycle, including precipitation, runoff, cloud formation, and ice and groundwater accumulation, stated CU-Boulder Assistant Professor Brian Hynek who completed the study with lead author CU-Boulder researcher Gaetano Di Achille. A paper on the subject appears in the June 13 issue of Nature Geoscience.
While the notion of a large, ancient ocean on Mars has been debated over the past two decades, the new study provides further support for the idea of a sustained sea on the red planet, Di Achille stated.
More than half of the 52 river delta deposits identified by the CU researchers likely marked the boundaries of the ocean. Twenty-nine of the 52 deltas were connected either to the ancient Mars ocean or to the groundwater table of the ocean and to several large, adjacent lakes, Di Achille said.
Di Achille and Hynek used a geographic information system to map the Martian terrain and conclude the ocean likely would have covered about 36 percent of the planet and contained about 30 million cubic miles, or 124 million cubic kilometers, of water. The amount of water in the ancient ocean would have formed the equivalent of a 1,800-foot deep layer of water spread out over the entire planet, the researchers stated.
Hynek also did a study that found about 40,000 river valleys on Mars. That is about four times the number of river valleys that have previously been identified by scientists, said Hynek.
NASA recently reported findings that furthered the water-on-Mars conundrum. NASA's 'now hibernating Mars rover Spirit spotted rocks scientists say could offer key clues to whether or not life ever did or still does exist on the red planet.
Sprit's Miniature Thermal Emission Spectrometer Mini-TES instrument found an outcrop of rock rich in what are known as carbonate minerals. Such minerals are crucial to understanding the early climate history of Mars and the related question of whether the planet might once have held life, NASA stated.
The outcrops are very rich in olivine, a volcanic mineral, but they appear to have been soaked in water, NASA stated. It's as if the granular material settled over a preexisting landscape, then the entire stack was flooded with carbonate-rich water, probably from a hydrothermal source.
Water-altered rocks have been found on Mars before but scientists think that water was highly acidic, not conducive to life in general. Acidic water quickly destroys carbonate minerals, as for example vinegar dissolves hard water deposits. Thus finding outcrops of carbonate rock shows that the hydrothermal water at Comanche was liquid, chemically neutral, and abundant, NASA stated.