On September 28, 2015, NASA announced that they found traces of water on Mars which indicated the possibility of the existence of life on that planet. NASA’s Mars Reconnaissance Orbiter (MRO) provided the strongest evidence to prove that liquid water flows on Mars.
Using an imaging spectrometer on the MRO, signs of hydrated salts were found on slopes, forming mysterious streaks. These streaks were dark and did not last since they appeared and disappeared with the change of weather over the year. The streaks were found in several locations on Mars when the temperature was above minus 10-degree Fahrenheit (minus 23 Celsius). The news of finding liquid water on Mars shook the internet and the possibility of finding life on Mars was all that people talked about in 2015 and 2016.
Water Flow on Mars
The downhill flows that were observed and named as recurring slope lineae (RSL) are said to be somehow related to liquid water. The theory presented back then was that the hydrated salts on the slopes indicate a connection to the previously observed dark features. Hydrated salts would function as salt does on earth – lowering the freezing point of liquids, causing them to melt more rapidly.
The most exciting discoveries can be overturned with more evidence and that is exactly what happened in this case. In 2017, the whole discovery was put to shame when new research from the US Geological Survey (USGS) surfaced, which proved that the whole discovery of liquid water flow on Mars, even though was very promising considering the theories presented to support the discovery, was false. The chances of microbial life on the planet are now very much decreased.
The dark streaks that show up periodically on the Martian surface called RSL (recurring slope lineae), when NASA’s spacecraft, MRO, observed these streaks more closely it was found that it was made up of hydrated salts, this claim was proved wrong by USGS.
Grain Flow: No Water on Mars?
According to the research carried out by USGS, these features look identical to certain types of slopes that are found on sand dunes on Earth. These dry sand grains form a slope by flowing downhill without the assistance of any water. Mars is believed to have water abundancy in earlier times but still, scientists believe that there are traces of water on Mars. The current pieces of evidence of lack of water on Mars have made it difficult for us to believe that Earth-like life can exist on Mars. Scientists from USGS, Planetary Science Institute, Durham University (England) and the University of Arizona presented the hypothesis after keen observations that the RSL features are growing incrementally. They disappear when inactive and recur yearly during the hottest time of the year. The appearance of RSL resembles oozing liquid water. The formation of these RSLs is still unclear.
The MRO (Mars Reconnaissance Orbiter) with a High-Resolution Imaging Science Experiment (HiRISE) camera was used by Colin Dundas, who is the lead author of this report. 151 features of RSL were observed at ten different sites with the data including 3D models of slope steepness. The RSL are all limited to slopes steeper than 27 degrees and the flow is said to end on a slope that matched the dynamic angle of repose. A 2016 report also doubted the possibility of finding water underground. Possible connections are described in the new report with theories about the formation of RSL.
One of the many theories includes that hydration of salts occurs by the absorption of water vapor from the atmosphere resulting in the formation of drops of salty water. Seasonal changes might have an impact on the grains containing salts, considering the hydration of the salts, leading to the stimulation of RSL grain flow like contraction, expansion, and release of some water. Darkening and fading can also be explained by this phenomenon but if atmospheric water is considered as a trigger then the appearance of RSL on some slopes, but not other slopes cannot be explained.
According to McEwen, the formation of RSL is probably due to some mechanism that is specific to the surroundings of Mars, which is an opportunity for us to find out more about the planet’s behavior. MRO Project Scientist of NASA’s Jet Propulsion Laboratory, Rich Zurek, stated that the current report indicates that RSL are not wet enough support microbial life on Mars, but the complete understanding of RSL depends upon on-site investigation that will require special operations to shield against the introduction of microbes from Earth.
A full explanation is still not available on the disappearance, recurrence or darkening and fading of these enigmatic features.
Is There Life on Mars?
The hopes of finding life on Mars are still up because researchers believe that places under the surface of Mars are warm enough for the existence of liquid water. The planet might not have as much water as we assumed, but it does not mean that water is completely absent from the planet. The discovery done by the MRO is still believed to be solid considering the involvement of hydrated salts. Mars is still believed to have the potential to have an early life form since scientists believed that Mars had a watery past and there may have been a drainage channel billions of years ago.
The Planet’s surface might not be as habitable as we assumed it would be, but further investigations are being done to find out more about the planet.
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