What he found was puzzling, and the weak evidence for life was disappointing. However, a new study suggests that Viking 1 could have ended up in a location linked to one of the most dramatic events in the history of the solar system.
The Chryse Planitia (lat. Chryse Planitia), where Viking-1 landed, is a giant lowland located northeast of the subequatorial part of the western hemisphere of the Red Planet. This site was chosen due to signs of water erosion such as numerous depressions.
The Chris Plain is one of the lowest points on the Martian surface, so hypothetical rivers flowing from the nearby highlands may have kept it filled with water long after most of the planet had dried up.
However, Viking 1 failed to find some of the expected evidence of the ancient Martian ocean, and subsequent missions have not always filled this mysterious gap.
Forty years later, it was suggested that two planetary-scale tsunamis may have obliterated some of this evidence.
Martian mega tsunami
The team of researchers who first hypothesized a Martian mega tsunami has published a new paper in Scientific Reports stating that a crater near the Viking 1 landing site could be the source of the earlier tsunami.
The megatsunami hypothesis has been proposed to explain the apparent lack of a Martian coastline at constant altitude, which would be expected if the Red Planet once had a global ocean.
Without violent tectonic activity, such changes – the disappearance of the coastline – were hardly possible, so asteroid falls are the likely reason for its absence.
On Earth, tectonic activity and erosion by wind and water have “erased” all craters older than 2.2 billion years. However, craters on Mars last longer, and the publication claims that the investigated crater, 110 kilometers wide, arose about 3.4 billion years ago, when the neighboring planet was still wet.
The International Astronomical Union named the crater Pol, after Frederick Pohl, an American science fiction writer . It is located 900 kilometers northeast of the Viking 1 landing site.
The authors of the study point to evidence that Paul was formed by an asteroid that crashed into water rather than land. This could have caused a megatsunami that was three times larger than previously thought.
The Rhys Plain is close enough to the impact site that the ejecta could have rained down on the lowlands, which explains some of the features Viking 1 detected, such as the different origins of nearby boulders and possible mud volcanoes.
Modeling showed that the height of the tsunami exceeded the depth of the Martian ocean.
If the researchers are correct, then the Chris Plain and nearby regions may be the best place on Mars to look for possible traces of ancient life.
This is because the hydrothermal heat generated from the formation of Pola could have created relatively comfortable conditions below the surface, where primitive life could have flourished for at least 300,000 years.
Later, smaller megatsunamis may have taken some of this evidence as far as Chris Plain. It follows that the Chrys Plain, or even the Pol crater itself, may become priority targets for future missions.
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