Mars, 1976: Traces of an ancient megatsunami captured by Viking 1 (2 photos)

This is one of the first color images ever taken from the surface of another planet. The image was taken by NASA's Viking 1 Mars lander, which soft-landed in Chryse Planitia on July 20, 1976, becoming the first successful permanent resident of the Red Planet.





This image is the result of a digital restoration of data acquired almost half a century ago. The quality has been enhanced, but the geometry and detail remain intact. The original image was transmitted to Earth on August 21, 1976, approximately 15 minutes before sunset.

Only recently has it become clear just how intriguing the landing site chosen for Viking 1 was. A study published in 2022 revealed that the lander landed on Mars near the rim of a gigantic, 110-kilometer-wide crater, estimated to be approximately 3.4 billion years old. This crater, according to planetary scientists, was formed by the impact of a large asteroid, which caused a Martian megatsunami—a wave tens of meters high that swept across the ancient ocean. The rocks captured in Viking 1's image may be silent witnesses to this ancient catastrophe.

That is why Chryse Planitia and the surrounding regions are among the most promising sites today for searching for possible traces of life on Mars.



Another frame from Viking 1, but unprocessed

If there really was an ocean on the Red Planet (and there's plenty of evidence to support this), its coastline, reshaped by asteroid impacts and megatsunamis, should have preserved both sedimentary rocks and possible biosignatures.

On Earth, such places—river deltas, ancient coastlines, areas that survived tsunamis—often turn out to be treasure troves of fossilized life. Mars may obey the same rules, and future missions will certainly test this.