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Did Viking I Find Proof of a Megatsunami on Mars?
(CNN) – When NASA's Viking 1 lander made history as the first spacecraft to touch down on Mars on July 20, 1976, it sent back images of a landscape no one was expecting.Those first images taken from the ground there showed a surprisingly boulder-strewn surface in the red planet’s northern equatorial region, rather than the smooth plains and flood channels expected based on images of the area taken from space.The mystery of the Viking landing site has long puzzled scientists, who believe an ocean once existed there.Now, new research suggests that the lander touched down where a Martian megatsunami deposited materials 3.4 billion years ago, according to a study published Thursday in the journal Scientific Reports.The catastrophic event likely occurred when an asteroid slammed into the shallow Martian ocean — similar to the Chicxulub asteroid impact that wiped out dinosaurs on Earth 66 million years ago, according to researchers. Solving an ancient riddleFive years before the Viking I landing, NASA’s Mariner 9 spacecraft had orbited Mars, spotting the first landscapes on another planet that suggested evidence of ancient flood channels there.The interest in the potential for life on the red planet prompted scientists to select its northern equatorial region, Chryse Planitia, as the first Martian landing site for Viking I.“The lander was designed to seek evidence of extant life on the Martian surface, so to select a suitable landing site, the engineers and scientists at the time faced the arduous task of using some of the planet’s earliest acquired images, accompanied by Earth-based radar probing of the planet’s surface,” said lead study author Alexis Rodriguez, senior scientist at the Planetary Science Institute in Tucson,