By Will Dunham<\/p>\n
WASHINGTON, April 15 (Reuters) – There is a lot of evidence from orbiting satellites and surface rovers indicating that liquid water was present long ago on the surface of Mars in the form of ponds, lakes and rivers. But the idea that Mars once had a huge and long-lived \u200cocean on its northern plains has remained a matter of debate.<\/p>\n
Scientists have now detected what might be the contours of this putative ocean on Earth’s planetary \u200cneighbor, using data collected by a NASA probe that orbited Mars for a decade. Their research indicates the presence of the Martian equivalent of the continental shelf that defines the boundaries of Earth’s oceans.<\/p>\n
They compared it to \u200ba huge “bathtub ring” showing where water may have once met land on Mars. Because Mars does not possess continents and lacks the geological process called plate tectonics that led to the formation of Earth’s continents, the researchers are calling the Martian landforms a coastal shelf.<\/p>\n
Like Earth and the solar system’s other planets, Mars formed roughly 4.5 billion years ago. Early in its history, Mars was warmer and wetter than the cold and arid place it is today.<\/p>\n
“The Martian ocean could have existed when the planet had an active hydrological cycle, with flowing rivers and lakes, nearly \u200c3.7 billion years ago, and it likely disappeared as the planet \u2060became dry. Exactly where the water went remains highly debated,” said University of Texas planetary scientist Abdallah Zaki, lead author of the research published on Wednesday in the journal Nature.<\/p>\n
A coastal shelf could have formed on Mars over millions of years due to rivers dumping sand \u2060and mud into an ocean, waves spreading those sediments around, and the sea level rising and falling over time. Looking from above, the sedimentary rock making up this shelf might superficially resemble the ring that remains after a bathtub has been drained.<\/p>\n
“A ‘bathtub ring’ on Mars means that if an ocean filled the northern lowlands, it may have left behind a shoreline, or shelf-like boundary, marking the water \u200blevel,” \u200bZaki said.<\/p>\n
“If we sent a rover, we would expect to see sedimentary rocks and structures similar to \u200bthose found on Earth’s continental shelves, including layering, sloping surfaces called clinoforms \u200cand textures produced by waves and currents,” Zaki said.<\/p>\n
The researchers examined topographical data for Mars that was obtained by NASA’s Mars Global Surveyor, and identified a band suggestive of oceanic contours. Previous research has indicated that this hypothesized ocean in the Martian northern hemisphere covered approximately a third of the planet’s surface, equivalent to about 13% of the total area of Earth’s oceans.<\/p>\n
The study builds on earlier evidence of a bygone Martian ocean including studies identifying features resembling an ancient shoreline. Ground-penetrating radar data obtained by China’s Zhurong rover, described in a study published last year, detected evidence suggesting sandy beaches from a Martian shoreline now buried underground.<\/p>\n
Scientists also have identified multiple landforms that appear to be remnants of ancient river \u200cdeltas, where rivers may have flowed into a larger body of water.<\/p>\n
“The northern ocean on Mars, if \u200bit existed, dried up a long time ago, and there have been billions of years of volcanic activity \u200band wind abrasion on Mars, so interpreting ancient landforms is not straightforward,” Caltech planetary \u200bscientist and study senior author Michael Lamb said.<\/p>\n
“Nonetheless, our study shows some telltale signs of a coastal shelf. And the shelf occurs in \u200cthe same zone as the deformed shorelines and where scientists have previously \u200bmapped river deltas and other landforms and deposits \u200bcharacteristic of a land-ocean transition,” Lamb said.<\/p>\n
Taken together, Lamb said, the evidence points toward a long-lived ancient ocean.<\/p>\n
“This means that Mars once looked much more like the Earth than it does today,” Lamb said.<\/p>\n
The existence of an ocean would be an important factor in understanding whether Mars was ever able to give rise to life.<\/p>\n
“If \u200bMars once had an ocean covering roughly one third of \u200cthe planet over geologic timescales, that would suggest that a large part of its surface had sustained water, which is a key ingredient for habitability,” Zaki \u200bsaid.<\/p>\n
“That does not mean Mars was inhabited, but it does suggest that potentially habitable environments may have been more widespread and longer-lived than if water \u200bhad only existed briefly or locally,” Zaki said.<\/p>\n
(Reporting by Will Dunham, Editing by Rosalba O’Brien)<\/p>\n","protected":false},"excerpt":{"rendered":"By Will Dunham WASHINGTON, April 15 (Reuters) – There is a lot of evidence from orbiting satellites and…\n","protected":false},"author":2,"featured_media":587412,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[256919,256917,256916,256914,196,242201,256918,256915,79,193],"class_list":{"0":"post-587411","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-abdallah-zaki","9":"tag-bathtub-ring","10":"tag-continental-shelf","11":"tag-land-on-mars","12":"tag-mars","13":"tag-mars-global-surveyor","14":"tag-michael-lamb","15":"tag-putative-ocean","16":"tag-science","17":"tag-space"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/587411","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=587411"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/587411\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/587412"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=587411"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=587411"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=587411"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}