Geronimo Villanueva\/Nasa An artists impression of the ancient ocean on Mars, which lasted for billions of years more than was previously thought. Credits: Mars Geronimo Villanueva\/Nasa <\/p>\n
A massive ancient ocean once covered nearly half of the northern hemisphere of Mars making the planet a more promising place for alien life to have gained a foothold, Nasa scientists say. <\/p>\n
The huge body of water spread over a fifth of the planets surface, as great a portion as the Atlantic covers the Earth, and was a mile deep in places. In total, the ocean held 20 million cubic kilometres of water, or more than is found in the Arctic Ocean, the researchers found.<\/p>\n
Unveiled by Nasa on Thursday, the compelling evidence for the primitive ocean adds to an emerging picture of Mars as a warm and wet world in its youth, which trickled with streams, winding river deltas, and long-standing lakes, soon after it formed 4.5bn years ago.<\/p>\n
The view of the planets ancient history radically re-writes what many scientists believed only a decade ago. Back then, flowing water was widely considered to have been a more erratic presence on Mars, gushing forth only rarely, and never forming long-standing seas and oceans.<\/p>\n
A major question has been how much water did Mars actually have when it was young and how did it lose that water? said Michael Mumma, a senior scientist at Nasa Goddard Space Flight Center in Maryland.<\/p>\n
Writing in the journal, Science, the Nasa team, and others at the European Southern Observatory (ESO) in Munich, provide an answer after studying Mars with three of the most powerful infra-red telescopes in the world.<\/p>\n
The scientists used the Keck II telescope and Nasas Infrared Telescope Facility, both in Hawaii, and the ESOs Very Large Telescope in Chile, to make maps of the Martian atmosphere over six years. They looked specifically at how different forms of water molecules in the Martian air varied from place to place over the changing seasons.<\/p>\n
Martian water, like that on Earth, contains standard water molecules, made from two hydrogen atoms and one oxygen atom, and another form of water made with a heavy isotope of hydrogen called deuterium. On Mars, water containing normal hydrogen is lost to space over time, but the heavier form is left behind. <\/p>\n
When normal water is lost on Mars, the concentration of deuterium in water left behind goes up. The process can be used to infer how much water there used to be on the planet. The higher the concentration of deuterium, the more water has been lost. <\/p>\n
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NASA finds evidence of a vast ancient ocean on Mars<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Geronimo Villanueva\/Nasa An artists impression of the ancient ocean on Mars, which lasted for billions of years more than was previously thought. Credits: Mars Geronimo Villanueva\/Nasa A massive ancient ocean once covered nearly half of the northern hemisphere of Mars making the planet a more promising place for alien life to have gained a foothold, Nasa scientists say. The huge body of water spread over a fifth of the planets surface, as great a portion as the Atlantic covers the Earth, and was a mile deep in places Continue reading