POLAR POOLING: Radar maps of Mars hint at the presence of an ocean long ago near the north pole.
Image: ESA, C. Carreau
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In the eyes of many planetary scientists, the surface of Mars's northern hemisphere has long looked like it once contained an ocean. Now it is "sounding" that way, too.
A European spacecraft equipped with sounding radar that bounces radio waves off the Red Planet to investigate its makeup has identified what appear to be sedimentary deposits in the Martian north. The sediments, which could be mixed with ice, would represent the remains of a shallow ocean that existed some three billion years ago, according to a study published in January in Geophysical Research Letters.
Previous evidence for an ancient northern ocean on Mars has come in the form of a somewhat controversial interpretation of certain landforms as shorelines, the striking smoothness of the northern terrain, and the presence of surfaces that appear to be sedimentary deposits.
The new research is based on a series of radar soundings by the MARSIS instrument on the European Space Agency's Mars Express orbiter, which has orbited the Red Planet since 2003. (MARSIS stands for Mars Advanced Radar for Subsurface and Ionosphere Sounding.) "We mapped the intensity of the surface echo all over the planet," says lead study author Jérémie Mouginot, an associate project scientist in Earth system science at the University of California, Irvine. In the Vastitas Borealis formation, a geologic deposit near the Martian north pole that has long been suspected of being sedimentary in origin, the radar reflectivity was quite low—lower than would be expected if the formation were volcanic rather than sedimentary. "The only interpretation we see is sediments," Mouginot says. "These sediments came from a flow or a shallow ocean that put the sediments there."
The sedimentary interpretation of the formation agrees with data obtained by another sounding radar on NASA's Mars Reconnaissance Orbiter, which surveyed the region a few years ago. That orbiter's SHARAD (Shallow Radar) instrument suggested that the Vastitas Borealis formation comprised a substantial sedimentary layer overlying volcanic plains.
Based on the extent of the sediments identified by Mars Express, the ocean would have covered a large region of the northern plains, but not for very long. Around three billion years ago, Mars appears to have had enough geothermal activity to melt a large amount of groundwater and feed a shallow ocean, perhaps 100 meters deep. (Mouginot notes that there may also have existed a more primitive ocean on Mars, which could be responsible for the supposed shorelines.) "I think what we had here is some episode of flash flooding, or something like that, that covered the northern plain," Mouginot says. But the environment would have been too cold and too dry to sustain a large body of water over geologic timescales. Within a million years or so, the ocean would have refroze and been buried underground or escaped as vapor.
The radar reflectivity of the Vastitas Borealis formation could be explained by sediments either standing alone or mixed with ice. So it is possible that some subsurface remnant of the ocean itself persists. But that seems a fairly remote possibility, according to planetary scientist Norbert Schörghofer of the Institute for Astronomy of the University of Hawaii at Manoa, who was not part of the research team. "It's much more likely that it's sediment, because it's just very hard to keep ice there for a long time," he says. "Physically, the ice should most likely have disappeared."
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16 Comments
Add CommentHey, that's easy to explain:
Reply | Report Abuse | Link to thisThe sea was there until 4,000 years ago, not Billions.
Then, the "Intelligent designer", we should probably rather call him the "Great plumber" used the water to flush the Earth in what is today called the "Great flood", in order to get rid of some misshaped pieces of mud.
When he was done with flushing, he had to deposit the water somewhere else, and the Saturn moon Europa came just handy for him.
Sometimes, the world is so easy to explain.
We have padded rooms for people like you Extremophile. Please have your next of kin contact your behavioral health provider for an immediate psychiatric evaluation.
Reply | Report Abuse | Link to thisI admire your sense of humor...
Reply | Report Abuse | Link to thisMaybe, mredmondm, I should say sorry for confusing you.
Reply | Report Abuse | Link to thisThe "Big plumber" came up in a recent discussions with Young Earth creationists, not just dumb people, rather imprisoned in their system of explanations, who desperately tried to explain how fish could survive a "Big flood", which would have changed the salinity and pressure conditions in water dramatically, conditions to which fish react very sensitive.
It became obvious in the end, that when they talk about an "Intelligent designer", they rather mean a big plumber.
Okay lets keep this simple. You seem to be referring to the flood myth which is found in all human cultures. Also we see arise of civilization that dates back to about 8,000 years ago. What might these have in common. Perhaps the end of the last Ice age (about 8,000 years ago) and if you have studied glaciers at all they tend to move a lot of rocks as they scrape the earth. No plumber needed when you have 1 to 2 mile high glaciers of ice moving and scraping.
Reply | Report Abuse | Link to thisAs the ice retreated (melted at the end of the ice age) the boulders and rocks would create natural dams that would hold so much water but as the glaciers released more water the build up of pressure would eventually let loose the natural dams and we would have some pretty damn big floods. The Black Sea is a pretty good candidate for proof of this but just keep in mind that during the last ice age the sea level was about 300 feet lower than it is today.
Regarding Noah, the myth we are most familiar with might have just been a smart man who saw the damn issue coming and decided a big boat would be a smart answer for when the levy broke. Exremophile, if you study Moses and the timing of Thera you may be able to blame that on the big plumber also but I blame it on good timing and astute awareness of the environment. The good timing has worked out very good in the Judea-Christian thinking but if you do a little research they were borrowed from Egyptian and Mesopotamian which can rightly state they thought of it first. Stick with the paleontological and geological facts and we will let you stay in public. I think putting you in a padded cell is a little extreme. A lot of scientist go out of their way to deny God but it is a defensive move to pseudo science like the Great Plumber. For your entertainment check out The Firesign Theaters 'Waiting for the Electrician or Someone Like Him'. You may find deep meaning in its humor.
Mars had maybe a billion years of climate conducive to life. It took 4 billion years to reach our so called complexity and 3.5 billion to reach multi-cellular life so the odds are not there, Besides with out a moon like we have there is too much wobble in the rotation to allow for sustainable seasons. Mars at best may have had cellular life but to give it more credit especially with all the colliding going on during that time is way too generous.
Reply | Report Abuse | Link to thisI think Europa has a better chance at complex life and by that I am thinking squids or octopi but with the ice shelf blocking the rest of the universe from any life I don't expect it to be anything we can communicate with.
Titan will have a brief moment when the sun goes Giant Red but again it took 3.5 billion years for complex life to get a foot hold on earth and with out a moon to keep the object in a stable rotation complexity will be hard to come by.
I have pondered it. And if you read the Bible if that is where you are coming from Christ says my Kingdom is not of this world, which I think means think bigger Multi-verse maybe.
Attention mredmondm and David Russell: Extremophile was clearly needling the stupid Creationists in his first post. The sarcasm seemed to fly right over your pointed heads.
Reply | Report Abuse | Link to thisOr was He?
Reply | Report Abuse | Link to thisIt took a second look. Well played sir, well played. I just had some guy spitting out Velikosky a week ago so I misread the humor. Oh the hubris, I can't wait until Santorum is in charge and God comes back and saves us all by ending the earth.
Reply | Report Abuse | Link to thisAgain Well Played. (Or was it?)
If you follow the Saturnian Mythologists you will find that Mars was known as Scarface by the Blackfoot Indians. The Aztecs linked their warrior god Tlaloc with scarring by lightning. If that is the case not only was Mars much closer to the Earth, it also suffered major damage VERY recently. The Greeks and Trojans also presumably witnessed interplanetary spark games according to their myths.
Reply | Report Abuse | Link to thisSo life could have existed on our neighbour but was completely destroyed, not that long ago?? Ah, but that would make me a Velikovskian, which would not please David!
Best myth book you will ever read is Decipher. It covers all of them and it is a great read. I read Velikosky as a teen after being told about it by a friend I worked with. I thought Sagan was pretty brutal on him and I think some of the super novas may well explain your myths. But read Decipher, it is very prophetic in its discussion of C60 and its association of pyramids and common stories. If you read some of the above comments they cover a lot of the myth based commonness and if I read my history right a lot of stories were borrowed by other cultures.
Reply | Report Abuse | Link to thisI think the end of the last ice age and the rise of civilization in Mesopotamia fits well together that there may have been cultures prior to ours but that would be water under the ice dam.
Extremophile, you must understand that we who participate on these SA threads are not known for our ability to recognise - or appreciate - irony....
Reply | Report Abuse | Link to thisHenri
How ironic. Or can we?
Reply | Report Abuse | Link to thisis that why mars is so red?
Reply | Report Abuse | Link to thisI am happy that you finally found my point.
Reply | Report Abuse | Link to thisI am happy that you finally found my point. Long live the Great Plummer.
Reply | Report Abuse | Link to this