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Curiosity finds 'stream gravel' on Mars

2012-09-28 10:30

Washington - Nasa's Mars rover has discovered gravel once carried by the waters of an ancient stream that "ran vigorously" through the area, the US space agency said.

Scientists had previously found other evidence of the one-time presence of water on the Red Planet, but this is the first time stream bed gravel has been discovered.

The rocky Hottah outcrop looks "like someone jack-hammered up a slab of city sidewalk, but it's really a tilted block of an ancient stream bed", project scientist John Grotzinger said in a statement.

The Curiosity rover, which has been exploring Mars since early August, also investigated a second outcrop known as Link.

The pictures transmitted by Curiosity show the pebbles have been cemented into layers of conglomerate rock at a site between the north rim of the Gale Crater and the base of Mount Sharp, where Curiosity is heading.

Water

The sizes and the shapes of the rocks give an idea of the speed and the depth of the stream, Nasa said.

"The shapes tell you they were transported, and the sizes tell you they couldn't be transported by wind. They were transported by water flow," said Curiosity scientist Rebecca Williams.

Scientists estimate the water was moving at a brisk pace of one metre per second, somewhere between ankle and hip deep.

"This is the first time we're actually seeing water-transported gravel on Mars," said Curiosity science co-investigator William Dietrich of the University of California, Berkeley.

"This is a transition from speculation about the size of streambed material to direct observation of it."

Some of the rocks are rounded, indicating they travelled a long distance from above the rim, fed from a channel named Peace Vallis, Nasa said.

And thanks to imagery previously captured from Mars's orbit, the scientists said they can see an alluvial fan of material washed down from the rim - with many apparent channels uphill of Link and Hottah.

The high number of channels between the rim and the newly-discovered rock bed suggests the stream wasn't a one-time occurrence, but that many streams flowed or repeated over a long period of time.

Curiosity is on a two-year mission to investigate whether it is possible to live on Mars and to learn whether conditions there might have been able to support life in the past.

The $2.5bn vehicle landed in Gale Crater on 6 August, opening a new chapter in the history of interplanetary exploration.

Comments
  • petrus.ngwenya.3 - 2012-09-28 10:42

    Globally, $2.5bn dollars is not that much, compared to the cost of wars, thefts, etc. Just think how mcuh we could have accomplished if everyone on earth were friends? Peace to the world.

      LanfearM - 2012-09-28 11:17

      Exactly. $2.5 billion is nothing when the US military budget alone is over $300 billion last year. Imagine if we took all the billions and trillions spent on war and hate and propaganda against perceived enemies, and spent it on scientific development!

      oscar.pretorius.52 - 2012-09-28 12:47

      Perhaps. But a lot of the technology used in science is firstly developed through military contracts. Just think how long it would have taken to develop rockets from a science budget if the Germans hadn't developed the V2 rockets.

  • arthur.hugh - 2012-09-28 11:11

    Awesome... if there was water, surely there was vegetation of some sort?

      hennie.ludick1 - 2012-09-28 12:21

      By looking at the terrain I would say that the water came from underground when a meteor slammed into the surface of Mars. This could explain the rapid flow and volume of the water, but I doubt that this could have led to the growth of vegetation as this water would have been very acidic by nature. Curiosity will need to dig deep.

      khumza - 2012-09-28 12:46

      you figured all that just by looking at the terrain?

      stirrer.stirrer - 2012-09-28 13:23

      Hennie, how deep did you have to dig to come up with that cr@p?

      hennie.ludick1 - 2012-09-28 14:00

      stirrer.stirrer please read the following. “The pictures transmitted by Curiosity show the pebbles have been cemented into layers of conglomerate rock at a site between the north rim of the Gale Crater and the base of Mount Sharp, where Curiosity is heading.” With the key word crater and a bit of my own common sense I came up with that.

      oscar.pretorius.52 - 2012-09-28 14:04

      Yeah hennie but I recall they saying the mountain in the centre of the crater was created through sedimentation. So it is likely the water flowed on surface and was unrelated to the actual impact event

      hennie.ludick1 - 2012-09-28 14:58

      The temperature on Mars averages 80°F below zero. Eighty degrees below zero should be cold enough to freeze any water, no matter what it holds in solution. The water on Mars lies in several places and the polar regions have abundant ice, often no more than a foot below ground. The Phoenix Lander found it in one of its first digs. Water on Mars cannot stay liquid on the surface. So it must come from below or from above. But if it comes from below, then first one must figure out what makes it warm down below. We cannot just assume that any planet will have a hot core. We have to know why it’s hot and how hot. Second, even if Mars has a hot core, the surface is so cold that any water that pushed up to within a mile or two below ground, would freeze. Balls of ice fell on Mars, melted when they fell, and re-froze. All the gullies have appeared on cliff faces or on crater walls. That is no coincidence. An impact makes a crater. And an impact releases heat. In the case of Mars, several comets and ice-laden asteroids fell onto Mars and melted. But Mars is cold so the water on Mars did not set up a “water cycle” like that on earth. Today, water flows on Mars only when another object, i.e. a meteor, falls to Mars and melts some of the ice. So Mars never had an ocean. Nor did the water disappear, as others have speculated before. It’s still on Mars, only frozen.

      oscar.pretorius.52 - 2012-09-28 15:02

      You of course assuming temperature of mars and atmosphere composition have remained constant. If however mars had a thicker atmosphere, through a greenhouse effect the temperature would have been higher allowing for surface water to exist.

  • khumbudzo.budeli - 2012-09-28 11:42

    Wow, this could prove mars might hav supported life in the past. Surely if the was a stream, vegetations might hav occured

      oscar.pretorius.52 - 2012-09-28 12:16

      Not necessarily. From the first evidence of life on earth to the first plant fossils, there's a time difference of over 3 billion years. It took a long time for plants to evolve on earth and by the same time frame it is thought Mars had dried up.

      hennie.ludick1 - 2012-09-28 12:21

      By looking at the terrain I would say that the water came from underground when a meteor slammed into the surface of Mars. This could explain the rapid flow and volume of the water, but I doubt that this could have led to the growth of vegetation as this water would have been very acidic by nature. Curiosity will need to dig deep.

      tommy.jones.754918 - 2012-09-28 12:49

      Or sometime in the future.

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