Thursday, September 24, 2009

SEPT. 24 - Water Ice Exposed in Mars Craters

Dear Friends,

"Where there's water there's life as we know it." - NASA Paste the link if you can't access the links.

Love and Light.


The HiRISE camera on NASA's Mars Reconnaissance Orbiter took this image of a new, 8-meter (26-foot)-diameter meteorite impact crater in the topographically flat, dark plains within Vastitas Borealis, Mars, on November 1, 2008. The crater was made sometime after Jan. 26, 2008. Bright water ice was excavated by, and now surrounds, the crater. This entire image is 50 meters (164 feet) across. Credit: NASA/JPL-Caltech/University of Arizona

Earlier and later HiRISE images of a fresh meteorite crater 12 meters, or 40 feet, across located within Arcadia Planitia on Mars show how water ice excavated at the crater faded with time. The images, each 35 meters, or 115 feet across, were taken in November 2008 and January 2009. Credit: NASA/JPL-Caltech/University of Arizona

Ice on Mars is exposed in two crater bottoms, but fades from view over the course of the Martian summer in this series of HiRISE images from MRO taken in late-2008/early-2009. Sublimation of the ice leaves behind a dust layer that gradually thickens to the point where it obscures the ice. Each panel is 75m (250 feet) across. Credit: NASA/JPL-Caltech/University of Arizona

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Water Ice Exposed in Mars Craters
By Andrea Thompson

posted: 24 September 2009
02:18 pm ET

Craters gouged into the ruddy Martian terrain have revealed subsurface water ice closer to the red planet's equator than would be expected, new orbiter images show.

The ice also seems to be 99 percent pure, instead of the dirty dust and ice mixture some scientists expected to see, scientists said today.

And while numerous surface features on Mars suggest that water once flowed on the red planet in the past, the new discovery - detailed in the Sept. 25 issue of the journal Science - adds to the evidence that has been piling up in recent years that water exists on present-day Mars, in the form of subsurface ice. It also gives scientists a way to further probe the Martian surface for signs of water ice.

Because water is essential to life as we know it, any findings of potentially once-liquid water has implications for the search for evidence of possible past Martian life.

The new finding comes just one day after scientists announced new evidence for water ice on Earth's moon.

Found just in time

In August 2008, members of the Mars Reconnaissance Orbiter's (MRO) Context camera team examined images of the northern Martian mid-latitudes taken by the camera for any dark spots or other changes not seen in earlier images. These dark marks are signs of meteorites that have recently crashed into the dust-covered Martian terrain.

They found several, and the following month, members of MRO's HiRISE camera team followed up by snapping high-resolution images of these suspected impact craters.

"We saw something very unusual when we followed up on the first of these impact craters," said HiRISE team member Shane Byrne of the University of Arizona, "and that was this bright blue material poking up from the bottom of the crater. It looked a lot like water ice."

A few days later, MRO's Compact Reconnaissance Imaging Spectrometer (CRISM) was used to take the spectrum of the material and, sure enough, it found the spectral signature of water ice.

The behavior of the material over the ensuing days also helped clinch its identity: "When we started monitoring the material, it faded away like you'd expect water ice to fade, because water ice is unstable on Mars' surface and turns directly into water vapor in the atmosphere," Byrne explained.

The relatively quick disappearance of the ice means the MRO teams were fortunate to have spotted the craters when they did.

"All of this had to happen very quickly because 200 days after we first saw the ice, it was gone, it was the color of dirt," Byrne said. "If we had taken HiRISE images just a few months later, we wouldn't have noticed anything unusual. This discovery would have just passed us by."

Further evidence

The evidence of these ice layers exposed by meteorite impacts stacks on top of other recently uncovered clues, including the excavation of a shallow water ice layer by NASA's Phoenix Mars Lander last year.

But Phoenix was at a more northerly locale than the new craters, so this fresh evidence shows that the subsurface water ice extends further south than previously thought.

"We knew there was ice below the surface at high latitudes of Mars, but we find that it extends far closer to the equator than you would think," Byrne said.

Also surprising was how clean the water ice was (something Phoenix also observed, along with the gradual sublimation of exposed ice).

"The thinking before was that ice accumulates below the surface between soil grains, so there would be a 50-50 mix of dirt and ice," Byrne said. "We were able to figure out, given how long it took that ice to fade from view, that the mixture is about one percent dirt and 99 percent ice."

The craters, which ranged from 1.5 to 8 feet (about 0.5 to 2.4 meters) deep, were located at five Martian sites.

Though the MRO researchers had identified 80 to 90 craters around the Martian globe before, this was the first time the spotted ice in the bottoms, likely because most of the others were more southerly and outside of the likely area of subsurface water ice.

Byrne told that it was surprising to the team to find the bluish ice, though "in retrospect maybe it shouldn't have been." Scientists knew of the existence of underground ice and had been monitoring craters as they formed, but "I guess we didn't put the two together," he said.

Several of the craters were also near the landing site of the Viking Lander 2. Viking also looked for water ice on Mars, but was only able to dig down about 6 inches (15 cm) below the surface — about 4 inches (10 cm) shy of where Byrne and his colleagues think the ice table sits.

"It's a shame that didn't happen," Byrne said. "You might have been having this conversation 30 years ago."

How the ice got there

There are several theories as to how such pure ice could form under the Martian surface. Byrne thinks that one of the most promising explanations is that the ice formed in the same way that so-called pure ice lenses form on Earth.

"That's where you have very thin films of liquid water around ice grains and soil grains and they migrate around to form clear ice lenses on top of the ice table, even at temperatures well below zero," he explained. "This process is called 'frost heave' on Earth, and it's considered a nuisance in most places because it cracks up roads and tilts walls and destroys the foundations of houses."

However the water ice got there, it tells scientists something about Mars recent climate. The ice is essentially "a remnant of a previous climate," Byrne said, one which likely existed around 10,000 years ago.

As the climate changes and becomes drier, the ice is expected to retreat, though based on estimates of its current extent, it hasn't done so quite as quickly as expected.

"The climate has changes but the ice is still there," Byrne said. Just why that is isn't clear yet.

These ice lenses are likely to be a source of interest to those studying the possibility of life on Mars as well, though Byrne said he's "not entirely sure if this is enough water to be interesting to a microbe."

Byrne and his colleagues suggest that fresh impact craters can be used as a new tool to probe the depth and extent of Mars' subsurface water ice.

"These impacts are really very useful," Byrne said.

And this time around, Byrne and the rest of the MRO team will be ready. Mars' northern hemisphere is heading into summer, and Byrne hopes to see about 10 more craters over this a subsequent seasons, building up a map of where known subsurface ice exists. Of course, the observations depend on MRO's successful reboot out of its current safe mode, which has temporarily suspended all science operations.

"This is I hope the start of a promising new method" of looking for water ice, he said.

Author: Andrea Thompson

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How to Digitally Record/Video a UFO sighting:

Como registar digitalmente ou gravar um vídeo de um avistamento de um UFO:

Stabilize the camera on a tripod. If there is no tripod, then set it on top of a stable, flat surface. If that is not possible lean against a wall to stabilize your body and prevent the camera from filming in a shaky, unsteady manner.

Estabilize a camera com um tripé. Se não tiver um tripé, então coloque-a em cima de uma superfície estável. Se não for possível, então encoste-se a uma parede para estabilizar o corpo e evitar que a camera registe de maneira tremida e instável.

Provide visual reference points for comparison. This includes the horizon, treetops, lampposts, houses, and geographical landmarks (i.e., Horsetooth Reservoir, Mt. Adams, etc.) Provide this in the video whenever is appropriate and doesn’t detract from what your focus is, the UFO.

Forneça pontos visuais de referência para comparação. Isso inclui o horizonte, cimo das árvores, postes de iluminação, pontos de referência geográficos (como o Reservatório de Horsetooth, Mone Adams, etc) Forneça esses pontos no vídeo sempre que for apropriado e não se distraia do que é o seu foco, o UFO/a Nave.

Narrate your videotape. Provide details of the date, time, location, and direction (N,S,E,W) you are looking in. Provide your observations on the weather, including approximate temperature, windspeed, any visible cloud cover or noticeable weather anomalies or events. Narrate on the shape, size, color, movements, approximate altitude of the UFO, etc and what it appears to be doing. Also include any unusual physical, psychological or emotional sensations you might have. Narrate any visual reference points on camera so they correlate with what the viewer will see, and thereby will be better able to understand.

Faça a narração do vídeo. Forneça pormenores sobre a data, hora, local e direcção (Norte, Sul, Este, Oeste) que está a observar. Faça observações sobre as condições atmosféricas, incluindo a temperatura aproximada, velocidade do vento, quantidade de nuvens, anomalias ou acontecimentos meteorológicos evidentes. Descreva a forma, o tamanho, a cor, os movimentos, a altitude aproximada onde se encontra o UFO/nave, etc e o que aparenta estar a fazer. Inclua também quaisquer aspectos pouco habituais de sensações físicas, psicológicas ou emocionais que possa ter. Faça a narração de todos os pontos de referência visual que o espectador irá ver e que, deste modo, será capaz de compreender melhor.

Be persistent and consistent. Return to the scene to videotape and record at this same location. If you have been successful once, the UFO sightings may be occurring in this region regularly, perhaps for specific reasons unknown, and you may be successful again. You may also wish to return to the same location at a different time of day (daylight hours) for better orientation and reference. Film just a minute or two under “normal” circumstances for comparison. Write down what you remember immediately after. As soon as you are done recording the experience/event, immediately write down your impressions, memories, thoughts, emotions, etc. so it is on the record in writing. If there were other witnesses, have them independently record their own impressions, thoughts, etc. Include in this exercise any drawings, sketches, or diagrams. Make sure you date and sign your documentation.

Seja persistente e não contraditório. Volte ao local da cena e registe o mesmo local. Se foi bem sucedido uma vez, pode ser que nessa região ocorram avistamentos de UFOs/naves com regularidade, talvez por razões específicas desconhecidas, e talvez possa ser novamente bem sucedido. Pode também desejar voltar ao mesmo lugar a horas diferentes do dia (durante as horas de luz)para ter uma orientação e referência melhor. Filme apenas um ,inuto ou dois em circunstâncias “normais” para ter um termo de comparação. Escreva tudo o que viu imediatamente após o acontecimento. Logo após ter feito o registo da experiência/acontecimento, escreva imediatamente as impressões, memórias, pensamentos, emoções, etc para que fiquem registadas por escrito. Se houver outras testemunhas, peça-lhes para registar independentemente as suas próprias impressões, pensamentos, etc. Inclua quaisquer desenhos, esbolos, diagramas. Certifique-se que data e assina o seu documento/testemunho.

Always be prepared. Have a digital camera or better yet a video camera with you, charged and ready to go, at all times. Make sure you know how to use your camera (and your cell phone video/photo camera) quickly and properly. These events can occur suddenly, unexpectedly, and often quite randomly, so you will need to be prepared.

Esteja sempre preparado, Tenha sempre uma camera digital, melhor ainda, uma camera vídeo consigo, carregada e pronta a usar sempre que necessário. Certifique-se que sabe como lidar com a sua camera (ou com o seu celular/camera fotográfica) rápida e adequadamente. Esses acontecimentos podem acontecer súbita e inesperadamente e, por vezes, acidentalmente, por isso, necessita estar preparado.

Look up. Be prepared. Report. Share.

Olhe para cima, Esteja preparado, Relate, Partilhe.



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