Científicos hallan pruebas de presencia actual de agua en Marte
Hasta ahora sólo había indicios de existencia del líquido hace miles de millones de años.
"Puede ser agua salina, agua que contenga una gran cantidad de sedimentos, agua ácida, no lo sabemos, pero es definitivamente agua, H2O", dijo el experto de la Nasa, Kennet Edgett.
Fecha edición: 06/12/2006 16:28
La exploración de la superficie de Marte ha permitido encontrar pruebas de la existencia de agua líquida en ese planeta, el cuarto del sistema solar, anunció hoy la agencia espacial estadounidense.
"Ya teníamos pruebas de que hubo agua hace millones de años en Marte. Ahora hemos encontrado pruebas de la presencia de agua líquida en la actualidad", dijo el experto Kennet Edgett en una conferencia de prensa en la sede de la Administración Nacional para la Aeronáutica y el Espacio (Nasa).
Edgett, de la empresa Malin de Ciencias Espaciales, mostró una serie de fotografías tomadas en los años 2000 y 2005 en laderas de cráteres volcánicos en las que se ven lo que parecen ser lechos de cursos de agua, estrechos en su comienzo y que se abren en deltas al llegar a la base.
"Puede ser agua salina, agua que contenga una gran cantidad de sedimentos, agua ácida, no lo sabemos, pero es definitivamente agua, H2O", afirmó Edgett.
Michael Malin, presidente y científico principal de ese laboratorio en San Diego, California, relató la forma en que los investigadores encontraron que las imágenes de una misma área de Marte, registradas en diferentes fechas, mostraban puntos y surcos que no aparecían en imágenes anteriores, o se habían movido.
El aspecto cambiante de las zanjas en Marte en pocos años ha fortalecido la creencia de los científicos de que ha habido flujo de agua recientemente en la superficie del planeta rojo.
"Esto del agua fue, claramente, una sorpresa para nosotros. El ambiente de Marte en su totalidad no parece muy propicio para el agua", dijo Malin.
POSTED: 1:25 p.m. EST, December 6, 2006 POSTED: 1:25 p.m. EST, December 6, 2006 POSTED: 1:25 p.m. EST, December 6, 2006
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Story Highlights• Photos suggests liquid water flowed on Mars as recently as several years ago • Strongest evidence yet that water even now sometimes flows on red planet • Scientists: Images of gullies and trenches carved by fast-moving water • NASA lost contact with Mars probe last month
LOS ANGELES, California (AP) -- A provocative new study of photographs taken from orbit suggests that liquid water flowed on the surface of Mars as recently as several years ago, raising the possibility that the red planet could harbor an environment favorable to life.
The crisp images taken by the Mars Global Surveyor do not directly show water. Rather, they show apparently recent changes in surface features that provide the strongest evidence yet that water even now sometimes flows on the dusty, frigid world. Water and a stable heat source are considered keys for life to emerge.
Until now, the question of liquid water has focused on ancient Mars, and on the Martian north pole, where water ice has been detected. Scientists have long noted Martian features that appear to have been scoured by water or look like shorelines, and have tried to prove that the red planet had liquid water eons ago.
"This underscores the importance of searching for life on Mars, either present or past," said Bruce Jakosky, an astrobiologist at the University of Colorado at Boulder, who had no role in the study. "It's one more reason to think that life could be there."
The new findings were published Wednesday in the journal Science and NASA scheduled a news conference for Wednesday afternoon to announce the results.
Oded Aharonson, an assistant professor of planetary science at the California Institute of Technology, said that while the interpretation of recent water activity on Mars was "compelling," it's just one possible explanation. Aharonson said further study is needed to determine whether the deposit could have been left there by the flow of dust rather than water.
The latest research emerged when the Global Surveyor spotted gullies and trenches that scientists believed were geologically young and carved by fast-moving water coursing down cliffs and steep crater walls.
Scientists at the San Diego-based Malin Space Science Systems, who operate a camera aboard the spacecraft, decided to retake photos of thousands of gullies in search of evidence of recent water activity.
Two gullies that were originally photographed in 1999 and 2001 and re-imaged in 2004 and 2005 showed changes consistent with water flowing down the crater walls, according to the study.
In both cases, scientists found bright, light-colored deposits in the gullies that weren't present in the original photos. They concluded the deposits -- possibly mud, salt or frost -- were left there when water recently cascaded through the channels.
The Global Surveyor, managed by NASA's Jet Propulsion Laboratory, abruptly lost radio contact with Earth last month. Attempts to locate the spacecraft, which has mapped Mars since 1996, have failed and scientists fear it is unusable. (Full story)
NASA's durable Mars rovers have sent scientists strong evidence that the planet once had liquid water at or near the surface, based on observations of alterations in ancient rocks.
"We're now realizing Mars is more active than we previously thought and that the mid-latitude section seems to be where all the action is," said Arizona State University scientist Phil Christensen, who was not part of the current research.
Mars formed more than 4.5 billion years ago and scientists generally believe it went through an early wet and warm era that ended after 1.5 billion to 2.5 billion years, leaving the planet extremely dry and cold.
Water cannot remain a liquid for long because of subzero surface temperatures and low atmospheric pressure that would turn water into ice or gas.
But some studies have pointed to the possibility of liquid water flowing briefly on the surface through a possible underground water source that periodically shoots up like an aquifer.
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