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Archive for May 31, 2013

SwRI-Led Team Calculates The Radiation Exposure Associated With A Trip To Mars


On November 26, 2011, the Mars Science Laboratory began a 253-day, 560-million-kilometer journey to deliver the Curiosity rover to the Red Planet. En route, the Southwest Research Institute-led Radiation Assessment Detector (RAD) made detailed measurements of the energetic particle radiation environment inside the spacecraft, providing important insights for future human missions to Mars.

“In terms of accumulated dose, it’s like getting a whole-body CT scan once every five or six days,” said Dr. Cary Zeitlin, a principal scientist in SwRI’s Space Science and Engineering Division and lead author of Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory, scheduled for publication in the journal Science on May 31.

“Understanding the radiation environment inside a spacecraft carrying humans to Mars or other deep space destinations is critical for planning future crewed missions,” Zeitlin said. “Based on RAD measurements, unless propulsion systems advance rapidly, a large share of mission radiation exposure will be during outbound and return travel, when the spacecraft and its inhabitants will be exposed to the radiation environment in interplanetary space, shielded only by the spacecraft itself.”

Full Story: http://www.swri.org/9what/releases/2013/rad.htm#.UagaCH4o5hF

Low Sodium Diet Key To Old Age For Stars


Credit: ESO

Credit: ESO

Astronomers expect that stars like the Sun will blow off much of their atmospheres into space near the ends of their lives. But new observations of a huge star cluster made using ESO’s Very Large Telescope have shown — against all expectations — that a majority of the stars studied simply did not get to this stage in their lives at all. The international team found that the amount of sodium in the stars was a very strong predictor of how they ended their lives.

The way in which stars evolve and end their lives was for many years considered to be well understood. Detailed computer models predicted that stars of a similar mass to the Sun would have a period towards the ends of their lives — called the asymptotic giant branch, or AGB — when they undergo a final burst of nuclear burning and puff off a lot of their mass in the form of gas and dust.

But when Australian stellar theory expert Simon Campbell of the Monash University Centre for Astrophysics, Melbourne, scoured old papers he found tantalising suggestions that some stars may somehow not follow the rules and might skip the AGB phase entirely. He takes up the story:

“For a stellar modelling scientist this suggestion was crazy! All stars go through the AGB phase according to our models. I double-checked all the old studies but found that this had not been properly investigated. I decided to investigate myself, despite having little observational experience.”

Full Story: http://www.eso.org/public/news/eso1323/

Rounded Stones On Mars Evidence Of Flowing Water


Image Credit: NASA/JPL-Caltech

Image Credit: NASA/JPL-Caltech

Observations by NASA’s Mars rover Curiosity have revealed areas with gravel and pebbles that are characteristic of a former riverbed. Researchers, including members of the Niels Bohr Institute, have analysed their shapes and sizes and the rounded pebbles clearly show that there has been flowing water on Mars. The results are published in the scientific journal, Science.

The Mars rover’s stereo camera took pictures of a few areas with densely packed pebbles, cemented together like concrete. The image field of an area named Hottah was a mosaic of approximately 1.4 meters x 80 centimeters. But when the picture is taken at an angle from the camera arm’s two meter high mast down towards the ground-level, it gives a slightly distorted view in which the size of the rocks depend on their location in the image frame. To remedy this, the researcher first had to process the image so the proportions are comparable.

“Next, we divided the image into smaller fields of 10 mm and analysed the gravel, which consists of coarse grains of sand around 1/3 mm. We examined the pebbles which are between 4 and 40 mm in greater detail. Altogether we made a thorough analysis of 515 pebbles”, explains Asmus Koefoed, research assistant in the Mars Group at the Niels Bohr Institute at the University of Copenhagen.

Full Story: http://www.nbi.ku.dk/english/news/news13/rounded-stones-on-mars-evidence-of-flowing-water/

Cassini Finds Hints Of Activity At Saturn Moon Dione


Image credit: NASA/JPL/Space Science Institute

Image credit: NASA/JPL/Space Science Institute

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA’s Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.

“A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn’s geyser moon Enceladus or perhaps a weaker copycat Enceladus,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. “There may turn out to be many more active worlds with water out there than we previously thought.”

Other bodies in the solar system thought to have a subsurface ocean – including Saturn’s moons Enceladus and Titan and Jupiter’s moon Europa – are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-178