Archive for August 3, 2012

Taking A Robotic Geologist To Mars

August 3, 2012 1 comment

Image: NASA/JPL-Caltech

As Mars rover Curiosity makes its final approach to the Red Planet, two UA geoscientists are getting ready to help solve some of the mysteries of its geologic past.

On Aug. 5, at about 10:30 p.m., an already busy summer will kick into overdrive for University of Arizona geosciences professor Bob Downs and one of his graduate students, Shaunna Morrison. At that time – provided everything goes as planned – Curiosity, the most sophisticated exploration vehicle ever sent to another planet, will parachute toward the Martian surface faster than the speed of sound after a nine-month journey through space. And as soon as it sinks its six wheels into the red dust, the two scientists specializing in mineralogy will have not one, but two planets to deal with.

As “primary data downlink leaders” designated by NASA, Downs and Morrison are part of a team of scientists tasked with the identification of rocks that Curiosity will encounter during its two-year expedition across the floor of Gale Crater near the Martian equator.

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What To Expect When Curiosity Starts Snapping Pictures

If a group of tourists piled out of a transport vehicle onto the surface of Mars, they’d no doubt start snapping pictures wildly. NASA’s Curiosity rover, set to touch down on the Red Planet the evening of Aug. 5 PDT (early morning EDT), will take a more careful approach to capturing its first scenic views.

The car-size rover’s very first images will come from the one-megapixel Hazard-Avoidance cameras (Hazcams) attached to the body of the rover. Once engineers have determined that it is safe to deploy the rover’s Remote Sensing Mast and its high-tech cameras, a process that may take several days, Curiosity will begin to survey its exotic surroundings.

“A set of low-resolution gray scale Hazcam images will be acquired within minutes of landing on the surface,” said Justin Maki of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Once all of the critical systems have been checked out by the engineering team and the mast is deployed, the rover will image the landing site with higher-resolution cameras.”

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Meddia Invited To “Origins of the Expanding Universe” Conference, Sept. 13-15, 2012

On September 17, 1912, Vesto Slipher obtained the first radial velocity of a “spiral nebula” – the Andromeda Galaxy. Using the 24-inch telescope at Lowell Observatory, he followed up with more Doppler shifts, and wrote a series of papers establishing that large velocities, usually in recession, are a general property of the spiral nebulae. Those early redshifts were recognized as remarkable by Slipher, and were critical to the discovery of what came eventually to be called the expanding Universe. Surprisingly, Slipher’s role in the story remains almost unknown to much of the astronomical community.

The nature, and especially the distance, of spiral nebulae was fiercely argued – most famously in the 1920 Shapley-Curtis debate. Hubble’s 1923 discovery of Cepheids in Andromeda, along with Henrietta Leavitt’s period-luminosity relation for Cepheids, led to a distance scale for the nebulae, enabling Lemaitre (1927) to derive a linear relation between velocity and distance (including a “Hubble constant” and, by 1931, a Primeval Atom theory).

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MESSENGER Marks 8th Anniversary Of Launch

The MESSENGER spacecraft launched eight years ago today — on August 3, 2004 — embarking on a six-and-a-half year journey to become the first spacecraft to orbit Mercury. The spacecraft’s 4.9-billion mile (7.9-billion kilometer) cruise to history included 15 trips around the Sun, a flyby of Earth, two flybys of Venus, and three flybys of Mercury.

MESSENGER made history on January 14, 2008, when it flew over a portion of Mercury that had never before been seen at close range. In this first of three flybys of the planet, the probe’s cameras took 1,213 images and other sophisticated instruments made the first spacecraft measurements of the planet and its environment since Mariner 10’s third and final flyby on March 16, 1975.

The mission’s penultimate accomplishment — entering orbit about Mercury — was celebrated on March 17, 2011, by a crowd of hundreds gathered at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The event was covered live, and the webcast is still available online at

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Signs Changing Fast For Voyager At Solar System Edge

Image credit: NASA/JPL-Caltech

Two of three key signs of changes expected to occur at the boundary of interstellar space have changed faster than at any other time in the last seven years, according to new data from NASA’s Voyager 1 spacecraft.

For the last seven years, Voyager 1 has been exploring the outer layer of the bubble of charged particles the sun blows around itself. In one day, on July 28, data from Voyager 1’s cosmic ray instrument showed the level of high-energy cosmic rays originating from outside our solar system jumped by five percent. During the last half of that same day, the level of lower-energy particles originating from inside our solar system dropped by half. However, in three days, the levels had recovered to near their previous levels.

A third key sign is the direction of the magnetic field, and scientists are eagerly analyzing the data to see whether that has, indeed, changed direction. Scientists expect that all three of these signs will have changed when Voyager 1 has crossed into interstellar space. A preliminary analysis of the latest magnetic field data is expected to be available in the next month.

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How To Spot Mars On The Eve Of Curiosity’s Arrival

NASA’s Curiosity lander will finally land on Mars around 1:31 a.m. EDT on August 6th, after cruising across 350 million miles of interplanetary space over 8½ months. This event is all over the news. But how many people know that you can go out after sunset and spot Mars for yourself with your unaided eyes?

Mars is practically on the far side of the Sun from Earth, 154 million miles (1.7 astronomical units) away. You can step outside this week to spot Curiosity’s destination low in the west after sunset (and maybe cheer the spacecraft on while you’re at it).

The Red Planet is joined by Saturn and the bright star Spica. All three are nearly equal in brightness, and they make a striking celestial triangle about 5° on a side. Spica’s color is icy white, Saturn is slightly creamy, and Mars is tinged with orange.

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Two UT Scientists To Begin Searching For Potential Habitats For Life On Mars

August 3, 2012 2 comments

NASA’s Curiosity rover is scheduled to land on Mars Sunday. Then, the work will begin for two University of Tennessee, Knoxville, professors searching for potentially habitable environments on the red planet.

Linda Kah and Jeffrey Moersch, associate professors in the Department of Earth and Planetary Sciences, are an integral part of the NASA team working on the rover.

The Curiosity rover is looking for clues to whether the Martian surface has ever had an environment capable of evolving or potentially sustaining life. Critical evidence may include liquid or frozen water, organic compounds, or other chemical ingredients related to life.

“In particular, we will be examining sedimentary rocks that form Mount Sharp, which is a more than five-kilometer-high mountain within Gale Crater, the area the rover is exploring,” said Kah. “These rocks might serve as a time capsule of Mars’s transition from a warm, wet planet to a cold, dry one.”

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Curiosity’s First Daredevil Stunt

Credit: NASA

When Curiosity enters the Martian atmosphere on August 6th, setting in motion “the seven minutes of terror” that people around the world have anticipated since launch a year ago, the intrepid rover will actually be performing the mission’s second daredevil stunt.

The first was completed in July.

For the past nine months, Curiosity has been acting as a stunt double for astronauts, exposing itself to the same cosmic radiation humans would experience following the same route to Mars1.

“Curiosity has been hit by five major flares and solar particle events in the Earth-Mars expanse,” says Don Hassler of the Southwest Research Institute in Boulder, Colorado. “The rover is safe, and it has been beaming back invaluable data.”

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Supernova Progenitor Found?

August 3, 2012 Leave a comment

Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the universe is expanding at an accelerating rate. But there is still too little known about the specifics of the processes by which these supernovae form. New research led by Carnegie’s Stella Kafka identifies a star, prior to explosion, which will possibly become a type Ia supernova.
The widely accepted theory is that type Ia supernovae are thermonuclear explosions of a white dwarf star that’s part of a binary system—two stars that are physically close and orbit around a common center of mass. This white dwarf has mass gradually donated to it by its companion. When the white dwarf mass eventually reaches 1.4 times the sun, it explodes to produce a type Ia supernova. The crucial questions are: What is the nature of the donor star and how does this white dwarf increase its mass. Also, how would that process affect the properties of the explosion?
With these questions in mind, scientists have been searching for candidate systems that could become type Ia supernovae. There are thousands of possibilities in the candidate pool, none of which have yet been observed to produce an explosion. Recent studies, some of which involved scientists at Carnegie observatories, have identified sodium gas associated with type Ia supernovae. This gas, might be ejected from the binary’s donor star, and linger around the system to be detected after the white dwarf explodes. This provides a clue to the progenitor. Even so, Kafka still compared the search to “looking for a needle in a stellar haystack.”
Using these gas signatures Kafka and her team—Kent Honeycutt of Indiana University and Bob Williams of the Space Telescope Science Institute—were able to identify a binary star called QU Carinae as a possible supernova progenitor. It contains a white dwarf, which is accumulating mass from a giant star, and sodium has been detected around the system.

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Subaru Telescope Reveals 3D Structure of Supernovae

August 3, 2012 Leave a comment

A research group led by Dr. Masaomi Tanaka (National Astronomical Observatory of Japan), Dr. Koji Kawabata (Hiroshima University), Dr. Takashi Hattori (National Astronomical Observatory of Japan), and Dr. Keiichi Maeda (University of Tokyo, Kavli Institute for the Physics and Mathematics of the Universe) used the Faint Object Camera and Spectrograph (FOCAS) on the Subaru Telescope to conduct observations that revealed a clumpy 3D structure of supernovae.  This finding supports a clumpy 3D scenario of supernovae explosions rather than the widely accepted bipolar explosion scenario. It advances our understanding of how supernovae explode, a process that has been a persistent mystery.

Stars heavier than eight solar masses will end their lives with a brilliant explosion called a “supernova”.  A supernova ejects elements synthesized within its star that are heavier than hydrogen and helium, the main elements of the primeval Universe. The ejection of these heavier elements into interstellar space has enriched the chemical composition of the Universe.

Despite its important role in the evolution of the Universe, the process of how supernovae explosions occur has been unclear. Based on recent numerical simulations, researchers agree that supernovae would not succeed as one-dimensional, spherical events and that multi-dimensional effects are important for understanding their occurrence. Scientists have proposed two main scenarios to explain how supernovae explosions occur: (1) a bipolar explosion facilitated by rotation, and (2) a clumpy 3D explosion driven by convection. However, scientists have not known which scenario is more plausible, because they have not actually observed the shape of supernovae.

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