Monday, November 28, 2011

New Earth-like planet may have water, life

Scientists claim to have discovered a potentially habitable planet which has an environment much similar to that of the Earth and may contain water and even life.

The exoplanet, called Gliese 581g, is located around 123 trillion miles away from the Earth and orbits a star at a distance that places it squarely in the habitable or the Goldilocks zone, the scientists said.

The research, published in the Astrophysical Journal, suggests that the planet could contain liquid water on its surface, meaning it tops the league of planets and moons rated as being most like Earth, they said.

Compelling case
“Our findings offer a very compelling case for a potentially habitable planet,” said lead researcher Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz.

“The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common,” Prof. Vogt was quoted as saying byDaily Mail.

The new findings are based on 11 years of observations of the nearby red dwarf star Gliese 581 using the HIRES spectrometer on the Keck I Telescope by a team from UC Santa Cruz and the Carnegie Institution of Washington.

The team reported the discovery of two new planets around Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system outside of our own.

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Thursday, November 24, 2011

Europa’s “Great Lake”

In a significant finding in the search for life beyond Earth, scientists from The University of Texas at Austin and elsewhere have discovered what appears to be a body of liquid water the volume of the North American Great Lakes locked inside the icy shell of Jupiter’s moon Europa.

The water could represent a potential habitat for life, and many more such lakes might exist throughout the shallow regions of Europa’s shell, lead author Britney Schmidt, a postdoctoral fellow at The University of Texas at Austin’s Institute for Geophysics, writes in the journal Nature.

Further increasing the potential for life, the newly discovered lake is covered by floating ice shelves that seem to be collapsing, providing a mechanism for transferring nutrients and energy between the surface and a vast ocean already inferred to exist below the thick ice shell.

“One opinion in the scientific community has been, ‘If the ice shell is thick, that’s bad for biology -- that it might mean the surface isn’t communicating with the underlying ocean,’” said Schmidt. “Now we see evidence that even though the ice shell is thick, it can mix vigorously. That could make Europa and its ocean more habitable.”

The scientists focused on Galileo spacecraft images of two roughly circular, bumpy features on Europa’s surface called chaos terrains. Based on similar processes seen here on Earth -- on ice shelves and under glaciers overlaying volcanoes -- the researchers developed a four-step model to explain how the features form on Europa. It resolves several conflicting observations, some of which seemed to suggest that the ice shell is thick and others that it is thin.

“I read the paper and immediately thought, yes, that’s it, that makes sense,” said Robert Pappalardo, senior research scientist at NASA’s Planetary Science Section who did not participate in the study. “It’s the only convincing model that fits the full range of observations. To me, that says yes, that’s the right answer.”

The scientists have good reason to believe their model is correct, based on observations of Europa from the Galileo spacecraft and of Earth. Still, because the inferred lakes are several kilometers below the surface, the only true confirmation of their presence would come from a future spacecraft mission designed to probe the ice shell. Such a mission was rated as the second-highest priority flagship mission by the National Research Council’s recent Planetary Science Decadal Survey and is currently being studied by NASA. On Earth, radar instruments are used to image similar features within the ice, and are among the instruments being considered for a future Europa mission.

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Monday, November 21, 2011

An uncertain future for solar system exploration

In less than two weeks, an Atlas V rocket is slated to lift off from Cape Canaveral, propelling NASA’s Mars Science Laboratory (MSL) spacecraft towards the Red Planet. MSL—aka Curiosity—is one of the most ambitious, and expensive, Mars missions ever flown: a rover roughly the size of a Mini Cooper automobile and equipped with a suite of instruments to study Mars and learn about when it was warmer, wetter, and perhaps more hospitable to life. Its landing in August 2012 will be the capstone to what NASA calls the “Year of the Solar System”, a Martian-year-long period that includes milestones ranging from the arrival of MESSENGER at Mercury and Dawn at Vesta to the launches of Juno to Jupiter and GRAIL to the Moon.

While this is something of a golden age for planetary exploration, with a dozen active NASA planetary missions today, there is growing unease in the planetary science community about the future. There were concerns earlier this year with the release of the decadal survey of planetary science missions, which warned of a mismatch between the highest-priority missions—a Mars rover to collect samples for later return to Earth, and a Europa orbiter—and projected budgets ExoMars estrangement

The future of Mars exploration, beyond MSL, had been intended to be one of enhanced collaboration between NASA and ESA. The two agencies had agreed in 2009 to effectively merge NASA’s long-term Mars exploration program with ESA’s ExoMars effort. In 2016 NASA would launch a European Mars orbiter carrying some US instruments, to be followed two years later by the NASA launch of what was originally planned to be separate NASA and ESA Mars rovers, later merged into a single, jointly-developed rover that would cache samples for return to Earth on later missions. That would fulfill the mission of the Mars Astrobiology Explorer-Cacher (MAX-C) that the decadal survey identified earlier this year as the highest priority large, or flagship, planetary science mission in the next decade.
“The Europeans are as mad as hell,” said Hubbard of NASA’s decision not to launch ESA’s 2016 Mars orbiter.

There is evidence, though, that NASA may be backing out of that commitment. In September it informed ESA it would not be able to launch the 2016 European Mars orbiter as planned, forcing ESA officials to scramble to find an alternative approach, one that may have Russia become a partner by launching the orbiter on a Proton rocket. That decision reportedly came at the behest of the Office of Management and Budget (OMB), which also seeks to put the brakes on a joint 2018 mission.

“The Europeans are as mad as hell,” said Scott Hubbard, former director of NASA’s Ames Research Center, at a November 3 Capitol Hill forum on the future of planetary exploration jointly organized by The Mars Society and The Planetary Society. “When I talk to my European colleagues, they’re really, really upset. They feel like they’ve been swindled.”

That frustration comes after NASA and ESA had worked to lower the cost of the 2018 mission. Hubbard said the NASA cost of the mission has been reduced to $1.4 billion, more in line with a midrange New Frontiers mission. “It’s no longer a flagship-class mission,” he said, thanks to $1.2 billion provided by ESA for its role on the mission.

Hubbard believes that OMB may be misinterpreting the “decision rules” included in the planetary science decadal report on how to accommodate reduced budgets. Citing an email from someone who had met with OMB officials about the budget, MAX-C was deemed a “non-starter” by the office under current budgets even with its reduced cost, as it considers flagship missions the lowest priority of all classes of missions.

Hubbard noted that “programmatic balance”—a mix of small, medium-sized, and large missions—was a key aspect of the planetary decadal. That report, moreover, did not place flagship missions as the lowest priority. Instead, it recommended that if costs exceeded projected budgets, flagship missions should be descoped or delayed, followed by changes to the New Frontiers and Discovery programs for smaller missions.

That’s exactly what NASA has done, reducing the cost of MAX-C from its original estimate of $3.5 billion to the new estimate of $1.4 billion. “I would argue that NASA has been extremely responsive to the decadal survey and to budgetary pressure,” Hubbard said.

NASA has said little publicly about the future of its Mars exploration program and cooperation with ESA. At a news briefing last week about the upcoming MSL launch, Doug McCuistion, director of NASA’s Mars program, talked briefly about the issue. “The US and ESA realize we may have some budget concerns in the future, so ESA has approached Russia about potentially providing a launch vehicle and being involved,” he said. He declined to go into more detail because both the fiscal year 2012 budget has yet to be approved by Congress—although that may happen this week—while the 2013 budget proposal won’t be released until early next year. The subject may also come up at a hearing Tuesday on NASA’s planetary science plans by the House Science Committee.

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Monday, November 14, 2011

Solar System May Have Lost Fifth Giant Planet

Astronomer David Nesvorny from the Southwest Research Institute in Texas believes that the solar system might have once contained a fifth gigantic planet, which was ejected deep into the galaxy in a moment of cosmic turmoil.

By looking at the population of the Kuiper belt — the icy-cold ring of asteroids beyond Neptune — and by studying the historical fingerprints left on the craters of the Moon, Nesvorny was able to piece together clues about our solar system’s adolescence.

He found that a dynamic instability, which occurred about 600 million years into the solar system’s life, greatly affected the orbit of our giant planets and scattered smaller bodies. Some moved into the Kuiper belt and others traveled inwards, marking their course as impacts on the Moon and planets.

But that scenario has a flaw. Slow changes in Jupiter’s orbit would have had a large effect on the orbits of the terrestrial planets. All hell would have broken lose, and the Earth could have collided with Mars or Venus. Something had to change.

“Colleagues suggested a clever way around this problem,” says Nesvorny in a press release. Instead of a slow movement, Jupiter’s orbit could have quickly changed, which would have altered the outer solar system but been less harmful to the inner planets.

Unfortunately, this too caused problems. Computer simulations, ran thousands of times, showed that Jupiter’s quick jump had the intended effect, but Uranus or Neptune was always knocked out of the solar system. “Something was clearly wrong,” Nesvorny explains.

So perhaps, instead, the early solar system could have had five giant planets instead of four. By plopping an additional giant planet with a mass similar to that of Uranus or Neptune the simulation worked as planned. Jupiter jumped into place, the inner planets remained unharmed and the outer planets stayed behind.

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Wednesday, November 09, 2011

How death gave birth to our solar system

Our solar system was born thanks to the death of a nearby star in a spectacular supernova event, say researchers.

The findings are based on new computer simulations developed by Dr Matthias Gritschneder, from Beijing's Peking University, and colleagues, and published on the pre-press website

Gritschneder and colleagues found shock waves generated by a supernova could have caused the collapse of a molecular gas and dust cloud, eventually leading to the formation of the Sun and planets.

The model also explains unusual isotope readings in some of the oldest bodies of the solar system.

Stars and solar systems are created in the collapse of molecular gas and dust clouds.

Scientists say this is what happened to our solar system about 4.6 billion years ago, but until now they didn't know what triggered that collapse.

Clues have been found in the ratio of aluminium isotopes found in meteorites formed during the molecular cloud collapse.

Ancient meteorites
The isotope aluminium-26 usually has a half life of 700,000 years, eventually changing in to aluminium-24.

However the ratio of aluminium isotopes in ancient carbonaceous chondrite meteorites, called CV-chondrites, is unusually high.

CV-chondrites are thought to have formed directly out of the collapse of the molecular cloud that gave birth to our solar system.

The unusual isotope measurements suggest fresh aluminium-26 was being fed into this molecular cloud as it collapsed, either by stellar winds from a local star, or by the blast of a nearby supernova explosion, caused by the death of a star.

Gritschneder and colleagues say their model shows a supernova event 15 light years away was the most likely trigger.

"The blast's shock wave and hot gases travelled through space eventually colliding with a molecular cloud of cold gas and dust, causing it to quickly collapse, forming the Sun and solar system," says Gritschneder.

"It also provides the right ratios of aluminium isotopes to explain the levels found in CV meteorites."

"The CV-chondrites probably formed when the temperature of gas cloud dropped below about 1800°C," says Gritschneder.

"The model also shows how this would have occurred over a period of just 20,000 years, matching isotope measurements which act like time stamps marking the formation of these meteorites to within 20,000 years of each other."

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Friday, November 04, 2011

City Lights Could Reveal ET, Researchers Say

If you look at the Earth from space, it's pretty clear that there's intelligent life here because you can pick out cities on the night side. Abraham Loeb, of Harvard University and Edwin Turner, from Princeton University, are saying that we might find other civilizations the same way.

The reason is that the way we usually listen for aliens -- via radio signals -- may not work that well. One issue is that contrary to popular belief, TV transmissions don't travel all that far. (It would actually be near-impossible to pick up old shows from more than a few light years away).

ANALYSIS: The Search For Extraterrestrial Polluters
Our own civilization is actually generating less residual energy as time goes on as communications move to optical fiber. Other civilizations may have done the same, so picking them up actually gets harder as their technology gets better.

The trick is to look for a certain kind of light that would be different from natural starlight. The two note the spectrum of LEDs and streetlights is different from that of the sun. An alien looking at Earth with a sufficiently sensitive telescope would notice that.

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