Fwd: NASA and Human Spaceflight News - Wednesday – December 10, 2014, plus new prospective losses

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Begin forwarded message:

From: "Moon, Larry J. (JSC-EA411)" <larry.j.moon@nasa.gov>
Date: December 10, 2014 at 10:36:59 AM CST
To: "Moon, Larry J. (JSC-EA411)" <larry.j.moon@nasa.gov>
Subject: FW: NASA and Human Spaceflight News - Wednesday – December 10, 2014, plus new prospective losses

3 more got added to the online list as of yesterday

RETIREMENT	JSC	JE111	FTP	KINES, MELONEE	01/31/15
RETIREMENT	JSC	EA411	FTP	MORRIS, MICHELLE	02/03/15
RETIREMENT	JSC	SD211	FTP	CHANDLER, MICHAEL	12/27/14

 

 

NASA and Human Spaceflight News

Wednesday – December 10, 2014

HEADLINES AND LEADS

NASA Gets Big Increase in FY2015 Omnibus, NOAA Satellites Do OK

Marcia S. Smith - Spacepolicyonline.com

House and Senate appropriators introduced the long-awaited compromise version of the FY2015 appropriations bill late today. If approved as expected, NASA will get a significant increase compared to the President's request, and NOAA satellite programs will fare well overall, with GOES-R and JPSS fully funded.

First look: New U.S. spending deal a mixed bag for science

David Malakoff, Jeffrey Mervis - Science Insider

 

NASA and the National Science Foundation (NSF) appear to be among the winners – relatively speaking – in a spending deal reached Tuesday night by lawmakers in the U.S. Senate and House of Representatives, with both agencies receiving modest funding boosts. But research budgets at the National Institutes of Health (NIH) and the Department of Energy would remain flat.

 

Obama "Proud" of Orion EFT-1, Praises Chief Engineer Julie Kramer White

Marcia S. Smith - Spacepolicyonline.com

In a talk to senior government leaders today, President Obama praised the work of Orion chief engineer Julie Kramer White and joked that he might hitch a ride to Mars himself one day. He also said he was "proud" to see the Orion Exploration Flight Test-1 (EFT-1) succeed in its mission last week.

After Failure, Orbital Orders Atlas 5 To Bridge Gap Between Old and New Antares

Dan Leone - Space News

Orbital Sciences Corp. will buy at least one Atlas 5 rocket from United Launch Alliance to resume cargo deliveries to the international space station for NASA in the fourth quarter of 2015 while it works to return its Antares rocket to flight after an October failure, Orbital said in a Dec. 9 press release.

 

Europe proposes joint Moon trips with Russia

Space-agency scientists present plan to piggyback on two missions.

Elizabeth Gibney - Nature News

 

Science ministers in Europe have resurrected plans to explore the Moon's surface — and the only strategy currently on the table is to join two uncrewed Russian missions. The developments, which follow the shelving of a proposed European Space Agency (ESA) Moon lander two years ago, come amid growing political tensions between Russia and Western nations.

 

Rivers, lakes and deltas, oh my! Mars rover probes crater's watery past

Amina Khan – Los Angeles

Was Mars once a land of lakes, protected by a thick atmosphere? That's been up for debate as scientists try to determine how wet the now-parched planet once was -- and how long it stayed that way. But NASA's Curiosity rover has uncovered evidence that Gale Crater was once filled with a lake whose water level could have risen and fallen over tens of millions of years.

Hubble Stares Deep into Glittering Stellar 'Snow Globe'

Ian O'Neill – Discovery.com

Just in time for the festive period, the Hubble Space Telescope has released a dazzling image of a globular star cluster filled with stellar glitter — resembling a festive snow globe.

Did Deadly Gamma-Ray Burst Cause a Mass Extinction on Earth?

Charles Q. Choi - Space.com

A gamma-ray burst, the most powerful kind of explosion known in the universe, may have triggered a mass extinction on Earth within the past billion years, researchers say.

Titan's 300-foot-high sand dunes were formed by westerly wind

Deborah Netburn – Los Angeles Times

There are dark and massive fields of sand dunes on the surface of Saturn's moon Titan, and this week two scientific papers look at how they came to be.

COMPLETE STORIES

NASA Gets Big Increase in FY2015 Omnibus, NOAA Satellites Do OK

Marcia S. Smith - Spacepolicyonline.com

House and Senate appropriators introduced the long-awaited compromise version of the FY2015 appropriations bill late today. If approved as expected, NASA will get a significant increase compared to the President's request, and NOAA satellite programs will fare well overall, with GOES-R and JPSS fully funded.

As expected, the bill combines 11 of the 12 regular appropriations bills, funding all of those departments and agencies for the rest of FY2015 (through September 30, 2015). The 12th bill, for the Department of Homeland Security (DHS), is funded only temporarily, through February 27, 2015, as a protest against President Obama's executive order on immigration. This combination of a Continuing Resolution (CR) for DHS and an omnibus for the rest of the government is sometimes referred to as a "cromnibus." It is designated as "Senate amendment to H.R. 83." NASA and NOAA are part of Division B, the Commerce-Justice-Science (CJS) portion.

 

The total for NASA in the compromise accord is $18.010 billion, a $549 million increase over the request of $17.461 billion. Despite the significant increase, some programs were cut, including:.

• Space Technology, which gets $596 million instead of $706 million.
• Commercial crew, which will receive $805 million instead of $848 million. Senate language that would have required adherence to certain regulations regarding cost and pricing data is not included, but the compromise requires technical and financial quarterly reports to Congress for each awardee.
• Space Operations (including the International Space Station), which gets $3.828 billion instead of $3.905 billion

But many others get increases. Among the big winners are --

• planetary science, receiving $1.438 billion instead of $1.280 billion, including not less than $100 million for a Europa mission
• astrophysics, $684 million instead of $607 million, including $70 million for SOFIA
• aeronautics, $651 million instead of $551 million
• Orion, $1.194 billion instead of $1.053 billion
• SLS, $1.700 billion instead of $1.380 billion

More information is in our fact sheet on NASA's FY2015 budget request.

NOAA's satellite programs also fare well. The two premier programs -- GOES-R and JPSS -- are fully funded. The Senate had proposed transferring two other programs, DSCOVR and Jason-3, to NASA, but that was not adopted and both programs are funded in NOAA's budget at or close to their requested levels. COSMIC-2 received its full request of $6.8 million.

The House-passed CJS bill and the version approved by the Senate Appropriations Committee both zeroed NOAA's $15 million request for the Solar Irradiance, Data and Rescue (SIDAR) program that pulls together plans for launching three instruments -- Total Solar Irradiance Sensor (TSIS), Advanced Data Collection System (A-DCS), and Search and Rescue Satellite-Aided Tracking (SARSAT). SIDAR fared better in the compromise omnibus bill, getting half its requested funding, $7.3 million. Report language accompanying the bill says it is to support hosting TSIS-1 on the International Space Station (ISS) and maintaining international partnerships on A-DCS and SARSAT. It notes that hosting TSIS-1 on ISS was not part of the President's FY2015 budget request and asks for a report on those plans.

NASA, NOAA and most of the rest of the government are currently funded by a CR that expires at midnight on Thursday, December 11. Because negotiations on this compromise bill took longer than planned, and ordinarily there is a three-day waiting period in the House for members to read a bill and other procedural steps in the Senate, Congress may not complete action on it before that deadline. A very short-term CR may be passed to cover a couple of days while Congress completes work on this bill.

First look: New U.S. spending deal a mixed bag for science

David Malakoff, Jeffrey Mervis - Science Insider

 

NASA and the National Science Foundation (NSF) appear to be among the winners – relatively speaking – in a spending deal reached Tuesday night by lawmakers in the U.S. Senate and House of Representatives, with both agencies receiving modest funding boosts. But research budgets at the National Institutes of Health (NIH) and the Department of Energy would remain flat.

 

The legislation also includes provisions that would continue efforts to open a national nuclear waste dump in Nevada, prevent the Obama Administration from moving ahead with new environmental rules aimed at strengthening protections for small streams and wetlands, and bar adding the sage grouse to the endangered species list.

 

The $1.013 trillion package sets spending levels for the 2015 fiscal year, which began October 1. Lawmakers were unable to reach agreement on 2015 spending levels in September, however, so the government has been operating on a temporary measure that has frozen spending at 2014 levels. The temporary measure expires on 12 December, and both bodies are now moving to vote on the new spending agreement later this week. It is expected to pass.

 

Below are highlights for some key science agencies drawn from summaries prepared by the House appropriations committee. Come back to ScienceInsider on Wednesday for more details.

 

National Institutes of Health – The nation's largest research funder gets $30 billion, $150 million above the fiscal year 2014 level. Advocates for biomedical research note that the small increase won't allow agency spending to keep pace with inflation. "Congress has missed a major opportunity to fund advances in science and medicine that improve our nation's health and economic outlook," said Carrie Wolinetz, a lobbyist with the Association of American Universities and president of United for Medical Research, a coalition that advocates for biomedical research funding, in a statement."Sustained increases to the NIH budget are necessary to close our nation's innovation deficit — the widening gap between the current medical research funding levels and the investment required to ensure the U.S. remains the world's innovation leader."

 

Department of Energy Office of Science –The nation's biggest funder of physical science research would get $5.1 billion, the same as 2014. Lawmakers rejected cuts proposed by the White House to domestic fusion energy research programs, and a Senate proposal to cancel funding for the ITER fusion project under construction in France. The bill retains language, however, making much of the ITER funding contingent on the project's willingness to make management reforms.

 

National Aeronautics and Space Administration – NASA will get about $18 billion overall, an increase of $364 million. One big winner is the space science program, which would grow to $5.245 billion, $94 million more than the 2014 level of $5.151 billion. The White House had requested a 3.5% cut to $4.972 billion.

 

National Science Foundation – NSF received a 2.4% increase, to $7.344 billion. That amount is $89 million above the president's request, although it falls short of the $222 million boost that the House of Representatives had approved in May. Within that total, NSF's six research directorates would grow by $125 million, to $5.93 billion, and its education directorate would rise by $20 million, to $866 million. NSF also gets two-thirds of the $40 million increase it had sought in operating expenses, most of which will go toward its planned move to a new building in northern Virginia.

 

National Institute of Standards and Technology (NIST) – NIST is funded at $864 million, which is $14 million above the fiscal year 2014 enacted level.

 

National Oceanic and Atmospheric Administration (NOAA) – The bill provides $5.4 billion for NOAA, $126 million above 2014, and includes funding to keep several troubled weather satellites on track.

Ebola – Efforts to combat the virus get about $5.2 billion in emergency spending (which is not counted as part of the regular budget), some $800 million less than the White House had requested. Included is $25 million for the Food and Drug Administration, some of which may be used to expedite testing and approval of human drugs and vaccines.

 

Other provisions:

• Language restricting an Obama Administration clean water plan to regulate farm ponds and irrigation ditches in agricultural areas.
• A ban on funding for the Army Corps to change the definition of "fill material."
• Funding for safety studies of the proposed Yucca Mountain nuclear waste facility in Nevada.
• No funding for the "Green Climate Fund," an international effort to finance climate change efforts in developing nations.
• A continuation of a ban on funding for the United Nations Educational, Scientific, and Cultural Organization (UNESCO).
• A ban on adding the sage grouse, a grassland species in the western U.S., to the endangered species list. Critics said a listing could cripple the oil and gas industry and private landowners. "It is outrageous that Congress would include such a grossly irresponsible rider," said Jamie Rappaport Clark, the president of Defenders of Wildlife, in a statement. "There are more than 350 species of conservation concern in the Sagebrush Sea, of which 60 are listed or candidates for listing under the Endangered Species Act – walking away from the sage-grouse for political expediency could condemn many of these other species to the same imperiled fate down the road."

Obama "Proud" of Orion EFT-1, Praises Chief Engineer Julie Kramer White

Marcia S. Smith - Spacepolicyonline.com

In a talk to senior government leaders today, President Obama praised the work of Orion chief engineer Julie Kramer White and joked that he might hitch a ride to Mars himself one day. He also said he was "proud" to see the Orion Exploration Flight Test-1 (EFT-1) succeed in its mission last week.

Obama gave three examples of outstanding work by government employees: a State Department employee helping with the Ebola outbreak in Africa, a Transportation Department employee involved in getting Syria's chemical weapons stockpiles safely onto a ship, and Kramer.

 

"Although everybody here is doing remarkable work, let's face it, usually what we do isn't rocket science -- unless it is. (Laughter.) So Julie Kramer White is helping America launch a new era of space exploration. Julie is NASA's chief engineer for Orion, the new spacecraft that could carry humans farther into space than we've ever seen before. (Applause.) I'm sure you were all as proud as I was to see Orion's first successful flight test last Friday. America was already the first nation to land a rover on Mars; when an American is the first human to set foot there, we'll have Julie and her team to thank. And at that point, I'll be out of the presidency and I might hitch a ride. (Laughter.) So thank you, Julie, for your great work. (Applause.)"

The President himself had not publicly commented on the EFT-1 mission until now, although his science adviser, John Holdren, released a short statement the day it flew.

After Failure, Orbital Orders Atlas 5 To Bridge Gap Between Old and New Antares

Dan Leone - Space News

Orbital Sciences Corp. will buy at least one Atlas 5 rocket from United Launch Alliance to resume cargo deliveries to the international space station for NASA in the fourth quarter of 2015 while it works to return its Antares rocket to flight after an October failure, Orbital said in a Dec. 9 press release.

 

Dulles, Virginia-based Orbital has contracted for one Atlas 5 launch of its Cygnus space capsule next year, with an option for a second Atlas 5 launch for 2016 "if needed," the press release said. The missions would launch from Cape Canaveral Air Force Station, Florida.

 

In what was to be its third paid cargo delivery to the space station for NASA, Orbital's Antares rocket exploded Oct. 28 moments after liftoff from its launch pad at the Virginia-operated Mid Atlantic Regional Spaceport at NASA's Wallops Flight Facility in Wallops Island, Virginia.

 

Orbital is on the hook to deliver 20,000 kilograms of cargo to the station by 2017 under a $1.9 billion Commercial Resupply Services contract signed in 2008. Originally the company planned eight flights, but now says it only needs seven because of the Atlas 5's extra lifting power and the impending introduction of a larger Cygnus capsule.

 

Meanwhile, Orbital said it finalized a deal with an unidentified supplier to replace the Antares first-stage AJ-26 engine, a Soviet-vintage product, refurbished and resold by Aerojet Rocketdyne, that Orbital has blamed for the failure. Each Antares uses two AJ-26 engines.

 

"The first new propulsion systems are expected to arrive at the Antares final assembly facility at Wallops Island, Virginia in mid-2015 to begin vehicle integration and testing," Orbital said, without identifying the engine or its manufacturer.

 

Repairs to Orbital's Virginia launch facility will be completed by the end of 2015, the company said. The upgraded Antares, with its new main stage engine, will begin launching in 2016, with flights now scheduled for the first, second and fourth quarters of that year, Orbital said.

 

Europe proposes joint Moon trips with Russia

Space-agency scientists present plan to piggyback on two missions.

Elizabeth Gibney - Nature News

 

Science ministers in Europe have resurrected plans to explore the Moon's surface — and the only strategy currently on the table is to join two uncrewed Russian missions. The developments, which follow the shelving of a proposed European Space Agency (ESA) Moon lander two years ago, come amid growing political tensions between Russia and Western nations.

 

On 2 December, at a meeting in Luxembourg to determine ESA's policy, the space agency got the go-ahead and funding to investigate "participation in robotic missions for the exploration of the Moon". Science ministers from the ESA member states did not approve collaboration with Russia specifically, but at the meeting, ESA scientists presented a proposal to join Russia on its missions to put a lander and a rover on the Moon's south pole.

 

Money for lunar exploration will come from a pot of €800 million (US$980 million) contributed by ESA's member states and dedicated to international space exploration; the pot will primarily pay for activities on the International Space Station and the development of a propulsion module for NASA's Orion spacecraft, which is eventually designed to carry astronauts to deep space, and was tested on 5 December in an uncrewed space flight.

 

In the 45 years since astronauts first walked on the Moon, no European country or space agency has launched a mission to the Moon's surface. And no lander or astronaut has been to the lunar south pole, a region thought to contain ice and thus deemed a probable spot for any future permanent lunar base. A 12-kilometre-deep crater there might provide access to material from the Moon's interior, also making it attractive for scientific study, says Ian Crawford, a lunar scientist at Birkbeck, University of London. The ancient material could reveal details of the collision between a Mars-sized planet and early Earth that is thought to have produced the Moon. "The idea that we've 'been there and done that' did last for a long time, but that's gone away now," says Crawford. "The Moon still has a lot to tell us."

 

A Moon lander proposed by ESA failed to gather enough support at a similar meeting of ministers in 2012. That left European scientists and industry mobilized to go — but without a mission. A group of ESA scientists has been discussing a partnership with the Russian space agency, Roscosmos, ever since.

 

The group's proposal, aired for the first time at the Luxembourg meeting, is that ESA contribute to Roscosmos's Luna-Resource Lander, also known as Luna 27, which is scheduled for launch in 2019, as well as the Lunar Sample Return, planned for the early 2020s. The first will study the lunar soil and atmosphere at the south pole; the second would bring samples back to Earth. ESA would provide precision landing and communications equipment, as well as drill and analysis instruments.

The ministerial decision, in principle, means that ESA can start to fund efforts to incorporate these technologies into the mission — although whether it will do so has still to be agreed. The preliminary phase is estimated to cost up to €50 million. The total price would be much higher, perhaps in the hundreds of millions.

ESA has said that pursuing lunar missions is strategically important, not only to secure access to the Moon's surface for European scientists, but also to ensure that European expertise and technology is involved in future lunar exploration — including, ultimately, international crewed missions and even a permanent lunar base. NASA currently has no plans to land on the Moon (Orion will be designed to take astronauts into lunar orbit), but Russia, China, Japan and several private companies are making plans to put rovers on the body. Representatives from these nations have more than hinted that permanent Moon bases and human exploration would be the next steps. "It would be crazy that an agency like ESA would not be part of lunar exploration," says Bérengère Houdou, who heads ESA's Lunar Exploration Office.

Ideally, Europe would not need to hitchhike on another agency's mission to get to the Moon, but the potential Russian collaboration is "a very welcome plan B", says Crawford. "We're primed for a lunar mission, so it's absolutely timely."

It is not clear whether the sour relationship between Russian and Western leadership will affect the proposal's chances of success. Crawford calls it "a potential worry" but stresses that so far, geopolitical problems have not affected space cooperation. ESA officials say that cooperation is continuing normally on existing missions that involve European–Russian collaboration, such as the International Space Station and ExoMars, which will put a demonstration lander on the red planet in 2016 to test technologies for a rover that will land in 2018 to search for signs of past life. The ExoMars rover received the funding it needs to stay on track for 2018 at the 2 December meeting.

In the longer term, Crawford believes that Europe should be looking beyond collaboration with Roscosmos. He adds that China's space agency, which last year became the first since the 1970s to put a lander on the Moon, is the only one that has working scientists and engineers who have Moon-landing experience. "There must be a case," he says, "for ESA broadening its collaboration with other potential space-faring nations."

Rivers, lakes and deltas, oh my! Mars rover probes crater's watery past

Amina Khan – Los Angeles

Was Mars once a land of lakes, protected by a thick atmosphere? That's been up for debate as scientists try to determine how wet the now-parched planet once was -- and how long it stayed that way. But NASA's Curiosity rover has uncovered evidence that Gale Crater was once filled with a lake whose water level could have risen and fallen over tens of millions of years.

The rover's findings from the base of Mt. Sharp raise the likelihood that Mars was habitable long enough for microbial life to potentially emerge.

Mars may be pretty dry now, but that wasn't always the case, scientists say. And while much of the water the planet once had was locked up in ice or stored underground, some of it must have made its way to the surface, said Curiosity deputy project scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory in La Cañada Flintridge.

"Mars was once a planet shaped by water," Vasavada said in a news briefing Monday. "Landscapes from that time are like relics today -- they're out of place, unexplained by the current climate."

Curiosity found signs of past water, as well as key chemical ingredients for microbial life, in a spot called Yellowknife Bay in 2013. But exactly how long did this habitable environment last? These conditions would have to persist for a long time -- millions of years, if not more -- to give rudimentary life a chance to emerge.

But around the base of Mt. Sharp, Curiosity has found slanted rock formations that, on Earth, are signs of a delta -- a zone where running water from a river meets the standing water in a lake. While this lake was probably only a few meters deep, it probably filled and drained multiple times over tens of millions of years, scientists at JPL said.

Mt. Sharp, which sits in the center of Gale Crater, probably did not exist when the crater was still a lake. The rocks Curiosity studied indicate that water was flowing toward the center, which would have been difficult to explain if Mt. Sharp was there.

Over time, as the lake rose and fell, the mountain was probably built up by tiny bits of sediment carried by water and wind, and then carved into a peak by winds blowing from the crater rim to the edge of the mountain, JPL researchers said.

All the water would indicate that Mars' atmosphere was much thicker, warmer and wetter than it is today, with a vigorous water cycle that would have fed these lakes, Vasavada said.

How thick and protective the Martian atmosphere really was could be answered by NASA's Mars Atmosphere and Volatile EvolutioN mission, which is orbiting Mars to study what remains of its thin upper atmosphere.

Hubble Stares Deep into Glittering Stellar 'Snow Globe'

Ian O'Neill – Discovery.com

Just in time for the festive period, the Hubble Space Telescope has released a dazzling image of a globular star cluster filled with stellar glitter — resembling a festive snow globe.

The observation, captured by the veteran telescope's Advanced Camera for Surveys (ACS) in optical and infrared wavelengths, shows the densely-packed central region of Messier 92, one of the brightest globular clusters in the Milky Way. Even at a distance of over 25,000 light-years from Earth, on a clear night, skywatchers can spot this cluster in the constellation of Hercules without the aid of a telescope.

PHOTOS: Hubble's Star Dust Stunners

Messier 92 is known to be "metal poor," otherwise known as an Oosterhoff type II (OoII) globular cluster. In astronomy terminology, "metal poor" means that this cluster is deficient in elements heavier than hydrogen and helium. The observed metallicity of globular clusters can provide clues as to their evolution and provide measurements of their age. As it turns out, Messier 92 is known to be one of the oldest globular clusters in our galaxy, corresponding to an age almost as old as the universe.

Globular clusters are balls of stars and Messier 92, which contains some 330,000 stars, orbits our galactic core.

For more on this beautiful Hubble Observation, explore the ESA Hubble site.

More Stunning Hubble Photos:

• Hubble's Sexiest Spiral Galaxies
• Hubble's Beautiful Butterfly Nebulae
• Hubble's Latest Mind Blowing Cosmic Pictures

Did Deadly Gamma-Ray Burst Cause a Mass Extinction on Earth?

Charles Q. Choi - Space.com

A gamma-ray burst, the most powerful kind of explosion known in the universe, may have triggered a mass extinction on Earth within the past billion years, researchers say.

These deadly outbursts could help explain the so-called Fermi paradox, the seeming contradiction between the high chance of alien life and the lack of evidence for it, scientists added.

Gamma-ray bursts are brief, intense explosions of high-frequency electromagnetic radiation. These outbursts give off as much energy as the sun during its entire 10-billion-year lifetime in anywhere from milliseconds to minutes. Scientists think gamma-ray bursts may be caused by giant exploding stars known as hypernovas, or by collisions between pairs of dead stars known as neutron stars. [Top 10 Greatest Explosions Ever]

If a gamma-ray burst exploded within the Milky Way, it could wreak extraordinary havoc if it were pointed directly at Earth, even from thousands of light-years away. Although gamma rays would not penetrate Earth's atmosphere well enough to burn the ground, they would chemically damage the atmosphere, depleting the ozone layer that protects the planet from damaging ultraviolet rays that could trigger mass extinctions. It's also possible that gamma-ray bursts may spew out cosmic rays, which are high-energy particles that may create an experience similar to a nuclear explosion for those on the side of the Earth facing the explosion, causing radiation sickness.

To see how great a threat gamma-ray bursts might pose to Earth, researchers investigated how likely it was that such an explosion could have inflicted damage on the planet in the past.

Gamma-ray bursts are traditionally divided into two groups — long and short — depending on whether they last more or less than 2 seconds. Long gamma-ray bursts are associated with the deaths of massive stars, while short gamma-ray bursts are most likely caused by the mergers of neutron stars.

For the most part, long gamma-ray bursts happen in galaxies very different from the Milky Way — dwarf galaxies low in any element heavier than hydrogen and helium. Any long gamma-ray bursts in the Milky Way will likely be confined in regions of the galaxy that are similarly low in any element heavier than hydrogen and helium, the researchers said.

The scientists discovered the chance that a long gamma-ray burst could trigger mass extinctions on Earth was 50 percent in the past 500 million years, 60 percent in the past 1 billion years, and more than 90 percent in the past 5 billion years. For comparison, the solar system is about 4.6 billion years old.

Short gamma-ray bursts happen about five times more often than long ones. However, since these shorter bursts are weaker, the researchers found they had negligible life-threatening effects on Earth. They also calculated that gamma-ray bursts from galaxies outside the Milky Way probably pose no threat to Earth.

These findings suggest that a nearby gamma-ray burst may have caused one of the five greatest mass extinctions on Earth, such as the Ordovician extinction that occurred 440 million years ago. The Ordovician extinction was the earliest of the so-called Big Five extinction events, and is thought by many to be the second largest. [Wipe Out: History's Most Mysterious Extinctions]

The scientists also investigated the danger that gamma-ray bursts may pose for life elsewhere in the Milky Way. Stars are packed more densely together toward the center of the galaxy, meaning worlds there face a greater danger of gamma-ray bursts. Worlds in the region about 6,500 light-years around the Milky Way's core, where 25 percent of the galaxy's stars reside, faced more than a 95 percent chance of a lethal gamma-ray burst within the past billion years. The researchers suggest that life as it is known on Earth could survive with certainty only in the outskirts of the Milky Way, more than 32,600 light-years from the galactic core.

The researchers also explored the danger gamma-ray bursts could pose for the universe as a whole. They suggest that because of gamma-ray bursts, life as it is known on Earth might safely develop in only 10 percent of galaxies. They also suggest that such life could only have developed in the past 5 billion years. Before then, galaxies were smaller in size, and gamma-ray bursts were therefore always close enough to cause mass extinctions to any potentially life-harboring planets.

"This may be an explanation, or at least a partial one, to what is called the Fermi paradox or the 'Big Silence,'" said lead study author Tsvi Piran, a physicist at the Hebrew University in Jerusalem. "Why we haven't encountered advanced civilizations so far? The Milky Way galaxy is much older than the solar system and there was ample time and ample space — the number of planetary systems with conditions similar to Earth is huge — for life to develop elsewhere in the galaxy. So why we haven't encountered advanced civilizations so far?"

The answer to Fermi's paradox may be that gamma-ray bursts have struck many life-harboring planets. The most severe criticism of these estimates "is that we address life as we know it on Earth," Piran told Live Science. "One can imagine very different forms of life that are resilient to the relevant radiation."

Piran and his colleague, Raul Jimenez, detailed their findings online today (Dec. 5) in the journal Physical Review Letters.

Titan's 300-foot-high sand dunes were formed by westerly wind

Deborah Netburn – Los Angeles Times

There are dark and massive fields of sand dunes on the surface of Saturn's moon Titan, and this week two scientific papers look at how they came to be.

Titan is one of the most intriguing moons in our solar system. It is the only other body besides Earth that has standing reservoirs of liquid on its surface, but the lakes and rivers of Titan are filled with methane and ethane, rather than water.

It has a thick atmosphere, about 1.5 times as dense as what we have on Earth. A person standing on the surface of Titan would encounter the same pressure as if they were standing at the bottom of a swimming pool on our planet.

And near the equator, scientists have discovered another mysterious feature - dark sand dunes the color of tar that stand hundreds of feet tall and stretch hundreds of miles in length.

Sand dunes have been found in just a few places throughout the solar system - on Venus, Mars, Earth and Titan - but Titan is the only moon where dunes have been discovered.

The sand that makes up Titan's dunes is not made of silicates like the sands we find on Earth, however. Instead, scientists believe it is made of

(Keep in mind that water ice is as hard as rock on Titan, where the surface temperature is negative 297 degrees Fahrenheit).

Because of their different compositions, the sands of Titan are much less dense and more powdery than the sand on Earth. Combine that with Titan's low gravity, which is just one-seventh of the gravity of Earth, and you get "sand" that is as light as freeze-dried coffee grains.

To understand how a 300-foot-tall dune of this material might form on this distant moon, a team of scientists tried to recreate the conditions of Titan in a wind tunnel in Arizona State University's Planetary Aeolian Laboratory. The wind tunnel was originally built in the 1980s to recreate the surface of Venus, but has been now been refurbished as a Titan simulator.

The results of their experiment, published Monday in a Nature study, revealed that it would take winds of at least 3.2 mph to lift the sand and cause it to move across the moon's surface.

That may not sound very strong, but it is 40% to 50% stronger than previous estimates, the scientists said.

"It still seems really slow, but it turns out that the winds on Titan are really slow because there is no real temperature difference or pressure difference to drive fast winds," said Joshua Emery, an assistant professor at the University of Tennessee and a coauthor of the paper.

Another conundrum was that the patterns of the dunes suggest they were created by westerly winds, even though the prevailing winds on Titan blow in an easterly direction.

But it turns out that about twice a year, when the sun crosses Titan's equator, the atmosphere becomes turbulent enough that the wind switches direction and gets significantly stronger.

"This work highlights the fact that the winds that blow 95% of the time might have no effect on what we see," said Devon Burr, a planetary scientists at the University of Tennessee, Knoxville, in a statement.

In a separate paper published in the journal Nature Geoscience, another set of researchers studied images of Titan's sand dunes taken by NASA's Cassini probe. They discovered that it would take at least 3,000 Saturn years (or 88,000 Earth years) for dunes on Titan to form. These findings suggest that the dunes of Titan, like the dune fields on our planet, are shaped by long-term climate cycles rather than seasonal cycles.

So that's a few mysteries solved from the surface of Titan, but there are plenty more to explore. For example, Emery said they may want to look into how much the grains of Titan sand stick together, which would also impact the forces needed for dune construction.

 

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