ESA Galileo: Soyuz launch glitch linked to frozen Hydrazine fuel pipe

A frozen fuel pipe in the upper stage of a Soyuz launcher likely caused the failure last month to place two European navigation satellites in orbit, a source close to the inquiry said Wednesday.

Confirming a report in French daily Le Monde, the source said investigators suspect a pipe containing hydrazine fuel, used by the Fregat upper stage to drive the satellites to their orbital slots, had frozen during launch.

The hydrazine pipes are located near a pipe that circulates ultra-cold liquid helium, the source said.

The two satellites, launched from Europe's base in Kourou, French Guiana, were intended to be the first two fully operational satellites in the new-generation navigation system Galileo.

30-satellite Galileo constellation. 

Credit: ESA

Two more satellites had been expected to be hoisted by the end of 2014, opening the way for a first phase of Galileo services in 2015, including applications for smartphones and in-car navigation and search-and-rescue location.

By 2017, according to the Galileo schedule, all 24 operational satellites would be in place.

Six backups would join the fleet by 2020, at which point the system would be fully operational.

Launched by a Russian-made Soyuz, the misplaced satellites should have been slotted into a circular orbit at an altitude of 23,500 kilometres (14,600 miles), inclined at 56 degrees to the equator.

Instead, they were placed in an useless elliptical orbit at a height of 17,000 kilometres (11,000 miles).

The failure adds to a catalogue of problems encountered by the 5.4-billion-euro ($7.2-billion) programme, designed to give the EU independence in satellite navigation from the US Global Positioning System (GPS).

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ESA Galileo IOV in orbit. 

Credit: ESA

Galileo, according to the project's defenders, will be more accurate and have a stronger signal, particularly in built-up areas, than its competitors.

NASA’s Hubble Finds Supernova Star System Linked to Potential “Zombie Star”

The two inset images show before-and-after images captured by NASA’s Hubble Space Telescope of Supernova 2012Z in the spiral galaxy NGC 1309. 

The white X at the top of the main image marks the location of the supernova in the galaxy.

Image Credit: NASA, ESA

Using NASA’s Hubble Space Telescope, a team of astronomers has spotted a star system that could have left behind a “zombie star” after an unusually weak supernova explosion.

A supernova typically obliterates the exploding white dwarf, or dying star.

On this occasion, scientists believe this faint supernova may have left behind a surviving portion of the dwarf star, a sort of zombie star.

While examining Hubble images taken years before the stellar explosion, astronomers identified a blue companion star feeding energy to a white dwarf, a process that ignited a nuclear reaction and released this weak supernova blast.

This supernova, Type Iax, is less common than its brighter cousin, Type Ia. Astronomers have identified more than 30 of these mini-supernovas that may leave behind a surviving white dwarf.

“Astronomers have been searching for decades for the star systems that produce Type Ia supernova explosions,” said scientist Saurabh Jha of Rutgers University in Piscataway, New Jersey.

“Type Ia’s are important because they’re used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes."

"The similarities between Type Iax’s and normal Type Ia’s make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified. This discovery shows us one way that you can get a white dwarf explosion.”

The team’s results will appear in the Thursday, Aug. 7 edition of the journal Nature.

The weak supernova, dubbed SN 2012Z, resides in the host galaxy NGC 1309 which is 110 million light-years away. It was discovered in the Lick Observatory Supernova Search in January 2012.

Luckily, Hubble’s Advanced Camera for Surveys also observed NGC 1309 for several years prior the supernova outburst, which allowed scientists to compare before-and-after images.

Curtis McCully, a graduate student at Rutgers and lead author of the team’s paper, sharpened the Hubble pre-explosion images and noticed a peculiar object near the location of the supernova.

“I was very surprised to see anything at the location of the supernova. We expected the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us,” McCully said.

After studying the object’s colors and comparing with computer simulations of possible Type Iax progenitor systems, the team concluded they were seeing the light of a star that had lost its outer hydrogen envelope, revealing its helium core.

The team plans to use Hubble again in 2015 to observe the area, giving time for the supernova’s light to dim enough to reveal any possible zombie star and helium companion to confirm their hypothesis.

“Back in 2009, when we were just starting to understand this class, we predicted these supernovae were produced by a white dwarf and helium star binary system,” said team member Ryan Foley of the University of Illinois at Urbana-Champaign, who helped identify Type Iax supernovae as a new class.

“There’s still a little uncertainty in this study, but it is essentially validation of our claim.”

Read the full article here

NASA AQUA MODIS Image: Totten Glazier melt rate linked to Sea Ice conditions

This image shows the Totten Glacier ice shelf in East Antarctica (the wrinkled white area at top left) on Sept. 25, 2013. 

Two large open-water polynyas appear on the sea ice below and to the right of the shelf, as well as several smaller ones. 

The open-water areas are bright black. 

The stippled diagonal line from lower left to upper right is the outer edge of the sea ice, with cloud cover to the right of that line. 

The image is from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite. 

Credit: NASA.

A new NASA-led study has discovered an intriguing link between sea ice conditions and the melting rate of Totten Glacier, the glacier in East Antarctica that discharges the most ice into the ocean.

The discovery, involving cold, extra salty water - brine - that forms within openings in sea ice, adds to our understanding of how ice sheets interact with the ocean, and may improve our ability to forecast and prepare for future sea level rise.

"I was curious why Totten was changing so fast when the glacier just next to it wasn't changing much," said Ala Khazender of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the new study, published online Dec. 5 in the journal Nature Communications.

Combining satellite observations with ocean numerical modeling, Khazender and his colleagues developed a hypothesis that reductions in the volume of brine would increase Totten's thinning and melting.

Additional research supported that hypothesis.

Ice loss seen in Antarctica is generally attributed to the well-documented rise in temperature of the surrounding ocean, but scientists are still puzzling out the mechanisms behind the regional variations that they are observing.

The new study highlights the key role of processes occurring on small geographic scales in determining how global climate change can affect the stability of ice sheets.

Satellite observations from NASA's ICESat-1, which measures how much ice surfaces are rising or falling over time, revealed that Totten Glacier was thinning rapidly.

It currently discharges enough ice into the surrounding ocean to fill Lake Erie in just over a week.

The nearby Moscow University Glacier and its floating ice shelf were showing little change. Why the difference?

"We were convinced that the answer must be in the ocean," Khazender said.

The ocean around Antarctica is warmer than both the continent's icy surface and the polar air. Ice shelves (the floating front edges of glaciers that extend tens to hundreds of miles offshore) melt more because of contact with ocean water below them than they do because of sunlight.

Melting at the undersides of ice shelves is part of Antarctica's natural water cycle, but when glaciers start melting unusually quickly, it's a sign that something is off balance.

Khazender and his team of colleagues from JPL; UCLA; the University of California, Irvine; and Utrecht University in the Netherlands combined ICESat remote sensing observations from 2003 to 2008 with ocean numerical computer models to seek insights into the interaction between the ice shelves and their ocean basin.

More information: For more information on ICESat, visit: icesat.gsfc.nasa.gov/ .For more information on the ECCO2 ocean modeling and data synthesis project, visit: ecco2.jpl.nasa.gov/

Norwegian Scientists find Dark Lightning Linked To Visible Lightning

Three images, left to right, of the same thundercloud depict a less-than-10-milliseconds-long sequence of events: (left) formation within the cloud of a small channel, or 'leader,' of electrical conductivity (yellow line) with weak emission of radio signals (ripples), to (middle) a burst of both dark lightning (pink) and radio waves (larger ripples), to (right) a discharge of bright lightning and more radio waves. 

Credit: Studio Gohde

Researchers have identified a burst of high-energy radiation known as "dark lightning" immediately preceding a flash of ordinary lightning.

The new finding provides observational evidence that the two phenomena are connected, although the exact nature of the relationship between ordinary bright lightning and the dark variety is still unclear, the scientists said.

Nikolai Ostgaard

"Our results indicate that both these phenomena, dark and bright lightning, are intrinsic processes in the discharge of lightning," said Nikolai Ostgaard, who is a space scientist at the University of Bergen in Norway and led the research team.

He and his collaborators describe their findings in an article recently accepted in Geophysical Research Letters - an AGU journal.

Dark lightning is a burst of gamma rays produced during thunderstorms by extremely fast moving electrons colliding with air molecules. Researchers refer to such a burst as a terrestrial gamma-ray flash.

Dark lightning is the most energetic radiation produced naturally on Earth, but was unknown before 1991.

While scientists now know that dark lightning naturally occurs in thunderstorms, they do not know how frequently these flashes take place or whether visible lightning always accompanies them.

In 2006, two independent satellites -- one equipped with an optical detector and the other carrying a gamma ray detector -- coincidentally flew within 300 kilometers (190 miles) of a Venezuelan storm as a powerful lightning bolt exploded within a thundercloud.

Scientists were unaware then that a weak flash of dark lightning had preceded the bright lightning.

Last year, Ostgaard and his colleagues discovered the previously unknown gamma ray burst while reprocessing the satellite data.

"We developed a new, improved search algorithm...and identified more than twice as many terrestrial gamma flashes than originally reported," said Ostgaard.

He and his team detected the gamma-ray flash and a discharge of radio waves immediately preceding the visible lightning.

"This observation was really lucky," Ostgaard said. "It was fortuitous that two independent satellites -- which are traveling at 7 kilometers per second (4.3 miles per second) -- passed right above the same thunderstorm right as the pulse occurred."

A radio receiver located 3,000 kilometers (1,900 miles) away at Duke University in Durham, North Carolina detected the radio discharge.

The satellites' observations combined with radio-wave data provided the information that Ostgaard and his team used to reconstruct this ethereal electrical event, which lasted 300 milliseconds.

Ostgaard and his team suspect that the flash of dark lightning was triggered by the strong electric field that developed immediately before the visible lightning.

This strong field created a cascade of electrons moving at close to the speed of light. When those relativistic electrons collided with air molecules, they generated gamma rays and lower energy electrons that were the main electric current carrier that produced the strong radio pulse before the visible lightning.

Dark and bright lightning may be intrinsic processes in the discharge of lightning, Ostgaard said, but he stressed that more research needs to be done to elucidate the link.

The European Space Agency is planning on launching the Atmospheric Space Interactions Monitor (ASIM) within the next three years, which will be able to better detect both dark and visible lightning from space, said Ostgaard, who is part of the team that is building the ASIM gamma-ray detector.

El Nino, Climate Change link Unclear

The frequency and volatility of El Nino, a weather pattern that hammers the tropical Pacific Ocean every five years or so, does not seem linked to climate change, said US research.

The study involved scientists measuring the monthly growth of ancient coral fossils found on two tropical Pacific islands to determine what, if any, impact the warming climate had on the weather phenomenon.

By reconstructing temperatures and precipitation over the millenniums, the study compared it to the frequency and intensity of El Nino and found that the latter had indeed become more intense and frequent in the 20th century.

But although the increase was statistically significant and could be linked to climate change, the long historic record provided by the coral fossils allowed the researchers to determine that the El Nino Southern Oscillation (ENSO), has also had large natural variations in past centuries.

Thus, it is not clear that changes seen in recent decades can be linked to climate change caused by rising levels of carbon dioxide, the researchers said.

"The level of ENSO variability we see in the 20th century is not unprecedented," said climatologist Professor Kim Cobb, from the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.

"But the 20th century does stand out, statistically, as being higher than the fossil coral baseline," she added.

The study was sponsored by the National Science Foundation and published in the journal Science.

Researchers from the Scripps Institution of Oceanography and the University of Minnesota also contributed to the study.

El Nino occurs every two to seven years, when the trade winds that circulate surface water in the tropical Pacific start to weaken.

A mass of warm water builds in the western Pacific and eventually rides over to the eastern side of the ocean, causing a major shift in rainfall, bringing floods and mudslides to usually arid countries in the region.

El Nino is ushered out by a cold phase, La Nina, which usually occurs the following year.