vendredi 4 avril 2014

Graceful Eruption

NASA - Solar Dynamics Observatory (SDO) patch.

April 4, 2014

Graceful Eruption

A mid-level flare, an M6.5, erupted from the sun on April 2, 2014, peaking at 10:05 a.m. EDT. This video from NASA's Solar Dynamics Observatory shows the flare in a blend of two wavelengths of extreme ultraviolet light: 304 Angstroms and 171 Angstroms, colorized in yellow and red, respectively. Credit: Solar Dynamics Observatory/NASA.

Image above: Powerful magnetic forces above an active region on the Sun twisted and pulled at a blob of plasma until it lost its connections and blew out into space (Mar. 26, 2014). The resultant swirling presented its own kind of graceful, almost ballet-like bends and sweeps. To offer some kind of size perspective that blob, before it broke away, was easily larger than several Earths. The event was observed in extreme ultraviolet light over about 5.5 hours beginning at 7:00 UT. The still image was taken at 10:45 UT. Credit: Solar Dynamics Observatory/NASA.

For more information about NASA's Solar Dynamics Observatory (SDO), visit: and

Image (mentioned), Video (mentioned), Text, Credit: NASA.


Take the Plunge: LADEE Impact Challenge

NASA - Lunar Atmosphere and Dust Environment Explorer (LADEE) patch.

April 4, 2014

NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft is gradually lowering its orbital altitude over the moon. LADEE will continue to make important science observations before its planned impact into the lunar surface later this month.

When will it impact the lunar surface? NASA wants to hear your best guess!

LADEE mission managers expect the spacecraft will impact the moon’s surface on or before April 21. On April 11, ground controllers at NASA's Ames Research Center in Moffett Field, Calif., will command LADEE to perform its final orbital maintenance maneuver prior to a total lunar eclipse on April 15, when Earth’s shadow passes over the moon. This eclipse, which will last approximately four hours, exposes the spacecraft to conditions just on the edge of what it was designed to survive.

This final maneuver will ensure that LADEE's trajectory will impact the far side of the moon, which is not in view of Earth and away from any previous lunar mission landings. There are no plans to target a particular impact location on the lunar surface, and the exact date and time depends on several factors.

"The moon's gravity field is so lumpy, and the terrain is so highly variable with crater ridges and valleys that frequent maneuvers are required or the LADEE spacecraft will impact the moon’s surface," said Butler Hine, LADEE project manager at Ames. "Even if we perform all maneuvers perfectly, there's still a chance LADEE could impact the moon sometime before April 21, which is when we expect LADEE's orbit to naturally decay after using all the fuel onboard."

Anyone is eligible to enter the "Take the Plunge: LADEE Impact Challenge." Winners will be announced after impact and will be e-mailed a commemorative, personalized certificate from the LADEE program. The submissions deadline is 3 p.m. PDT Friday, April 11.

For more information about the challenge and to enter, visit:

“We want to thank all those that watched LADEE launch and have followed the mission these past months,” said Jim Green, NASA’s Director for Planetary Science at NASA Headquarters in Washington. “Our Moon holds a special place in so many cultures, and because of LADEE, we’ll know more than ever before about our nearest neighbor.”

LADEE's mission marked several firsts. It was the first demonstration of Optical Laser Communications from space (sent data six times faster than radio), and the first deep space spacecraft designed and built "in house" at NASA’s Ames Research Center.  It was also the first payload to launch on a U.S. Air Force Minotaur V rocket integrated by Orbital Sciences Corp., Va., and was the first deep space mission to launch from NASA's Goddard Space Flight Center's Wallops Flight Facility on Wallops Island, Va., when millions watched the night launch on Sept. 6, 2013.

The vending-machine size spacecraft has been orbiting the moon since Oct. 6. On Nov. 10, LADEE began gathering science data, and on Nov. 20, the spacecraft entered its science orbit around the moon's equator. LADEE has been in extended mission operations following a highly successful 100-day prime science phase.

Lunar Atmosphere and Dust Environment Explorer (LADEE) orbiting the Moon

LADEE's three science payload instruments have been working to unravel the mysteries of the lunar atmosphere and dust environment acquiring to date more than 700,000 measurements. In its previous orbit, LADEE's closest approach to the moon’s surface was between 20 and 50 km, and its farthest point was between 75 and 150 km – a unique position that allows the spacecraft to frequently pass from lunar day to lunar night, approximately every two hours. This vantage provides data about the full scope of changes and processes occurring within the moon's tenuous atmosphere.

Scientists hope to address a long-standing question: Was lunar dust, electrically charged by sunlight, responsible for the pre-sunrise glow detected during several Apollo missions above the lunar horizon? LADEE also is gathering detailed information about the structure and composition of the thin lunar atmosphere.

A thorough understanding of these characteristics of our nearest celestial neighbor will help researchers understand other bodies in the solar system, such as large asteroids, Mercury, and the moons of outer planets.

For more information about LADEE mission, visit:

Images, Text, Credit: NASA.

Best regards,

ISS orbit changed

ISS - International Space Station patch.


April 4, 2014 an exceptional correction orbit of the International Space Station, the purpose of which was the creation of a safe flight path station.

In accordance with the information received from the service ballistic and navigation support MCC TsNIIMash tonight at 00 hours 42 minutes Moscow time included engines cargo vehicle Progress M-21M. Ship's engines worked 220 seconds. As a result, the average height of the ISS orbit has increased by 0.9 km and reached 415.2 km.

ISS reboost with Progress-M cargo

According to the service ballistic and navigation support MCC after the ISS orbit maneuver parameters were as follows:

- Minimum height - 414.0 km;
- Maximum height - 432.7 km;
- Period - 92.81 min;
- Inclination - 51,66°.

ROSCOSMOS Press Release:

Image, Text, Credits: Roscosmos press service and PCO / ROSCOSMOS / NASA / Translation: Aerospace.


Hubble Team Finds Monster "El Gordo" Galaxy Cluster Bigger Than Thought

NASA - Hubble Space Telescope patch.

April 4, 2014

Image above: This is a Hubble image of the most massive cluster of galaxies ever seen to exist when the universe was just half its current age of 13.8 billion years. The cluster contains several hundred galaxies. Image Credit: NASA, ESA, and J. Jee (University of California, Davis).

Hubble Space Telescope has weighed the largest known galaxy cluster in the distant universe, catalogued as ACT-CL J0102-4915, and found it definitely lives up to its nickname -- El Gordo (Spanish for "the fat one").

By measuring how much the cluster's gravity warps images of galaxies in the distant background, a team of astronomers has calculated the cluster's mass to be as much as 3 million billion times the mass of our sun. Hubble data show the galaxy cluster, which is 9.7 billion light-years away from Earth, is roughly 43 percent more massive than earlier estimates.

The team used Hubble to measure how strongly the mass of the cluster warped space. Hubble's high resolution allowed measurements of so-called "weak lensing," where the cluster's immense gravity subtly distorts space like a funhouse mirror and warps images of background galaxies. The greater the warping, the more mass is locked up in the cluster.

"What I did is basically look at the shapes of the background galaxies that are farther away than the cluster itself," explained lead author James Jee of the University of California at Davis. "It's given us an even stronger probability that this is really an amazing system very early in the universe."

A fraction of this mass is locked up in several hundred galaxies that inhabit the cluster and a larger fraction is in hot gas that fills the entire volume of the cluster. The rest is tied up in dark matter, an invisible form of matter that makes up the bulk of the mass of the universe.

Though equally massive galaxy clusters are found in the nearby part of the universe, such as the Bullet cluster, nothing like this has ever been discovered to exist so far back in time, when the universe was roughly half its current estimated age of 13.8 billion years. The team suspects such monster galaxy clusters are rare in the early universe, based on current cosmological models.

The immense size of El Gordo was first reported in January 2012. Astronomers estimated its mass based on observations made by NASA's Chandra X-ray Observatory, and galaxy velocities measured by the European Southern Observatory's Very Large Telescope array in Paranal, Chile. They were able to put together estimates of the cluster's mass based on the motions of the galaxies moving inside the cluster and the temperatures of the hot gas between those galaxies.

The challenge was that El Gordo looked as if it might have been the result of a titanic collision between a pair of galaxy clusters -- an event researchers describe as two cosmic cannonballs hitting each other.

"We wondered what happens when you catch a cluster in the midst of a major merger and how the merger process influences both the X-ray gas and the motion of the galaxies," explained John Hughes of Rutgers University. "So, the bottom line is because of the complicated merger state, it left some questions about the reliability of the mass estimates we were making."

That is where the Hubble data came in, according to Felipe Menanteau of the University of Illinois at Urbana-Champaign.

"We were in dire need for an independent and more robust mass estimate given how extreme this cluster is and how rare its existence is in the current cosmological model. There was all this kinematic energy that was unaccounted for and could potentially suggest that we were actually underestimating the mass," Menanteau said.

Hubble orbiting the Earth

The expectation of "unaccounted energy" comes from the fact the merger of galaxy clusters is occurring tangentially to the observers' line-of-sight. This means they are potentially missing a good fraction of the kinetic energy of the merger because their spectroscopic measurements only track the radial speeds of the galaxies.

The team's next step with Hubble will be to compile an image of the cluster. Because El Gordo does not fit into Hubble's field of view, the team will capture images of sections of the galaxy cluster and piece them together into a mosaic.

Researchers say it is like observing a giant from the side.

"We can tell it's a pretty big El Gordo, but we don't know what kind of legs he has, so we need to have a larger field of view to get the complete picture of the giant," said Menanteau.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For images and more information about Hubble, visit: and

Images, Video, Text, Credits: ESA / NASA / J.D. Harrington / Space Science Telescope Institute / Ray Villard.


jeudi 3 avril 2014

Icy moon Enceladus has underground sea

ESA - Cassini Mission to Saturn logo.

3 April 2014

Inside Enceladus

Saturn’s icy moon Enceladus has an underground sea of liquid water, according to the international Cassini spacecraft.

Understanding the interior structure of 500 km-diameter Enceladus has been a top priority of the Cassini mission since plumes of ice and water vapour were discovered jetting from ‘tiger stripe’ fractures at the moon’s south pole in 2005.

Subsequent observations of the jets showed them to be relatively warm compared with other regions of the moon and to be salty – strong arguments for there being liquid water below the surface.

But planetary scientists have now been able to investigate the interior of the enigmatic moon directly, using Cassini’s radio science experiment.

Enceladus plumes

On three separate occasions in 2010 and 2012, the spacecraft passed within 100 km of Enceladus, twice over the southern hemisphere and once over the northern hemisphere.

During the flybys, Cassini was pulled slightly off course by the moon’s gravity, changing its velocity by just 0.2–0.3 millimetres per second.

As tiny as these deviations were, they were detectable in the spacecraft’s radio signals as they were beamed back to Earth, providing a measurement of how the gravity of Enceladus varied along the spacecraft’s orbit. These measurements could then be used to infer the distribution of mass inside the moon.

For example, a higher-than-average gravity ‘anomaly’ might suggest the presence of a mountain, while a lower-than-average reading implies a mass deficit.

On Enceladus, the scientists measured a negative mass anomaly at the surface of the south pole, accompanied by a positive one some 30-40 km below.

Enceladus' craters and complex, fractured terrains

“By analysing the spacecraft’s motion in this way, and taking into account the topography of the moon we see with Cassini’s cameras, we are given a window into the internal structure of Enceladus,” says Luciano Iess, lead author of the results published in Science.

“The perturbations in the spacecraft’s motion can be most simply explained by the moon having an asymmetric internal structure, such that an ice shell overlies liquid water at a depth of around 30–40 km in the southern hemisphere.”

While the gravity data cannot rule out a global ocean, a regional sea extending from the south pole to 50ºS latitude is most consistent with the moon’s topography and high local temperatures observed around the tiger stripes.

“This experiment provides a crucial new piece of information towards understanding the formation of plumes on this intriguing moon,” says Nicolas Altobelli, ESA’s Cassini project scientist.

More information:

“The gravity field and interior structure of Enceladus,” by L. Iess et al, is published in Science, 4 April 2014.

The Cassini–Huygens mission is a cooperative project of NASA, ESA and ASI, the Italian space agency. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington.

For information about Cassini, visit: and

Images, Text, Credits: ESA / NASA / JPL  / JPL-Caltech / Space Science Institute.


Europe lofts first Copernicus environmental satellite

Arianespace / ESA - Flight VS 07 Sentinel-1A poster.

3 April 2014

Sentinel-1A liftoff

The ability of European citizens, policymakers and service providers to access key environmental data on a routine basis will take a major step forward following the launch today of ESA’s Sentinel-1A satellite.

The 2.3 tonne satellite lifted off on a Soyuz rocket from Europe’s Spaceport in Kourou, French Guiana at 21:02 GMT (23:02 CEST). The first stage separated 118 sec later, followed by the fairing (209 sec), stage 2 (287 sec) and the upper assembly (526 sec).

Arianespace boosts Sentinel-1A Earth observation satellite

After a 617 sec burn, the Fregat upper stage delivered Sentinel into a Sun-synchronous orbit at 693 km altitude. The satellite separated from the upper stage 23 min 24 sec after liftoff.

“Sentinel-1A opens a new page in the implementation of Copernicus, the second EU flagship space initiative, after the Galileo positioning system,” said Jean-Jacques Dordain, Director General of ESA.

“The Copernicus programme will provide European citizens with the most ambitious space-based services in the world for environmental and security applications.

“The cooperation between the EU and ESA Member States in the funding of the space infrastructure, the combination of competences and expertise between the European Commission and ESA, and the capabilities of European industry, are putting Europe at the forefront of utilisation of space to benefit citizens, policymakers and the  economy.”

The mission is the first of six families of dedicated missions that will make up the core of Europe’s Copernicus environmental monitoring network. Copernicus will provide operational information on the world’s land surfaces, oceans and atmosphere to support environmental and security policymaking and the needs of individual citizens and service providers.

Sentinel-1 launch on a Soyuz

Designed as a two-satellite constellation – Sentinel-1A and -1B – the C‑band radar mission will provide all-weather day-and-night imagery of land and ocean surfaces of Europe, Canada and the polar regions in near‑real time.

Equipped with a powerful ‘synthetic aperture radar’, it will ensure continuity with the European Envisat satellite, which stopped working in 2012 after 10 years of service. The technology is based on a long heritage of radar satellites, starting with ERS-1 23 years ago. 

“The launch of the first Sentinel-1 satellite marks a change in philosophy for our Earth observation programmes,” said Volker Liebig, ESA’s Director of Earth Observation Programmes. “In meteorology, satellites have been providing reliable data for weather forecasts for over 35 years.

“With the Copernicus programme, we will now have a similar information source for environmental services as well as for applications in the security and disaster management domain.”

In addition to transmitting data to a number of ground stations around the world for rapid dissemination, Sentinel-1 is also equipped with a laser terminal to transmit data via European Data Relay System satellites in geostationary orbit for continual data delivery.

Radar vision

The satellite’s solar panels and antenna are now being deployed in a complex sequence expected to take around 11 hours. The completion of deployment will be announced at and via Twitter @ESA_EO

After the initial ‘launch and early orbit phase’, the satellite will go into the commissioning phase, when all instruments will be checked and calibrated. The mission is expected to begin operations within three months.

Thales Alenia Space Italy is the prime contractor and Airbus DS Germany is responsible for the C‑band radar. Airbus DS UK supplied the central radar electronics subsystem.

Data from the Sentinel satellites will be provided on a free and open basis. Raw data will be analysed and processed by public and private sector service providers.

For more information about Arianespace, visit:

Images, Video, Text, Credits: ESA/ATG medialab/CNES/Arianespace.

Best regards,

NASA Mars Rover Curiosity Scoping Out Next Study Area

NASA - Mars Science Laboratory (MSL) patch.

April 3, 2014

Curiosity's View From Arrival Point at 'The Kimberley' Waypoint

Image above: NASA's Curiosity Mars rover recorded this view of various rock types at waypoint called "the Kimberley" shortly after arriving at the location on April 2, 2014. The site offers a diversity of rock types exposed close together in a decipherable geological relationship to each other. Image Credit: NASA/JPL-Caltech.

On Wednesday, NASA's Curiosity Mars rover drove the last 98 feet feet (30 meters) needed to arrive at a site planned since early 2013 as a destination for studying rock clues about ancient environments that may have been favorable for life.

Map of Curiosity Mars Rover's Drives to 'the Kimberley' Waypoint

Image above: This map shows the route driven by NASA's Curiosity Mars in its approach to and April 1, 2014, arrival at a waypoint called "the Kimberley," which rover team scientists chose in 2013 as the location for the mission's next major investigations. Image Credit: NASA/JPL-Caltech/Univ. of Arizona.

The rover reached a vantage point for its cameras to survey four different types of rock intersecting in an area called "the Kimberley," after a region of western Australia.

"This is the spot on the map we've been headed for, on a little rise that gives us a great view for context imaging of the outcrops at the Kimberley," said Melissa Rice of the California Institute of Technology, Pasadena. Rice is the science planning lead for what are expected to be several weeks of observations, sample-drilling and onboard laboratory analysis of the area's rocks.

Curiosity's View From Before Final Approach to 'The Kimberley' Waypoint

Image above: This view from NASA's Curiosity Mars rover was taken the day before the rover's final approach drive to "the Kimberley" waypoint, selected months ago as the location for the mission's next major investigations. It combines several frames taken by the Navigation Camera on April 1, 2014. Image Credit: NASA/JPL-Caltech.

With arrival at this location, Curiosity has driven at total of 3.8 miles (6.1 kilometers) since landing inside Gale Crater on Mars in August 2012.

The mission's investigations at the Kimberley are planned as the most extensive since Curiosity spent the first half of 2013 in an area called Yellowknife Bay. At Yellowknife Bay, the one-ton rover examined the first samples ever drilled from rocks on Mars and found the signature of an ancient lakebed environment providing chemical ingredients and energy necessary for life.

Curiosity Mars Rover's Route from Landing to 'The Kimberley' Waypoint

Image above: This map shows the route driven by NASA's Curiosity Mars rover from the "Bradbury Landing" location where it landed in August 2012 (the start of the line in upper right) to a major waypoint called "the Kimberley." Image Credit: NASA/JPL-Caltech/Univ. of Arizona.

At the Kimberley and, later, at outcrops on the slope of Mount Sharp inside Gale Crater, researchers plan to use Curiosity's science instruments to learn more about habitable past conditions and environmental changes.

NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. The project designed and built Curiosity and operates the rover on Mars.

For more information about Curiosity, visit and You can follow the mission on Facebook at and on Twitter at

Images (mentioned), Text, Credits: NASA / JPL / Guy Webster.


Launch of DMSP F19 Weather Satellite

DMSP F19 Mission patch.

April 3, 2014

The United Launch Alliance (ULA) used an Atlas V rocket to deploy the DMSP-5D3 F-19 satellite for the US Air Force. Liftoff from Vandenberg Air Force Base was on schedule at 07:46 local time (14:46 UTC) on Thursday. This first attempt launch played into evaluations for which rocket – which has now been confirmed as the Atlas V with NROL-67 – will launch first from Cape Canaveral next week.

Launch of DMSP F19 Weather Satellite on Atlas V 401 Rocket 
The 44th launch of an  Atlas placed the 19th Defense Meteorological Satellite Program (DMSP), block 5D3, weather satellite Flight 19 into orbit for the United States Air Force. The launch of this Atlas clears the flight team to proceed with another Atlas launch on the East coast in Cape Canaveral.

The Defense Meteorological Satellite Program (DMSP), which was named the Defense Satellite Application Program (DSAP) until December 1973, began in the early 1960s.

DMSP satellite

Originally operated by the National Reconnaissance Office, the satellites’ original purpose was to support early reconnaissance satellites by forecasting which areas of Soviet and Chinese territory would be covered in cloud, and which areas would be visible to the satellites. Over time the program has evolved to fulfil other roles, including providing real-time tactical weather data to troops.

For more information about United Launch Alliance (ULA), visit:

Image, Video, Text, Credits: ULA / / Aerospace.


ISS - Meet Space Station’s Small Satellite Launcher Suite

ISS - International Space Station patch.

April 3, 2014

It used to be that building and launching a working satellite was an enormously expensive and complex undertaking, feasible only for governmental and military agencies. But the CubeSat revolution of the past decade has placed satellite technology within reach of private companies, universities and even unaffiliated individuals. That revolution has been boosted by the existence of the International Space Station, which provides an additional launching platform enabled through regular commercial cargo flights.

CubeSats are a class of research spacecraft called nanosatellites. The cube-shaped satellites measure about 4 inches on each side, have a volume of about 1 quart and weigh less than 3 pounds.

Image of Cyclops hardware. Image Credit: NASA

Putting the tiny satellites into orbit from the space station isn't as simple as shoving them out an airlock. It requires a special apparatus called a CubeSat deployer. This tool places a satellite into position to be grabbed by one of the space station’s robotic arms, which places the CubeSat deployer into the correct position to release the miniature satellites into their proper orbits. At present, two CubeSat deployers operate aboard the station: the Japanese Experiment Module (JEM) Small Satellite Orbital Deployer (J-SSOD) and the NanoRacks CubeSat Deployer. The upcoming launch of the SpaceX-4 commercial resupply mission, currently scheduled for August will enhance the space station’s satellite deployment capabilities with the delivery of Cyclops. This tool, also known as the Space Station Integrated Kinetic Launcher for Orbital Payload Systems (SSIKLOPS), will provide still another means to release other small satellites from the orbiting outpost.

Image above: Illustration of Cyclops flight hardware with SpinSat satellite attached. Image Credit: NASA.

Daniel Newswander, an engineer with NASA’s Johnson Space Center in Houston, said this addition will “fill out the quiver” of existing space station satellite deployment capabilities. The project is a joint effort of the International Space Station Program at Johnson and the Department of Defense's Space Test Program.

"Satellites come in all shapes and sizes," Newswander noted. "We were aware of several satellites that didn’t really fit into the CubeSat launchers. We are deploying a spherical satellite as well as a cubic one that does not fit in the existing launchers. We are attempting to complement the other deployers that have been developed so that the [space station] has several deployment options to choose from. We are targeting satellites in the 50 to 100 kg [110 to 220 lb] class, especially those which geometrically do not fit in the existing launchers."

Image above: Japan Aerospace Exploration Agency astronaut Koichi Wakata prepares a batch of NanoRacks CubeSats for deployment. Image Credit: NASA.

CubeSats have varied missions, and this year has been a particularly busy one for deployment of the satellites from the space station. Whether looking to help with imaging Earth for weather and ground data or advancing communications capabilities, the ability to set these satellites into orbit from the space station is the first step to enabling their missions. The resulting technology developments may contribute to advances in satellite technology for commercial use while enhancing Earth observation techniques.

Camille Alleyne, assistant space station program scientist, explained: "Because of the relatively low costs to build this technology, the demand for the CubeSat deployment capability has increased dramatically. Adding this third deployer as a space station facility allows us to meet demand and demonstrates the value of the unique platform for both space research and STEM education."

Cyclops will operate from the JEM and take advantage of the airlock's existing slide table. Newswander said, "The launcher will be stowed inside the [space station] for use whenever a satellite is ready to be deployed. Cyclops is placed onto the airlock slide table with the attached satellite and processed through to the external environment. Cyclops, with its attached satellite, is subsequently grasped by the robotic arm and taken to the deployment position. Cyclops then deploys the satellite and is returned to the airlock where it is processed back through and stowed internally for future utilization. Our design utilizes the Japanese robotic arm but does have the capability to use the [station's] main robotic arm if necessary."

Image above: A set of CubeSats is photographed by an Expedition 38 crew member after deployment by the NanoRacks Launcher attached to the end of the Japanese robotic arm. Image Credit: NASA.

It took Cyclops less than two years to launch. The space station program office approved the concept in October 2012, and the facility was ready for flight by spring of 2014. "It's been very rewarding, yet challenging at the same time," Newswander remarked. "You want to move as fast as you can because everyone's excited for the capability, but you need to ensure you do it right. So it's a continual tradeoff."

Animation of Station's Cyclops Satellite Deployer

Newswander described one challenge: "how do you certify something in an environment that you can't replicate on Earth?" The answer is found in a great deal of engineering rigor, analysis, testing, safety assessments, verification and quality assurance. "You focus on applying the proper engineering and safety practices and processes to the design. We're trying to maximize the usable envelope available in the airlock, which is not something that anyone has really tried to do for satellite deployments. That, coupled with the challenges of satellite deployment from an orbiting space station really pushes your boundaries."

When it becomes operational later this year, the Cyclops deployer not only will add a permanent enhancement to the capabilities of the station, but perhaps it also will serve as a model for further technological innovation. "We built something that should be up there for the duration of the station," Newswander noted. "It is designed to accommodate several deployments a year, so we anticipate that it's going to be able to handle whatever need the [space station] community requires. We don’t know if that will drive second generation designs; but, if someone comes forward in the future and takes an idea that we started off with and makes it better, we would welcome the enhanced capabilities. We consider the [space station] to be an invaluable resource not only to NASA but to the entire international community."

For more information about the International Space Station (ISS), visit:

Related links:

Japanese Experiment Module (JEM) Small Satellite Orbital Deployer (J-SSOD):


CubeSat Deployer:

Images (mentioned), Video, Text, Credits: NASA / Mark Wolverton.


Fermi Data Tantalize With New Clues To Dark Matter

NASA - Fermi Gamma-ray Space Telescope logo.

April 3, 2014

A new study of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe. Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

"The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it," said Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study. "The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models."

Fermi Galactic Center Zoom

Animation above: This animation zooms into an image of the Milky Way, shown in visible light, and superimposes a gamma-ray map of the galactic center from NASA's Fermi. Raw data transitions to a view with all known sources removed, revealing a gamma-ray excess hinting at the presence of dark matter. Image Credit: NASA Goddard; A. Mellinger, CMU; T. Linden, Univ. of Chicago.

The galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas. It's also where astronomers expect to find the galaxy's highest density of dark matter, which only affects normal matter and radiation through its gravity. Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built.

No one knows the true nature of dark matter, but WIMPs, or Weakly Interacting Massive Particles, represent a leading class of candidates. Theorists have envisioned a wide range of WIMP types, some of which may either mutually annihilate or produce an intermediate, quickly decaying particle when they collide. Both of these pathways end with the production of gamma rays -- the most energetic form of light -- at energies within the detection range of Fermi's Large Area Telescope (LAT).

When astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains. This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) -- roughly a billion times greater than that of visible light -- and extends outward at least 5,000 light-years from the galactic center.

Hooper and his colleagues conclude that annihilations of dark matter particles with a mass between 31 and 40 GeV provide a remarkable fit for the excess based on its gamma-ray spectrum, its symmetry around the galactic center, and its overall brightness. Writing in a paper submitted to the journal Physical Review D, the researchers say that these features are difficult to reconcile with other explanations proposed so far, although they note that plausible alternatives not requiring dark matter may yet materialize.

"Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we're already learning about its interactions from the lack of detection so far," said co-author Tracy Slatyer, a theoretical physicist at MIT in Cambridge, Mass. "This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time."

The researchers caution that it will take multiple sightings – in other astronomical objects, the LHC or in some of the direct-detection experiments now being conducted around the world -- to validate their dark matter interpretation.

Images above: At left is a map of gamma rays with energies between 1 and 3.16 GeV detected in the galactic center by Fermi's LAT; red indicates the greatest number. Prominent pulsars are labeled. Removing all known gamma-ray sources (right) reveals excess emission that may arise from dark matter annihilations. Image Credit: T. Linden, Univ. of Chicago.

"Our case is very much a process-of-elimination argument. We made a list, scratched off things that didn't work, and ended up with dark matter," said co-author Douglas Finkbeiner, a professor of astronomy and physics at the CfA, also in Cambridge.

"This study is an example of innovative techniques applied to Fermi data by the science community," said Peter Michelson, a professor of physics at Stanford University in California and the LAT principal investigator. "The Fermi LAT Collaboration continues to examine the extraordinarily complex central region of the galaxy, but until this study is complete we can neither confirm nor refute this interesting analysis."

While the great amount of dark matter expected at the galactic center should produce a strong signal, competition from many other gamma-ray sources complicates any case for a detection. But turning the problem on its head provides another way to attack it. Instead of looking at the largest nearby collection of dark matter, look where the signal has fewer challenges.

Dwarf galaxies orbiting the Milky Way lack other types of gamma-ray emitters and contain large amounts of dark matter for their size – in fact, they're the most dark-matter-dominated sources known. But there's a tradeoff. Because they lie much farther away and contain much less total dark matter than the center of the Milky Way, dwarf galaxies produce a much weaker signal and require many years of observations to establish a secure detection.

For the past four years, the LAT team has been searching dwarf galaxies for hints of dark matter. The published results of these studies have set stringent limits on the mass ranges and interaction rates for many proposed WIMPs, even eliminating some models. In the study's most recent results, published in Physical Review D on Feb. 11, the Fermi team took note of a small but provocative gamma-ray excess.

"There's about a one-in-12 chance that what we're seeing in the dwarf galaxies is not even a signal at all, just a fluctuation in the gamma-ray background," explained Elliott Bloom, a member of the LAT Collaboration at the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the SLAC National Accelerator Laboratory and Stanford University. If it's real, the signal should grow stronger as Fermi acquires additional years of observations and as wide-field astronomical surveys discover new dwarfs. "If we ultimately see a significant signal," he added, "it could be a very strong confirmation of the dark matter signal claimed in the galactic center."

Related Links:

Download additional graphics from NASA Goddard's Scientific Visualization Studio:

Paper: "The characterization of the gamma-ray signal from the central Milky Way: A compelling case for annihilating dark matter":

Paper: "Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope":

"Fermi Observations of Dwarf Galaxies Provide New Insights on Dark Matter" (03.02.12):

Images (mentioned), Animation (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Francis Reddy.

Best regards,

mercredi 2 avril 2014

Spacesuit Maintenance for Station Crew

ISS - International Space Station logo.

April 2, 2014

The International Space Station’s Expedition 39 crew supported scientific research and performed routine spacesuit maintenance Wednesday, while the three newest crew members continued learning the ropes of their new orbital home for the next six months.

Image above: Commander Koichi Wakata performs troubleshooting on the Waste and Hygiene Compartment aboard the International Space Station. Image Credit: NASA TV.

Commander Koichi Wakata began the workday troubleshooting an issue with the Waste and Hygiene Compartment – one of the two toilets aboard the station – to track down the noise problem believed to be coming from internal gear wear of the pump separator. The Japan Aerospace Exploration Agency astronaut checked the compartment panels, components and noise abatement equipment to make sure the noise was not being amplified or inadequately suppressed.

Afterward, Flight Engineer Steve Swanson, who arrived aboard the station Thursday along with fellow Soyuz TMA-12M crewmates Alexander Skvortsov and Oleg Artemyev, removed and replaced the compartment’s pump separator.

Image above: Flight Engineer Steve Swanson smiles as he checks out the International Space Station's cupola. Image Credit: NASA.

Read more about the Soyuz TMA-12M docking:

Flight Engineer Rick Mastracchio spent a good portion of the day working in the Quest airlock as he tested the water within the cooling loops of the U.S. spacesuits. Mastracchio checked for signs of microbial contamination and performed a conductivity test of the water. Wakata later joined his crewmate in Quest to initiate the recharge of a spacesuit battery. Wakata also dumped water from the payload water reservoirs inside the airlock to flush out an umbilical interface assembly. While there are no spacewalks planned for Expedition 39, routine maintenance assures that the equipment remains ready to support a contingency spacewalk.

Wakata later deployed 22 sensors throughout the complex to measure the radiation levels aboard the station.

Mastracchio rounded out his day in the Columbus laboratory relocating a sensor enclosure for the Space Acceleration Measurement System, or SAMS, to support FASTER -- the Facility for Absorption and Surface Tension. FASTER investigates the physical principles that determine the stability of different emulsions. Results from FASTER can aid industry in the design of compounds to stabilize, or destabilize, different emulsions depending on their use, and assist in the creation of more environmentally friendly products. SAMS will track any vibrations on the station that could affect FASTER.

Learn more about FASTER:

Image above: The ISS Progress 55 cargo vehicle is prepared for launch in the Spacecraft Assembly and Testing Facility at the Baikonur Cosmodrome in Kazakhstan. Image Credit: RSC/Energia.

On the Russian side of the complex, Flight Engineer Mikhail Tyurin spent his morning packing trash into the ISS Progress 54 cargo ship attached to the station’s Pirs docking compartment. Progress 54, which arrived at the station back on Feb. 5 with 2.8 tons of cargo, is set to depart the station on at 9:58 a.m. EDT on April 7 for a destructive re-entry over the Pacific Ocean. Its departure will clear the way for ISS Progress 55, which is scheduled to launch from the Baikonur Cosmodrome in Kazakhstan on April 9 at 11:26 a.m. (9:26 p.m., Kazakh time) and dock with Pirs at 5:16 p.m. the same day.

Flight Engineers Skvortsov and Artemyev cleaned ventilation screens in the Russian segment. Proper air flow inside the station’s modules is essential to crew health because in the absence of gravity stagnant air can form dangerous pockets of carbon dioxide.

As the newest crew members aboard the station, Skvortsov, Artemyev and Swanson had time set aside throughout the day for crew orientation to become accustomed to living and working aboard the station during their first two weeks on orbit. Swanson also tagged up with Mastracchio for some one-on-one training on station systems and experiment facilities.

For more information about the International Space Station (ISS), visit:

Images (mentioned), Text, Credit: NASA.


OCO-2 Brings Sharp New Focus on Global Carbon

NASA - OCO-1 Mission logo.

April 2, 2014

Simply by breathing, humans have played a small part in the planet-wide balancing act called the carbon cycle throughout our existence. However, in the last few hundred years, we have taken a larger role. Our activities, such as fossil fuel burning and deforestation, are pushing the cycle out of its natural balance, adding more and more carbon dioxide to the atmosphere.

Natural processes are working hard to keep the carbon cycle in balance by absorbing about half of our carbon emissions, limiting the extent of climate change. There's a lot we don't know about these processes, including where they are occurring and how they might change as the climate warms. To understand and prepare for the carbon cycle of the future, we have an urgent need to find out.

In July 2014, NASA will launch the Orbiting Carbon Observatory-2 (OCO-2) to study the fate of carbon dioxide worldwide. "Right now, the land and the ocean are taking up almost half of the carbon dioxide we add to the atmosphere by burning fossil fuels, but the future is fundamentally unknown," said Paul Wennberg, a professor of atmospheric chemistry at the California Institute of Technology in Pasadena. "OCO-2 is a key to getting answers." The mission has been developed and is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Carbon dioxide is both one of the best measured greenhouse gases and one of the least measured. The emissions that remain in the atmosphere become evenly distributed around the globe in a matter of months. As a result, the average atmospheric concentration can be monitored well by existing ground stations (about 160 worldwide). The other half of our emissions -- the half that is being absorbed through natural processes into the land or the ocean -- is not evenly distributed. To understand where that carbon dioxide is going, we need precise, comprehensive, ongoing data about carbon dioxide absorption and emission by forests, the ocean and many other regions. For some of these regions, we have far too few observations.

Animation above: This animation shows the Orbiting Carbon Observatory-2, the first NASA spacecraft dedicated to studying carbon dioxide in Earth’s atmosphere. Image Credit: NASA/JPL-Caltech.

"A research ship moves about the speed of a 10-speed bicycle," said Scott Doney, director of the Ocean and Climate Change Institute at the Woods Hole Oceanographic Institution, Woods Hole, Mass. "Think about the size of the ocean. There's only so much research you can do at the speed of a bicycle." Oceanographers have made up some of the observational deficit by contracting with shipping lines to gather data along commercial routes. But there's little shipping in the Southern Ocean, and Doney said that's a region of high concern. "With warming, we expect big changes. The winds are changing there, and carbon dioxide uptake may change too."

On land, Earth's great forests might be the least understood areas. In northern Siberia, a region with no permanent settlements and few roads, there are only six year-round monitoring sites across seven time zones. Forests remove carbon from the air during photosynthesis and store it in wood and roots, making these forests what scientists call carbon sinks. But droughts and wildfires can turn forests into carbon sources, releasing the stored carbon back into the atmosphere. We don't know when and how often forests cross the line from sink to source.

OCO-2 will not be the first satellite to measure carbon dioxide, but it's the first with the observational strategy, precision, resolution and coverage needed to answer these questions about these little-monitored regions, according to Ralph Basilio, OCO-2 project manager at JPL.

OCO-2's scientific instrument uses spectrometers, which split sunlight into a spectrum of component colors, or wavelengths. Like all other molecules, carbon dioxide molecules absorb only certain colors of light, producing a unique pattern of dark features in the spectrum. The intensity of the dark features increases as the number of carbon dioxide molecules increases in the air that the spectrometer is looking through.

Carbon dioxide concentrations in the atmosphere are measured in parts per million, the number of molecules of carbon dioxide there are in every million molecules of air. That number is currently around 400. OCO-2's spectrometers can detect changes of one or two carbon dioxide molecules out of the 400 -- an unprecedented level of precision, and one that scientists think will be adequate to detect changes in natural sources and sinks, once enough measurements have been collected.

OCO-2 will collect 24 measurements a second over Earth’s sunlit hemisphere, totaling more than a million measurements each day. Fewer than 20 percent of these measurements will be sufficiently cloud-free to allow an accurate estimate of carbon dioxide, but that number will still yield 100 to 200 times as many measurements as the currently observing Japanese Greenhouse gases Observing SATellite (GOSAT) mission. The measurements will be used as input for global atmospheric models. Combined with data on winds and other conditions, the OCO-2 data will allow modelers to better locate carbon sources and sinks at regional scales -- areas the size of France or Texas.

"With atmospheric carbon dioxide at unprecedented levels, our sense of urgency has only increased,” said Basilio. “What will happen if we keep emitting carbon dioxide at the same rate? The ultimate goal for OCO-2 is to provide data so that organizations and individuals throughout the world can make better-informed decisions about carbon."

For more information about OCO-2, visit:

OCO-2 is one of five new NASA missions launching in 2014. NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to see better how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA's Earth science activities in 2014, visit:

Animation, Text, Credits: NASA / JPL / Alan Buis / JPL-Caltech.


Galactic Serial Killer

ESO - European Southern Observatory logo.

2 April 2014

The contrasting galaxies NGC 1316 and 1317

This new image from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile shows two contrasting galaxies: NGC 1316, and its smaller neighbour NGC 1317. These two are quite close to each other in space, but they have very different histories. The small spiral NGC 1317 has led an uneventful life, but NGC 1316 has engulfed several other galaxies in its violent history and shows the battle scars.

The galaxy pair NGC 1316 and 1317 in the constellation of Fornax

Several clues in the structure of NGC 1316 reveal that its past was turbulent. For instance, it has some unusual dust lanes [1] embedded within a much larger envelope of stars, and a population of unusually small globular star clusters. These suggest that it may have already swallowed a dust-rich spiral galaxy about three billion years ago.

Wide-field view of the sky around the galaxies NGC 1316 and 1317

Also seen around the galaxy are very faint tidal tails — wisps and shells of stars that have been torn from their original locations and flung into intergalactic space. These features are produced by complex gravitational effects on the orbits of stars when another galaxy comes too close. All of these signs point to a violent past during which NGC 1316 annexed other galaxies and suggest that the disruptive behaviour is continuing.

Zooming in on the galaxies NGC 1316 and 1317

NGC 1316 is located about 60 million light-years away from Earth in the southern constellation of Fornax (The Furnace). It also bears the name Fornax A, reflecting the fact that it is the brightest source of radio emission in the constellation — and in fact the fourth brightest radio source in the entire sky [2]. This radio emission is driven by material falling into the supermassive black hole at the centre of the galaxy and has probably been provided with extra fuel by the interactions with other galaxies.

Panning across the galaxies NGC 1316 and 1317

This very detailed new image from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile was created by combining many individual images in the ESO archive. The aim of the original observations was to reveal the faintest features and study the disruption of this interesting system.

As a bonus the new picture also provides a window into the distant Universe far beyond the two bright galaxies in the foreground. Most of the faint fuzzy spots in the picture are much more distant galaxies — and there is a particularly dense concentration just to the left of NGC 1316.


[1] These dust lanes have been imaged in detail by the NASA/ESA Hubble Space Telescope.

[2] This applies at a radio frequency of 1400 MHz, at other frequencies the order will be different.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.


Photos of the MPG/ESO 2.2-metre telescope:

Photos from the MPG/ESO 2.2-metre telescope:

Photos of La Silla:

Images, Text, Credits: ESO / IAU and Sky & Telescope / Digitized Sky Survey 2 /  Videos: ESO / Digitized Sky Survey 2 / A. Fujii / Nick Risinger ( Music: movetwo.


mardi 1 avril 2014

CERN - CMS presents new boundary of Higgs width

CERN - European Organization for Nuclear Research logo.

April 1, 2014

Rencontres de Moriond 2014 (Image: CERN)

At last year's Moriond conference, CERN physicists announced the retirement of the "Higgs-like" particle and the arrival of "boson, Higgs boson". Now, one year later, at the same session in the same conference, physicists are back with more exciting news about the famed particle. This time: the best constraint yet of the Higgs boson “width”, a parameter that determines the particle’s lifetime.

As a key indicator for new physics, the Higgs "width" has long been on the LHC "to-do" list. Now less than two years post-discovery, the CMS experiment has gotten the closest yet to pinning it down, constraining the parameter to < 17 MeV with 95% confidence. This result is some two orders of magnitude better than previous limits: stronger evidence that this boson looks like the Standard Model Higgs boson. "It's been exciting to see how well the result has been received by the scientific community; it's been the buzz topic of the Moriond conference," said Nicola De Filippis, CMS collaboration member from Politecnico and INFN Bari.

The Standard prediction

For a Higgs mass of ~125 GeV, the Standard Model predicts a Higgs width of ~4 MeV. Quite a low width, especially when compared to its compatriots, the W and Z bosons (with ~2 GeV and ~ 2.5 GeV widths, respectively). Before this new result, the best limit on Higgs width had it under 3.4 GeV, based on direct measurements.

Large Hadron Collider (LHC). Image : CERN

A new approach

With the new constraint some 200 times tighter than previous limits, let's ask the obvious question: how did this improvement come about?

"Until now, measurements of the Higgs width had been heavily limited by experimental resolution, which is about 2 or 3 GeV - much larger than the width they were trying to determine," said Roberto Covarelli, CMS collaboration member from the University of Rochester.

One can also extract an upper limit on the Higgs width at the price of assuming that its couplings to the known particles are given by the Standard Model, yet allowing new particles to affect the width. With this, previous CMS results and newly updated ATLAS results can be translated in upper limits on the Higgs width below 10 MeV.

In 2012, theorists demonstrated that, with fewer assumptions and using events with pairs of Z particles, the high invariant mass tail can be used to constrain the Higgs width. Using this technique, the CMS collaboration was able to produce the impressive new result.

New answers to old problems

It's interesting to note that this much-improved constraint was revealed not by new data, but rather by an improved approach to analysis. “It is awesome to see how, with a bit of ingenuity, the LHC is becoming a precision instrument even in the Higgs sector,” said Luca Malgeri, CMS Physics Coordinator. The experimental era of Higgs physics is still in its infancy, and we have a lot more to learn before we can ship out to new shores. Stay tuned for more new answers to old problems.

Learn more:

Higgs boson:

The full CMS Higgs width result is available here on the CERN Document Server:

Also see the presentations given at 2014 Moriond EW and Moriond QCD:

2014 Moriond EW:

2014 Moriond QCD:

For more about the analysis method used, see the following papers:

N. Kauer and G. Passarino, JHEP 08 (2012) 116:

F. Caola, K. Melnikov (Phys. Rev. D88 (2013) 054024):

J. Campbell et al. (arXiv:1311.3589):


CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

Related links:

Large Hadron Collider (LHC):

CMS experiment:

For more information about the European Organization for Nuclear Research (CERN), visit:

Images, Text, Credits: CERN / Katarina Anthony.

Best regards,

lundi 31 mars 2014

Arctic Melt Season Lengthening, Ocean Warming

NASA logo /  NSIDC logo.

March 31, 2014

NSIDC, NASA Say Arctic Melt Season Lengthening, Ocean Rapidly Warming

Video above: The length of the melt season for Arctic sea ice is growing by several days each decade, and an earlier start to the melt season is allowing the Arctic Ocean to absorb enough additional solar radiation in some places to melt as much as four feet of the Arctic ice cap’s thickness.

The length of the melt season for Arctic sea ice is growing by several days each decade, and an earlier start to the melt season is allowing the Arctic Ocean to absorb enough additional solar radiation in some places to melt as much as four feet of the Arctic ice cap’s thickness, according to a new study by National Snow and Ice Data Center (NSIDC) and NASA researchers.

Arctic sea ice has been in sharp decline during the last four decades. The sea ice cover is shrinking and thinning, making scientists think an ice-free Arctic Ocean during the summer might be reached this century. The seven lowest September sea ice extents in the satellite record have all occurred in the past seven years.

"The Arctic is warming and this is causing the melt season to last longer," said Julienne Stroeve, a senior scientist at NSIDC, Boulder and lead author of the new study, which has been accepted for publication in Geophysical Research Letters. "The lengthening of the melt season is allowing for more of the sun’s energy to get stored in the ocean and increase ice melt during the summer, overall weakening the sea ice cover."

To study the evolution of sea ice melt onset and freeze-up dates from 1979 to the present day, Stroeve’s team used passive microwave data from NASA’s Nimbus-7 Scanning Multichannel Microwave Radiometer, and the Special Sensor Microwave/Imager and the Special Sensor Microwave Imager and Sounder carried onboard Defense Meteorological Satellite Program spacecraft.

NASA’s Nimbus-7 spacecraft. Image Credit: NASA

When ice and snow begin to melt, the presence of water causes spikes in the microwave radiation that the snow grains emit, which these sensors can detect. Once the melt season is in full force, the microwave emissivity of the ice and snow stabilizes, and it doesn’t change again until the onset of the freezing season causes another set of spikes. Scientists can measure the changes in the ice’s microwave emissivity using a formula developed by Thorsten Markus, co-author of the paper and chief of the Cryospheric Sciences Laboratory at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Results show that although the melt season is lengthening at both ends, with an earlier melt onset in the spring and a later freeze-up in the fall, the predominant phenomenon extending the melting is the later start of the freeze season. Some areas, such as the Beaufort and Chukchi Seas, are freezing up between six and 11 days later per decade. But while melt onset variations are smaller, the timing of the beginning of the melt season has a larger impact on the amount of solar radiation absorbed by the ocean, because its timing coincides with when the sun is higher and brighter in the Arctic sky.

Despite large regional variations in the beginning and end of the melt season, the Arctic melt season has lengthened on average by five days per decade from 1979 to 2013.

Still, weather makes the timing of the autumn freeze-up vary a lot from year to year.

"There is a trend for later freeze-up, but we can’t tell whether a particular year is going to have an earlier or later freeze-up," Stroeve said. "There remains a lot of variability from year to year as to the exact timing of when the ice will reform, making it difficult for industry to plan when to stop operations in the Arctic."

To measure changes in the amount of solar energy absorbed by the ice and ocean, the researchers looked at the evolution of sea surface temperatures and studied monthly surface albedo data (the amount of solar energy reflected by the ice and the ocean) together with the incoming solar radiation for the months of May through October. The albedo and sea surface temperature data the researchers used comes from the National Oceanic and Atmospheric Administration’s polar-orbiting satellites.

Image above: An image mosaic of sea ice in the Canadian Basin, taken by Operation IceBridge's Digital Mapping System on Mar. 28, 2014. Image Credit: Digital Mapping System/NASA Ames.

They found that the ice pack and ocean waters are absorbing more and more sunlight due both to an earlier opening of the waters and a darkening of the sea ice. The sea ice cover is becoming less reflective because it now mostly consists of thinner, younger ice, which is less reflective than the older ice that previously dominated the ice pack. Also, the young ice is flatter, allowing the dark melt ponds that form at the early stages of the melt season are able to spread more widely, further lowering its albedo.

The researchers calculated the increase in solar radiation absorbed by the ice and ocean for the period ranging from 2007 to 2011, which in some areas of the Arctic Ocean exceed 300 to 400 megajoules per square meter, or the amount of energy needed to thin the ice by an additional 3.1 to 4.2 feet (97 to 130 centimeters).

The increases in surface ocean temperatures, combined with a warming Arctic atmosphere due to climate change, explain the delayed freeze up in the fall.

"If air and ocean temperatures are similar, the ocean is not going to lose heat to the atmosphere as fast as it would when the differences are greater," said Linette Boisvert, co-author of the paper and a cryospheric scientist at Goddard. "In the last years, the upper ocean heat content is much higher than it used to be, so it’s going to take a longer time to cool off and for freeze up to begin."

For more information about Nimbus Mission, visit:

For more information about Nimbus 7, visit:

National Snow and Ice Data Center (NSIDC):

Images (mentioned), Video, Text, Credits: NASA / Maria-José Viñas.

Hubble: Magnifying the Distant Universe

NASA - Hubble Space Telescope patch.

March 31, 2014

Galaxy clusters are some of the most massive structures that can be found in the Universe — large groups of galaxies bound together by gravity. This image from the NASA/ESA Hubble Space Telescope reveals one of these clusters, known as MACS J0454.1-0300. Each of the bright spots seen here is a galaxy, and each is home to many millions, or even billions, of stars.

Astronomers have determined the mass of MACS J0454.1-0300 to be around 180 trillion times the mass of the sun. Clusters like this are so massive that their gravity can even change the behavior of space around them, bending the path of light as it travels through them, sometimes amplifying it and acting like a cosmic magnifying glass. Thanks to this effect, it is possible to see objects that are so far away from us that they would otherwise be too faint to be detected.

In this case, several objects appear to be dramatically elongated and are seen as sweeping arcs to the left of this image. These are galaxies located at vast distances behind the cluster — their image has been amplified, but also distorted, as their light passes through MACS J0454.1-0300. This process, known as gravitational lensing, is an extremely valuable tool for astronomers as they peer at very distant objects.

Hubble orbiting Earth

This effect will be put to good use with the start of Hubble's Frontier Fields program over the next few years, which aims to explore very distant objects located behind lensing clusters, similar to MACS J0454.1-0300, to investigate how stars and galaxies formed and evolved in the early Universe.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For images and more information about Hubble, visit: and

Image, Text, Credits: ESA/Hubble & NASA, Acknowledgement: Nick Rose.