vendredi 6 février 2015

Retreating glaciers - 36 years of radar vision

ESA - Sentinel-1 Mission logo.

6 February 2015

ESA has recently recovered imagery from the oldest synthetic aperture radar – or SAR – in space, renewing our view of a changing Earth.

Greenland glaciers seen by three generations of radar missions

Comparing data from three generations of radar missions – Seasat, ERS and Sentinel-1 – the retreat of two large glaciers in southeast Greenland over a 36-year period is evident in the video above.

This preliminary analysis shows that the effects of climate change on the world’s second largest ice sheet have had a major impact over the past three decades. The glaciers show significant retreat, with the upper glacier receding by about 5.5 km over the past 36 years. This melt is contributing to sea-level rise and the release of more freshwater into the North Atlantic.

This is just one example of how scientists can exploit heritage satellite data such as the recently recovered and reprocessed radar data from the veteran Seasat mission.


Launched in June 1978 and managed by NASA’s Jet Propulsion Laboratory, Seasat was the first to carry a SAR instrument to space – paving the way for the development of follow-on SAR missions like ESA’s ERS, Envisat and Sentinel-1.

During its brief lifetime of just over 100 days, the satellite acquired information on ocean phenomena, such as surface and internal waves, currents and sea-surface winds for the study of ocean circulation. It also captured imagery of glaciers, sea ice, coastal regions, volcanoes, forests and land cover.

Last year, NASA released newly reprocessed digital Seasat imagery. Today, ESA is releasing its own full digitally processed Seasat dataset acquired at the UK’s Oakhanger ground station, which supplements the NASA dataset.

Now available to the user community, this unique dataset holds high value, as only a few of ESA’s Seasat data holdings were digitally processed in the past.

ESA’s Seasat data holdings coverage

The majority of ESA’s Seasat data holdings cover parts of Europe, the North Atlantic and northern Africa from 13 July to 10 October 1978. The dataset also contains several scenes over North America and Guadeloupe.

In addition to providing us with a historical view, the decades-old data can be paired with SAR scans from other missions to observe long-term changes in coastal erosion, urban growth, land use and glaciers.

SAR data are especially suited to monitor glaciers, as they can measure flow speed and ice thickness, offering additional clues to what is happening in these sensitive ecosystems.

The efforts to retrieve, consolidate and reprocess the ESA Seasat SAR data holdings were carried out under the Long Term Data Preservation Programme. The data are now available to the user community and may be downloaded after fast registration via the online dissemination portal.

Related links:

Seasat dataset:

ESA Seasat SAR data:

Related missions:


ERS overview:

ERS technical site:


Sentinel-1 technical site:

Images, Video, Text, Credits: ESA/NASA/JPL.

Best regards,

Hubble's Little Sombrero

NASA - Hubble Space Telescope patch.

February 6, 2015

Galaxies can take many shapes and be oriented any way relative to us in the sky. This can make it hard to figure out their actual morphology, as a galaxy can look very different from different viewpoints. A special case is when we are lucky enough to observe a spiral galaxy directly from its edge, providing us with a spectacular view like the one seen in this picture of the week.

This is NGC 7814, also known as the “Little Sombrero.” Its larger namesake, the Sombrero Galaxy, is another stunning example of an edge-on galaxy — in fact, the “Little Sombrero” is about the same size as its bright namesake at about 60,000 light-years across, but as it lies farther away, and so appears smaller in the sky.

Hubble and the sunrise over Earth

NGC 7814 has a bright central bulge and a bright halo of glowing gas extending outwards into space. The dusty spiral arms appear as dark streaks. They consist of dusty material that absorbs and blocks light from the galactic center behind it. The field of view of this NASA/ESA Hubble Space Telescope image would be very impressive even without NGC 7814 in front; nearly all the objects seen in this image are galaxies as well.

For more information about Hubble Space Telescope, visit: and

Image, Video, Text, Credits: ESA/Hubble & NASA/Acknowledgement: Josh Barrington.


Camera to record doomed ATV’s disintegration – from inside

ESA - ATV-5 Georges Lemaître logo / ESA-NASA - ATV-5 Re-Entry Observation Campaign logo.

6 February 2015

Next Monday, ESA astronaut Samantha Christoforetti will float into Europe’s space ferry to install a special infrared camera, set to capture unique interior views of the spacecraft’s break-up on reentry.

“The battery-powered camera will be trained on the Automated Transfer Vehicle’s forward hatch, and will record the shifting temperatures of the scene before it,” explains Neil Murray, overseeing the project for ESA.

ATV-5 free flight

“Recording at 10 frames per second, it should show us the last 10 seconds or so of the ATV. We don’t know exactly what we might see – might there be gradual deformations appearing as the spacecraft comes under strain, or will everything come apart extremely quickly?

“Our Break-Up Camera, or BUC, flying for the first time on this mission, will complement NASA’s Reentry Break-up Recorder.

“Whatever results we get back will be shared by our teams, and should tell us a lot about the eventual reentry of the International Space Station as well as spacecraft reentry in general.”

BUC Infrared Camera and SatCom

Every mission of ESA’s ATV ferry ends in the same way – filled with Space Station rubbish then burning up in the atmosphere, aiming at a designated ‘spacecraft graveyard’ in an empty stretch of the South Pacific.

But the reentry of this fifth and final ATV is something special. NASA and ESA are treating it as an opportunity to gather detailed information that will help future spacecraft reentries.

Accordingly, ATV-5 will be steered into a shallow descent compared to the standard deorbit path.

Camera calibration targets

This ATV’s fiery demise will be tracked with a battery of cameras and imagers, on the ground, in the air and even from the Station itself, and this time on the vehicle itself.

ESA’s camera will not survive the reentry, expected to occur some 80–70 km up, but it is linked to the ‘SatCom’ sphere with a ceramic thermal protection system to endure the searing 1500°C.

Once SatCom is falling free, it will transmit its stored data to any Iridium communication satellites in view.

ATV-1 reentry

Plunging through the top of the atmosphere at around 7 km/s, it will itself be surrounded by scorching plasma known to block radio signals, but the hope is that its omnidirectional antenna will be able to exploit a gap in its trail.

If not, signalling will continue after the plasma has cleared – somewhere below 40 km altitude.

Japan’s i-Ball camera managed to gather images of its Station supply ferry breaking up in 2012. Another i-Ball was planned to fly with ATV-5, but was lost in the Antares rocket explosion last October.

ESA’s camera team had to develop flight-ready hardware in just nine months. The camera and capsule was constructed by Ruag in Switzerland, with thermal protection contributed by the DLR German Aerospace Center, Switzerland’s ETH Zurich contributing software, Switzerland’s Viasat responsible for antenna and electronics and Denmark’s GomSpace delivering batteries.

“Between us and the NASA side, there are a lot of fingers crossed at the moment,” Neil adds.

ATV cutaway

“For the future, now the development has already been done, the camera has broader potential as a ‘blackbox for reentry’, flyable on a wide range of satellites and launchers.”

The camera will be activated by a set sequence of acceleration by ATV. Some 10 seconds’ worth of 320x256 frames from the camera will be buffered in the SatCom memory at a time plus about one-frame-per-second reference images of the previous set, and progressively overwritten as fresh imagery arrives.

Related links:

ATV 5 Georges Lemaître:

ATV-5 ESA/NASA reentry observation campaign:

About Propulsion and Aerothermodynamics:

NASA Re-entry Break-up Recorder:

JAXA i-Ball images of HTV break-up:

RUAG Space Switzerland:


ETH Zurich:

ViaSat Antenna Systems:


Images, Video, Text, Credits: ESA/D. Ducros/Roscosmos/O. Artemyev.


Venus Climate Orbiter “AKATSUKI” Re-injection to Venus Orbit and Observation Plan

JAXA - Venus Climate Orbiter PLANET-C logo.

February 6, 2015

The Japan Aerospace Exploration Agency has decided the schedule for the Venus Climate Orbiter “AKATSUKI” to be injected into the Venus orbit in the winter of 2015, as well as its observation plan.

After failing to be inserted into the Venus orbit in December 2010, JAXA has been carefully studying another attempt opportunity for the injection when the orbiter meets Venus in the winter of 2015.

Venus Climate Orbiter “AKATSUKI” (PLANET-C) spacecraft

After being injected into the orbit, the AKATSUKI will observe the atmosphere of Venus, which is often referred to as a twin sister of the Earth, through remote sensing. Its observations are expected to develop “Planetary Meteorology” further by elucidating the atmospheric circulation mechanism and studying the comparison with the Earth.

1. Injection schedule to Venus orbit

Planned date: Dec. 7 (Mon.), 2015 (Japan Standard Time).

2. Observation plan

The observation plan of the AKATSUKI is to measures the following with a multiple number of wave lengths from an elliptical orbit around Venus whose period is eight to nine days.

- When flying further away from Venus, or about 10 times the radius of Venus from the planet, the AKATSUKI will continuously observe Venus as a whole to understand its clouds, deep atmosphere, and surface conditions.

- When flying closer to Venus, or less than 10 times the radius of Venus, the orbiter will conduct close-up observations to clarify cloud convection, the distribution of minute undulatory motions and their changes.

- When the AKATSUKI comes closest to Venus, it will observe the layer structure of clouds and the atmosphere from a lateral direction.

- When the orbiter is in the shade of the sun, it will monitor lightning and airglow (night glow.).

- The AKATSUKI will also observe to capture the atmospheric layer structure and its changes by emitting radio waves that penetrates the atmosphere of Venus and receiving them on the ground.

For more information about Venus Climate Orbiter "AKATSUKI" (PLANET-C):

Image, Text, Credit: Japan Aerospace Exploration Agency (JAXA).


jeudi 5 février 2015

NASA's Curiosity Analyzing Sample of Martian Mountain

NASA - Mars Science Laboratory (MSL) patch.

February 5, 2015

-- Analysis underway of Curiosity's second drilled rock sample at Mount Sharp

-- Preliminary results suggest acidic ancient conditions

-- New drilling technique uses less-forceful hammering on fragile rock

The second bite of a Martian mountain taken by NASA's Curiosity Mars rover hints at long-ago effects of water that was more acidic than any evidenced in the rover's first taste of Mount Sharp, a layered rock record of ancient Martian environments.

The rover used a new, low-percussion-level drilling technique to collect sample powder last week from a rock target called "Mojave 2."

Curiosity reached the base of Mount Sharp five months ago after two years of examining other sites inside Gale Crater and driving toward the mountain at the crater's center. The first sample of the mountain's base layer came from a target called "Confidence Hills," drilled in September.

Image above: Gray cuttings from Curiosity's drilling into a target called "Mohave 2" are visible surrounding the sample-collection hole in this Jan. 31, 2015, image from the rover's MAHLI camera. This site in the "Pahrump Hills" outcrop provided the mission's second drilled sample of Mars' Mount Sharp. Image Credit: NASA/JPL-Caltech/MSSS.

A preliminary check of the minerals in the Mojave 2 sample comes from analyzing it with the Chemistry and Mineralogy (CheMin) instrument inside Curiosity. The still-partial analysis shows a significant amount of jarosite, an oxidized mineral containing iron and sulfur that forms in acidic environments.

"Our initial assessment of the newest sample indicates that it has much more jarosite than Confidence Hills," said CheMin Deputy Principal Investigator David Vaniman, of the Planetary Science Institute, Tucson, Arizona. The minerals in Confidence Hills indicate less acidic conditions of formation.

Open questions include whether the more acidic water evident at Mojave 2 was part of environmental conditions when sediments building the mountain were first deposited, or fluid that soaked the site later.

Both target sites lie in a outcrop called "Pahrump Hills," an exposure of the Murray formation that is the basal geological unit of Mount Sharp. The Curiosity mission team has already proposed a hypothesis that this mountain, the size of Mount Rainier in Washington, began as sediments deposited in a series of lakes filling and drying.

In the months between Curiosity's drilling of these two targets, the rover team based at NASA's Jet Propulsion Laboratory, Pasadena, California, directed the vehicle through an intensive campaign at Pahrump Hills. The one-ton roving laboratory zig-zagged up and down the outcrop's slope, using cameras and spectrometer instruments to study features of interest at increasing levels of detail. One goal was to select which targets, if any, to drill for samples to be delivered into the rover's internal analytical instruments.

The team chose a target called "Mojave," largely due to an abundance of slender features, slightly smaller than rice grains, visible on the rock surface. Researchers sought to determine whether these are salt-mineral crystals, such as those that could result from evaporation of a drying lake, or if they have some other composition. In a preparatory drilling test of the Mojave target, the rock broke. This ruled out sample-collection drilling at that spot, but produced chunks with freshly exposed surfaces to be examined.     

Mojave 2, an alternative drilling target selected at the Mojave site, has the same type of crystal-shaped features. The preliminary look at CheMin data from the drilled sample material did not identify a clear candidate mineral for these features. Possibly, minerals that originally formed the crystals may have been replaced by other minerals during later periods of wet environmental conditions.

The drilling to collect Mojave 2 sample material might not have succeeded if the rover team had not recently expanded its options for operating the drill.

Image above: Self-Portrait by Curiosity Rover Arm Camera square. Image Credit: NASA/JPL-Caltech/MSSS.

"This was our first use of low-percussion drilling on Mars, designed to reduce the energy we impart to the rock," said JPL's John Michael Morookian, the team's surface science and sampling activity lead for the Pahrump Hills campaign. "Curiosity's drill is essentially a hammer and chisel, and this gives us a way not to hammer as hard."

Extensive tests on Earth validated the technique after the team became concerned about fragility of some finely layered rocks near the base of Mount Sharp.

The rover's drill has six percussion-level settings ranging nearly 20-fold in energy, from tapping gently to banging vigorously, all at 30 times per second. The drill monitors how rapidly or slowly it is penetrating the rock and autonomously adjusts its percussion level. At the four targets before Mojave 2 -- including three before Curiosity reached Mount Sharp -- sample-collection drilling began at level four and used an algorithm that tended to remain at that level. The new algorithm starts at level one, then shifts to a higher level only if drilling progress is too slow. The Mojave 2 rock is so soft, the drill reached its full depth of about 2.6 inches (6.5 centimeters) in 10 minutes using just levels one and two of percussion energy.

Curiosity has also delivered Mojave 2 powder to the internal Sample Analysis at Mars (SAM) suite of instruments, for chemical analysis. The rover may drive to one or more additional sampling sites at Pahrump Hills before heading higher on Mount Sharp.

NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.

For more information about Curiosity, visit: and

You can follow the mission on Facebook and Twitter at: and

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


Dawn Gets Closer Views of Ceres

NASA - Dawn Mission patch.

February 5, 2015

NASA's Dawn spacecraft, on approach to dwarf planet Ceres, has acquired its latest and closest-yet snapshot of this mysterious world.

At a resolution of 8.5 miles (14 kilometers) per pixel, the pictures represent the sharpest images to date of Ceres.

Animation above: This animation showcases a series of images NASA's Dawn spacecraft took on approach to Ceres on Feb. 4, 2015 at a distance of about 90,000 miles (145,000 kilometers) from the dwarf planet. Animation Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI.

After the spacecraft arrives and enters into orbit around the dwarf planet, it will study the intriguing world in great detail. Ceres, with a diameter of 590 miles (950 kilometers), is the largest object in the main asteroid belt, located between Mars and Jupiter.

Dawn's mission to Vesta and Ceres is managed by the Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Virginia, designed and built the spacecraft. 

Image above: This image is one several images NASA's Dawn spacecraft took on approach to Ceres on Feb. 4, 2015 at a distance of about 90,000 miles (145,000 kilometers) from the dwarf planet. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

JPL is managed for NASA by the California Institute of Technology in Pasadena. The framing cameras were provided by the Max Planck Institute for Solar System Research, Gottingen, Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig.

The visible and infrared mapping spectrometer was provided by the Italian Space Agency and the Italian National Institute for Astrophysics, built by Selex ES, and is managed and operated by the Italian Institute for Space Astrophysics and Planetology, Rome. The gamma ray and neutron detector was built by Los Alamos National Laboratory, New Mexico, and is operated by the Planetary Science Institute, Tucson, Arizona.

For more information about Dawn, visit:

Image (mentioned), Animation (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau.


Hubble captures rare triple moon transit of Jupiter

ESA - Hubble Space Telescope logo.

5 February 2015

March of the moons

Images above: Three moons and their shadows parade across Jupiter — Comparison of beginning and end of sequence, including annotations.

These new NASA/ESA Hubble Space Telescope images capture a rare occurrence as three of Jupiter’s largest moons parade across the giant gas planet’s banded face. Hubble took a string of images of the event which show the three satellites — Europa, Callisto and Io — in action.

Images above: Three moons and their shadows parade across Jupiter — comparison of beginning and end of sequence, without annotations.

There are four Galilean satellites — named after the 17th century scientist Galileo Galilei who discovered them [1]. They complete orbits around Jupiter ranging from two to seventeen days in duration. The moons can commonly be seen transiting the face of Jupiter and casting shadows onto its layers of cloud. However, seeing three of them transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade.

Images above: Three moons and their shadows parade across Jupiter — comparison of beginning and end of sequence, with annotations.

The image on the left shows the Hubble observation at the beginning of the event. On the left is the moon Callisto and on the right, Io. The shadows from Callisto, Io and Europa are strung out from left to right. Europa itself cannot be seen in the image.

Image above: Three moons and their shadows parade across Jupiter — beginning of event

The image on the right shows the end of the event, just over 40 minutes later. Europa has entered the frame at lower left with slower-moving Callisto above and to the right of it. Meanwhile Io — which orbits significantly closer to Jupiter and so moves much more quickly — is approaching the eastern limb of the planet. Whilst Callisto’s shadow seems hardly to have moved, Io’s has set over the planet’s eastern edge and Europa’s has risen further in the west. The event is also shown from start to finish in a video.

Image above: Three moons and their shadows parade across Jupiter — beginning of event, annotated.

Missing from this sequence is the Galilean moon Ganymede which was outside Hubble’s field of view.

Image above: Three moons and their shadows parade across Jupiter — end of event

The moons of Jupiter have very distinctive colours. The smooth icy surface of Europa is yellow-white, the volcanic sulphur surface of Io is orange and the surface of Callisto, which is one of the oldest and most cratered surfaces known in the Solar System, is a brownish colour.

Image above: Three moons and their shadows parade across Jupiter — end of event, annotated

The images were taken with Hubble’s Wide Field Camera 3 in visible light on 23 January 2015. Whilst Hubble captures these moons in great clarity they can also be seen with a small telescope or even a decent pair of binoculars. Why not try it at home?

Time-lapse of Jupiter’s three moon transit

Time-lapse of Jupiter’s three moon transit, annotated

Simulation of Galilean Satellites orbiting Jupiter


[1] These were among the first observations ever made using a telescope. They revolutionised our understanding of the Universe, and finally laid to rest the theory that the Earth is the centre of the Solar System.
Notes for editors

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.


Images of Hubble:

Link to hubblesite release:

Link to Hubble Heritage release:

Images, Videos,Text, Credits: NASA, ESA, Hubble Heritage Team/Animation: NASA, ESA, and G. Bacon, L. Frattare, Z. Levay, and F. Summers (STScI/AURA).


Planck reveals first stars were born late

ESA - Planck Mission patch.

5 February 2015

New maps from ESA’s Planck satellite uncover the ‘polarised’ light from the early Universe across the entire sky, revealing that the first stars formed much later than previously thought.

The history of our Universe is a 13.8 billion-year tale that scientists endeavour to read by studying the planets, asteroids, comets and other objects in our Solar System, and gathering light emitted by distant stars, galaxies and the matter spread between them.

A major source of information used to piece together this story is the Cosmic Microwave Background, or CMB, the fossil light resulting from a time when the Universe was hot and dense, only 380 000 years after the Big Bang.

Polarisation of the Cosmic Microwave Background

Thanks to the expansion of the Universe, we see this light today covering the whole sky at microwave wavelengths.

Between 2009 and 2013, Planck surveyed the sky to study this ancient light in unprecedented detail. Tiny differences in the background’s temperature trace regions of slightly different density in the early cosmos, representing the seeds of all future structure, the stars and galaxies of today.

Scientists from the Planck collaboration have published the results from the analysis of these data in a large number of scientific papers over the past two years, confirming the standard cosmological picture of our Universe with ever greater accuracy.

“But there is more: the CMB carries additional clues about our cosmic history that are encoded in its ‘polarisation’,” explains Jan Tauber, ESA’s Planck project scientist.

“Planck has measured this signal for the first time at high resolution over the entire sky, producing the unique maps released today.” 

History of the Universe

Light is polarised when it vibrates in a preferred direction, something that may arise as a result of photons – the particles of light – bouncing off other particles. This is exactly what happened when the CMB originated in the early Universe.

Initially, photons were trapped in a hot, dense soup of particles that, by the time the Universe was a few seconds old, consisted mainly of electrons, protons and neutrinos. Owing to the high density, electrons and photons collided with one another so frequently that light could not travel any significant distant before bumping into another electron, making the early Universe extremely ‘foggy’.

Slowly but surely, as the cosmos expanded and cooled, photons and the other particles grew farther apart, and collisions became less frequent.

This had two consequences: electrons and protons could finally combine and form neutral atoms without them being torn apart again by an incoming photon, and photons had enough room to travel, being no longer trapped in the cosmic fog.

Once freed from the fog, the light was set on its cosmic journey that would take it all the way to the present day, where telescopes like Planck detect it as the CMB. But the light also retains a memory of its last encounter with the electrons, captured in its polarisation.

CMB polarisation: full sky and details

“The polarisation of the CMB also shows minuscule fluctuations from one place to another across the sky: like the temperature fluctuations, these reflect the state of the cosmos at the time when light and matter parted company,” says François Bouchet of the Institut d’Astrophysique de Paris, France.

“This provides a powerful tool to estimate in a new and independent way parameters such as the age of the Universe, its rate of expansion and its essential composition of normal matter, dark matter and dark energy.”

Planck’s polarisation data confirm the details of the standard cosmological picture determined from its measurement of the CMB temperature fluctuations, but add an important new answer to a fundamental question: when were the first stars born?

“After the CMB was released, the Universe was still very different from the one we live in today, and it took a long time until the first stars were able to form,” explains Marco Bersanelli of Università degli Studi di Milano, Italy.

CMB polarisation: zoom

“Planck’s observations of the CMB polarisation now tell us that these ‘Dark Ages’ ended some 550 million years after the Big Bang – more than 100 million years later than previously thought.

“While these 100 million years may seem negligible compared to the Universe’s age of almost 14 billion years, they make a significant difference when it comes to the formation of the first stars.”

The Dark Ages ended as the first stars began to shine. And as their light interacted with gas in the Universe, more and more of the atoms were turned back into their constituent particles: electrons and protons.

This key phase in the history of the cosmos is known as the ‘epoch of reionisation’.

The newly liberated electrons were once again able to collide with the light from the CMB, albeit much less frequently now that the Universe had significantly expanded. Nevertheless, just as they had 380 000 years after the Big Bang, these encounters between electrons and photons left a tell-tale imprint on the polarisation of the CMB.

CMB polarisation: finer detail

“From our measurements of the most distant galaxies and quasars, we know that the process of reionisation was complete by the time that the Universe was about 900 million years old,” says George Efstathiou of the University of Cambridge, UK.

“But, at the moment, it is only with the CMB data that we can learn when this process began.”

Planck’s new results are critical, because previous studies of the CMB polarisation seemed to point towards an earlier dawn of the first stars, placing the beginning of reionisation about 450 million years after the Big Bang.

This posed a problem. Very deep images of the sky from the NASA–ESA Hubble Space Telescope have provided a census of the earliest known galaxies in the Universe, which started forming perhaps 300–400 million years after the Big Bang.

However, these would not have been powerful enough to succeed at ending the Dark Ages within 450 million years.

“In that case, we would have needed additional, more exotic sources of energy to explain the history of reionisation,” says Professor Efstathiou.

The new evidence from Planck significantly reduces the problem, indicating that reionisation started later than previously believed, and that the earliest stars and galaxies alone might have been enough to drive it.

This later end of the Dark Ages also implies that it might be easier to detect the very first generation of galaxies with the next generation of observatories, including the James Webb Space Telescope. 

But the first stars are definitely not the limit. With the new Planck data released today, scientists are also studying the polarisation of foreground emission from gas and dust in the Milky Way to analyse the structure of the Galactic magnetic field.

Galactic dust

The data have also enabled new important insights into the early cosmos and its components, including the intriguing dark matter and the elusive neutrinos, as described in papers also released today.

The Planck data have delved into the even earlier history of the cosmos, all the way to inflation – the brief era of accelerated expansion that the Universe underwent when it was a tiny fraction of a second old. As the ultimate probe of this epoch, astronomers are looking for a signature of gravitational waves triggered by inflation and later imprinted on the polarisation of the CMB.

No direct detection of this signal has yet been achieved, as reported last week. However, when combining the newest all-sky Planck data with those latest results, the limits on the amount of primordial gravitational waves are pushed even further down to achieve the best upper limits yet.

“These are only a few highlights from the scrutiny of Planck's observations of the CMB polarisation, which is revealing the sky and the Universe in a brand new way,” says Jan Tauber.

“This is an incredibly rich data set and the harvest of discoveries has just begun.”

Notes for Editors:

A series of scientific papers describing the new results was published on 5 February and it can be downloaded here:

The new results from Planck are based on the complete surveys of the entire sky, performed between 2009 and 2013. New data, including temperature maps of the CMB at all nine frequencies observed by Planck and polarisation maps at four frequencies (30, 44, 70 and 353 GHz), are also released today.

The three principal scientific leaders of the Planck mission, Nazzareno Mandolesi, Jean-Loup Puget and Jan Tauber, were recently awarded the 2015 EPS Edison Volta Prize for "directing the development of the Planck payload and the analysis of its data, resulting in the refinement of our knowledge of the temperature fluctuations in the Cosmic Microwave Background as a vastly improved tool for doing precision cosmology at unprecedented levels of accuracy, and consolidating our understanding of the very early universe."

More about Planck:

Launched in 2009, Planck was designed to map the sky in nine frequencies using two state-of-the-art instruments: the Low Frequency Instrument (LFI), which includes three frequency bands in the range 30–70 GHz, and the High Frequency Instrument (HFI), which includes six frequency bands in the range 100–857 GHz.

HFI completed its survey in January 2012, while LFI continued to make science observations until 3 October 2013, before being switched off on 19 October 2013. Seven of Planck's nine frequency channels were equipped with polarisation-sensitive detectors.

The Planck Scientific Collaboration consists of all the scientists who have contributed to the development of the mission, and who participate in the scientific exploitation of the data during the proprietary period.

These scientists are members of one or more of four consortia: the LFI Consortium, the HFI Consortium, the DK-Planck Consortium, and ESA’s Planck Science Office. The two European-led Planck Data Processing Centres are located in Paris, France and Trieste, Italy.

The LFI consortium is led by N. Mandolesi, Università degli Studi di Ferrara, Italy (deputy PI: M. Bersanelli, Università degli Studi di Milano, Italy), and was responsible for the development and operation of LFI. The HFI consortium is led by J.L. Puget, Institut d’Astrophysique Spatiale in Orsay (CNRS/Université Paris-Sud), France (deputy PI: F. Bouchet, Institut d’Astrophysique de Paris (CNRS/UPMC), France), and was responsible for the development and operation of HFI.

Related links:

Planck: looking back at the dawn of time:

Planck Toolkit:

Planck toolkit introduction:

Planck and the CMB:

CMB and inflation:

CMB and the distribution of matter:

Tools to study the distribution of matter:

History of cosmic structure formation:

Effect of cosmic structure on CMB:

Images, Animation, Text, Credits: ESA and the Planck Collaboration.

Best regards,

mercredi 4 février 2015

Canadarm2 Grabs Dragon; Life Science for Crew

ISS - Expedition 42 Mission patch.

February 4, 2015

Mission Controllers in Houston will send commands to the 57.7 foot long Canadarm2 to grapple the SpaceX Dragon space freighter Tuesday. The robotic arm will latch on to a grapple fixture ahead of next week’s release of Dragon from the Harmony module. It will splash down off the Pacific coast of Baja California loaded with research and gear for analysis on Earth.

Read more about the SpaceX CRS-5 mission:

Back inside the International Space Station, the crew is working on more visiting vehicle activities, spacewalk preparations as well as ongoing microgravity science.

Image above: ISS042E119876 (01/10/2015) — US Astronaut and Flight Engineer Terry Virts a member of Expedition 42 on the International Space Station prepares to take scientific photographs on Jan. 10, 2015. Image Credit: NASA.

Commander Barry Wilmore is loading Europe’s Automated Transfer Vehicle-5 (ATV-5) with trash readying the vehicle for its departure Feb. 14. Cosmonauts Alexander Samokutyaev and Anton Shkaplerov practiced using the telerobotically operated rendezvous system, or TORU, ahead of the Feb. 17 arrival of the ISS Progress 58 resupply ship. The TORU would be used in the unlikely event the Kurs automated rendezvous system failed during the Progress’ approach.

Image above: Canadarm2 Grab Dragon (CRS-3). Image Credit: NASA.

Wilmore also harvested plants for the APEX-03 botany experiment. That study observes the effects of microgravity on the development of roots and cells on plant seedlings. Italian astronaut Samantha Cristoforetti looked at roundworms for the Epigenetics study that researches if new cell generations adapt to microgravity.

Read more about the APEX-03 botany experiment:

Read about the Epigenetics study:

This entry was posted in Expedition 42 and tagged Automated Transfer Vehicle, dragon, European Space Agency, Expedition 42, International Space Station, NASA, Roscosmos, spacex on February 3, 2015 by Mark.

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

Images (mentioned), Text, Credit: NASA.


NASA Spacecraft Returns New Images of Pluto En Route to Historic Encounter

NASA - New Horizons Mission logo.

February 4, 2015

NASA’s New Horizons spacecraft returned its first new images of Pluto on Wednesday, as the probe closes in on the dwarf planet. Although still just a dot along with its largest moon, Charon, the images come on the 109th birthday of Clyde Tombaugh, who discovered the distant icy world in 1930.

“My dad would be thrilled with New Horizons,” said Clyde Tombaugh’s daughter Annette Tombaugh, of Las Cruces, New Mexico. “To actually see the planet that he had discovered, and find out more about it -- to get to see the moons of Pluto-- he would have been astounded. I'm sure it would have meant so much to him if he were still alive today.”

New Horizons was more than 126 million miles (nearly 203 million kilometers) away from Pluto when it began taking images. The new images, taken with New Horizons’ telescopic Long-Range Reconnaissance Imager (LORRI) on Jan. 25 and Jan. 27, are the first acquired during the spacecraft’s 2015 approach to the Pluto system, which culminates with a close flyby of Pluto and its moons on July 14.

Image above: The image of Pluto and its moon Charon, taken by NASA’s New Horizons spacecraft, was magnified four times to make the objects more visible. Over the next several months, the apparent sizes of Pluto and Charon, as well as the separation between them, will continue to expand in the images. Image Credit: NASA/JHU APL/SwRI.

“This is our birthday tribute to Professor Tombaugh and the Tombaugh family, in honor of his discovery and life achievements -- which truly became a harbinger of 21st century planetary astronomy,” said Alan Stern, New Horizons principal investigator at the Southwest Research Institute (SwRI) in Boulder, Colorado. “These images of Pluto, clearly brighter and closer than those New Horizons took last July from twice as far away, represent our first steps at turning the pinpoint of light Clyde saw in the telescopes at Lowell Observatory 85 years ago, into a planet before the eyes of the world this summer.”

Over the next few months, LORRI will take hundreds of pictures of Pluto, against a starry backdrop, to refine the team’s estimates of New Horizons’ distance to Pluto. As in these first images, the Pluto system will resemble little more than bright dots in the camera’s view until late spring. However, mission navigators can still use such images to design course-correcting engine maneuvers to direct the spacecraft for a more precise approach. The first such maneuver based on these optical navigation images, or OpNavs, is scheduled for March 10.

“Pluto is finally becoming more than just a pinpoint of light,” said Hal Weaver, New Horizons project scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.  “LORRI has now resolved Pluto, and the dwarf planet will continue to grow larger and larger in the images as New Horizons spacecraft hurtles toward its targets. The new LORRI images also demonstrate that the camera’s performance is unchanged since it was launched more than nine years ago.”

Closing in on Pluto at about 31,000 mph, New Horizons already has covered more than 3 billion miles since it launched on Jan. 19, 2006. Its journey has taken it past each planet’s orbit, from Mars to Neptune, in record time, and it is now in the first stage of an encounter with Pluto that includes long-distance imaging as well as dust, energetic particle and solar wind measurements to characterize the space environment near Pluto.

New Horizons spacecraft. Image Credit: NASA

“The U.S. has led the exploration of the planets and continues to do so with New Horizons,” said Curt Niebur, New Horizons program scientist at NASA Headquarters in Washington. “This mission will obtain images to map Pluto and its moons better than has ever been achieved by any previous planetary mission.”

APL manages the New Horizons mission for NASA’s Science Mission Directorate in Washington. Alan Stern, of SwRI, is the principal investigator and leads the mission. SwRI leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the spacecraft.

To view the Pluto image online and see the mission timeline for upcoming images, visit: and

NASA/Dwayne Brown/Johns Hopkins University Applied Physics Laboratory/Michael Buckley/Southwest Research Institute/Maria Stothoff.


NASA's LRO Discovers Lunar Hydrogen More Abundant on Moon's Pole-Facing Slopes

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

February 4, 2015

Space travel is difficult and expensive – it would cost thousands of dollars to launch a bottle of water to the moon. The recent discovery of hydrogen-bearing molecules, possibly including water, on the moon has explorers excited because these deposits could be mined if they are sufficiently abundant, sparing the considerable expense of bringing water from Earth. Lunar water could be used for drinking or its components – hydrogen and oxygen – could be used to manufacture important products on the surface that future visitors to the moon will need, like rocket fuel and breathable air.

Image above: LRO image of the moon's Hayn Crater, located just northeast of Mare Humboldtianum, dramatically illuminated by the low Sun casting long shadows across the crater floor. Image Credit: NASA/GSFC/Arizona State University.

Recent observations by NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft indicate these deposits may be slightly more abundant on crater slopes in the southern hemisphere that face the lunar South Pole. "There’s an average of about 23 parts-per-million-by-weight (ppmw) more hydrogen on Pole-Facing Slopes (PFS) than on Equator-Facing Slopes (EFS)," said Timothy McClanahan of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

This is the first time a widespread geochemical difference in hydrogen abundance between PFS and EFS on the moon has been detected. It is equal to a one-percent difference in the neutron signal detected by LRO's Lunar Exploration Neutron Detector (LEND) instrument. McClanahan is lead author of a paper about this research published online October 19 in the journal Icarus.

The hydrogen-bearing material is volatile (easily vaporized), and may be in the form of water molecules (two hydrogen atoms bound to an oxygen atom) or hydroxyl molecules (an oxygen bound to a hydrogen) that are loosely bound to the lunar surface. The cause of the discrepancy between PFS and EFS may be similar to how the Sun mobilizes or redistributes frozen water from warmer to colder places on the surface of the Earth, according to McClanahan.

"Here in the northern hemisphere, if you go outside on a sunny day after a snowfall, you'll notice that there's more snow on north-facing slopes because they lose water at slower rates than the more sunlit south-facing slopes" said McClanahan. "We think a similar phenomenon is happening with the volatiles on the moon – PFS don't get as much sunlight as EFS, so this easily vaporized material stays longer and possibly accumulates to a greater extent on PFS."

The team observed the greater hydrogen abundance on PFS in the topography of the moon's southern hemisphere, beginning at between 50 and 60 degrees south latitude.  Slopes closer to the South Pole show a larger hydrogen concentration difference. Also, hydrogen was detected in greater concentrations on the larger PFS, about 45 ppmw near the poles. Spatially broader slopes provide more detectable signals than smaller slopes. The result indicates that PFS have greater hydrogen concentrations than their surrounding regions. Also, the LEND measurements over the larger EFS don't contrast with their surrounding regions, which indicates EFS have hydrogen concentrations that are equal to their surroundings, according to McClanahan. The team thinks more hydrogen may be found on PFS in northern hemisphere craters as well, but they are still gathering and analyzing LEND data for this region.

There are different possible sources for the hydrogen on the moon. Comets and some asteroids contain large amounts of water, and impacts by these objects may bring hydrogen to the moon. Hydrogen-bearing molecules could also be created on the lunar surface by interaction with the solar wind. The solar wind is a thin stream of gas that's constantly blown off the Sun. Most of it is hydrogen, and this hydrogen may interact with oxygen in silicate rock and dust on the moon to form hydroxyl and possibly water molecules. After these molecules arrive at the moon, it is thought they get energized by sunlight and then bounce across the lunar surface; and they get stuck, at least temporarily, in colder and more shadowy areas.

Since the 1960's scientists thought that only in permanently shadowed areas in craters near the lunar poles was it cold enough to accumulate this volatile material, but recent observations by a number of spacecraft, including LRO, suggest that hydrogen on the moon is more widespread.

NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft. Image Credit: NASA/GSFC

It's uncertain if the hydrogen is abundant enough to economically mine. "The amounts we are detecting are still drier than the driest desert on Earth," said McClanahan. However, the resolution of the LEND instrument is greater than the size of most PFS, so smaller PFS slopes, perhaps approaching yards in size, may have significantly higher abundances, and indications are that the greatest hydrogen concentrations are within the permanently shaded regions, according to McClanahan.

The team made the observations using LRO's LEND instrument, which detects hydrogen by counting the number of subatomic particles called neutrons flying off the lunar surface. The neutrons are produced when the lunar surface gets bombarded by cosmic rays. Space is permeated by cosmic rays, which are high-speed particles produced by powerful events like flares on the Sun or exploding stars in deep space. Cosmic rays shatter atoms in material near the lunar surface, generating neutrons that bounce from atom to atom like a billiard ball. Some neutrons happen to bounce back into space where they can be counted by neutron detectors.

Neutrons from cosmic ray collisions have a wide range of speeds, and hydrogen atoms are most efficient at stopping neutrons in their medium speed range, called epithermal neutrons. Collisions with hydrogen atoms in the lunar regolith reduce the numbers of epithermal neutrons that fly into space. The more hydrogen present, the fewer epithermal neutrons the LEND detector will count.

The team interpreted a widespread decrease in the number of epithermal neutrons detected by LEND as a signal that hydrogen is present on PFS. They combined data from LEND with lunar topography and illumination maps derived from LRO's LOLA instrument (Lunar Orbiter Laser Altimeter), and temperature maps from LRO's Diviner instrument (Diviner Lunar Radiometer Experiment) to discover the greater hydrogen abundance and associated surface conditions on PFS.

In addition to seeing if the same pattern exists in the moon's northern hemisphere, the team wants to see if the hydrogen abundance changes with the transition from day to night. If so, it would substantiate existing evidence of a very active production and cycling of hydrogen on the lunar surface, according to McClanahan.

The research was funded by NASA's LRO mission. LEND was supplied by the Russian Federal Space Agency Roscosmos. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington.

For more information about Lunar Reconnaissance Orbiter (LRO), visit: and

Images (mentioned), Text, Credits: NASA Goddard Space Flight Center/Bill Steigerwald.


Rosetta swoops in for a close encounter

ESA - Rosetta Mission patch.

4 February 2015

ESA’s Rosetta probe is preparing to make a close encounter with its comet on 14 February, passing just 6 km from the surface.

Yesterday was Rosetta’s last day at 26 km from Comet 67P/Churyumov–Gerasimenko, marking the end of the current orbiting period and the start of a new phase for the rest of this year.

Rosetta’s closest approach

Today, Rosetta is moving into a new path ahead of a very close encounter next week. First, it will move out to a distance of roughly 140 km from the comet by 7 February, before swooping in for the close encounter at 12:41 GMT (13:41 CET) on 14 February. The closest pass occurs over the comet’s larger lobe, above the Imhotep region.

“The upcoming close flyby will allow unique scientific observations, providing us with high-resolution measurements of the surface over a range of wavelengths and giving us the opportunity to sample – taste or sniff – the very innermost parts of the comet’s atmosphere,” says Matt Taylor, ESA’s Rosetta project scientist.

The flyby will take Rosetta over the most active regions of the comet, helping scientists to understand the connection between the source of the observed activity and the atmosphere, or coma.

In particular, they will be looking for zones where the outflowing gas and dust accelerates from the surface and how these constituents evolve at larger distances from the comet.

The comet’s surface is already known to be very dark, reflecting just 6% of the light that falls on it. During the close flyby, Rosetta will pass over the comet with the Sun directly behind, allowing shadow-free images to be collected. By studying the reflectivity of the nucleus as it varies with the angle of the sunlight falling on it, scientists hope to gain a more detailed insight into the dust grains on the surface.

“After this close flyby, a new phase will begin, when Rosetta will execute sets of flybys past the comet at a range of distances, between about 15 km and 100 km,” says Sylvain Lodiot, ESA’s spacecraft operations manager.

Rosetta's close flyby

It was always planned to change from ‘bound orbits’ to flyby trajectories at this point in the mission, based on predictions of increasing cometary activity. The range of flyby distances also balances the various needs of Rosetta’s 11 instruments in order to optimise the mission’s scientific return.

During some of the close flybys, Rosetta will encounter the comet almost in step with the rotation, allowing the instruments to monitor a single point on the surface as it passes by.

Meanwhile, the more distant flybys will provide the broader context of a wide-angle view of the nucleus and its growing coma.

“We’re in the main science phase of the mission now, so throughout the year we’ll be continuing with high-resolution mapping of the comet,” says Matt.

“We’ll sample the gas, dust and plasma from a range of distances as the comet’s activity increases and then subsides again later in the year.”

Perihelion, closest approach to the Sun, occurs on 13 August when the comet and Rosetta will be 186 million kilometres from the Sun, between the orbits of Earth and Mars.

Comet on 22 January 2015 – NavCam

In the month before perihelion, as activity is reaching a peak, the team are planning to study one of the comet’s jets in greater detail than ever.

“We hope to target one of these regions for a fly-through, to really get a taste of the outflow of the comet,” adds Matt.

After perihelion and once the comet’s activity begins to subside, the mission team will determine if and when to return to a bound orbit around the comet, and how long Rosetta might be able to operate beyond the end of 2015.

Follow the Rosetta blog and the @ESA_Rosetta and @esaoperations twitter accounts for further details on the upcoming spacecraft operations.

ESA blog:

Read the blog article “Where is Philae? When will it wake up?” for more information on the status of Rosetta’s lander:

Images, Video, Text, Credits: ESA/C. Carreau/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

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Curiosity Rover at 'Pahrump Hills'

NASA - Mars Reconnaissance Orbiter (MRO) logo.

4 February 2015

NASA's Curiosity Mars rover can be seen at the "Pahrump Hills" area of Gale Crater in this view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.  Pahrump Hills is an outcrop at the base of Mount Sharp. The region contains sedimentary rocks that scientists believe formed in the presence of water.

The location of the rover, with its shadow extending toward the upper right, is indicated with an inscribed rectangle. Figure A is an unannotated version of the image.  North is toward the top. The view covers an area about 360 yards (330 meters) across.

HiRISE made the observation on Dec. 13, 2014. At that time, Curiosity was near a feature called "Whale Rock."  A map showing the rover's path for the weeks leading up to that date is at .  The inset map at labels the location of Whale Rock and other features in the Pahrump Hills area.

The bright features in the landscape are sedimentary rock and the dark areas are sand.  The HiRISE team plans to periodically image Curiosity, as well as NASA's other active Mars rover, Opportunity, as the vehicles continue to explore Mars.

NASA's Mars Reconnaissance Orbiter spacecraft

This image is an excerpt from HiRISE observation ESP_039280_1755. Other image products from this observation are available at .

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project and Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington.

For more information about Mars Curiosity (MSL) rover and Mars Reconnaissance Orbiter (MRO), visit: and

Images, Text, Credit: NASA/JPL-Caltech/Univ. of Arizona.