Swarm’s precise sense of magnetism

ESA - SWARM Mission logo.

7 May 2014

Although they were launched only five months ago, ESA’s trio of Swarm satellites are already delivering results with a precision that took earlier missions 10 years to achieve.

Engineers have spent the last five months commissioning the identical satellites and carefully guiding them into their orbits to provide the crucial measurements that will unravel the mysteries of Earth’s magnetic field.

Swarm has a challenging task ahead.

Swarm magnetic field compared to model

Together, the satellites will measure and untangle the different magnetic readings that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere.

In addition, information will also be provided to calculate the electric field near each satellite – an important counterpart to the magnetic field for studying the upper atmosphere.

Two satellites are now orbiting almost side by side and have started their operational life at 462 km altitude. The third is higher, at 510 km. 

The readings made at different locations will be used to distinguish between the changes in the magnetic field caused by the Sun’s activity and those signals that originate from inside Earth.

Swarm is now in its fine-tuning phase but it has already produced enough information to build models of the magnetic field for comparison with existing models.

Swarm: a new constellation in the sky

This proves that only a few months of Swarm data agree very well with a decade or more of predecessor missions.

For example, the image above shows the differences between Swarm’s version of the magnetic field from Earth’s crust compared to the 'Chaos-4' model. There are very few differences, demonstrating that the mission is working well.

ESA’s mission manager, Rune Floberghagen, said, "Although it has certainly been a big job getting the three satellites ready for operations, we are all very happy with how well the mission is doing so soon after launch.

Earth's magnetic field

"Scientists will start to have access to the mission’s magnetic field data in a couple of weeks."

Over the coming years, this innovative mission will provide new insight into many natural processes, from those occurring deep inside the planet to weather in space caused by solar activity.

In turn, this information will yield a better understanding of why the magnetic field is weakening.

The first results and status of the mission will be presented at a Swarm science meeting on 19–20 June in Denmark.

For more information about SWARM mission, visit: http://www.esa.int/Our_Activities/Observing_the_Earth/The_Living_Planet_Programme/Earth_Explorers/Swarm/ESA_s_magnetic_field_mission_Swarm

Images, Video, Text, Credits: ESA/DTU Space–N. Olsen/ATG Medialab/AOES Medialab.

Best regards, Orbiter.ch

NASA's Chandra Observatory Delivers New Insight into Formation of Star Clusters

NASA - Chandra X-ray Observatory patch.

May 7, 2014

Image above: Astronomers have studied two star clusters (NGC 2024 and Orion) to gain insight on how clusters of stars like our Sun form. They found the stars on the outskirts of these clusters are older than those in the center, which is different from what the simplest idea of star formation predicts.

Using data from NASA's Chandra X-ray Observatory and infrared telescopes, astronomers have made an important advance in the understanding of how clusters of stars come into being.

The data show early notions of how star clusters are formed cannot be correct. The simplest idea is stars form into clusters when a giant cloud of gas and dust condenses. The center of the cloud pulls in material from its surroundings until it becomes dense enough to trigger star formation. This process occurs in the center of the cloud first, implying that the stars in the middle of the cluster form first and, therefore, are the oldest.

However, the latest data from Chandra suggest something else is happening. Researchers studied two clusters where sun-like stars currently are forming – NGC 2024, located in the center of the Flame Nebula, and the Orion Nebula Cluster.  From this study, they discovered the stars on the outskirts of the clusters actually are the oldest.

"Our findings are counterintuitive," said Konstantin Getman of Penn State University, who led the study. "It means we need to think harder and come up with more ideas of how stars like our sun are formed."

Getman and his colleagues developed a new two-step approach that led to this discovery. First, they used Chandra data on the brightness of the stars in X-rays to determine their masses. Then they determined how bright these stars were in infrared light using ground-based telescopes and data from NASA's Spitzer Space Telescope. By combining this information with theoretical models, the ages of the stars throughout the two clusters were estimated.

The results were contrary to what the basic model predicted. At the center of NGC 2024, the stars were about 200,000 years old, while those on the outskirts were about 1.5 million years in age. In the Orion Nebula, star ages ranged from 1.2 million years in the middle of the cluster to almost 2 million years near the edges.

"A key conclusion from our study is we can reject the basic model where clusters form from the inside out," said co-author Eric Feigelson, also of Penn State. "So we need to consider more complex models that are now emerging from star formation studies."

Explanations for the new findings can be grouped into three broad notions. The first is star formation continues to occur in the inner regions because the gas in the inner regions of a star-forming cloud is denser -- contains more material from which to build stars -- than the more diffuse outer regions. Over time, if the density falls below a threshold where it can no longer collapse to form stars, star formation will cease in the outer regions, whereas stars will continue to form in the inner regions, leading to a concentration of younger stars there.

Chandra X-ray Observatory

Another idea is old stars have had more time to drift away from the center of the cluster, or be kicked outward by interactions with other stars. One final notion is the observations could be explained if young stars are formed in massive filaments of gas that fall toward the center of the cluster.

Previous studies of the Orion Nebula Cluster revealed hints of this reversed age spread, but these earlier efforts were based on limited or biased star samples. This latest research provides the first evidence of such age differences in the Flame Nebula.

"The next steps will be to see if we find this same age range in other young clusters," said Penn State graduate student Michael Kuhn, who also worked on the study.

These results will be published in two separate papers in The Astrophysical Journal and are available online. They are part of the MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) project led by Penn State astronomers.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.

For an additional interactive image, podcast, and video on the finding, visit: http://chandra.si.edu

For Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

Images, Text, Credits: NASA / J.D. Harrington / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

Greetings, Orbiter.ch

Year-old Proba-V charting global greenery

ESA - Proba-V Mission logo.

7 May 2014

A year after its launch, ESA’s Proba-V is set to make a giant leap for a minisatellite: formally taking over the task of continuously charting our planet’s global vegetation.

For 5880 days – 16 years in all – the Vegetation cameras on France’s full-sized Spot-4 and Spot-5 satellites have been monitoring plant growth across Earth, compiling a new global map every two days.

Scientific teams around the world use these sensors to predict crop yields, chart the progress of drought and desertification, pinpoint deforestation and improve climate change models.

Proba-V

But Spot-4 stopped operating last year and Spot-5 is nearing the end. The torch will shortly be passed to Proba-V, ESA’s latest minisatellite, launched on 7 May last year. 

On 30 May Proba-V’s own Vegetation camera will formally take over the task of collecting this information from Spot-5.

The two instruments enjoyed a one-year overlap, which has allowed detailed cross-calibration between the two, ensuring a consistent time series for scientists to employ seamlessly.

“Proba-V’s new job is a notable first for a small satellite,” explained Bianca Hoersch, ESA’s Proba-V Mission Manager.

Proba-V images Europe

“At less than a cubic metre, the entire satellite is actually compact enough to fit inside the former generation of Vegetation sensors, which were housed aboard the van-sized Spot satellites.”

This new generation had to be extensively redesigned to fit aboard ESA’s minisatellite, while retaining the wide 2250 km field of view that allows it to chart all vegetation every two days.  

At the same time, the redesign also sharpened its acuity considerably, from 1 km to 300 m, down to 100 m in its central swath.

Proba-V was designed and built rapidly by a Belgian consortium of companies, specifically to serve as a gapfiller between Spot and ESA’s coming Sentinel-3 mission.

Preparing Proba-V for launch

The latest in ESA’s ‘Project for Onboard Autonomy’ satellite family, Proba-V is not only one of the smallest missions in space but also the smartest.

The high-performance satellite requires minimal human involvement. For example, its fully autonomous navigation means it can change orientation while automatically avoiding hazards such as turning towards sunlight which might blind its camera. 

And its flight computer, developed by mission prime contractor QinetiQ Space in Belgium, stores data using solid state flash memory, more typically found in consumer USB sticks, digital cameras and mobile phones.

This is a tenfold improvement on previous techniques, allowing the satellite to store imagery for half the world between its 10-times-per-day data downlinks to the ground.

Mouth of Ganges at 100-m resolution

“And, as with the previous Proba missions, the satellite also hosts extra technology payloads,” added ESA’s Karim Mellab, who oversaw the mission’s flight preparations.

“These are experimental hardware that have proved themselves in orbit, with some significant world firsts among them.”

Proba-V launch (Vega VV02)

These include the very first space-based monitoring system for air traffic, picking up signals which are planned to take the place of ground-based radar tracking.

Proba-V’s receiver was only supposed to operate periodically but the satellite’s power availability has been good enough to keep it running continuously.

Detecting aircraft in vicinity of Europe

And an experimental radio-frequency amplifier built from gallium nitride – a high-power semiconductor widely described as the most promising material of its kind since silicon – is now used routinely to downlink data, boosting the flexibility and redundancy of Proba-V’s communication system.

A pair of radiation detectors is helping to map a mysterious ‘hole’ in Earth’s magnetic field, called the South Atlantic Anomaly, in sharper detail than ever before.

Related links:

Proba-V's first year - in pictures: http://www.esa.int/Our_Activities/Observing_the_Earth/Proba-V/Highlights/Happy_Birthday_Proba-V

Proba Missions: http://www.esa.int/Our_Activities/Technology/Proba_Missions

Images, Text, Credits: ESA / P. Carril / S. Corvaja / Karim Mellab / VITO / DLR / SES TechCom.

Cheers, Orbiter.ch

NASA's Curiosity Rover Drills Sandstone Slab on Mars

NASA - Mars Science Laboratory (MSL) logo.

May 6, 2014

Image above: This May 5, 2014, image from the Navigation Camera on NASA's Curiosity Mars rover shows two holes at top center drilled into a sandstone target called "Windjana." The farther hole was created by the rover's drill while it collected rock-powder sample material from the interior of the rock. Image Credit: NASA/JPL-Caltech.

Portions of rock powder collected by the hammering drill on NASA's Curiosity Mars rover from a slab of Martian sandstone will be delivered to the rover's internal instruments.

Rover team members at NASA's Jet Propulsion Laboratory, Pasadena, Calif., received confirmation early today (Tuesday) of Curiosity's third successful acquisition of a drilled rock sample, following the drilling Monday evening (PDT).  The fresh hole in the rock target "Windjana," visible in images from the rover, is 0.63 inch (1.6 centimeters) in diameter and about 2.6 inches (6.5 centimeters) deep.

The full-depth hole for sample collection is close to a shallower test hole drilled last week in the same rock, which gave researchers a preview of the interior material as tailings around the hole.

"The drill tailings from this rock are darker-toned and less red than we saw at the two previous drill sites," said Jim Bell of Arizona State University, Tempe, deputy principal investigator for Curiosity's Mast Camera (Mastcam). "This suggests that the detailed chemical and mineral analysis that will be coming from Curiosity's other instruments could reveal different materials than we've seen before. We can't wait to find out!"

The mission's two previous rock-drilling sites, at mudstone targets in the Yellowknife Bay area, yielded evidence last year of an ancient lakebed environment with key chemical elements and a chemical energy source that long ago provided conditions favorable for microbial life. The rover's current location is at a waypoint called "The Kimberley," about 2.5 miles (4 kilometers) southwest of Yellowknife Bay, and along the route toward the mission's long-term destination on lower slopes of Mount Sharp.

Mars Science Laboratory (MSL)  rover "Curiosity". Image Credits: NASA/JPL-Caltech

Sample material from Windjana will be sieved, then delivered in coming days to onboard laboratories for determining the mineral and chemical composition:  the Chemistry and Mineralogy instrument (CheMin) and the Sample Analysis at Mars instrument (SAM).  The analysis of the sample may continue as the rover drives on from The Kimberley toward Mount Sharp. One motive for the team's selection of Windjana for drilling is to analyze the cementing material that holds together sand-size grains in this sandstone.

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

For more information about Curiosity, visit http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/. You can follow the mission on Facebook at http://www.facebook.com/marscuriosity and on Twitter at  http://www.twitter.com/marscuriosity.

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

Best regards, Orbiter.ch

Plank takes magnetic fingerprint of our Galaxy

ESA - Plank Mission patch.

6 May 2014

Our Galaxy’s magnetic field is revealed in a new image from ESA’s Planck satellite. This image was compiled from the first all-sky observations of ‘polarised’ light emitted by interstellar dust in the Milky Way.

Light is a very familiar form of energy and yet some of its properties are all but hidden to everyday human experience. One of these – polarisation – carries a wealth of information about what happened along a light ray’s path, and can be exploited by astronomers.

Milky Way's magnetic fingerprint

Light can be described as a series of waves of electric and magnetic fields that vibrate in directions that are at right angles to each other and to their direction of travel.

Usually, these fields can vibrate at all orientations. However, if they happen to vibrate preferentially in certain directions, we say the light is ‘polarised’. This can happen, for example, when light bounces off a reflective surface like a mirror or the sea. Special filters can be used to absorb this polarised light, which is how polarised sunglasses eliminate glare.

In space, the light emitted by stars, gas and dust can also be polarised in various ways. By measuring the amount of polarisation in this light, astronomers can study the physical processes that caused the polarisation.

In particular, polarisation may reveal the existence and properties of magnetic fields in the medium light has travelled through.

The map presented here was obtained using detectors on Planck that acted as the astronomical equivalent of polarised sunglasses. Swirls, loops and arches in this new image trace the structure of the magnetic field in our home galaxy, the Milky Way.

In addition to its hundreds of billions of stars, our Galaxy is filled with a mixture of gas and dust, the raw material from which stars are born. Even though the tiny dust grains are very cold, they do emit light but at very long wavelengths – from the infrared to the microwave domain. If the grains are not symmetrical, more of that light comes out vibrating parallel to the longest axis of the grain, making the light polarised.

If the orientations of a whole cloud of dust grains were random, no net polarisation would be seen. However, cosmic dust grains are almost always spinning rapidly, tens of millions of times per second, due to collisions with photons and rapidly moving atoms.

Then, because interstellar clouds in the Milky Way are threaded by magnetic fields, the spinning dust grains become aligned preferentially with their long axis perpendicular to the direction of the magnetic field. As a result, there is a net polarisation in the emitted light, which can then be measured.

Plank space telescope

In this way, astronomers can use polarised light from dust grains to study the structure of the Galactic magnetic field and, in particular, the orientation of the field lines projected on the plane of the sky.

In the new Planck image, darker regions correspond to stronger polarised emission, and the striations indicate the direction of the magnetic field projected on the plane of the sky. Since the magnetic field of the Milky Way has a 3D structure, the net orientation is difficult to interpret if the field lines are highly disorganised along the line of sight, like looking through a tangled ball of string and trying to perceive some net alignment.

However, the Planck image shows that there is large-scale organisation in some parts of the Galactic magnetic field.

The dark band running horizontally across the centre corresponds to the Galactic Plane. Here, the polarisation reveals a regular pattern on large angular scales, which is due to the magnetic field lines being predominantly parallel to the plane of the Milky Way.

The data also reveal variations of the polarisation direction within nearby clouds of gas and dust. This can be seen in the tangled features above and below the plane, where the local magnetic field is particularly disorganised.

Planck’s Galactic polarisation data are analysed in a series of four papers just submitted to the journal Astronomy & Astrophysics, but studying the magnetic field of the Milky Way is not the only reason why Planck scientists are interested in these data. Hidden behind the foreground emission from our Galaxy is the primordial signal from the Cosmic Microwave Background (CMB), the most ancient light in the Universe.

The brightness of the CMB has already been mapped by Planck in unprecedented detail and scientists are now scrutinising the data to measure the polarisation of this light. This is one of the main goals of the Planck mission, because it could provide evidence for gravitational waves generated in the Universe immediately after its birth.

In March 2014, scientists from the BICEP2 collaboration claimed the first detection of such a signal in data collected using a ground-based telescope observing a patch of the sky at a single microwave frequency. Critically, the claim relies on the assumption that foreground polarised emissions are almost negligible in this region.

Later this year, scientists from the Planck collaboration will release data based on Planck’s observations of polarised light covering the entire sky at seven different frequencies. The multiple frequency data should allow astronomers to separate with great confidence any possible foreground contamination from the tenuous primordial polarised signal.

This will enable a much more detailed investigation of the early history of the cosmos, from the accelerated expansion when the Universe was much less than one second old to the period when the first stars were born, several hundred million years later.

More information

This image is based on data from ESA’s Planck satellite that are published in a series of four papers submitted to the journal Astronomy & Astrophysics, where more details on the data analysis and interpretation can be found:

-Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust: http://arxiv.org/abs/1405.0871
-Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence: http://arxiv.org/abs/1405.0872
-Planck intermediate results. XXI. Comparison of polarized thermal emission from Galactic dust at 353 GHz with optical interstellar polarization: http://arxiv.org/abs/1405.0873
-Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization: http://arxiv.org/abs/1405.0874

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, which includes three frequency bands in the range 30–70 GHz, and the High Frequency Instrument, 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 image presented here is based on polarisation data collected at a frequency of 353 GHz with HFI.

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, Agenzia Spaziale Italiana ASI, Italy (deputy PI: M. Bersanelli, Universita’ 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, France (deputy PI: F. Bouchet, Institut d’Astrophysique de Paris, France), and was responsible for the development and operation of HFI.

For more information about Plank mission, visit: http://www.esa.int/Our_Activities/Space_Science/Planck

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

Greetings, Orbiter.ch

LHC consolidations: 27,000 shunts now in place

CERN - European Organization for Nuclear Research logo.

May 5, 2014

Since April last year, the Superconducting Magnets And Circuits Consolidation (SMACC) team has been strengthening the electrical connections of the superconducting circuits on the Large Hadron Collider (LHC). Last week they installed the last of 27,000 electrical shunts to consolidate "splices" – connections between superconducting magnets – on the accelerator.

Each of the LHC's 10,000 splices carries a hefty 13,000 amps. A shunt is a low-resistance connection that provides an alternative path for a portion of the current in the event that a splice loses its superconducting state.

Image above: An engineer uses a small mirror to inspect a shunt on an interconnection between superconducting magnets on the Large Hadron Collider (Image: Maximilien Brice/CERN).

On 19 September 2008, during powering tests on the LHC, a fault occurred in one of the splices, resulting in mechanical damage and release of helium from the magnet cold mass into the tunnel. Proper safety procedures were in force, the safety systems performed as expected, and no-one was put at risk. But the fault did delay operation of the accelerator by six months. The new shunts make such a fault unlikely to happen again.

To install a shunt the SMACC team first has to open the area around the interconnection they want to work on. They slide the custom-built metallic bellows out of the way and remove the thermal shielding inside, revealing a series of metallic pipes linking the magnets to each other. One set of these pipes – the "M-lines" – must then be cut open to access the splices between the superconducting cables. The team opened up the last of the M lines in February and has been at work ever since adding the shunts.

Check out some more of the main LHC consolidations: http://cds.cern.ch/record/1516031?ln=en

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 20 Member States.

Related link:

Large Hadron Collider (LHC): http://home.web.cern.ch/topics/large-hadron-collider

For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Image (mentioned), Text, Credits: CERN / Cian O'Luanaigh.

Greetings, Orbiter.ch

Saturn’s rainbow rings

NASA / ESA - Cassini Mission to Saturn patch.

May 5, 2014

This colorful cosmic rainbow portrays a section of Saturn’s beautiful rings, four centuries after they were discovered by Galileo Galilei.

Saturn’s rings were first observed in 1610. Despite using his newly created telescope, Galileo was confounded by what he saw: he referred to the peculiar shapes surrounding the planet as “Saturn’s children”. Only later did Christiaan Huygens propose that the mysterious shapes were actually rings orbiting the planet. These were named in the order in which they were discovered, using the first seven letters of the alphabet: the D-ring is closest to the planet, followed by C, B, A, F, G and E.

The data for this image, which shows the portion of the C-ring closest to Saturn on the left, with the B-ring beginning just right of centre, were acquired by Cassini’s Ultraviolet Imaging Spectrograph, or UVIS, as the spacecraft entered into orbit around Saturn on 30 June 2004.

UVIS, as its name suggests, carries out observations in ultraviolet wavelengths. During the Saturn orbit insertion manoeuvre, when Cassini flew closest to the rings, UVIS could resolve features up to 97 km across. The region shown in this image spans about 10 000 km.

The variation in the colour of the rings arises from the differences in their composition. Turquoise-hued rings contain particles of nearly pure water ice, whereas reddish rings contain ice particles with more contaminants.

Saturn’s prominent and complex ensemble of rings is the best studied in the Solar System, but it is still not known how the rings formed. One suggestion is that they formed at the same time as the planet and that they are as old as the Solar System. Another idea is that they formed when icy material was pulled from another body into Saturn’s gravitational field, in which case the rings could be younger than the planet.

One thing is sure: as Cassini searches for answers it is providing amazing images of these rainbow rings.

The Cassini–Huygens mission is a cooperative project of NASA, ESA and Italy’s ASI space agency.

This image was first published at the NASA Cassini website, in 2004.

For more information about Cassini mission, Visit: http://www.nasa.gov/mission_pages/cassini/main/ and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/JPL/University of Colorado / ESA.

Cheers, Orbiter.ch