vendredi 9 mai 2014

Hubble Eyes a Scale of the Universe











NASA - Hubble Space Telescope patch.

May 9, 2014

Hubble Eyes a Scale of the Universe

This bundle of bright stars and dark dust is a dwarf spiral galaxy known as NGC 4605, located around 16 million light-years away in the constellation of Ursa Major (The Great Bear). This galaxy’s spiral structure is not obvious from this image, but NGC 4605 is classified as an SBc type galaxy — meaning that it has sprawling, loosely wound arms and a bright bar of stars cutting through its center.

NGC 4605 is a member of the Messier 81 group of galaxies, a gathering of bright galaxies including its namesake Messier 81 (heic0710), and the well-known Messier 82 (heic0604a). Galaxy groups like this usually contain around 50 galaxies, all loosely bound together by gravity. This group is famous for its unusual members, many of which formed from collisions between galaxies. With its somewhat unusual form, NGC 4605 fits in well with the family of perturbed galaxies in the M81 group, although the origin of its abnormal features is not yet clear.

The Messier 81 group is one of the nearest groups to our own, the Local Group, which houses the Milky Way and some of its well-known neighbors, including the Andromeda Galaxy and the Magellanic Clouds. Galaxy groups provide environments where galaxies can evolve through interactions like collisions and mergers. These galaxy groups are then lumped together into even larger gatherings of galaxies known as clusters and superclusters. The Local and Messier 81 groups both belong to the Virgo Supercluster, a large and massive collection of some 100 galaxy groups and clusters.

video
Hubble orbiting Earth

With so many galaxies swarming around, NGC 4605 may seem unremarkable. However, astronomers are using this galaxy to test our knowledge of stellar evolution. The newly-formed stars in NGC 4605 are being used to investigate how interactions between galaxies affect the formation, evolution, and behavior of the stars within, how bright stellar nurseries come together to form stellar clusters and stellar associations, and how these stars evolve over time.

And that's not all — NGC 4605 is also proving to be a good testing ground for dark matter. Theories on this hypothetical type of matter.have had good success at describing how the Universe looks and behaves on a large scale — for example at the galaxy supercluster level — but when looking at individual galaxies, they have run into problems. Observations of NGC 4605 show that the way in which dark matter is spread throughout its halo is not quite as these models predict. While intriguing, observations in this area are still inconclusive, leaving astronomers to ponder over the contents of the Universe.

For images and more information about Hubble, visit: http://www.nasa.gov/hubble and http://www.spacetelescope.org/

Image, Video, Text, Credits: ESA/Hubble & NASA, Acknowledgement: D. Calzetti (University of Massachusetts) and the LEGUS Team.

Best regards, Orbiter.ch

TRMM Satellite See Spring Storms Hit the U.S. Great Plains












NASA / NASDA - TRMM Mission patch.

May 9, 2014


Image above: The TRMM satellite flew above tornado spawning thunderstorms in the southern United States on May 9, 2014 at 0115 UTC. Image Credit: SSAI/NASA, Hal Pierce.

The Tropical Rainfall Measuring Mission or TRMM satellite captured rainfall and cloud height information about the powerful thunderstorms and severe weather that affected the Great Plains over May 8 and 9.

Severe weather extended from Minnesota to southern Texas on Thursday afternoon, May 8 and Friday morning, May 9. During that time there were three tornadoes reported in Minnesota, two in Colorado and two in Missouri.

The TRMM satellite flew above tornado spawning thunderstorms in the southern United States on May 9, 2014 at 0115 UTC (May 8, 2014 at 8:15 PM CTD). A rainfall analysis from TRMM's Precipitation Radar (PR) and Microwave Imager (TMI) was created at NASA's Goddard Space Flight Center in Greenbelt, Md.

video
TRMM Satellite Sees Thunderstorms in the South

Video above: The TRMM satellite flew above tornado spawning thunderstorms in the southern United States on May 9, 2014 at 0115 UTC. This simulated 3-D TRMM animation shows the location of intense radar echoes within the stormy area. Image Credit: SSAI/NASA, Hal Pierce.

The TRMM data was overlaid on an infrared image from NOAA's GOES-East satellite that showed the extent of the clouds at the same time. TRMM's PR instrument found rain falling at a rate of over almost 163 mm (about 6.4 inches) per hour in an intense line of storms extending from Arkansas into Texas.

TRMM Satellite. Image Credit: NASA.

TRMM noticed that some of the highest thunderstorms topped out at around 11 km (6.8 miles) high. Some of these powerful storms were returning reflectivity values of over 55dBZ to the satellite.

For updated conditions, please visit NOAA's National Weather Service Severe Storm Prediction Center website: http://www.spc.ncep.noaa.gov/

Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Hal Pierce.

Greetings, Orbiter.ch

jeudi 8 mai 2014

More Plant Science as Expedition 39 Trio Trains for Departure












ISS - Expedition 39 Mission patch.

May 8, 2014

More botany experiments were being worked Thursday as scientists learn how to sustain future crews on long-term space missions. Meanwhile, three Expedition 39 crew members are preparing to complete their mission aboard the International Space Station.

Veggie operations officially kicked off Thursday as astronaut Steve Swanson installed and set up the plant experiment to deliver water to lettuce seeds. Veggie is a test bed to determine if lettuce grown in space is safe for consumption by future crews. The lettuce will be harvested aboard the station, stored in a science freezer and returned to Earth for analysis.


Image above: Expedition 39 crew members pose around a globe inside the Kibo laboratory as the International Space Station orbits around the Earth.

Read more about the Veggie investigation: http://www.nasa.gov/mission_pages/station/research/experiments/383.html

Flight Engineer Rick Mastracchio worked in the evening completing a run of the Gravi-2 experiment as he disassembled and stowed the science hardware. The botany investigation observes how lentil roots grow in space using a centrifuge which helps scientists determine the reliability of plants as a source of oxygen, food and water for future missions.

Read more about the Gravi-2 experiment: http://www.nasa.gov/mission_pages/station/research/experiments/2.html

Commander Koichi Wakata started his morning with some plumbing work partially filling a flush tank in the Waste and Hygiene Compartment. Afterward, Wakata familiarized himself with gear and prepared a sample for the CsPINs plant growth study taking place in the Kibo laboratory. That study examines how plants, specifically cucumber seedlings, sense gravity which may have impacts on future plant cultivation in space.

Read more about CsPINs: http://www.nasa.gov/mission_pages/station/research/experiments/831.html

Mastracchio and veteran cosmonaut Mikhail Tyurin started their day testing the motion control system of their Soyuz spacecraft. In the afternoon, Wakata joined the duo for a few hours of Soyuz descent and entry training exercises. The trio will return to Earth May 13 inside the Soyuz TMA-11M spacecraft after undocking from the Rassvet module which marks the end of Expedition 39.


Image above: Cosmonaut Mikhail Tyurin trims the hair of Commander Koichi Wakata inside the Unity node.

Read more about the departure of Expedition 39: http://www.nasa.gov/press/2014/may/nasa-television-to-air-expedition-39-crews-return-from-space-station

At that time, Expedition 40 will officially be under way with Swanson assuming command of the orbital laboratory and cosmonauts Alexander Skvortsov and Oleg Artemyev continuing their stay. Waiting on Earth to join Expedition 40 are Soyuz Commander Maxim Suraev and Flight Engineers Reid Wiseman and Alexander Gerst. They are scheduled for launch May 28 from Baikonur Cosmodrome, Kazakhstan, for a six-hour ride to the space station aboard the Soyuz TMA-13M spacecraft.

Swanson joined Skvortsov and Artemyev at the end of their day to review their roles and responsibilities in the unlikely event of an emergency. They checked escape routes and safety gear, ensured Soyuz readiness and reviewed communication procedures in response to a rapid depressurization event, fire or chemical leak.

Back on the ground, flight controllers reported a power channel failure in the space station’s 3A power channel connected to a solar array located on the S4 truss. Power was transferred seamlessly to the 3B channel with impacts being assessed including those to the backup heater power of the station’s external robotics system. Inside the station, the crew is working normally, payload operations are continuing as planned and there is no direct impact on next week’s Soyuz undocking.

For more information about the International Space Station (ISS), visit: http://www.nasa.gov/mission_pages/station/main/index.html

Images, Text, Credit: NASA.

Cheers, Orbiter.ch

Cluster helps to model Earth's mysterious magnetosphere












ESA - Cluster II Mission patch.

08 May 2014

For many years, scientists have been striving to understand the constantly changing structure and behaviour of the huge magnetic bubble that surrounds our planet. One approach – pioneered by Russian scientist Nikolai Tsyganenko - has been to develop models based on data sent back by spacecraft, such as ESA's Cluster quartet.

ESA's Cluster quartet. Image credit: ESA

As Earth sweeps around the Sun, it is constantly bombarded by energetic particles from solar storms and deep space. Fortunately, the planet generates a powerful magnetic field which largely shields the atmosphere and surface against this perpetual, but variable, assault.

At the same time, the magnetosphere serves as a huge reservoir, storing energy which is pumped in from the solar wind and then released into near-Earth space and the upper atmosphere during magnetic storms.

As humankind becomes more and more dependent on space technologies, it becomes increasingly important to be able to map the terrestrial magnetosphere accurately and predict its dynamics, using all available data from spacecraft and ground-based observatories. In this sense, models of the magnetosphere play the same role as maps drawn up by early explorers when they encountered new, uncharted lands.

Model magnetosphere field plots. Credit: Images courtesy of N. Tsyganenko

Over recent decades, two approaches have been developed in an effort to improve our understanding of how the magnetised gas of the solar wind interacts with the geomagnetic field. One is a purely theoretical approach, which relies on the power of supercomputers and sophisticated numerical methods, modified by simplifying assumptions made along the way.

The other approach – developed by Nikolai Tsyganenko and others - is based on direct observations by spacecraft. In essence, this approach involves a description of the global magnetic field and its responses to interactions with the solar wind by developing a model that provides the best agreement with spacecraft data.

A principal problem is that the magnetosphere is a highly variable system, and the most important task of the modelling is to reproduce its dynamics during stormy space weather events. In particular, there is often an extreme disparity between the enormous multitude of possible geomagnetic disturbances and the fact that the huge magnetosphere is being monitored by only a few spacecraft.

Model of changing magnetosphere. Credit: Animation courtesy of N. Tsyganenko

On the other hand, five decades of space missions have produced enormous amounts of archived data, and a whole suite of so-called empirical models have already been developed on that basis. Recent and ongoing multi-spacecraft missions, such as Cluster, keep adding a flood of valuable new data. In most cases, their observations are supported by simultaneous data from solar wind probes and ground-based geomagnetic observatories.

Taking advantage of the latest space missions, Tsyganenko has published the first results of data-based modelling of Earth's magnetic field based on information sent back by the Cluster, Polar, Geotail and THEMIS spacecraft during the period 1995–2012. His recent paper in the Journal of Geophysical Research: Space Physics analyses solar wind – magnetosphere interactions covering 123 geomagnetic storms.

"Most of the spacecraft that contributed to the existing archived database covered the near-equatorial part of the magnetosphere, where most of the electric currents flow," said Nikolai Tsyganenko. "However, to construct a global model one also needs observations made in high-latitude geospace, including the dayside polar cusps, where solar wind plasma penetrates the magnetosphere.

"The Cluster mission is an especially valuable source of data, owing to its multi-year long operation period, high orbital inclination, and its ability to resolve the fine structure of electric currents, owing to the specially designed constellation of four spacecraft, flying in close proximity of each other."

"Thanks to the Cluster Science Data System and the Cluster Active Archive, which provide easy access to the best calibrated Cluster data, such essential models can be produced to support magnetospheric physicists worldwide," said Philippe Escoubet, ESA's Cluster Project Scientist.

Background information

The model described in this article is reported in "Data-based modeling of the geomagnetosphere with an IMF-dependent magnetopause" by Nikolai Tsyganenko, published online in the Journal of Geophysical Research: Space Physics on 23 January 2014 (doi: 10.1002/2013JA019346).

Cluster is a constellation of four spacecraft flying in formation around Earth. It is the first space mission able to study, in three dimensions, the natural physical processes occurring within and in the near vicinity of the Earth's magnetosphere. Launched in 2000, it is composed of four identical spacecraft orbiting the Earth in a pyramidal configuration, along a nominal polar orbit of 4 × 19.6 Earth radii (1 Earth radius = 6380 km). Cluster's payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields over wide frequency ranges, and key physical parameters characterising electrons and ions from energies of near 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC) at the Rutherford Appleton Laboratory, United Kingdom, and implemented by ESA's European Space Operations Centre (ESOC), in Darmstadt, Germany.

The Cluster Science Data System is a set of nationally distributed data centres, which generate and maintain selected data sets for the experiments most closely associated with each centre.

The Cluster Active Archive is the depository of processed and validated Cluster data, raw data, processing software, calibration data, documentation and other value-added products. All of the Cluster data are public domain.

Related Publications:

Tsyganenko, N. A. [2014]: http://sci.esa.int/cluster/54023-tsyganenko-n-a-2014/

Related Links:

Cluster Science Data System: http://sci.esa.int/cluster/52770-csds/

Cluster Active Archive: http://caa.estec.esa.int/caa/home.xml

Images, Text, Credits: ESA / Images courtesy of  N. Tsyganenko / Animation courtesy of  N. Tsyganenko.

Greetings, Orbiter.ch

Experts demonstrate versatility of Sentinel-1








ESA - Sentinel-1 Mission logo.

8 May 2014

Sentinel-1 satellite

From climate change monitoring to supporting humanitarian aid and crisis situations, early data applications from the month-old Sentinel-1A satellite show how the radar mission’s critical observations can be used to keep us and our planet safe.

Launched from Europe’s Spaceport in French Guiana on 3 April, Sentinel-1A is the first satellite in Europe’s Copernicus environmental monitoring network. The mission uses radar to provide an all-weather, day-and-night supply of imagery of Earth’s surface.

Ice chart

At an event in Brussels today, experts who had been given access to early Sentinel-1A radar data presented how a variety of operational and scientific applications will benefit.

“These [radar] images and their analyses will benefit European citizens, enterprises and decision makers, as well as the international scientific community. They will allow us to better protect our planet and improve the quality of life of our citizens,” said Philippe Brunet, Director of Aerospace, Maritime, Security and Defence Industries at the European Commission.

Oil platforms

Leif Toudal Pedersen from the Danish Meteorological Institute and involved in the Copernicus marine core service MyOcean presented the first ‘ice chart’ from Sentinel-1A, showing how the radar will be used to map sea-ice conditions for the safe passage of vessels.

Another marine application is detecting oil spills, as outlined by Machteld Price from the European Maritime Safety Agency. Imagery from Sentinel-1 will be essential tools for supporting EU policies in maritime safety.

The spread of an oil spill can be forecast using information on waves, currents and winds – and such information can also be derived from the data. Bertrand Chapron from Ifremer in France can already see the benefits of the radar’s high performance even before the satellite is fully calibrated.

Wave imagette

The mission also has many applications over land. Christiane Schmullius from the University of Jena used early images to demonstrate the mission’s potential to map land cover over parts of Germany, differentiating between forests, agricultural areas and urban areas.

The ‘radar interferometry’ remote sensing technique was outlined by Alessandro Ferretti from the Tele-Rilevamento Europa in Italy. It combines two or more radar scans over the same area to detect ground movement down to a few millimetres between them.

As well as being a valuable resource for urban planners, this kind of information is essential for monitoring shifts from earthquakes, landslides and volcanic uplift.

Land cover mapping

Dr Ferretti also discussed how Sentinel-1 will foster development in European space and service industries, maximising opportunities for small and medium enterprises to grow.

The Sentinel-1 mission is also already supporting humanitarian aid and crisis situations. Just 10 days after its launch, the satellite captured an image of flooding in the Caprivi plain from the Zambezi River in Namibia. The image was downloaded within two hours and the resulting products were available in less than an hour.

Jan Kucera from the Joint Research Centre outlined how this timely information offers a clear picture of the extent of inundation, and can be used to for assessing the damage to property and the environment.

Ice in motion

Sentinel-1 continues more than 20 years of radar imagery from satellites. This archive is not only essential for practical applications that need long time series of data, but also for understanding the long-term effects of climate change, such as those on Arctic sea-ice cover, continental ice sheets and glaciers.

Andrew Shepherd from the UK’s University of Leeds has already used some of the mission’s early data to demonstrate the rapid movement of the Austfonna ice cap in Norway’s Svalbard archipelago.

Sentinel Island

Combining new Sentinel-1 coverage with data from the German TerraSAR-X mission, he discovered an acceleration in ice motion in the southeastern section, which is now flowing at least 10 times faster than previously measured.

More early results from the new satellite were also presented at the Brussels event. Although the satellite is not yet in its operational orbit, nor is it calibrated for supplying true data, the images offer a taste of what’s to come in the near future.

“It’s truly amazing to get so much positive feedback from the user community at such an early stage in the mission,” said Volker Liebig, Director of ESA’s Earth Observation Programmes.

“We now look forward to the satellite’s ‘operational phase’ to realise its full potential.”

From 9 May, initial samples of Sentinel-1 prequalified products will be accessible through a new portal: https://senthub.esa.int/

Related links:

European Commission Copernicus site: http://www.copernicus.eu/

MyOcean: http://www.myocean.eu/

Danish Meteorological Institute: http://www.dmi.dk/dmi/index

European Maritime Safety Agency: http://www.emsa.europa.eu/

JRC: http://ec.europa.eu/dgs/jrc/index.cfm

University of Jena: http://www.uni-jena.de/en/start.html

IFREMER: http://www.ifremer.fr/anglais/

University of Leeds: http://www.leeds.ac.uk/

Tele-Rilevamento Europa (TRE): http://treuropa.com/

Images, Text, Credits: ESA / DMI / Ifremer / OceanDataLab / Norut / CLS / University of Jena / Gamma/University of Leeds/University of Edinburgh.

Greetings, Orbiter.ch

mercredi 7 mai 2014

NASA Telescopes Coordinate Best-Ever Flare Observations















NASA - Solar Dynamics Observatory (SDO) patch / NASA - HESSI Mission patch.

May 7, 2014

On March 29, 2014, an X-class flare erupted from the right side of the sun... and vaulted into history as the best-observed flare of all time. The flare was witnessed by four different NASA spacecraft and one ground-based observatory – three of which had been fortuitously focused in on the correct spot as programmed into their viewing schedule a full day in advance.

To have a record of such an intense flare from so many observatories is unprecedented.  Such research can help scientists better understand what catalyst sets off these large explosions on the sun. Perhaps we may even some day be able to predict their onset and forewarn of the radio blackouts solar flares can cause near Earth – blackouts that can interfere with airplane, ship and military communications.

March 29 X-class Flare - 1

Image above: This combined image shows the March 29, 2014, X-class flare as seen through the eyes of different observatories. SDO is on the bottom/left, which helps show the position of the flare on the sun. The darker orange square is IRIS data. The red rectangular inset is from Sacramento Peak. The violet spots show the flare's footpoints from RHESSI.

"This is the most comprehensive data set ever collected by NASA's Heliophysics Systems Observatory," said Jonathan Cirtain, project scientist for Hinode at NASA's Marshall Space Flight Center in Huntsville, Ala. "Some of the spacecraft observe the whole sun all the time, but three of the observatories had coordinated in advance to focus on a specific active region of the sun. We need at least a day to program in observation time and the target – so it was extremely fortunate that we caught this X-class flare."

Images and data from the various observations can be seen in the accompanying slide show. The telescopes involved were: NASA's Interface Region Imaging Spectrograph, or IRIS; NASA's Solar Dynamics Observatory, or SDO; NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager, or RHESSI; the Japanese Aerospace Exploration Agency's Hinode; and the National Solar Observatory's Dunn Solar Telescope located at Sacramento Peak in New Mexico. Numerous other spacecraft provided additional data about what was happening on the sun during the event and what the effects were at Earth. NASA's Solar Terrestrial Relations Observatory and the joint European Space Agency and NASA's Solar and Heliospheric Observatory both watched the great cloud of solar material that erupted off the sun with the flare, an event called a coronal mass ejection.  The U.S. National Oceanic and Atmospheric Administrations GOES satellite tracked X-rays from the flare, and other spacecraft measured the effects of the flare as it came toward Earth.

This event was particularly exciting for the IRIS team, as this was the first X-class flare ever observed by IRIS. IRIS launched in June 2013 to zoom in on layers of the sun, called the chromosphere and transition region, through which all the energy and heat of a flare must travel as it forms. This region, overall is called the interface region, has typically been very hard to untangle – but on March 29, IRIS provided scientists with the first detailed view of what happens in this region during a flare.

video
 The Best Observed X-class Flare. Video Credit: NASA/NSO/Goddard Space Flight Center

Coordinated observations are crucial to understanding such eruptions on the sun and their effects on space weather near Earth. Where terrestrial weather watching involves thousands of sensors and innumerable thermometers, solar observations still rely on a mere handful of telescopes. The instruments on the observatories are planned so that each shows a different aspect of the flare at a different heights off the sun's surface and at different temperatures. Together the observatories can paint a three-dimensional picture of what happens during any given event on the sun.

In this case, the Dunn Solar Telescope helped coordinate the space-based observatories. Lucia Kleint is the principal investigator of a NASA-funded grant at the Bay Area Environmental Research Institute grant to coordinate ground-based and space-based flare observations. While she and her team were hunting for flares during ten observing days scheduled at Sacramento Peak, they worked with the Hinode and IRIS teams a day in advance to coordinate viewing of the same active region at the same time. Active regions are often the source of solar eruptions, and this one was showing intense magnetic fields that moved in opposite directions in close proximity – a possible harbinger of a flare. However, researchers do not yet know exactly what conditions will lead to a flare so this was a best guess, not a guarantee.

But the guess paid off. In the space of just a few minutes, the most comprehensive flare data set of all time had been collected. Now scientists are hard at work teasing out a more detailed picture of how a flare starts and peaks – an effort that will help unravel the origins of these little-understood explosions on the sun.

Scroll through the slideshow to take a look at the various images captured and to see how they fit together.

Related Links:

Google+ Hangout on these results will be held at 2:30 pm EDT on May 8, 2014: https://plus.google.com/+NASAGoddard/posts/1Awitfdiq7u

Original NASA News Post: http://www.nasa.gov/content/goddard/nasa-releases-images-of-x-class-solar-flare/

Download high-res media: http://svs.gsfc.nasa.gov/vis/a010000/a011500/a011522/

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Karen C. Fox.

Greetings, Orbiter.ch

Pioneering Test Pilot Bill Dana Dies at Age 83












NASA - Flight Research Center - Test Pilot patch.


May 7, 2014


Image above: "William H. Dana, Flight Research Pilot” Acrylic by Robert L. Schaar . Depicted in the painting are the X-15 rocket plane, the M2-F3 lifting body and the F-104 Starfighter aircraft. All three of these historic aircraft flown by Bill Dana are now hanging in the National Air & Space Museum. Image Credit: Smithsonian.

Bill Dana was an aeronautical engineer, a test pilot. He was an astronaut.

His career at the NASA High-Speed Flight Station (now Armstrong Flight Research Center) began on October 1, 1958; coincidentally the same day NASA came into being. He piloted some of the agency's most remarkable craft and was with us from the agency's infancy through the maturity of the Space Shuttle and the creation of the International Space Station.Bill retired on May 29, 1998, a few month's shy of 40 years of distinguished service to NASA. He passed away Tuesday, May 6, 2014, at the age of 83.


Image above: NASA research pilot Bill Dana takes a moment to watch NASA's NB-52B cruise overhead after a research flight in the HL-10 in this image from November 30, 1968. Image Credit: NASA.

His long and illustrious career at NASA’s Armstrong Flight Research Center did not end when he retired. He returned to Armstrong seven months later as a contractor with Analytical Services and Materials, Inc., to write histories of various programs and to evaluate lessons learned. During a period of budget reductions, this man of integrity and accomplishment gave up his salary and continued to work as a volunteer with the History Office. Over the course of his career, Dana logged more than 8,000 hours in over 60 different aircraft from helicopters and sailplanes to the hypersonic X-15. Several of the airplanes he flew are displayed at the National Air and Space Museum in Washington, D.C.

A graduate of the United States Military Academy at West Point, Dana spent 4 years in the Air Force before he was hired as an aeronautical research engineer. His first assignments included development of a rudimentary performance simulator for the X-15 rocket plane and stability and control research involving the F-107A fighter prototype. In September 1959, he transferred to the Flight Operations Branch as a research pilot. Over the next three decades he flew a variety of aircraft, including the rocket powered X-15 and wingless lifting bodies. Dana flew to the edge of space in the X-15, attaining a maximum speed of Mach 5.53 (3,897 mph) and a maximum altitude of 306,900 feet (nearly 59 miles). He was then assigned to fly the HL-10, M2-F3, and X-24B lifting bodies to validate engineers’ assertions that such vehicles could be precisely controlled during approach and landing, and providing NASA with the confidence needed to proceed with designs for the Space Shuttle orbiter.


Image above: The X-24B is seen here on the lakebed at the NASA Armstr Flight Research Center, Edwards, California. The X-24B was the last aircraft to fly in the Center's Lifting Body program. The final powered flight with the X-24B was on September 23, l975, piloted by Bill Dana. Image Credit: NASA.

In addition, he flew hundreds of research flights in advanced jet fighters, including the F-14, F-15, F-16, and YF-17. He evaluated the X-29 forward-swept-wing technology demonstrator and flew the pioneering F-18 High Alpha Research Vehicle, the first aircraft to use multi-axis thrust vectoring for vehicle control. Because of his demonstrated leadership and extraordinary service in flight research, Dana was appointed chief pilot in 1986 with responsibility for recruiting, developing, and training Armstrong’s cadre of research pilots.

In 1993, he retired from flying to become Armstrong’s chief engineer. In this position, he oversaw all of the center’s research projects and was responsible for flight safety. Dana held this position until his retirement from civil service in May 1998.He returned to Armstrong seven months later as a contractor with Analytical Services and Materials, Inc. During a period of budget reductions, he gave up his salary and continued to work as a volunteer with the History Office.

His numerous awards and honors include the AIAA Haley Space Flight Award (1976), NASA Exceptional Service Medal (1976), Lancaster Aerospace Walk of Honor (1993), NASA Distinguished Service Medal (1997), and the Milton O. Thompson Lifetime Achievement Award (2000). He was honored in the “Salute to Test Pilots” at the Experimental Aircraft Association’s Annual Convention in 1996. Dana was awarded astronaut wings on Aug. 23, 2005, for two of his X-15 flights that exceeded 50 miles altitude. That honor came nearly 40 years after the flights themselves because at the time of the X-15 program, NASA did not confer astronaut wings on its pilots. Dana was a distinguished member of the Society of Experimental Test Pilots. He joined the SETP in 1961 and was elected a fellow in 1998.

Images (mentioned), Text, Credit: NASA.

Condolences, Orbiter.ch

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.

video
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

mardi 6 mai 2014

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

lundi 5 mai 2014

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