vendredi 22 avril 2016

SolarImpulse resumes round-the-world journey with leg from Hawaii to Silicon Valley











SolarImpulse - Around The World patch.

April 22, 2016

The solar-powered plane on a record-setting around-the-world journey was about a third of the way along a treacherous flight from Hawaii to California early Friday, according to the project's mission control.

Bertrand Piccard, piloting the Solar Impulse 2 aircraft, watched the sun rise over the north Pacific after taking off on battery power during darkness, according to a livestream from a website documenting the journey: http://www.solarimpulse.com/leg-9-from-Hawaii-to-Mountain_View_CA


Image above: The solar-powered plane Solar Impulse 2 soars over the Pacific Ocean after taking off from Kalaeloa Airport in Hawaii for a non-stop, three-day flight to Silicon Valley. The team behind the aircraft are attempting a record-setting round-the-world trip. Image Credit: SolarImpulse.

"Absolutely fantastic moment.... That's a sunrise I will remember all my life," he said.

The trans-Pacific leg is the riskiest part of the plane's global travels due to the lack of emergency landing sites.

After some uncertainty about winds, the plane took off from Kalaeloa Airport in Hawaii on Thursday morning and was on course to land in Mountain View, Calif., over the weekend. The crew that helped it take off was clearing out of its Hawaiian hangar and headed for the mainland for the weekend arrival.

At one point passengers on a Hawaiian Air jet caught a glimpse of the Solar Impulse 2 before the airliner sped past the slow-moving sun-powered aircraft.

The Solar Impulse 2 landed in Hawaii in July and was forced to stay in the islands after the plane's battery system sustained heat damage on its trip from Japan.


Image above: First sunset of the flight for Bertrand Piccard, flying over the ocean. The night will be long and dark but we have energy! Image Credit: SolarImpulse.

The aircraft started its around-the-world journey in March 2015 from Abu Dhabi, the capital of the United Arab Emirates, and made stops in Oman, Myanmar, China and Japan. It's on the ninth leg of its circumnavigation.

Piccard said the next destination, in the heart of Silicon Valley, is fitting, as the plane will land "in the middle of the pioneering spirit." Various West Coast destinations had been in the running as possible stopovers, including Vancouver and Los Angeles.

The next flights are expected to take the aircraft to somewhere in the U.S. Midwest followed by JFK airport in New York, before beginning the transatlantic crossing to either Europe or North Africa.

Bertrand Piccard, flying over the ocean. Image Credit: SolarImpulse.

Piccard and co-pilot Andre Borschberg take turns flying legs of the journey on the single-seat plane. Borschberg flew the stretch from Japan to Hawaii. They can take short naps while strapped in at the controls, and there is a modest toilet under the seat. 

The plane's ideal flight speed is about 45 km/h, though that can double during the day when the sun's rays are strongest. The carbon-fibre aircraft weighs more than 2,200 kilograms, or about as much as a midsize truck.

The wings of Solar Impulse 2, which stretch wider than those of a Boeing 747, are equipped with 17,000 solar cells that power propellers and charge batteries. The plane runs on stored energy at night.

For more information about SolarImpulse Around The World, visit: http://blog.solarimpulse.com/

Images (mentioned), Text, Credits: SolarImpulse/ATS/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

Kepler Recovered and Returned to the K2 Mission












NASA - Kepler Space Telescope patch.

April 22, 2016

The Kepler spacecraft has been recovered and, as of 8:30 a.m. PDT today, it is back on the job as the K2 mission searching for exoplanets—planets beyond our solar system.

The team began the process of returning the spacecraft to science late on Tuesday. The process involved a succession of steps over the course of the next two days. The pointing tables and science targets—instructions that tell the spacecraft where to look and at what—were reloaded and confirmed, onboard logs and counters were reset and a new command sequence was created, tested and uploaded to account for the late start of the campaign.  The spacecraft is now ready for science operations, officially starting K2's new gravitational microlensing campaign, known as Campaign 9 or C9.

During NASA's Deep Space Network (DSN) contact with the spacecraft yesterday, flight operations engineers at Ball Aerospace and the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado, both located in Boulder, turned the spacecraft to point the telescope towards the center of the Milky Way galaxy to start collecting data for C9.

The K2 microlensing team and the ground-based observatories collaborating on C9's global experiment in exoplanet observation are searching through the collected data from the ground telescopes for possible events suitable for observations on larger telescopes, such as the 10-meter telescopes at the W. M. Keck Observatory atop Mauna Kea in Hawaii. During the three-day campaign break, beginning on May 24, data accumulated to that point will be downlinked from the spacecraft to Earth. Shortly thereafter, the scientists will have their first chance to see K2’s view of the same events seen on the ground.

Kepler spacecraft


The C9 observing period will conclude on July 1, when the galactic center is no longer in view from the vantage point of the spacecraft. K2 will then begin Campaign 10, which will proceed to investigate an entirely new set of interesting astrophysical targets.

Using the DSN, the team will check in on the spacecraft throughout the weekend to ensure it remains stable and continues its task. The following is the schedule of upcoming contacts:

Contact Date (PDT)             Start (PDT/UTC)      End (PDT/UTC)      Antenna

Friday, Apr. 22                      8:30 a.m./15:30        1:55 p.m./20:55       DSS-63

                                              4:45 p.m./23:45       10:05 p.m./05:05      DSS-26

Saturday, Apr. 23                   9:25 a.m./16:25        2:40 p.m./21:40       DSS-55

                                               5:10 p.m./00:10        9:40 p.m./04:40       DSS-26

                                                9:45 p.m./04:45       12:45 a.m./07:45      DSS-35

Sunday, Apr. 24                     9:35 a.m./16:35        2:45 p.m./21:45        DSS-63

Monday, Apr. 25                    8:45 a.m./15:45        2:45 p.m./21:45        DSS-55

To track the contacts with Kepler, tune-in to the DSN Now website. Contacts with the smaller antennas will merely verify that the spacecraft has not gone to Safe or Emergency Mode, while contacts with the larger antennas—indicated as 63, 14 and 43 on the DSN Now—will provide a higher transfer rate to receive health data from the spacecraft.

The cause of the anomaly, first reported on April 8, remains under investigation. The nature of the problem has indications of a transient event, which triggered a barrage of false alarms that eventually overwhelmed the system, placing Kepler in Emergency Mode. Power-cycling the onboard computers and subsystems appears to have cleared the problem. We’ve returned to science data collection while the investigation proceeds.

The Kepler and K2 missions have been a rewarding job for everyone involved, but there’s a special satisfaction to responding well to an emergency like this. The recovery and spacecraft teams at Ball, LASP and NASA's Ames Research Center, had to rely on their own talents and abilities to recover the spacecraft rather than external experts in the short time they had. It is extremely satisfying to see that the challenge was successfully met, and that the team performed in the best traditions of NASA.

Related articles:

Kepler Spacecraft in Emergency Mode:
http://orbiterchspacenews.blogspot.ch/2016/04/kepler-spacecraft-in-emergency-mode.html

For more information about K2 Mission, related article:
http://orbiterchspacenews.blogspot.ch/2016/04/searching-for-far-out-and-wandering.html

K2 mission: http://orbiterchspacenews.blogspot.ch/2016/03/nasas-k2-mission-kepler-space.html

Related links:

DSN Now website: http://eyes.nasa.gov/dsn/dsn.html

NASA's Deep Space Network (DSN): http://deepspace.jpl.nasa.gov/

Image, Text, Credits: NASA's Ames Research Center/Kepler and K2 mission manager/Charlie Sobeck​.

Greetings, Orbiter.ch

New Herschel maps and catalogues reveal stellar nurseries across the Galactic Plane












ESA - Herschel Mission patch.

22 April 2016

ESA's Herschel mission releases today a series of unprecedented maps of star-forming hubs in the plane of our Milky Way galaxy. This is accompanied by a set of catalogues of hundreds of thousands of compact sources that span all phases leading to the birth of stars in our Galaxy. These maps and catalogues will be very valuable resources for astronomers, to exploit scientifically and for planning follow-up studies of particularly interesting regions in the Galactic Plane.

Herschel's view of the Galactic Plane

Video above: Herschel's view of the Galactic Plane. Video Credits: ESA/Herschel/PACS, SPIRE/Hi-GAL Project.

During its four years of operations (2009-2013), the Herschel space observatory scanned the sky at far-infrared and sub-millimetre wavelengths. Observations in this portion of the electromagnetic spectrum are sensitive to some of the coldest objects in the Universe, including cosmic dust, a minor but crucial component of the interstellar material from which stars are born.

The Herschel infrared Galactic Plane Survey (Hi-GAL) is the largest of all observing programmes carried out with Herschel, in terms of both observing time – over 900 hours of total observations, equivalent to almost 40 days – and sky coverage – about 800 square degrees, or two percent of the entire sky. Its aim was to map the entire disc of the Milky Way, where most of its stars form and reside, in five of Herschel's wavelength channels: 70, 160, 250, 350 and 500 μm.


Image above: Herschel's view of the Eagle Nebula. Image Credits: ESA/Herschel/PACS, SPIRE/Hi-GAL Project.

Over the past two years, the Hi-GAL team has processed the data to obtain a series of calibrated maps of extraordinary quality and resolution. With a dynamical range of at least two orders of magnitude, these maps reveal the emission by diffuse material as well as huge filamentary structures and individual, point-like sources scattered across the images.

The images provide an unprecedented view of the Galactic Plane, ranging from diffuse interstellar material to denser filamentary structures of gas and dust that fragment into clumps where star formation sets in. They include pre-stellar clumps, protostars in various evolutionary stages and compact cores on the verge of turning into stars, as well as fully-fledged stars and the bubbles carved by their highly energetic radiation.


Image above: Herschel's view of RCW 120. Image Credits: ESA/Herschel/PACS, SPIRE/Hi-GAL Project.

Today, the team releases the first part of this data set, consisting of 70 maps, each measuring two times two degrees, and provided in the five surveyed wavelengths.

"These maps are not only stunning from an aesthetic point of view, but they represent a rich data set for astronomers to investigate the different phases of star formation in our Galaxy," explains Sergio Molinari from IAPS/INAF, Italy, Principal Investigator for the Hi-GAL Project.

Astronomers have been able to avail of data from Hi-GAL from the very beginning of the observing programme since the team agreed to waive their right to a proprietary period. The observations have been made available through the ESA Herschel Science Archive, including raw data as well as data products generated by systematic pipeline processing. The data has regularly been reprocessed to gradually higher quality and fidelity products.


Image above: Herschel's view of the Galactic Centre. Image Credits: ESA/Herschel/PACS, SPIRE/Hi-GAL Project.

The present release represents an extra step in the data processing. The newly released maps are accompanied by source catalogues in each of the five bands, which can be directly used by the community to study a variety of subjects, including the distribution of diffuse dust and of star-forming regions across the Galactic Plane.

The maps cover the inner part of the Milky Way, towards the Galactic Centre as seen from the Sun, with Galactic longitudes between +68° and -70°. A second release, with the remaining part of the survey, is foreseen for the end of 2016.


Image above: Herschel's view of the War and Peace and Cat's Paw nebulas. Image Credits: ESA/Herschel/PACS, SPIRE/Hi-GAL Project.

 "It is not straightforward to extract compact sources from far-infrared images, where pre-stellar clumps and other proto-stellar objects are embedded in the diffuse interstellar medium that also shines brightly at the same wavelengths," explains Molinari.

"For this reason, we developed a special technique to extract individual sources from the maps, maximising the contrast in order to amplify the compact objects with respect to the background."

The result is a set of five catalogues, one for each of the surveyed wavelengths, listing the source position, flux, size, signal-to-noise ratio and other parameters related to their emission. The largest catalogue is the one compiled from the 160-μm maps, with over 300 000 sources.

"The Hi-GAL maps and catalogues provide a complete census of stellar nurseries in the inner Galaxy," says Göran Pilbratt, Herschel Project Scientist at ESA.

"These will be an extremely useful resource for studies of star formation across the Milky Way, helping astronomers to delve into the Galactic Plane and also to identify targets for follow-up observations with other facilities."

Related publication:

S. Molinari, et al., "Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68°≥ l ≥ −70°", 2016, Astronomy & Astrophysics: http://www.aanda.org/10.1051/0004-6361/201526380

More information:

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Herschel was launched on 14 May 2009 and completed science observations on 29 April 2013.

The Herschel infrared Galactic Plane Survey (Hi-GAL) started out as one of the 21 Open Time Key Programmes carried out with the observatory, and later gained additional time in subsequent calls for observing proposals.

ESA’s Herschel space observatory: http://sci.esa.int/herschel/

Images (mentioned), Video (mentioned), Text, Credits: ESA/Göran Pilbratt/IAPS/INAF/Sergio Molinari.

Best regards, Orbiter.ch

jeudi 21 avril 2016

Pluto’s ‘Halo’ Craters












NASA - New Horizons Mission logo.

April 21, 2016

Within Pluto’s informally named Vega Terra region is a field of eye-catching craters that looks like a cluster of bright halos scattered across a dark landscape.


The region is far west of the hemisphere NASA’s New Horizons spacecraft viewed during close approach last summer. The upper image – in black and white – sports several dozen “haloed” craters. The largest crater, at bottom-right, measures about 30 miles (50 kilometers) across. The craters’ bright walls and rims stand out from their dark floors and surrounding terrain, creating the halo effect.

In the lower image, composition data from New Horizons’ Ralph/Linear Etalon Imaging Spectral Array (LEISA) indicate a connection between the bright halos and distribution of methane ice, shown in false color as purple. The floors and terrain between craters show signs of water ice, colored in blue. Exactly why the bright methane ice settles on these crater rims and walls is a mystery; also puzzling is why this same effect doesn’t occur broadly across Pluto.

The upper view is a mosaic made from two separate images obtained by New Horizons’ Long Range Reconnaissance Imager (LORRI). A high-resolution strip taken at approximately 760 feet (232 meters) per pixel is overlain on a broader, low-resolution image taken at 2,910 feet (889 meters) per pixel.  The images were obtained at ranges of 28,800 miles (46,400 kilometers) and 106,700 miles (171,700 kilometers) from Pluto, respectively, on July 14, 2015. The LEISA data came the same day, during the instrument’s highest-resolution scan of Pluto, with New Horizons 28,000 miles (45,500 kilometers) from Pluto, with a resolution of 1.7 miles (2.7 kilometers) per pixel.

For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.

Greetings, Orbiter.ch

Solar Impulse 2 take off from Hawaii











SolarImpulse - Around The World patch.

April 21, 2016

Goodbye Hawaii thank you for those past months!

Solar Impulse 2 take off Thursday evening at 7:00 p.m. local time from the airport to Kalaeloa, the Swiss solar plane resumed its world tour after a forced break of nine months in Hawaii.

Bertrand Piccard is the control of the aircraft, it will join Mountain View near San Francisco in Northern California after 62 hours of flying.

Bertrand passed the Northernmost point of Hawaii

Departure from Abu Dhabi on March 9, 2015, the solar airplane has accomplished so far nearly 18,000 kilometers. SolarImpulse Around the world an interruption in July following several damages, including batteries that overheated and necessity of their replacement.

Nine months of repairs

The device has been locked for nine months, the time to repair damaged batteries at its final stage over the Pacific Ocean, a record journey of five days and nights between the Japanese city of Nagoya and American archipelago of 'Hawaii.

SolarImpulse Around The World - Road Map (click on the image for enlarge)

He scored his first test flight in late February and performed since then nine flights in total. the plane's wings are covered with over 17,000 photovoltaic cells, which charge the batteries with the sun the day.

Follow the flight live: http://www.solarimpulse.com/leg-8-from-Nagoya-to-Hawaii

For more information about SolarImpulse Around The World, visit: http://blog.solarimpulse.com/

Images, Text, Credits: SolarImpulse/Orbiter.ch Aerospace/Roland Berga.

Greetings, Orbiter.ch

Microscopic "Timers" Reveal Likely Source of Galactic Space Radiation









NASA - Advanced Composition Explorer (ACE) logo.

April 21, 2016

Most of the cosmic rays that we detect at Earth originated relatively recently in nearby clusters of massive stars, according to new results from NASA's Advanced Composition Explorer (ACE) spacecraft. ACE allowed the research team to determine the source of these cosmic rays by making the first observations of a very rare type of cosmic ray that acts like a tiny timer, limiting the distance the source can be from Earth.


Image above: A cluster of massive stars seen with the Hubble Space Telescope. The cluster is surrounded by clouds of interstellar gas and dust called a nebula. The nebula, located 20,000 light-years away in the constellation Carina, contains the central cluster of huge, hot stars, called NGC 3603. Image Credits: NASA/U. Virginia/INAF, Bologna, Italy/USRA/Ames/STScI/AURA.

"Before the ACE observations, we didn't know if this radiation was created a long time ago and far, far away, or relatively recently and nearby," said Eric Christian of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Christian is co-author of a paper on this research published April 21 in Science.

Cosmic rays are high-speed atomic nuclei with a wide range of energy -- the most powerful race at almost the speed of light. Earth's atmosphere and magnetic field shield us from less-energetic cosmic rays, which are the most common. However, cosmic rays will present a hazard to unprotected astronauts traveling beyond Earth's magnetic field because they can act like microscopic bullets, damaging structures and breaking apart molecules in living cells. NASA is currently researching ways to reduce or mitigate the effects of cosmic radiation to protect astronauts traveling to Mars.

Cosmic rays are produced by a variety of violent events in space. Most cosmic rays originating within our solar system have relatively low energy and come from explosive events on the Sun, like flares and coronal mass ejections. The highest-energy cosmic rays are extremely rare and are thought to be powered by massive black holes gorging on matter at the center of other galaxies. The cosmic rays that are the subject of this study come from outside our solar system but within our Galaxy and are called galactic cosmic rays. They are thought to be generated by shock waves from exploding stars called supernovae.


Image above: This is a mosaic image-- one of the largest ever taken by NASA's Hubble Space Telescope -- of the Crab Nebula, a six-light-year-wide expanding remnant of a star's supernova explosion. Image Credits: NASA/ESA/Arizona State University.

The galactic cosmic rays detected by ACE that allowed the team to estimate the age of the cosmic rays, and the distance to their source, contain a radioactive form of iron called Iron-60 (60Fe). It is created inside massive stars when they explode and then blasted into space by the shock waves from the supernova. Some 60Fe in the debris from the destroyed star is accelerated to cosmic-ray speed when another nearby massive star in the cluster explodes and its shock wave collides with the remnants of the earlier stellar explosion.

60Fe galactic cosmic rays zip through space at half the speed of light or more, about 90,000 miles per second. This seems very fast, but the 60Fe cosmic rays won't travel far on a galactic scale for two reasons. First, they can't travel in straight lines because they are electrically charged and respond to magnetic forces. Therefore they are forced to take convoluted paths along the tangled magnetic fields in our Galaxy. Second, 60Fe is radioactive and over a period of about 2.6 million years, half of it will self-destruct, decaying into other elements (Cobalt-60 and then Nickel-60). If the 60Fe cosmic rays were created hundreds of millions of years or more ago, or very far away, eventually there would be too little left for the ACE spacecraft to detect.

"Our detection of radioactive cosmic-ray iron nuclei is a smoking gun indicating that there has likely been more than one supernova in the last few million years in our neighborhood of the Galaxy," said Robert Binns of Washington University, St. Louis, Missouri, lead author of the paper.


Advanced Composition Explorer (ACE) spacecraft. Image Credit: NASA

"In 17 years of observing, ACE detected about 300,000 galactic cosmic rays of ordinary iron, but just 15 of the radioactive Iron-60," said Christian. "The fact that we see any Iron-60 at all means these cosmic ray nuclei must have been created fairly recently (within the last few million years) and that the source must be relatively nearby, within about 3,000 light years, or approximately the width of the local spiral arm in our Galaxy." A light year is the distance light travels in a year, almost six trillion miles. A few thousand light years is relatively nearby because the vast swarm of hundreds of billions of stars that make up our Galaxy is about 100,000 light years wide.

There are more than 20 clusters of massive stars within a few thousand light years, including Upper Scorpius (83 stars), Upper Centaurus Lupus (134 stars), and Lower Centaurus Crux (97 stars). These are very likely major contributors to the 60Fe that ACE detected, owing to their size and proximity, according to the research team.

ACE was launched on August 25, 1997 to a point 900,000 miles away between Earth and the Sun where it has acted as a sentinel, detecting space radiation from solar storms, the Galaxy, and beyond. This research was funded by NASA's ACE program.

Additional co-authors on this paper were: Martin Israel and Kelly Lave at Washington University, St. Louis, Missouri; Alan Cummings, Rick Leske, Richard Mewaldt and Ed Stone at Caltech in Pasadena, California; Georgia de Nolfo and Tycho von Rosenvinge at Goddard; and Mark Wiedenbeck at NASA's Jet Propulsion Laboratory in Pasadena, California.

Related link:

Advanced Composition Explorer (ACE): http://science.nasa.gov/missions/ace/

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

Greetings, Orbiter.ch

Hubble captures birthday bubble












ESA - Hubble Space Telescope logo.

21 April 2016

The Bubble Nebula

This new NASA/ESA Hubble Space Telescope image, released to celebrate Hubble’s 26th year in orbit, captures in stunning clarity what looks like a gigantic cosmic soap bubble. The object, known as the Bubble Nebula, is in fact a cloud of gas and dust illuminated by the brilliant star within it. The vivid new portrait of this dramatic scene wins the Bubble Nebula a place in the exclusive Hubble hall of fame, following an impressive lineage of Hubble anniversary images.

Twenty six years ago, on 24 April 1990, the NASA/ESA Hubble Space Telescope was launched into orbit aboard the space shuttle Discovery as the first space telescope of its kind. Every year, to commemorate this momentous day in space history, Hubble spends a modest portion of its observing time capturing a spectacular view of a specially chosen astronomical object.

Wide-field image of the Bubble Nebula (ground-based image)

This year’s anniversary object is the Bubble Nebula, also known as NGC 7635, which lies 8 000 light-years away in the constellation Cassiopeia. This object was first discovered by William Herschel in 1787 and this is not the first time it has caught Hubble’s eye. However, due to its very large size on the sky, previous Hubble images have only shown small sections of the nebula, providing a much less spectacular overall effect. Now, a mosaic of four images from Hubble’s Wide Field Camera 3 (WFC3) allows us to see the whole object in one picture for the first time.

This complete view of the Bubble Nebula allows us to fully appreciate the almost perfectly symmetrical shell which gives the nebula its name. This shell is the result of a powerful flow of gas — known as a stellar wind — from the bright star visible just to the left of centre in this image. The star, SAO 20575, is between ten and twenty times the mass of the Sun and the pressure created by its stellar wind forces the surrounding interstellar material outwards into this bubble-like form.

video
Zoom into the Bubble Nebula

The giant molecular cloud that surrounds the star — glowing in the star’s intense ultraviolet radiation — tries to stop the expansion of the bubble. However, although the sphere already measures around ten light-years in diameter, it is still growing, owing to the constant pressure of the stellar wind — currently at more than 100 000 kilometres per hour!

Aside from the symmetry of the bubble itself, one of the more striking features is that the star is not located at the centre. Astronomers are still discussing why this is the case and how the perfectly round bubble is created nonetheless.

video
Pan across the Bubble Nebula

The star causing the spectacular colourful bubble is also notable for something less obvious. It is surrounded by a complex system of cometary knots, which can be seen most clearly in this image just to the right of the star. The individual knots, which are generally larger in size than the Solar System and have masses comparable to Earth’s, consist of crescent shaped globules of dust with large trailing tails illuminated and ionised by the star. Observations of these knots, and of the nebula as a whole, help astronomers to better understand the geometry and dynamics of these very complicated systems.

As always, and twenty six years on, Hubble gives us much more than a pretty picture.

More information:

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

Links:

Hubblecast 92: 26th anniversary: http://www.spacetelescope.org/videos/heic1608a/

Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Link to hubblesite release: http://hubblesite.org/newscenter/archive/releases/2016/13/

Bubble Nebula in 2000: http://www.spacetelescope.org/images/opo0004a/

Bubble Nebula in 1998: http://www.spacetelescope.org/images/opo9828e/

For images and more information about Hubble Space Telescope:

    https://www.spacetelescope.org/
    http://hubblesite.org/
    http://www.nasa.gov/hubble

Images, Text, Credits: NASA, ESA, Hubble Heritage Team/Digitized Sky Survey 2/Acknowledgement: Davide De Martin/Videos: ESA/Hubble, Digitized Sky Survey 2, Nick Risinger (skysurvey.org); Music: Johan B. Monell.

Best regards, Orbiter.ch

Shijian-10 successful return on Earth












CASC - China Aerospace Science and Technology Corporation logo.

April 21, 2016


China’s ‪‎Shijian-10‬ research spacecraft made a successful return on Monday, bringing back experiments after a two-week stay in space for extensive analysis on the ground covering various fields of scientific research.


The scientific purpose of the program is to promote the scientific research in the space microgravity environment by operating Shijian-10 at low Earth orbit on two weeks.


Landing occurred Monday morning in Inner Mongolia and the return capsule was retrieved shortly after landing to quickly gain access to the experiments on board.

Related article:

Long March 2D launches the recoverable Shijian-10
http://orbiterchspacenews.blogspot.ch/2016/04/long-march-2d-launches-recoverable.html

For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html

Images, Text, Credits: CASC/Xinhua/News.CN/Orbiter.ch Aerospace.

Greetings, Orbiter.ch

mercredi 20 avril 2016

GPM Satellite Looks at Texas Heavy Rainfall













NASA & JAXA - Global Precipitation Measurement (GPM) logo.

April 20, 2016

A slow-moving frontal system associated with a stagnant upper-air pattern set the stage for heavy rains and flooding early this week from East Texas all the way up through the Central and Northern Plains. NASA estimated the heavy rainfall using satellite data that showed the hardest hit region was in and around the Houston area.


Image above: NASA's IMERG showed heavy rainfall from April 15 to 19 for eastern Texas and the surrounding region,. At least 6 to 12 inches (shown in dark red, purple and pink) covering most of East Texas, eastern Oklahoma and the far western portions of Arkansas and Louisiana. North and west of Houston almost 15 inches of rain fell (coral). Image Credits: NASA/JAXA/SSAI, Hal Pierce.

The Global Precipitation Measurement or GPM mission core satellite provides next-generation observations of rain and snow worldwide every three hours. NASA and the Japanese Aerospace Exploration Agency (JAXA) co-manage the satellite. The data provided is used to unify precipitation measurements made by an international network of partner satellites to quantify when, where, and how much it rains or snows around the world.

On Monday, April 18 the National Weather Service reported that Houston International Airport broke its all-time daily rainfall record with 9.92 inches of rain.  Elsewhere in Harris County, over 17 inches of rain was recorded as of Monday evening.  The main culprit was a stationary upper-level low pressure center spinning over the Central Rockies that had become detached from the main jet stream, causing it to remain in place.

video
Heavy Rainfall Seen in Texas

Video above: Rainfall was estimated from April 15 at 00:00 UTC (April 14 at 8 p.m. EDT) to April 19 at 08:30 UTC (4:30 a.m. EDT) for eastern Texas and the surrounding region by NASA's IMERG product. IMERG showed rainfall amounts of at least 6 to 12 inches (shown in dark red, purple and pink) covering most of East Texas, eastern Oklahoma and the far western portions of Arkansas and Louisiana. The highest totals are located north and west of Houston and are near 15 inches (shown in coral). Video Credits: NASA/JAXA/SSAI, Hal Pierce.

At the surface, the corresponding north-south oriented frontal system, which extended from the Southern into the Northern Plains, pulled up stationary across Central Texas.  The result was a steady flow of warm, moist unstable air being drawn up from the Gulf of Mexico northward across East Texas, which set the stage for and fueled numerous showers and thunderstorms across the region, including a massive thunderstorm complex that slowing moved across East Texas.

The Integrated Multi-satellitE Retrievals for GPM or IMERG is used to make estimates of precipitation from a combination of passive microwave sensors, including the GMI microwave sensor onboard the GPM satellite, and geostationary IR (infrared) data.

The data was created into an image at NASA's Goddard Space Flight Center in Greenbelt, Maryland and included IMERG rainfall estimates for the period from April 15 at 00:00 UTC (April 14 at 8 p.m. EDT) to April 19 at 08:30 UTC (4:30 a.m. EDT) for eastern Texas and the surrounding region.

Global Precipitation Measurement (GPM) spacecraft. Image Credits: NASA/JAXA

IMERG showed rainfall amounts of at least 6 to 12 inches covering most of East Texas, eastern Oklahoma and the far western portions of Arkansas and Louisiana.  The highest totals are located north and west of Houston and are near 15 inches.  So far 5 persons are reported to have died in the area as a result of the some of the worst flooding there since Tropical Storm Allison in 2001. For updated forecasts, visit: http://www.weather.gov.

On Wednesday, April 20, 2016, the National Weather Service Weather Prediction Center in College Park, Maryland said "Showers and thunderstorms will continue over already soaked portions of the Texas Gulf Coast and portions of the southern Plains. The system that brought widespread heavy precipitation flooding to portions of the southern and central plains will slowly track to the east through the end of the week. "

For more information about GPM, visit: http://www.nasa.gov/gpm and http://global.jaxa.jp/projects/sat/gpm/topics.html

Images (mentioned), Video (mentioned), Text, Credits: SSAI/NASA's Goddard Space Flight Center/Steve Lang/Lynn Jenner.


Best regards, Orbiter.ch

Staying Strong: Spaceflight Muscle Loss Study Aims to Benefit Patients on Earth












ISS - International Space Station patch.

April 20, 2016

“Exercise and eat right” is a common prescription for maintaining muscle and building bone, but more advanced solutions are needed to address serious diseases that lead to loss of muscle function in the general population. The International Space Station is providing researchers a unique opportunity to study muscle loss and to investigate means for muscle preservation.

Rodent Research-3, a study sponsored by Eli Lilly and Company and the Center for the Advancement of Science in Space (CASIS), focuses on assessing the ability of a novel compound to prevent skeletal muscle wasting and weakness in mice exposed to long-duration spaceflight. The investigation launched aboard the eighth SpaceX resupply mission to the space station on April 8.


Image above: NASA’s Rodent Habitat, shown here with one of the two access doors open, provides long-term housing for rodents aboard the International Space Station. Image Credits: NASA/Dominic Hart.

How can spaceflight help researchers better understand terrestrial musculoskeletal diseases and interventions? When we unload, or remove the force of our body weight from the muscles that normally work against gravity to support us, those muscles rapidly atrophy, or waste away and weaken. That’s exactly what happens in microgravity unless countermeasures are applied. The astronauts on the space station, for example, follow rigorous exercise programs that apply forces to their musculoskeletal systems and help them stay strong throughout their missions.

Mice exposed to spaceflight have proved to be valuable research models to understand, target and treat causes of human muscle atrophy.

“This includes modeling serious diseases that involve muscle wasting such as muscular dystrophy, amyotrophic lateral sclerosis, cancer cachexia and even aging-related musculoskeletal frailty,” said Rosamund Smith, research fellow at Eli Lilly and Company, and the principal investigator for the Rodent Research-3 mission.


Image above: Under the direction of the International Space Station Utilization Office and the Space Biology Project, NASA’s Rodent Research Hardware System was developed and built at NASA’s Ames Research Center to provide a research platform for long-duration rodent studies in space. Image Credit: NASA.

“The ability to expose all muscles of an organism to conditions that induce muscle atrophy is not easily achieved on Earth,” said Smith. “Lilly is excited to have the opportunity to conduct this investigation in space.”

Loss of muscle function, rather than just a decrease in muscle size, is the critical aspect that leads to problems with physical performance in patients suffering from muscle-wasting conditions. Therefore, Eli Lilly and Company has contributed expertise, techniques and equipment for studying muscle function in the mission.

“The Rodent Research-3 study is unique not only in the experimental compound that will be tested, but also because, for the first time, muscle function of the mice will be assessed during spaceflight,” said Janet Beegle, Rodent Research-3 project manager at NASA’s Ames Research Center in California’s Silicon Valley.


Image above: Expedition 43 Commander Terry Virts and Flight Engineer Scott Kelly perform operations for Rodent Research-2, a commercial investigation of the effects of spaceflight on the musculoskeletal and nervous systems that was launched to the station on April 14, 2015. Image Credit: NASA.

Rodent Research-3 uses NASA’s Rodent Research Hardware System. Developed and built at Ames, this system takes advantage of experience gained from 27 prior flight investigations with rodents using a space shuttle-based system. The space station now supports much longer-duration rodent studies than were previously possible during space shuttle missions, which were typically two weeks in duration. Rodent Research-3 is a six-week long study.

Although the primary research focus of Rodent Research-3 is skeletal muscle, the investigators are studying other organ systems, such as bone, both at the tissue and molecular levels. Their goal is to characterize tissue responses to spaceflight and observe how these changes vary with the length of time spent in microgravity. The findings will advance our understanding of the risks that long-term space exploration poses to astronauts, and can be applied towards the development of countermeasures to protect astronaut health. Additionally, Eli Lilly and Company plans to share Rodent Research-3 experimental samples with the scientific community, further broadening the potential benefits of this research mission.

video
Rodent Research in Microgravity

Results from Rodent Research-3 will be applied to ongoing discovery efforts at Eli Lilly and Company, seeking treatments for serious muscle-wasting diseases and conditions that may potentially help patients afflicted with degenerative diseases to stay strong.

The space station is a blueprint for global cooperation and scientific advancements, a destination for growing a commercial marketplace in low-Earth orbit, and a test bed for demonstrating new technologies. The orbiting laboratory is also the major springboard to NASA's next great leap in exploration, including future missions to an asteroid and Mars.

Related links:

NASA’s Rodent Research Hardware System: http://www.nasa.gov/mission_pages/station/research/news/rodent_research

Rodent Research-3: http://www.nasa.gov/mission_pages/station/research/experiments/1722.html

Center for the Advancement of Science in Space (CASIS): http://www.iss-casis.org/

Exercise programs: https://www.youtube.com/watch?v=QPghbtqKdBg

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

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

Images (mentioned, Video, Text, Credits: NASA’s Ames Research Center/Space Biosciences Division/Gianine Figliozzi/JSC/Kristine Rainey.

Greetings, Orbiter.ch

CERN - In Theory: Which came first…?












CERN - European Organization for Nuclear Research logo.

April 22, 2016


Image above: “The experiments need to speak a common language and also to speak the same language as the theorists”, explains Chiara Mariotti, an experimental physicist at the CMS experiment. Image Credit: CERN.

Over the last century, fundamental physics has undergone a change of scale. To push forward the knowledge of the infinitely small, physicists have been using increasingly sophisticated tools and have formed larger and larger collaborations. The scientists of old, who divided their time between their blackboards and their own small laboratories, have been succeeded by a myriad of specialists. Theorists are no longer experimental physicists, and vice versa.

“100 years ago, no distinction was made between theoretical and experimental physicists. Enrico Fermi was both a genius of theory and an exceptional experimentalist”, says Christophe Grojean, a theorist at DESY who collaborates with the experimental physicists working on the Large Hadron Collider (LHC). ”Today, experimental physics involves such sophisticated technology, and theory requires such a deep knowledge of mathematics, that it’s virtually impossible for one person to cover everything”.

Today, a physicist can be anything from a theorist whose work is far removed from experimental observations to an experimentalist doing R&D on detector components. In the middle of this broad spectrum of specialisations, theoretical and experimental physicists work alongside each other in close collaboration.

    “I’m interested in physics theories beyond the Standard Model that can be tested. If I’ve got an idea, I want it to be used to interpret data. I don’t like speculating just for the sake of it” – John Ellis of King’s College London, who has worked at CERN since 1973.

… the theorist or the experimentalist?

Be that as it may, yesterday’s scientists and today’s physicists all have one thing in common: the thirst for a result or, even better, a discovery. The only difference is that they are now divided into two big communities, the theorists and the experimentalists. With which group does the initiative lie?  Are the experimentalists dependent on the theorists’ predictions for their discoveries or, on the contrary, do the theorists rely on the experimentalists’ data to improve their models?

“It’s a bit like the chicken and the egg”, smiles Christophe. But neither theorists nor experimentalists claim to be either the egg or the chicken (not that we really know which came first!). Each relies on the other’s knowledge to advance.

“In an ideal world, experimentalists would be able to understand Nature simply by observing it, but in reality they need the theorists’ input to interpret what they see”, explains Michelangelo Mangano, a theorist at CERN. “Likewise, theorists would love to be able to explain everything without recourse to experiments, finding the theory to rival all others since, in simple terms, Nature could not possibly function any other way. In reality, it’s much more complicated than that. There is always more than one possibility, and the Universe has evolved by taking one of the many paths open to it. This is why theorists also need experimental data to guide them”.

“If we want to understand what we’re measuring, we need a theoretical framework”, adds Chiara Mariotti, an experimental physicist with the CMS experiment at the LHC. "Even if we discover something that the theorists have never predicted, it’s important for us to understand the underlying framework, to have the wider view that the theorists give us”.


Image above: Chiara Mariotti, an experimental physicist with the CMS experiment, and Christophe Grojean, a theoretical physicist working at DESY, are two of the coordinators of the LHC Higgs cross-section working group. The group brings together theoretical and experimental physicists with the aim of agreeing common theoretical predictions as the basis for analysing the data from the experiments. (Image: CERN).

A frenzy of interpretation

Research at the LHC is a perfect example of the continuous cross-fertilisation between theoretical and experimental physicists that drives scientific progress. The experimentalists' search for the Higgs boson was triggered by theory, but now the theorists are waiting for more data from the LHC to show them which way to go (we will elaborate on this in the next article in this series). Whenever the experiments start to buzz with signs of something new, however weak the signal is, there is a flood of theoretical interpretations. On 15 December 2015, the ATLAS and CMS experiments announced their first results from Run 2 of the LHC, revealing an unexpected (albeit small) signal. A dozen articles containing theoretical interpretations had been posted on the arXiv scientific repository within 24 hours. By April, the number had risen to 312!

“The Standard Model was formulated over 40 years ago. Dozens of models taking it further have emerged in the meantime, but none has gained the upper hand. The experiments will ultimately show who is right”, says Michelangelo. Hence the theorists’ frenzied trawling through the experimental data and the note of urgency in the avalanche of interpretations.

However, the theorists and experimentalists don’t simply stand by and watch like jealous neighbours observing the preparations for a party next door. They sometimes jump over the fence and join in. At CERN, where they’re separated only by a few corridors, cooperation is the name of the game. Michelangelo Mangano is one of the promoters and organisers of this dialogue. When the LHC began operation he set up the LHC Physics Centre at CERN (LPCC), a structure that supports collaboration between experimental and theoretical physicists. “One of my main tasks is to facilitate the interaction between theory and experiments”, he explains.


Image above: “Theorists and experimental physicists complement each other. They have a different approach to understanding”, explains Michelangelo Mangano, a CERN theorist who facilitates cooperation between the two communities at the LHC. (Image: CERN).

The LHC Higgs cross-section working group is one of the platforms for discussions between theoretical and experimental physicists. The group was set up in 2010 with the aim of making joint predictions for the discovery of the then hypothetical Higgs boson.

“We wanted to prepare for the discovery of the Higgs  and it was important for the experiments to use the same theoretical predictions and analysis criteria”, says Chiara Mariotti, one of the group’s founding members. “That way, once the experiments had observed a signal, it was easier for them to compare their data and check that it really was a discovery”.


Image above: “The experiments need to speak a common language and also to speak the same language as the theorists”, explains Chiara Mariotti, an experimental physicist at the CMS experiment. (Image: CERN).

Accordingly, on 4 July 2012, the ATLAS and CMS experiments rapidly converged on the same conclusion.  Both had seen a signal, of course, but they were also relying on criteria that had been defined in conjunction with the theorists.

“This cooperation allowed us to focus on the main issues rather than wasting time comparing our methods. It accelerated the discovery”, explains Christophe Grojean, one of the group's current coordinators. The group, which initially comprised around fifty theorists and experimentalists, has now expanded. Between 100 and 200 physicists are active members, and the diverse subjects it covers range from precision Higgs measurements to searches for physics beyond the Standard Model.

Although essential, collaboration between the two communities of physicists is not always straightforward, not least because of the very different social structure of the large experiment collaborations compared to that of the small theory groups.

“A theorist’s work is ultimately much more solitary than that of an experimentalist who is part of a large collaboration and thus inevitably subject to constraints. Theorists are a lot freer, their work is their own, while an experimental physicist is part of a big team", says Christophe.

Confidentiality lies at the heart of the large experiment collaborations, and there’s no question of revealing results if they haven’t been approved. This means that theorists work only on the data that the experiments have already published, unless an experiment turns to them for help with its analysis, in which case they are asked to keep the information to themselves. In such cases, they can add their names to the relevant publication alongside the collaboration members.
Precious autonomy

When you ask theorists if they wish they had taken up a career as an experimental physicist, the answer is usually no. “I enjoy working closely with experimental physicists, but I’m happy to retain my independence as a theorist”, says Michelangelo Mangano. Theorists set great store by their freedom. Freedom of initiative is not always a given in the large experiment collaborations, and the theorists are aware of their privileged position.

“If I’m not satisfied with the results in one field of theory, I can always move to another one where I can put my ideas to good use”, says Slava Rychkov, a CERN theorist. “It’s less easy for experimental physicists. If they don’t get any results from a complex experiment that they’ve spent a lot of time building it can be very demotivating”.

Slava feels that theorists should be more aware of their responsibility when they point the experimentalists in a certain direction.

The relationship between theoretical and experimental physicists is even more complicated when it comes to discoveries. Who should be given the credit for them? The theorist who predicted the phenomenon or the experimentalist who found proof of it? Both, certainly, but the juries who award the prizes are not always so magnanimous.

Alvaro de Rújula, an honorary member of CERN’s theory department, talked ironically about this unspoken competition in an article on the relationship between theorists and experimentalists.  “The relationship between experimentalists and theorists is often one of healthy competition for truth and less healthy competition for fame”, he wrote, illustrating his words with a riddle comparing a theorist, an experimentalist and a discovery with a farmer, his pig and a truffle.

What is similar and what is different between the following two sets?


Images above: The farmer takes his pig to the woods. The pig sniffs around looking for a truffle. When the pig gets it and is about to eat it, the farmer knocks the pig on the head with his club and steals the truffle. Those are the similarities: a theorist would also claim recognition for an experimenter's discovery (if it has anything to do with her/his theories) even if [s]he did not make it! The difference is that the farmer always takes the pig to woods where there are truffles, while, more often than not, the suggestions by the theorists take the experimentalists to "woods'' where there are no "truffles'' (by suggesting experiments that do not lead to interesting discoveries). Not to be unfair to theorists, one must add that there are notable exceptions to these rules, progress is made by trial and error, and the theorists' guidance is occasionally in the right direction! Even more often, while looking for the theorists' "truffles'' the experimentalists find "gold'': something unexpected but even more interesting! (Nature tends to be more creative than we are).(Image: Alvaro de Rújula/ CERN).

The next article in the “In Theory” series will discuss the theorists' hopes for the future and what the next steps are for the discipline. You can read the previous articles in the series here:

CERN - In Theory: Why are theoreticians filled with wanderlust?
http://orbiterchspacenews.blogspot.ch/2016/04/cern-in-theory-why-are-theoreticians.html

CERN - In Theory: Are theoreticians just football fanatics?
http://orbiterchspacenews.blogspot.ch/2016/03/cern-in-theory-are-theoreticians-just.html

CERN - In theory: Welcome to the Theory corridor:
http://orbiterchspacenews.blogspot.ch/2016/02/cern-in-theory-welcome-to-theory.html

CERN - In Theory: why bother with theoretical physics?:
http://orbiterchspacenews.blogspot.ch/2016/03/cern-in-theory-why-bother-with.html

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 22 Member States.

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

CERN's "Group of Theoretical Studies": http://home.cern/cern-people/opinion/2014/10/theory-cern-turns-62

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

Images (mentioned), Text, Credits: CERN/Corinne Pralavorio/Harriet Kim Jarlett.

Best regards, Orbiter.ch

SolarImpulse - Ultimate takeoff from Hawaii scheduled!











SolarImpulse - Around The World patch.

April 20, 2016

We knew this day would come where we can finally say: tomorrow we will be taking off. After 9 months having put our round-the-world solar flights on hold because of a battery complication during the 5 day/night flight from Nagoya to Hawaii, we are able to resume our attempt to accomplish this solar-powered challenge.


SolarImpulse 2 have announced a takeoff from Kalaeloa Airport on April 21st at 3PM UTC. Last week we declared Mission Mode and this week we have found a weather window that would give way to a 62 hour flight to reach Moffett Airfield, Mountain View, California, USA. The team next to the aircraft will also be leaving Hawaii just after Bertrand Piccard takes off with Si2 in order to meet him on the other side.

Even during these past 9 months, the adventure has never stopped. We have built an experimental aircraft that we use to explore not only altitudes, but also unknown territories within the realm of clean technology and creative team building.


Here’s what’s in store for you during this epic flight across the inviting ocean:

- A peek into Bertrand Piccard’s journey across the Pacific Ocean with our TV Presenter Kari

- Details about the technical and psychological challenges our pilot and team will be facing during this flight

- Interviews on solarimpulse.com with passionate ambassador of clean technology, among them Boyan Slat (initiator of The Ocean Cleanup), Achim Steiner (Executive Director of UNEP), and Christiana Figueres (Executive Secretary of UNFCCC)

- Facebook Live from our team at the Mission Control Center in Monaco

- André’s reflections on his 117-hour flight over the Pacific Ocean from Nagoya to Hawaii and his advice to Bertrand

- Bertrand’s message to World Leaders on Earth Day to accompany their meeting in New York to sign the Paris Climate Agreement

- A tribute to Amelia Earhart’s legacy as the first woman to fly solo across the Pacific Ocean in 1935


Become a part of our adventure by tuning into our website and reading our logbook while watching solarimpulse.com. If you haven’t already, you can subscribe link bellow and you will be notified whenever we have an update to share with you: http://www.solarimpulse.com/subscribe

If you have already subscribed, then you can tweak your subscriber preferences link bellow in order to regulate the amount of updates you receive from us during the Mission. You have two choices: interactive and basic. Become an interactive crew member and you will receive regular updates announcing important milestones before, during and after the flight, as well as being the first to receive our most interesting releases that have been prepared only for you. Become a basic crew member and you will receive the main newsletters and be notified of the most important releases and events: http://www.solarimpulse.com/leg-8-from-Nagoya-to-Hawaii

For more information about SolarImpulse Around The World, visit: http://blog.solarimpulse.com/

Images, Animation, Text, Credits: SolarImpulse.

Greetings, Orbiter.ch

mardi 19 avril 2016

Seeing Double: NASA Missions Measure Solar Flare from 2 Spots in Space














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

April 19, 2016

Solar flares are intense bursts of light from the sun. They are created when complicated magnetic fields suddenly and explosively rearrange themselves, converting magnetic energy into light through a process called magnetic reconnection – at least, that’s the theory, because the signatures of this process are hard to detect. But during a December 2013 solar flare, three solar observatories captured the most comprehensive observations of an electromagnetic phenomenon called a current sheet, strengthening the evidence that this understanding of solar flares is correct.


Animations above: During a December 2013 solar flare, three NASA missions observed a current sheet form – a strong clue for explaining what initiates the flares. This animation shows four views of the flare from NASA’s Solar Dynamics Observatory, NASA’s Solar and Terrestrial Relations Observatory, and JAXA/NASA’s Hinode, allowing scientists to make unprecedented measurements of its characteristics. The current sheet is a long, thin structure, especially visible in the views on the left. Those two animations depict light emitted by material with higher temperatures, so they better show the extremely hot current sheet. Animations Credits: NASA/JAXA/SDO/STEREO/Hinode (courtesy Zhu, et al.).

These eruptions on the sun eject radiation in all directions. The strongest solar flares can impact the ionized part of Earth’s atmosphere – the ionosphere – and interfere with our communications systems, like radio and GPS, and also disrupt onboard satellite electronics. Additionally, high-energy particles – including electrons, protons and heavier ions – are accelerated by solar flares.

Unlike other space weather events, solar flares travel at the speed of light, meaning we get no warning that they’re coming. So scientists want to pin down the processes that create solar flares – and even some day predict them before our communications can be interrupted.

“The existence of a current sheet is crucial in all our models of solar flares,” said James McAteer, an astrophysicist at New Mexico State University in Las Cruces and an author of a study on the December 2013 event, published on April 19, 2016, in the Astrophysical Journal Letters. “So these observations make us much more comfortable that our models are good.”

And better models lead to better forecasting, said Michael Kirk, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the study. “These complementary observations allowed unprecedented measurements of magnetic reconnection in three dimensions,” Kirk said. “This will help refine how we model and predict the evolution of solar flares."

Looking at Current Sheets

A current sheet is a very fast, very flat flow of electrically-charged material, defined in part by its extreme thinness compared to its length and width. Current sheets form when two oppositely-aligned magnetic fields come in close contact, creating very high magnetic pressure. Electric current flowing through this high-pressure area is squeezed, compressing it down to a very fast and thin sheet. It’s a bit like putting your thumb over the opening of a water hose – the water, or, in this case, the electrical current, is forced out of a tiny opening much, much faster. This configuration of magnetic fields is unstable, meaning that the same conditions that create current sheets are also ripe for magnetic reconnection.


Animation above: Current sheets are formed in the space between two oppositely-aligned magnetic fields that are in close contact. This illustration shows how such oppositely-aligned fields can explosively realign to a new configuration, in a process called magnetic reconnection. Because current sheets are so closely tied to magnetic reconnection, observations of a current sheet during a December 2013 solar flare bolster the idea that solar flares are the result of magnetic reconnection on the sun. Animation Credits: ESA (European Space Agency).

“Magnetic reconnection happens at the interface of oppositely-aligned magnetic fields,” said Chunming Zhu, a space scientist at New Mexico State University and lead author on the study. “The magnetic fields break and reconnect, leading to a transformation of the magnetic energy into heat and light, producing a solar flare.”

Because current sheets are so closely associated with magnetic reconnection, observing a current sheet in such detail backs up the idea that magnetic reconnection is the force behind solar flares.

“You have to be watching at the right time, at the right angle, with the right instruments to see a current sheet,” said McAteer. “It’s hard to get all those ducks in a row.”

This isn’t the first time scientists have observed a current sheet during a solar flare, but this study is unique in that several measurements of the current sheet – such as speed, temperature, density and size – were observed from more than one angle or derived from more than method.

This multi-faceted view of the December 2013 flare was made possible by the wealth of instruments aboard three solar-watching missions: NASA’s Solar Dynamics Observatory, or SDO, NASA’s Solar and Terrestrial Relations Observatory, or STEREO – which has a unique viewing angle on the far side of the sun – and Hinode, which is a collaboration between the space agencies of Japan, the United States, the United Kingdom and Europe led by the Japan Aerospace Exploration Agency.

Even when scientists think they’ve spotted something that might be a current sheet in solar data, they can’t be certain without ticking off a long list of attributes. Since this current sheet was so well-observed, the team was able to confirm that its temperature, density, and size over the course of the event were consistent with a current sheet.

As scientists work up a better picture of how current sheets and magnetic reconnection lead to solar eruptions, they'll be able to produce better models of the complex physics happening there – providing us with ever more insight on how our closest star affects space all around us.

This research was funded by a CAREER grant from the National Science Foundation awarded to James McAteer.

Related Links:

NASA’s SDO website: https://www.nasa.gov/mission_pages/sdo/main/index.html

NASA’s STEREO website: https://www.nasa.gov/mission_pages/stereo/main/index.html

NASA’s Hinode website: http://www.nasa.gov/mission_pages/hinode/index.html

Animations (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Sarah Frazier/Rob Garner.

Greetings, Orbiter.ch