samedi 7 novembre 2015
LHC completes proton run for 2015, preps for lead
CERN - European Organization for Nuclear Research logo.
Nov. 7, 2015
Image above: The Large Hadron Collider will switch to colliding lead ions at the end of November (Image: Maximilien Brice/CERN).
The Large Hadron Collider (LHC) has successfully completed its planned proton run for 2015, delivering the equivalent of about 400 trillion (1012) proton-proton collisions – some 4 inverse femtobarns of data – to both the ATLAS and CMS experiments. LHCb and ALICE have also enjoyed successful data taking at lower collision rates. CERN engineers will now prepare the accelerator to collide lead ions, for a physics run due to start in late November. These heavy-ion collisions allow physicists to investigate quark-gluon plasma, a state of matter thought to have formed just after the Big Bang.
"The accelerator has been performing well given the challenges of running at the new collision energy of 13 teraelectronvolts (TeV)," says Mike Lamont of the LHC Operations team. "We're currently running with 2244 bunches of protons in the machine, spaced at intervals of 25 nanoseconds, which is an achievement in itself."
The new energy regime highlighted several issues for the Operations team, including increased electron-cloud effects at high beam intensities, and falling particles of dust inside the beam-pipe causing premature beam dumps. To resolve these issues, the team has been patiently ramping up the beam intensity over a period of weeks using small numbers of bunches in various configurations. With the LHC now confidently colliding protons at 13 TeV, it's time to switch to lead.
Image above: One of the first lead-lead collisions at the LHC, recorded by the ALICE detector in November 2010. Note the large number of particle tracks (Image: ALICE).
"The main scope of our upcoming technical stop is to install zero-degree calorimeters for CMS and ATLAS to prepare for the upcoming lead run," says Marzia Bernardini of the CERN Engineering department. These detectors, just next to the beamline at two interaction points of the LHC ring, measure the energy of neutral particles coming from the collisions. These measurements help physicists to understand the size of the collision area in lead-lead interactions.
Of the seven experiments on the LHC ring, the 10,000 tonne ALICE detector is the most specialized for studying lead-lead collisions, in which the hundreds of protons and neutrons in two lead nuclei smash into one another at energies of upwards of a few trillion electronvolts each. This forms a miniscule fireball in which everything “melts” into a quark-gluon plasma.
"This new energy regime is of course very interesting for ALICE," says ALICE spokesperson Paolo Giubellino. “In this run we will also have much larger statistics to work with and our detector has been significantly upgraded since the LHC’s first run. So we now have a better instrument to study the system to a much higher precision and at even higher temperatures than during run 1!”
And ALICE is not the only collaboration interested in lead ions. “There's a big team in CMS studying the data and ATLAS is also very interested,” says Lamont. Following their participation in the 2013 proton-lead run, LHCb will now be taking lead-lead data too; evidence of a growing enthusiasm for the study of lead-lead collisions at the LHC’s new energy frontier.
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.
Protons smash lead ions in first LHC collisions of 2013:
Large Hadron Collider (LHC): http://home.cern/topics/large-hadron-collider
ATLAS experiment: http://home.cern/about/experiments/atlas
CMS experiment: http://home.cern/about/experiments/cms
ALICE experiment: http://home.cern/about/experiments/alice
LHCb experiment: http://home.cern/about/experiments/lhcb
Big Bang theory: http://home.cern/about/physics/early-universe
For more information about European Organization for Nuclear Research (CERN), Visit: http://home.web.cern.ch/
Image (mentioned), Text, Credits: CERN/Cian O'Luanaigh.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 10:07
Long March 3B launches Chinasat-2C satellite
CASC - China Aerospace Science and Technology Corporation logo.
Nov. 7, 2015
Image above: A Long March 3B carrier rocket carrying the ChinaSat-2C satellite liftoff from the Xichang Satellite Launch Center on Nov. 3, 2015. Image Credits: Xinhua/Zhao.
China launched a new communications satellite on Tuesday November 3, 2015 – one that may sport military applications. The Zhongxing-2C spacecraft – otherwise known as Chinasat-2C – was launched at 16:25 UTC, lifting off via a Long March 3B/G2 from the Xichang Satellite Launch Center.
Chinasat-2C satellite. Image Credit: Günter Space Page
Zhongxing-2C – the name cited by Chinese media – is possibly the second satellite of the second generation Shentong geostationary military communication satellites.
China uses two types of satellites for secure military communications: the Fenghuo and the Shentong.
China Launches New Communication Satellite. Video Credit: CCTV+
The Xichang Satellite Launch Centre is situated in the Sichuan Province, south-western China and is the country’s launch site for geosynchronous orbital launches.
For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html
Images (mentioned), Video (mentioned), Text, Credits: CASC/Orbiter.ch Aerospace.
Publié par Orbiter.ch à 09:37
Gaia's sensors scan a lunar transit
ESA - Gaia Mission patch.
November 7, 2015
Gaia mapping the stars. Image Credit: ESA
Located 1.5 million km from the Earth, ESA's Gaia spacecraft is scanning the sky to conduct the most detailed census of stars in our Galaxy. However, on 6 November, it will be perfectly placed to witness a rare event that will involve objects much closer to home – a lunar transit across the Sun.
Transits occur when planets move in front of a nearby star. Such events occur occasionally in our Solar System when we see Venus and Mercury pass across the Sun's brilliant disc. As the small worlds drift across the illuminated stellar disc they appear as dark dots or circles. They also block some of the light and heat emitted by the star.
The Moon sometimes covers the Sun – an event known as an eclipse - but we never see Earth's satellite as a small, dark circle crossing the face of the Sun. However, Gaia is far enough away to observe such a transit.
Image above: Gaia's perspective on the lunar transit. Image courtesy of F. Mignard, Observatoire de la Côte d'Azur, Nice.
Although its sensitive optics must be pointed well away from the Sun and Moon, Gaia's temperature sensors (thermistors) will be able to detect a lunar transit that will not be visible to any human eye or other spacecraft.
For more than 10 hours on 6 November, a near perfect alignment between Gaia, the Moon and the Sun will enable the star mapping spacecraft to chart how its temperature changes during the transit.
A lunar transit as seen by Gaia
Video above: A lunar transit as seen by Gaia. Video Credits: Courtesy of F. Mignard, Observatoire de la Côte d'Azur, Nice.
In order to monitor its health and physical condition, thermistors monitor the temperature at many places in the Gaia spacecraft. A series of measurements is taken every minute and subsequently sent back to Earth. During the passage of the Moon in front of the Sun, the Gaia team expects to detect a noticeable drop in the spacecraft’s temperature.
During the first year of Gaia's science mission scientists have already seen small variations in the temperature data collected. The yearly change in solar distance due to the elliptical orbit of Gaia about the Sun results in a variation equivalent to ± 3.4% in the solar flux. This leads to a change of ± 1.2 °C in the temperature records.
Image above: Transit contacts. Image courtesy of F. Mignard, Observatoire de la Côte d'Azur, Nice.
Changes are also seen during the 6-hour spin period of Gaia. On the antenna, the temperature follows a very regular cyclical pattern, changing by 2 °C over each rotation-period.
The passage of 6 November 2015 will start at 08:18 UTC (GMT) with the first contact (outer contact) between the disc of the Moon and that of the Sun. The solar flux will gradually decrease for about 2 hours, until the Moon’s entire disc is visible in front of the Sun.
Over the next 6 hours the levels of incoming solar radiation will remain steady until the third contact. During the next two hours the Moon will move away from the solar disc and the event will end at 18:35 UTC.
Graphic above: Predicted drop in flux during the lunar transit. Image courtesy of F. Mignard, Observatoire de la Côte d'Azur, Nice.
The total duration of more than 10 hours equals 1.7 spin periods of the Gaia spacecraft. This should be enough to see a temperature drop of about 1.5 °C and to estimate the thermal inertia of the spacecraft’s components.
No temperature increase is expected to be measurable in the most insulated part of the spacecraft, but the Gaia team is looking forward to examining carefully the temperature records to see what really happened.
Gaia's orbit at L2, 1.5 million km from Earth in the anti-Sun direction, was aligned so that the number of lunar transits would be minimised and the spacecraft’s thermal environment would be as stable as possible. However, a similar celestial conjunction will occur in May 2016, and grazing transits, when only a fraction of the Moon’s disc will cover the Sun, are predicted for April 2016 and February 2019.
For more information about Gaia mission, visit: http://www.esa.int/Our_Activities/Space_Science/Gaia
Vodcast: Charting the Galaxy - from Hipparcos to Gaia: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=45772&fattributeid=885
Little books of Gaia: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35010
Make a Gaia model: http://www.rssd.esa.int/index.php?project=Gaia&page=Gaia_model
Explore stellar neighbourhood in 3D: http://workshop.chromeexperiments.com/stars/
Gaia launch campaign photos: http://sci.esa.int/gaia-launch-campaign-photos/
Images (mentioned), Graphic (mentioned), Video (mentioned), Text, Credits: ESA/Timo Prusti/Observatoire de la Côte d'Azur/François
Publié par Orbiter.ch à 07:14
NASA's RapidScat Celebrates One-Year Anniversary
NASA - ISS-RapidScat mission logo.
November 7, 2015
Where do predictions for regional weather patterns come from? For one source, look to the ocean. About 70 percent of Earth's surface is covered in oceans, and changes in ocean winds are good predictors of many weather phenomena on small and large scales.
NASA's ISS-RapidScat instrument, which last month celebrated its one-year anniversary, helps make these ocean wind measurements to enhance weather forecasting and understanding of climate. The instrument was first activated on the International Space Station on Oct. 1, 2014.
Image above: RapidScat's antenna, lower right, was pointed at Hurricane Patricia as the powerful storm approached Mexico on Oct. 23, 2015. Image Credit: NASA.
"Especially with the recent hurricane season, our data have been appearing on weather websites around the world," said Glen Havens, project manager for the mission, based at NASA's Jet Propulsion Laboratory, Pasadena, California.
In its first year in action, the instrument has collected data on many severe storms, including typhoons and tropical cyclones. RapidScat has proven valuable for tracking the Southern Hemisphere's hurricane season and the Northern Hemisphere's winter storm season.
Most recently, RapidScat played a role in tracking Hurricane Patricia, which loomed over Mexico in October. Patricia was the strongest hurricane ever recorded in the Western Hemisphere, with maximum winds of 200 mph (320 kilometers per hour). When it first made landfall on the Pacific coast of Mexico on Oct. 23, it was a destructive Category 5 storm.
Image above: RapidScat's antenna, lower right, was pointed at Hurricane Patricia as the powerful storm approached Mexico on Oct. 23, 2015. Image Credit: NASA.
Worldwide, many meteorological agencies include RapidScat data in the ensemble of data sets used to create forecasts. The agencies include the U.S. Navy, the National Oceanographic and Atmospheric Administration (NOAA), and the European Organization for the Exploitation of Meteorological Satellites.
High wind warnings, to which RapidScat data contribute, are especially important for anyone involved in shipping and sailing. Wind information from RapidScat can also be useful for enthusiasts of water sports.
"People who go sailing, and sometimes even surfers, look at RapidScat data to find where big waves are," said Stacey Boland, project systems engineer for RapidScat at JPL.
RapidScat measures winds that are just above the ocean surface. The instrument is a Ku-band scatterometer that transmits pulses of microwave energy toward Earth. The surface of Earth reflects this signal, and RapidScat measures the strength of the pulse that comes back. Stronger return signals from the ocean indicate larger waves. The return signal also carries information about wind direction.
ISS-RapidScat in action. Animation Credit: NASA
Most scatterometers are launched in sun-synchronous orbits, such that each time they fly over the same place on Earth, it's at the same local time. But because RapidScat is mounted on the space station, which is not in a sun-synchronous orbit, it sees different places at different local times. The instrument samples all local times of day over the course of about two months, allowing scientists to learn more about how winds vary over the course of a day for a given location.
Another unique aspect of the mission is that the instrument was constructed using hardware built in the 1990s. Engineers adapted hardware that was originally built to test QuikScat, which was launched in 1999 into a sun-synchronous orbit. They added a smaller reflector antenna and a new interface to the repurposed instrument to make it work on the space station.
Repurposing the QuikScat test hardware significantly reduced the cost of the mission compared to what it would have been if the instrument had been built from scratch. It also allowed for a relatively quick turnaround time for building the instrument: A mere two years from approval to launch.
The RapidScat team addressed challenges that come with using older technology, such as the radar receiver electronics. But the "plucky radar" system, as Havens calls it, continues collecting science data and sending it back to Earth.
"We immediately started getting high-quality data after the instrument began operating," said Howard Eisen of JPL, who served as project manager at the beginning of the mission.
The instrument resides on the Columbus module on the space station, and will stay there until at least early 2017.
For more information on RapidScat, visit:
http://winds.jpl.nasa.gov/missions/RapidScat/ and http://www.nasa.gov/rapidscat
For more information about NASA's Earth science activities, visit: http://www.nasa.gov/earth
Images (mentioned), Animation (mentioned), Text, Credits: NASA/JPL/Alan Buis/Elizabeth Landau.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 06:59
vendredi 6 novembre 2015
A Galaxy at the Center of the Hubble Tuning Fork
NASA - Hubble Space Telescope patch.
Nov. 6, 2015
This galaxy is known as Mrk 820 and is classified as a lenticular galaxy — type S0 on the Hubble Tuning Fork. The Hubble Tuning Fork is used to classify galaxies according to their morphology. Elliptical galaxies look like smooth blobs in the sky and lie on the handle of the fork. They are arranged along the handle based on how elliptical they are, with the more spherical galaxies furthest from the tines of the fork, and the more egg-shaped ones closest to the end of the handle where it divides. The two prongs of the tuning fork represent types of unbarred and barred spiral galaxies.
Lenticular galaxies like Mrk 820 are in the transition zone between ellipticals and spirals and lie right where the fork divides. A closer look at the appearance of Mrk 820 reveals hints of a spiral structure embedded in a circular halo of stars.
Surrounding Mrk 820 in this image is a good sampling of other galaxy types, covering almost every type found on the Hubble Tuning Fork, both elliptical and spiral. Most of the smears and specks are distant galaxies, but the prominent bright object at the bottom is a foreground star called TYC 4386-787-1.
Hubble orbiting Earth
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.
For images and more information about Hubble, visit: http://www.nasa.gov/hubble and http://hubblesite.org/ and http://www.spacetelescope.org/
Image, Video, Credits: ESA/Hubble & NASA and N. Grogin (STScI)/Acknowledgement: Judy Schmidt/Text Credits: European Space Agency/Ashley Morrow.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 14:30
Swift Spots its Thousandth Gamma-ray Burst
NASA - Swift Mission patch.
Nov. 6, 2015
Image above: GRB 151027B, Swift's 1,000th burst (center), is shown in this composite X-ray, ultraviolet and optical image. X-rays were captured by Swift's X-Ray Telescope, which began observing the field 3.4 minutes after the Burst Alert Telescope detected the blast. Swift's Ultraviolet/Optical Telescope (UVOT) began observations seven seconds later and faintly detected the burst in visible light. The image includes X-rays with energies from 300 to 6,000 electron volts, primarily from the burst, and lower-energy light seen through the UVOT's visible, blue and ultraviolet filters (shown, respectively, in red, green and blue). The image has a cumulative exposure of 10.4 hours. Image Credits: NASA/Swift/Phil Evans, Univ. of Leicester.
NASA's Swift spacecraft has detected its 1,000th gamma-ray burst (GRB). GRBs are the most powerful explosions in the universe, typically associated with the collapse of a massive star and the birth of a black hole.
"Detecting GRBs is Swift's bread and butter, and we're now at 1,000 and counting," said Neil Gehrels, the Swift principal investigator at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The spacecraft remains in great shape after nearly 11 years in space, and we expect to see many more GRBs to come."
A GRB is a fleeting blast of high-energy light, often lasting a minute or less, occurring somewhere in the sky every couple of days. Scientists are looking for exceptional bursts that offer the deepest insights into the extreme physical processes at work.
Image above: This illustration shows the ingredients of the most common type of gamma-ray burst. The core of a massive star (left) has collapsed, forming a black hole that sends a jet moving through the collapsing star and out into space at near the speed of light. Radiation across the spectrum arises from hot ionized gas in the vicinity of the newborn black hole, collisions among shells of fast-moving gas within the jet, and from the leading edge of the jet as it sweeps up and interacts with its surroundings. Image Credits: NASA's Goddard Space Flight Center.
Shortly before 6:41 p.m. EDT on Oct. 27, Swift's Burst Alert Telescope detected the 1,000th GRB as a sudden pulse of gamma rays arising from a location toward the constellation Eridanus. Astronomers dubbed the event GRB 151027B, after the detection date and the fact that it was the second burst of the day. Swift automatically determined its location, broadcast the position to astronomers around the world, and turned to investigate the source with its own sensitive X-ray, ultraviolet and optical telescopes.
Astronomers classify GRBs by their duration. Like GRB 151027B, roughly 90 percent of bursts are of the "long" variety, where the gamma-ray pulse lasts more than two seconds. They are believed to occur in a massive star whose core has run out of fuel and collapsed into a black hole. As matter falls toward the newly formed black hole, it launches jets of subatomic particles that move out through the star's outer layers at nearly the speed of light. When the particle jets reach the stellar surface, they emit gamma rays, the most energetic form of light. In many cases, the star is later seen to explode as a supernova.
"Short" bursts last less than two seconds -- and sometimes just thousandths of a second. Swift observations provide strong evidence these events are caused by mergers of orbiting neutron stars or black holes.
Artist's view of Swift spacecraft. Image Credit: NASA/GSFC
Once a GRB is identified, the race is on to observe its fading light with as many instruments as possible. Based on alerts from Swift, robotic observatories and human-operated telescopes turn to the blast site to measure its rapidly fading afterglow, which emits X-rays, ultraviolet, visible and infrared light, and radio waves. While optical afterglows are generally faint, they can briefly become bright enough to be seen with the unaided eye.
"Over the years, astronomers have constantly refined their techniques to get their telescopes onto the burst site in the shortest possible time," said John Nousek, Swift’s director of mission operations and a professor of astronomy and astrophysics at Penn State University in University Park, Pennsylvania. "In fact, the process to follow up Swift GRB alerts is as productive as ever."
GRB 151027B provides a perfect example. Five hours after the Swift alert, the burst location first became visible from the European Southern Observatory (ESO) in Paranal, Chile. There a team led by Dong Xu of the Chinese National Astronomical Observatories in Beijing captured the afterglow's visible light using the Very Large Telescope's X-shooter spectrograph. The ESO observations show that light from the burst had been traveling to us for more than 12 billion years, placing it in the most distant few percent of GRBs Swift has recorded.
Astronomers now have distance measurements for about 30 percent of Swift GRBs, which makes it possible to investigate how these powerful events are distributed across space and time. The distance record is held by GRB 090429B, which exploded at the dawn of star formation in the universe. Its light took more than 13 billion years to reach Earth.
Image above: This illustration shows the positions of 1,000 Swift GRBs on an all-sky map oriented so that the plane of our galaxy, the Milky Way, runs across the center. Bursts are color coded by year, and the location of GRB 151027B is shown at lower right. An annual tally of the number of bursts Swift has detected appears below the label for each year. Background: An infrared view from the Two Micron All-Sky Survey.
Image Credits: NASA's Goddard Space Flight Center and 2MASS/J. Carpenter, T. H. Jarrett, and R. Hurt.
In addition to its GRB studies, Swift conducts multiwavelength observations of a wide array of astrophysical phenomena, from nearby comets and asteroids to faraway quasars and blazars, galaxies where supermassive black holes produce unpredictable high-energy flares.
"Swift is an amazingly versatile observatory, with gamma-ray burst detections every week, target-of-opportunity observations every day, and with a vast users' community covering all fields of astronomy," said Patrizia Caraveo, director of research at the Italian National Institute for Astrophysics in Milan and a co-investigator on Swift.
"Swift has been a fabulous discovery machine, finding previously unknown types of outbursts from stars, galaxies and from gamma-ray bursts themselves," said Julian Osborne, who leads the U.K. Swift team at the University of Leicester. "It's great to see our national contributions to the mission's X-ray and UV/optical telescopes having such a big impact."
With new types of astronomical observatories ramping up, Swift is poised to take on a new role. Ghostly particles called neutrinos have been detected from outside the solar system, and soon astronomers expect that gravitational wave observatories will detect the first ripples in space-time, a phenomenon predicted by Einstein's relativity theory. Swift scientists plan to use the satellite's capabilities to search for high-energy light associated with neutrino and gravitational wave sources.
Swift was launched on Nov. 20, 2004. Managed by NASA Goddard, the mission is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corporation in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional contributions from Germany and Japan.
Gamma-Ray Bursts: http://www.nasa.gov/subject/8730/gammaray-bursts
For more information about Swift mission, visit: http://www.nasa.gov/mission_pages/swift/main/index.html
Images 8mentioned), Text, Credits: NASA's Goddard Space Flight Center/Francis Reddy/Ashley Morrow.
Publié par Orbiter.ch à 14:21
Pair of NASA Astronauts Wrap Up Second Spacewalk
ISS - Expedition 45 Mission patch / NASA - Extra Vehicular Activities (EVA) patch.
November 6, 2015
Image above: NASA Astronauts Scott Kelly (left) and Kjell Lindgren will conduct a spacewalk today to upgrade and service the International Space Station. Image Credit: NASA TV.
NASA astronauts Scott Kelly and Kjell Lindgren ended their spacewalk at 2:10 p.m. EST with the repressurization of the U.S. Quest airlock. The astronauts restored the port truss (P6) ammonia cooling system to its original configuration, the main task for today’s spacewalk. They also returned ammonia to the desired levels in both the prime and back-up systems.
Image above: Astronauts Scott Kelly and Kjell Lindgren translate along the port truss structure back to the Quest airlock after completing cooling system servicing work. Image Credit: NASA TV.
In a minor departure from the planned tasks, the astronauts ran out of time to cinch and cover a spare radiator known as the Trailing Thermal Control Radiator. The radiator, which Lindgren retracted earlier in the spacewalk, was fully redeployed and locked into place in a dormant state.
Image above: Spacewalker Scott Kelly works on cables in the P6 truss structure to restore its cooling system back to its original configuration. Image Credit: NASA TV.
The radiator had been deployed during a November 2012 spacewalk by astronauts Sunita Williams and Aki Hoshide as they tried to isolate a leak in the truss’ cooling supply by re-plumbing the system to the backup radiator. The leak persisted and was subsequently traced to a different component that was replaced during a spacewalk in May 2013.
Outdoor Activity on the Space Station
The 7 hour and 48 minute spacewalk was the second for both astronauts, and the 190th in support of assembly and maintenance of the orbiting laboratory. Crew members have now spent a total of 1,192 hours and 4 minutes working outside the orbital laboratory.
One-Year Crew: https://www.nasa.gov/content/one-year-crew/
Expedition 45: https://www.nasa.gov/mission_pages/station/expeditions/expedition45/
For more information about the International Space Station, visit:
Images (mentioned), Video, Text, Credits: NASA/NASA TV/Mark Garcia.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 12:13
jeudi 5 novembre 2015
NASA’s New Horizons Completes Record-Setting Kuiper Belt Targeting Maneuvers
NASA - New Horizons Mission logo.
Nov. 5, 2015
NASA’s New Horizons spacecraft has successfully performed the last in a series of four targeting maneuvers that set it on course for a potential January 2019 encounter with 2014 MU69. This ancient body in the Kuiper Belt is more than a billion miles beyond Pluto; New Horizons will explore it if NASA approves an extended mission.
Image above: Getting the data: Following the last in a series of four maneuvers targeting NASA's New Horizons spacecraft toward Kuiper Belt object 2014 MU69, flight controller George Lawrence monitors spacecraft data as it streams into the New Horizons Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory on Nov. 4, 2015. Image Credits: NASA/JHUAPL/SwRI.
The four propulsive maneuvers were the most distant trajectory corrections ever performed by any spacecraft. The fourth maneuver, programmed into the spacecraft’s computers and executed with New Horizons’ hydrazine-fueled thrusters, started at approximately 1:15 p.m. EST on Wednesday, Nov. 4, and lasted just under 20 minutes. Spacecraft operators at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, began receiving data through NASA’s Deep Space Network just before 7 p.m. EST on Wednesday indicating the final targeting maneuver went as planned.
The maneuvers didn’t speed or slow the spacecraft as much as they “pushed” New Horizons sideways, giving it a 57 meter per second (128 mile per hour) nudge toward the Kuiper Belt object (KBO). That’s enough to allow New Horizons to intercept MU69 in just over three years.
"This is another milestone in the life of an already successful mission that's returning exciting new data every day," said Curt Niebur, New Horizons program scientist at NASA Headquarters in Washington. "These course adjustments preserve the option of studying an even more distant object in the future, as New Horizons continues its remarkable journey."
Graphic above: Path to a KBO: Projected route of NASA’s New Horizons spacecraft toward 2014 MU69, which orbits in the Kuiper Belt about 1 billion miles beyond Pluto. Planets are shown in their positions on Jan. 1, 2019, when New Horizons is projected to reach the small Kuiper Belt object. NASA must approve an extended mission for New Horizons to study the ancient KBO. Graphic Credits: NASA/JHUAPL/SwRI.
The New Horizons team will submit a formal proposal to NASA for the extended mission to 2014 MU69 in early 2016. The science team hopes to explore even closer to MU69 than New Horizons came to Pluto on July 14, which was approximately 7,750 miles (12,500 kilometers).
“New Horizons is healthy and now on course to make the first exploration of a building block of small planets like Pluto, and we’re excited to propose its exploration to NASA,” said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), Boulder, Colorado.
The KBO targeting maneuvers were the mission’s largest and longest, and carried out in a succession faster than any sequence of previous New Horizons engine burns. They were also accurate, performing almost exactly as they were designed and setting New Horizons on the course mission designers predicted. “The performance of each maneuver was spot on,” said APL’s Gabe Rogers, New Horizons spacecraft systems engineer and guidance and control lead.
New Horizons deep space probe. Image Credits: NASA/JHUAPL
The first three maneuvers were carried out on Oct. 22, 25 and 28. At the time of the Nov. 4 maneuver, New Horizons, speeding toward deeper space at more than 32,000 miles per hour, was approximately 84 million miles (135 million kilometers) beyond Pluto and nearly 3.2 billion miles (about 5.1 billion kilometers) from Earth. The spacecraft is currently 895 million miles (1.44 billion kilometers) from MU69. All systems remain healthy and the spacecraft continues to transmit data stored on its digital recorders from its flight through the Pluto system in July.
For more information about New Horizons mission, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html
Solar System: http://www.nasa.gov/topics/solarsystem/index.html
Kuiper Belt: http://www.nasa.gov/subject/3151/kuiper-belt
Images (mentioned), Graphic (mentioned), Text, Credits: NASA/Tricia Talbert.
Publié par Orbiter.ch à 19:17
Spacewalkers Ready to Wrap Up Cooling System Repair Job
ISS - Expedition 45 Mission patch.
November 5, 2015
Two astronauts are ready to finish a cooling system repair job that was started three years ago on the outside of the International Space Station. NASA astronauts Scott Kelly and Kjell Lindgren will exit the U.S. Quest airlock Friday at 7:10 a.m. EST for about six hours and 30 minutes of spacewalking tasks.
Image above: A solar array is seen in the foreground as the International Space Station flies over an aurora. Image Credit: NASA.
Kelly and Lindgren are restoring the port truss cooling system back to its original configuration after leak repair work done in November 2012 by spacewalkers Suni Williams and Aki Hoshide. More leak repair work was done to the system during a May 2013 spacewalk by NASA astronauts Chris Cassidy and Tom Marshburn.
Kelly and Lindgren will also top off the cooling system’s ammonia levels using storage tanks. The Photovoltaic Thermal Control System dissipates heat generated at the space station from radiators attached to the truss structure. This will be the second spacewalk for both astronauts whose first was on Oct. 28.
Image above: NASA astronaut Scott Kelly snaps a quick space selfie during his first ever spacewalk on Oct 28, 2015. Image Credit: NASA.
Japanese astronaut Kimiya Yui and veteran cosmonaut Sergey Volkov will assist the spacewalkers into their spacesuits and the airlock before depressurization begins. Yui and Volkov will also welcome the spacewalkers back into the station at the end of their excursion.
Station Spacewalk Today; Debris Avoidance Maneuver Completed Thursday (Nov. 2012):
Spacewalk Under Way to Repair Ammonia Leak (May 2013):
NASA Astronauts Complete Their First Spacewalk 8Oct. 28, 2015):
One-Year Crew: https://www.nasa.gov/content/one-year-crew/
Expedition 45: https://www.nasa.gov/mission_pages/station/expeditions/expedition45/
For more information about the International Space Station, visit: http://www.nasa.gov/mission_pages/station/main/index.html
Images (mentioned), Text, Credits: NASA/Mark Garcia.
Publié par Orbiter.ch à 15:47
Hubble Uncovers the Fading Cinders of Some of Our Galaxy’s Earliest Homesteaders
NASA - Hubble Space Telescope patch.
Nov. 5, 2015
Using NASA’s Hubble Space Telescope to conduct a “cosmic archaeological dig” at the very heart of our Milky Way galaxy, astronomers have uncovered the blueprints of our galaxy’s early construction phase.
Peering deep into the Milky Way’s crowded central hub of stars, Hubble researchers have uncovered for the first time a population of ancient white dwarfs -- smoldering remnants of once-vibrant stars that inhabited the core. Finding these relics at last can yield clues to how our galaxy was built, long before Earth and our sun formed.
Image above: Ground-based view of the Milky Way’s central bulge, seen in the direction of the constellation Sagittarius. Giant dust clouds block most of the starlight coming from the galactic center. Hubble however, peered through a region (marked by the arrow) called the Sagittarius Window, which offers a keyhole view into the galaxy’s hub. Image Credit: A. Fujii.
The observations are the deepest, most detailed study of the galaxy’s foundational city structure— its vast central bulge that lies in the middle of a pancake-shaped disk of stars, where our solar system dwells.
As with any archaeological relic, the white dwarfs contain the history of a bygone era. They contain information about the stars that existed about 12 billion years ago that burned out to form the white dwarfs. As these dying embers of once-radiant stars cool, they serve as multi-billion-year-old time pieces that tell astronomers about the Milky Way’s groundbreaking years.
An analysis of the Hubble data supports the idea that the Milky Way’s bulge formed first and that its stellar inhabitants were born very quickly—in less than roughly 2 billion years. The rest of the galaxy’s sprawling disk of second- and third-generation stars grew more slowly in the suburbs, encircling the central bulge like a giant sombrero.
“It is important to observe the Milky Way’s bulge because it is the only bulge we can study in detail,” explained Annalisa Calamida of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, the science paper’s lead author. “You can see bulges in distant galaxies, but you cannot resolve the very faint stars, such as the white dwarfs. The Milky Way’s bulge includes almost a quarter of the galaxy’s stellar mass. Characterizing the properties of the bulge stars can then provide important information to understanding the formation of the entire Milky Way galaxy and that of similar, more distant galaxies.”
The Hubble survey also found slightly more low-mass stars in the bulge, compared to those in the galaxy’s disk population. “This result suggests that the environment in the bulge may have been different than the one in the disk, resulting in a different star-formation mechanism,” Calamida said.
The observations were so sensitive that the astronomers also used the data to pick out the feeble glow of white dwarfs. The team based its results on an analysis of 70 of the hottest white dwarfs detectable by Hubble in a small region of the bulge among tens of thousands of stars.
These stellar relics are small and extremely dense. They are about the size of Earth but 200,000 times denser. A teaspoon of white dwarf material would weigh about 15 tons. Their tiny stature makes them so dim that it would be as challenging as looking for the glow of a pocket flashlight located on the moon. Astronomers used the sharp Hubble images to separate the bulge stars from the myriad stars in the foreground of our galaxy’s disk by tracking their movements over time. The team accomplished this task by analyzing Hubble images of the same field of 240,000 stars, taken 10 years apart. The long timespan allowed the astronomers to make very precise measurements of the stars’ motion and pick out 70,000 bulge stars. The bulge’s stellar inhabitants move at a different rate than stars in the disk, allowing the astronomers to identify them.
The region surveyed is part of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) and is located 26,000 light-years away. The unusually dust-free location on the sky offers a unique keyhole view into the “downtown” bulge. Hubble’s Advanced Camera for Surveys made the observations in 2004 and 2011 through 2013.
Image above: Small section of Hubble's view of the dense collection of stars crammed together in the galactic bulge. The region surveyed is part of the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) field and is located 26,000 light-years away. Image Credits: NASA/ESA/STScI/SWEEPS Science Team.
“Comparing the positions of the stars from now and 10 years ago we were able to measure accurate motions of the stars,” said Kailash Sahu of STScI, and the study’s leader. “The motions allowed us to tell if they were disk stars, bulge stars, or halo stars.”
The astronomers identified the white dwarfs by analyzing the colors of the bulge stars and comparing them with theoretical models. The extremely hot white dwarfs appear bluer relative to sun-like stars. As white dwarfs age, they become cooler and fainter, becoming difficult even for sharp-eyed Hubble to detect.
“These 70 white dwarfs represent the peak of the iceberg,” Sahu said. “We estimate that the total number of white dwarfs is about 100,000 in this tiny Hubble view of the bulge. Future telescopes such as NASA’s James Webb Space Telescope will allow us to count almost all of the stars in the bulge down to the faintest ones, which today’s telescopes, even Hubble, cannot see.”
Images above: Hubble uncovered extremely faint and hot white dwarfs. This is a sample of 4 out of the 70 brightest white dwarfs spied by Hubble in the Milky Way's bulge. Astronomers picked them out based on their faintness, blue-white color, and motion relative to our sun. Images Credits: NASA/ESA/STScI/SWEEPS Science Team.
The team next plans to increase their sample of white dwarfs by analyzing other portions of the SWEEPS field. This should ultimately lead to a more precise estimate of the age of the galactic bulge. They might also determine if star formation processes in the bulge billions of years ago were different from what’s seen in the younger disk of our galaxy.
The team’s results appeared in the Sept. 1, 2015, issue of The Astrophysical Journal. A companion paper appeared in The Astrophysical Journal in 2014.
Hubble and the sunrise over Earth
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.
For images and more information about this study and Hubble, visit:
Images (mentioned), Video, Text, Credits: NASA/Space Telescope Science Institute/Donna Weaver/Ray Villard/ESA.
Publié par Orbiter.ch à 15:33
Shining a light on the aurora of Mars
ESA - Mars Express Mission patch.
5 November 2015
ESA’s Mars Express has shed new light on the Red Planet’s rare ultraviolet aurora by combining for the first time remote observations with in situ measurements of electrons hitting the atmosphere.
On Earth, auroras are often-spectacular light shows at high northern and southern polar latitudes as the solar wind interacts with Earth’s magnetic field.
As charged atomic particles from the Sun are drawn along Earth’s magnetic field, they collide with different molecules and atoms in the atmosphere to create dynamic, colourful curtains and rays in the sky, typically green and red, but sometimes including blues and violets.
Mars Express aurora detections
These light displays are also found on other planets, including those with powerful magnetic fields such as Jupiter and Saturn. But they can even occur on planets with no magnetic field, such as Venus and Mars.
In the absence of a global magnetic field, solar particles can directly strike the planet’s atmosphere to generate an aurora.
While Mars no longer has a global magnetic field, residual magnetism in the crust is known in the highlands of the southern hemisphere from measurements made by NASA’s Mars Global Surveyor.
Even these weak fields can increase the chances of an aurora. Soon after it arrived in 2003, Mars Express became the first satellite to observe ultraviolet light over these regions during local night.
Now armed with 10 years of observations, scientists have detected ultraviolet auroras on many occasions, and have analysed in detail how and where they are produced in the martian atmosphere.
“With 10 years of data, we’ve gone much further than the initial detection, and we now have a better understanding of the characteristics and occurrences of this interesting phenomenon,” says Jean-Claude Gérard of the University of Liège, Belgium, lead author of the paper published in the Journal of Geophysical Research: Space Physics.
“The ultraviolet auroras turn out to be very rare and transient: they last only a few seconds. Even though Mars Express has passed over each location many times, detections at a given location do not seem to repeat at later times,” adds Lauriane Soret, also of the University of Liège and lead author of the paper published in Icarus.
From a total of 113 nightside orbits looking straight down on the planet, nine were confirmed to show auroras, with some multiple detections along individual orbits leading to a total of 16 detections.
Looking down, Mars Express can monitor their brightness over time, but observations through the atmosphere at an angle are required to determine the aurora altitudes. Three more auroras were observed in this way, with altitudes determined around an average of 137 km.
Mars’ night-time aurora
When the auroras were detected with its ultraviolet sensor, Mars Express also measured the energy of the electrons hitting the atmosphere at the position of the spacecraft.
By combining these observations, the scientists found that the auroras appear only under special conditions, near the boundary between open and closed magnetic field lines.
In addition, an unexpected displacement observed between the location of the electron bursts and that of the ultraviolet aurora indicate that the field lines guiding the electrons may be tilted from the vertical. ?
“It seems that the emissions are controlled by a special shape of the local magnetic field: as it starts to become open, it makes an umbrella shape, allowing access to the energised electrons,” explains Jean-Claude.
The incoming energetic electrons are accelerated by a transient electric field along the residual magnetic field lines to interact with the carbon dioxide molecules in the atmosphere, resulting in the ultraviolet emission observed by Mars Express.
“We have now also been able to use the particle values in our simulations of this process to reproduce the measured altitudes of the auroras,” says Lauriane.
“We’ve found that the ultraviolet auroras associated with known magnetic anomalies in Mars’ crust are confined, rare and transient events that vary in time and space. They are very different from the auroras seen on other planets.”
“By scouring the rich data from Mars Express, we now have a much better idea of how this type of martian aurora ‘works’, says Dmitri Titov, ESA’s Mars Express project scientist.
Notes for Editors
“Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express,” by Gérard et al. is published in the Journal of Geophysical Research: Space Physics, 120, doi:10.1002/2015JA021150
“SPICAM observations and modelling of Mars aurorae,” by L. Soret et al. is published in Icarus doi:10.1016/j.icarus.2015.09.023
The results were collected with the SPICAM and ASPERA instruments between 2004 and 2014. SPICAM is the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars and ASPERA is the Analyzer of Space Plasma and Energetic Atoms/Electron Spectrometer.
Looking at Mars: http://www.esa.int/Our_Activities/Space_Science/Mars_Express
Mars Express overview: http://www.esa.int/Our_Activities/Space_Science/Mars_Express_overview
Mars Express 10 year brochure: http://esamultimedia.esa.int/multimedia/publications/BR-312/
Images, Text, Credits: ESA/Based on data from J-C. Gérard et al (2015)/Spacecraft: ESA/ATG medialab; data: J-C. Gérard & L. Soret (2015)/Alex Lutkus.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 14:37
NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere
NASA - MAVEN Mission logo.
Nov. 5, 2015
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission has identified the process that appears to have played a key role in the transition of the Martian climate from an early, warm and wet environment that might have supported surface life to the cold, arid planet Mars is today.
MAVEN data have enabled researchers to determine the rate at which the Martian atmosphere currently is losing gas to space via stripping by the solar wind. The findings reveal that the erosion of Mars’ atmosphere increases significantly during solar storms. The scientific results from the mission appear in the Nov. 5 issues of the journals Science and Geophysical Research Letters.
Image above: Artist’s rendering of a solar storm hitting Mars and stripping ions from the planet's upper atmosphere. Image Credits: NASA/GSFC.
“Mars appears to have had a thick atmosphere warm enough to support liquid water which is a key ingredient and medium for life as we currently know it,” said John Grunsfeld, astronaut and associate administrator for the NASA Science Mission Directorate in Washington. “Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere. Learning what can cause changes to a planet’s environment from one that could host microbes at the surface to one that doesn’t is important to know, and is a key question that is being addressed in NASA’s journey to Mars.”
MAVEN measurements indicate that the solar wind strips away gas at a rate of about 100 grams (equivalent to roughly 1/4 pound) every second. "Like the theft of a few coins from a cash register every day, the loss becomes significant over time," said Bruce Jakosky, MAVEN principal investigator at the University of Colorado, Boulder. "We've seen that the atmospheric erosion increases significantly during solar storms, so we think the loss rate was much higher billions of years ago when the sun was young and more active.”
In addition, a series of dramatic solar storms hit Mars’ atmosphere in March 2015, and MAVEN found that the loss was accelerated. The combination of greater loss rates and increased solar storms in the past suggests that loss of atmosphere to space was likely a major process in changing the Martian climate.
The solar wind is a stream of particles, mainly protons and electrons, flowing from the sun's atmosphere at a speed of about one million miles per hour. The magnetic field carried by the solar wind as it flows past Mars can generate an electric field, much as a turbine on Earth can be used to generate electricity. This electric field accelerates electrically charged gas atoms, called ions, in Mars’ upper atmosphere and shoots them into space.
MAVEN has been examining how solar wind and ultraviolet light strip gas from of the top of the planet's atmosphere. New results indicate that the loss is experienced in three different regions of the Red Planet: down the "tail," where the solar wind flows behind Mars, above the Martian poles in a "polar plume," and from an extended cloud of gas surrounding Mars. The science team determined that almost 75 percent of the escaping ions come from the tail region, and nearly 25 percent are from the plume region, with just a minor contribution from the extended cloud.
Solar Wind Strips Martian Atmosphere
Video above: Created using data from NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, this visualization shows how the solar wind strips ions from the Mars' upper atmosphere into space. Video Credits: NASA-GSFC/CU Boulder LASP/University of Iowa.
Ancient regions on Mars bear signs of abundant water – such as features resembling valleys carved by rivers and mineral deposits that only form in the presence of liquid water. These features have led scientists to think that billions of years ago, the atmosphere of Mars was much denser and warm enough to form rivers, lakes and perhaps even oceans of liquid water.
Recently, researchers using NASA's Mars Reconnaissance Orbiter observed the seasonal appearance of hydrated salts indicating briny liquid water on Mars. However, the current Martian atmosphere is far too cold and thin to support long-lived or extensive amounts of liquid water on the planet's surface.
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Image Credit: NASA
"Solar-wind erosion is an important mechanism for atmospheric loss, and was important enough to account for significant change in the Martian climate,” said Joe Grebowsky, MAVEN project scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “MAVEN also is studying other loss processes -- such as loss due to impact of ions or escape of hydrogen atoms -- and these will only increase the importance of atmospheric escape.”
The goal of NASA's MAVEN mission, launched to Mars in November 2013, is to determine how much of the planet's atmosphere and water have been lost to space. It is the first such mission devoted to understanding how the sun might have influenced atmospheric changes on the Red Planet. MAVEN has been operating at Mars for just over a year and will complete its primary science mission on Nov. 16.
To view an animation simulating the loss of atmosphere and water on Mars:
For more information and images on Mars’ lost atmosphere, visit:
MAVEN Results Find Mars Behaving Like a Rock Star:
For more information about NASA’s MAVEN mission, visit: http://www.nasa.gov/maven
Images (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/GSFC/Nancy Neal-Jones/Bill Steigerwald/University of Colorado/Jim Scott.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 14:23
Europe comes together for space weather
Space Weather logo / ESA - European Space Agency patch.
5 November 2015
Working with scientists in 14 countries across Europe, ESA is developing a warning network that will help protect us from the effects of our Sun’s activity.
ESA’s Space Situational Awareness efforts now generate almost 60 ‘products’ – including high-quality measurements, forecasts, alerts and expert analysis – from teams participating in the Agency’s space weather network, heading for over 140 next year.
Many use realtime data on our Sun and the resulting disturbances detected in the environment around Earth, our atmosphere and down to the surface.
The raw information is gathered from a large and increasing number of ground and space sensors, and delivered through a network of Expert Service Centres, established by ESA to combine and build on existing facilities in Member States.
“The Centres federate the wealth of space weather expertise and capabilities that exist at the national level,” says ESA’s Alexi Glover, responsible for network development.
“This provides a large added value not only to our Member States and their industries but to Europe as a whole.”
Watching out for space weather
Numerous sectors are potentially affected by space weather in Europe’s economy, ranging from telecoms, broadcasting, drilling, exploration, navigation and power distribution, the latter especially at northern latitudes.
The Sun causes ‘storms’ within Earth’s magnetosphere when giant eruptions from the Sun’s outer atmosphere – coronal mass ejections (CMEs) – wash across our planet. The most recent very large event occurred in 2012, though it missed Earth. Lesser CMEs happen regularly and do reach the planet, affecting daily economic activities.
ESA launched its space awareness effort in 2009 in part to develop a Europe-wide capability to monitor, study and warn about such space weather effects.
Building a robust European network
“The current expansion of the network, interconnected via ESA’s Space Weather Coordination Centre in Brussels, Belgium, brings to fruition several years of work,” says Juha-Pekka Luntama, ESA’s space weather manager.
ESA’s Proba-2 Sun-watching satellite also contributes. In the near future, instruments on satellites operated by a number of ESA partners will be flown, and the Agency is studying a dedicated mission for early warning of coronal mass ejections and other space weather events.
In 2016, ESA’s space weather network will grow to encompass over 140 separate products providing scientific and pre-operational applications as part of 39 services provided to users.
Space weather business
“The development of space-weather precursor services in Europe is a growing success, and also promises commercial opportunities that we could not foresee just a few years ago,” says Juha-Pekka.
In addition to business and government agency uses of space weather data, he points to opportunities for application developers who could use realtime information to serve, for example, the tourist industry, as many Nordic hotels and tour operators would like to offer predictable aurora viewing.
Coronal mass ejections (CMEs): http://www.esa.int/ESA_Multimedia/Images/2003/04/Coronal_mass_ejection_CME_blast_and_subsequent_impact_at_Earth
SWE for professionals:
Proba-2 Science Centre: http://proba2.sidc.be/
Space Weather portal: http://swe.ssa.esa.int/
ESA Space Environments and Effects: http://space-env.esa.int/
Redu station: http://www.esa.int/Our_Activities/Operations/Estrack/Redu_station
Space weather: http://www.esa.int/Our_Activities/Space_Science/Cluster/Space_weather2
International GNSS Service (IGS): http://igscb.jpl.nasa.gov/
International Space Environment Service: http://www.ises-spaceweather.org/
European Space Weather Portal: http://www.spaceweather.eu/
Images, Text, Credits: ESA/P.Carril - CC BY-SA IGO 3.0/Kate Arkless Gray/ROB/Royal Observatory Belgium.
Publié par Orbiter.ch à 06:20
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