vendredi 27 octobre 2017
Xenon in the SPS: First tests for a photon factory
CERN - European Organization for Nuclear Research logo.
27 Oct 2017
Image above: The Super Proton Synchrotron (SPS), pictured during a recent technical stop. (Image: Max Brice/CERN).
Accelerator operators can perform amazing acrobatics with particle beams, most recently in the Super Proton Synchrotron (SPS), CERN’s second-largest accelerator. For the first time, they have successfully injected a beam of partially ionised xenon particles into the SPS and accelerated it. Before they were injected into the SPS, these atoms were stripped of 39 of their 54 electrons.
During the first test, which took place in September, the beam was injected into the SPS ring and circulated for about one second. Now, the beam has been accelerated for the first time, reaching an energy of 81.6 gigaelectronvolts (GeV) per nucleon.
What makes this performance so remarkable is that these beams of partially ionised xenon atoms are extremely fragile and have a very short lifespan. If an atom loses just one of its 15 electrons, it changes orbit and is lost. “The SPS vacuum is not quite as high as that of the LHC. The residual gas molecules present in the vacuum chamber disturb the beam, which explains why it is lost quite quickly,” says Reyes Alemany, who is responsible for the SPS tests. “But keeping the beam going for one cycle in the SPS is already a very promising result!”
So why are accelerator physicists experimenting with these atoms? It’s to test a novel idea: a high-intensity source of gamma rays (photons with energies in the megaelectronvolt (MeV) range). This gamma factory, as it is known, would generate photons of up to 400 MeV in energy and at intensities comparable to those of synchrotrons or X-ray free-electron lasers (XFELs). XFELs produce high-intensity beams of X-rays – that is, photons of an energy of less than about 100 kiloelectronvolts (keV).
“A source of that kind would pave the way for studies never done before in fundamental physics, in the fields of quantum electrodynamics or dark matter research,” explains Witold Krasny, a CNRS physicist and CERN associate who founded the project and leads the work group. “It also opens the door for industrial and medical applications.” It could even serve as a test bench for a future neutrino factory or muon collider.
The principle is to accelerate partially ionised atoms and then excite them using a laser. As they return to their stable state, the atoms release high-energy photons.
Image above: Particle Accelerators at CERN:
LEP: Large Electron-Positron Collider
SPS: Super Proton Synchrotron
AAC: Antiproton Accumulator Complex
ISOLDE: Isotope Separator Online Device
PSB: Proton Synchrotron Booster
PS : Proton Synchrotron LPI: Lep Pre-Injector
EPA: Electron Positron Accumulator
LIL: Lep Injector Linac
LINAC2: Linear Accelerator 2
LINAC3: Linear Accelerator 3
LEAR: Low Energy Antiproton RingRudolf Ley, PS Division, CERN
Image Credit: CERN.
The team took advantage of the presence of xenon in the accelerator complex to carry out this first test without disrupting the other ongoing physics programmes. Next year, during the LHC heavy-ion run, the team will repeat the experiment using ionised lead atoms, which will be stripped of all but one or two electrons. Those beams will be much more stable; having fewer electrons means that the atoms are less at risk of losing them. In addition, their electrons are only found in the “K” shell, the closest to the nucleus, and therefore have a stronger link to the nucleus than in the xenon atoms. The heavy-ion beams could be accelerated first in the SPS and then in the LHC.
The gamma factory project is part of the Physics Beyond Colliders study, which was launched in 2016 with the goal of investigating all possible non-collider experiments, particularly those that could be done using CERN’s accelerator complex. Hundreds of scientists are expected to attend the annual Physics Beyond Colliders conference at CERN at the end of November.
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.
Super Proton Synchrotron (SPS): http://home.cern/about/accelerators/super-proton-synchrotron
For more information about European Organization for Nuclear Research (CERN), Visit: http://home.cern/
Images (mentioned), Text, Credits: CERN/Corinne Pralavorio.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 16:12
How Does Your Space Garden Grow?
ISS - Veggie Mission patch.
Oct. 27, 2017
Image above: Three different varieties of plants growing in the Veggie plant growth chamber on the International Space Station were harvested this morning. Photo credits: NASA/ISS.
Early Friday morning, astronauts onboard the International Space Station were busy at work, harvesting three varieties of leafy greens from the Veggie growth chamber and installing the next generation of plant research – the high-tech Advanced Plant Habitat.
Simultaneously Growing Three Plant Varieties a First for Veggie
The Veggie plant growth team kicked it up a notch with their sixth round of crops grown aboard the International Space Station with experiment VEG-03D. For the first time, three different plant varieties are simultaneously growing in the Veggie chamber.
On Oct. 27, station astronaut Joe Acaba harvested Mizuna mustard, Waldmann’s green lettuce and Outredgeous Red Romaine lettuce, providing himself and his crew with the makings of a salad — once they top it with salad dressing sent up by the ground crew at Kennedy Space Center in Florida, of course.
Image above: Charles Spern, project manager on the Engineering Services Contract, communicates instructions for the Veggie system to astronaut Joe Acaba on the International Space Station. Spern is in the Experiment Monitoring Room in the Space Station Processing Facility at Kennedy Space Center in Florida. Three different varieties of plants from the Veg-03D plant experiment were harvested. Photo credit: NASA/Amanda Griffin.
“It's an impressive harvest. Joe did a great job!" said Veggie project manager Nicole Dufour.
“As a continuation of our Veg-03 tech demo efforts, we wanted to try something a little bit different. Building on some of our current ground testing, we decided to attempt a mixed crop. We were hoping that the visual diversity of the plants would be more enjoyable to the crew, as well as the variety of flavors offered by the different types of leafy greens.”
During the harvest, Acaba only clipped about half of the leafy greens, leaving the rest to continue growing for a future yield. This technique, called cut-and-come-again repetitive harvesting, allows the crew to have access to fresh produce for a longer period of time.
Growing three different crops at the same time wasn't without its challenges.
“The biggest complication we have faced thus far has been how well the Mizuna has been growing," Dufour said. "Its long, spear-like stalks tend to get caught in the bellows as the crew opens and closes the unit to water the plants.”
After the Veggie harvest, the crew kept on their virtual overalls and went on to install the Advanced Plant Habitat (APH), NASA’s largest plant growth chamber.
Advanced Plant Habitat Turns On, Turns Up Research
As Acaba switched gears from Veggie to the new plant habitat around 5:45 a.m. EDT Friday, APH project manager Bryan Onate and his team walked Acaba through procedures to install the plant habitat into an Expedite the Processing of Experiments to Space Station, or EXPRESS, rack in the Japanese Experiment Module Kibo.
"It's amazing that a plant growth system that began from a blank sheet of paper about five years ago now is installed on the space station," Onate said. "Plant scientists are really going to be able to learn utilizing this system."
The plant habitat is a fully enclosed, closed-loop system with an environmentally controlled growth chamber. It uses red, blue and green LED lights, and broad spectrum white LED lights. The system's more than 180 sensors will relay real-time information, including temperature, oxygen content and moisture levels back to the team at Kennedy.
Image above: A test unit, or prototype, of NASA's Advanced Plant Habitat (APH) with its first initial grow test in the Space Station Processing Facility at Kennedy Space Center in Florida. The taller plants are dwarf what and the smaller plants are Arabidopsis. Developed by NASA and ORBITEC of Madison, Wisconsin, the APH is the largest plant chamber built for the agency. Photo credit: NASA.
"APH will be the largest plant growth system on the space station," Howard Levine, the chief scientist in Kennedy's Utilization and Life Science Office who started working on APH seven years ago, said. "It will be capable of hosting multigenerational studies with environmental variables tracked and controlled in support of whole plant physiological testing and bioregenerative life support system investigations."
Once the team at Marshall completes an EXPRESS rack water flow test, the Kennedy team will power up the system. After the water cooling system with the APH passes the test, functional checkout of the plant habitat will begin and take about one week to complete.
Four power feeds to the plant habitat will be turned on and the Kennedy team will monitor the system's Plant Habitat Avionics Real-Time Manager, or PHARMER, for a response. This unique system provides real-time telemetry, remote commanding and photo downlink to the team at Kennedy.
Image above: Nicole Dufour, flight integration lead, communicates directly with astronaut Joe Acaba during installation of NASA’s Advanced Plant Habitat in the Japanese Kibo module on the International Space Station. Dufour is in the Experiment Monitoring Room in the Space Station Processing Facility at Kennedy Space Center in Florida. The procedures to install the system took about six hours. Photo credit: NASA/Amanda Griffin.
After the PHARMER has verified all subsystems are a go, space station crew members will install the science carrier and initiate the growth of test crops - Arabidopsis seeds, small flowering plants related to cabbage and mustard, and dwarf wheat - during an overlapping timetable of about five weeks. During this time, the system will be monitored for its capability to grow plants, capture and reuse water, and maintain the atmosphere in the growth chamber.
"The test will help us to determine if the planting procedure is good and the habitat is operating as designed," Onate said. "The results of plant growth in the habitat will be compared with the results of tests completed in the control unit here at Kennedy."
All of these preparations are leading up to the initiation of PH-01, which will grow five different types of Arabidopsis and is scheduled to launch on Orbital ATK's ninth commercial resupply mission to the space station.
The nutritional boost of fresh food and the psychological benefits of growing plants become paramount as the agency plans for future missions to deep space destinations.
Expedite the Processing of Experiments to Space Station, or EXPRESS: https://www.nasa.gov/mission_pages/station/research/experiments/608.html
Advanced Plant Habitat: http://go.nasa.gov/2mUSxSC
Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Images (mentioned), Text, Credits: NASA/Linda Herridge.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 15:34
September 2017's Intense Solar Activity Viewed From Space
NASA Space Weather logo.
Oct. 27, 2017
September 2017 saw a spate of solar activity, with the Sun emitting 27 M-class and four X-class flares and releasing several powerful coronal mass ejections, or CMEs, between Sept. 6-10. Solar flares are powerful bursts of radiation, while coronal mass ejections are massive clouds of solar material and magnetic fields that erupt from the Sun at incredible speeds.
The activity originated from one fast-growing active region — an area of intense and complex magnetic fields — as it travelled across the Sun’s Earth-facing side in concert with the star’s normal rotation. As always, NASA and its partners had many instruments observing the Sun from both Earth and space, enabling scientists to study these events from multiple perspectives.
With multiple views of solar activity, scientists can better track the evolution and propagation of solar eruptions, with the goal of improving our understanding of space weather. Harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel. On the other hand, depending on the direction they’re traveling in, CMEs can spark powerful geomagnetic storms in Earth’s magnetic field.
To better understand the fundamental processes that drive these events, and ultimately improve space weather forecasts, many observatories watch the Sun around the clock in dozens of different wavelengths of light. Each can reveal unique structures and dynamics in the Sun’s surface and lower atmosphere, giving researchers an integrated picture of the conditions driving space weather.
Scientists also have their eyes on the Sun’s influence on Earth and even other planets. Effects from September’s solar activity were observed as Martian aurora and across the globe on Earth, in the form of events known as ground-level enhancements — showers of neutrons detected on the ground, produced when energetic particles accelerated by a solar eruption stream along Earth’s magnetic field lines and flood the atmosphere.
The imagery below shows the wide swath of views available to researchers as they use these recent space weather events to learn more and more about the star we live with.
Animation Credits: NOAA/GOES
NOAA’s Geostationary Operational Environmental Satellite-16, or GOES-16, watches the Sun’s upper atmosphere — called the corona — at six different wavelengths, allowing it to observe a wide range of solar phenomena. GOES-16 caught this footage of an X9.3 flare on Sept. 6, 2017. This was the most intense flare recorded during the current 11-year solar cycle. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc. GOES also detected solar energetic particles associated with this activity.
Animation Credits: NASA/GSFC/SDO
NASA’s Solar Dynamics Observatory watches the corona at 10 different wavelengths on a 12-second cadence, enabling scientists to track highly dynamic events on the Sun such as these X2.2 and X9.3 solar flares. These images were captured on Sept. 6, 2017, in a wavelength of extreme ultraviolet light that shows solar material heated to over one million degrees Fahrenheit. The X9.3 flare was the most intense flare recorded during the current solar cycle.
Animation Credits: JAXA/NASA/Hinode/SAO/MSU/Joy Ng
JAXA/NASA’s Hinode caught this video of an X8.2 flare on Sept. 10, 2017, the second largest flare of this solar cycle, with its X-ray Telescope. The instrument captures X-ray images of the corona to help scientists link changes in the Sun’s magnetic field to explosive solar events like this flare. The flare originated from an extremely active region on the Sun’s surface — the same region from which the cycle’s largest flare came.
Animation Credits: NASA/GSFC/STEREO/Joy Ng
Key instruments aboard NASA’s Solar and Terrestrial Relations Observatory, or STEREO, include a pair of coronagraphs — instruments that use a metal disk called an occulting disk to study the corona. The occulting disk blocks the Sun’s bright light, making it possible to discern the detailed features of the Sun’s outer atmosphere and track coronal mass ejections as they erupt from the Sun.
On Sept. 9, 2017, STEREO watched a CME erupt from the Sun. The next day, STEREO observed an even bigger CME, which was associated with the X8.2 flare of the same day. The Sept. 10 CME traveled away from the Sun at calculated speeds as high as 7 million mph, and was one of the fastest CMEs ever recorded. The CME was not Earth-directed. It side-swiped Earth’s magnetic field, and therefore did not cause significant geomagnetic activity. Mercury is in view as the bright white dot moving leftwards in the frame.
Animation Credits: ESA/NASA/SOHO/Joy Ng
Like STEREO, ESA/NASA’s Solar and Heliospheric Observatory, or SOHO, uses a coronagraph to track solar storms. SOHO also observed the CMEs that occurred during Sept. 9-10, 2017; multiple views provide more information for space weather models. As the CME expands beyond SOHO’s field of view, a flurry of what looks like snow floods the frame. These are high-energy particles flung out ahead of the CME at near-light speeds that struck SOHO’s imager.
Animation Credits: NASA/GSFC/LMSAL/Joy Ng
NASA’s Interface Region Imaging Spectrometer, or IRIS, peers into a lower level of the Sun’s atmosphere — called the interface region — to determine how this area drives constant changes in the Sun’s outer atmosphere. The interface region feeds solar material into the corona and solar wind: In this video, captured on Sept. 10, 2017, jets of solar material appear like tadpoles swimming down toward the Sun’s surface. These structures — called supra-arcade downflows — are sometimes observed in the corona during solar flares, and this particular set was associated with the X8.2 flare of the same day.
Animation Credits: NASA/GSFC/Univ. of Colorado/LASP/Joy Ng
NASA’s Solar Radiation and Climate Experiment, or SORCE, collected this data on total solar irradiance, the total amount of the Sun’s radiant energy, throughout Sept. 2017. While the Sun produced high levels of extreme ultraviolet light, SORCE actually detected a dip in total irradiance during the month’s intense solar activity. A possible explanation for this observation is that over the active regions — where solar flares originate — the darkening effect of sunspots is greater than the brightening effect of the flare’s extreme ultraviolet emissions. As a result, the total solar irradiance suddenly dropped during the flare events. Scientists gather long-term solar irradiance data in order to understand not only our dynamic star, but also its relationship to Earth’s environment and climate. NASA is ready to launch the Total Spectral solar Irradiance Sensor-1, or TSIS-1, this December to continue making total solar irradiance measurements.
Image above: Credits: NASA/GSFC/Univ. of Colorado/LASP
The intense solar activity also sparked global aurora on Mars more than 25 times brighter than any previously seen by NASA’s Mars Atmosphere and Volatile Evolution, or MAVEN, mission. MAVEN studies the Martian atmosphere’s interaction with the solar wind, the constant flow of charged particles from the Sun. These images from MAVEN’s Imaging Ultraviolet Spectrograph show the appearance of bright aurora on Mars during the September solar storm. The purple-white colors show the intensity of ultraviolet light on Mars’ night side before (left) and during (right) the event.
NOAA’s Geostationary Operational Environmental Satellite-16, or GOES-16: http://www.nasa.gov/goes
NASA’s Solar Dynamics Observatory (SDO): https://www.nasa.gov/mission_pages/sdo/main/index.html
JAXA/NASA’s Hinode: https://www.nasa.gov/mission_pages/hinode/mission.html
NASA’s Solar and Terrestrial Relations Observatory, or STEREO: https://www.nasa.gov/mission_pages/stereo/main/index.html
ESA/NASA’s Solar and Heliospheric Observatory, or SOHO: https://www.nasa.gov/mission_pages/soho/overview/index.html
NASA’s Interface Region Imaging Spectrometer, or IRIS: https://www.nasa.gov/mission_pages/iris/index.html
NASA’s Solar Radiation and Climate Experiment, or SORCE: https://earthobservatory.nasa.gov/Features/SORCE/
NASA’s Mars Atmosphere and Volatile Evolution, or MAVEN: https://www.nasa.gov/mission_pages/maven/main/index.html
Animations (mentioned), Image (mentioned), Text, Credits: NASA/Sara Blumberg/Goddard Space Flight Center, by Lina Tran.
Publié par Orbiter.ch à 15:14
Hubble Digs into Cosmic Archaeology
NASA Hubble Space Telescope patch.
Oct. 27, 2017
This NASA/ESA Hubble Space Telescope image is chock-full of galaxies. Each glowing speck is a different galaxy, except the bright flash in the middle of the image which is actually a star lying within our own galaxy that just happened to be in the way. At the center of the image lies something especially interesting, the center of the massive galaxy cluster called WHL J24.3324-8.477, including the brightest galaxy of the cluster.
The Universe contains structures on various scales — planets collect around stars, stars collect into galaxies, galaxies collect into groups, and galaxy groups collect into clusters. Galaxy clusters contain hundreds to thousands of galaxies bound together by gravity. Dark matter and dark energy play key roles in the formation and evolution of these clusters, so studying massive galaxy clusters can help scientists to unravel the mysteries of these elusive phenomena.
This infrared image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing program called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope to study. Such research will tell us more about our cosmic origins.
Hubble Space Telescope
For images and more information about Hubble, visit:
Animation, Image, Text, Credits: ESA/Hubble & NASA/Text Credits: European Space Agency/NASA/Karl Hille.
Publié par Orbiter.ch à 14:32
Prolific Earth Gravity Satellites End Science Mission
NASA & DLR - GRACE Mission patch.
October 27, 2017
After more than 15 productive years in orbit, the U.S./German GRACE (Gravity Recovery and Climate Experiment) satellite mission has ended science operations. During their mission, the twin GRACE satellites have provided unprecedented insights into how our planet is changing by tracking the continuous movement of liquid water, ice and the solid Earth.
GRACE made science measurements by precisely measuring the distance between its twin satellites, GRACE-1 and GRACE-2, which required that both spacecraft and their instruments be fully functional. Following an age-related battery issue on GRACE-2 in September, it became apparent by mid-October that GRACE-2's remaining battery capacity would not be sufficient to operate its science instruments and telemetry transmitter. Consequently, the decision was made to decommission the GRACE-2 satellite and end GRACE's science mission.
GRACE, a mission led by Principal Investigator Byron Tapley at the University of Texas at Austin, launched in March 2002 on a planned five-year mission to precisely map our planet's ever-changing gravity field. It has revealed how water, ice and solid Earth mass move on or near Earth's surface due to Earth's changing seasons, weather and climate processes, earthquakes and even human activities, such as from the depletion of large aquifers. It did thisby sensing minute changes in the gravitational pull caused by local changes in Earth's mass, which are due mostly to changes in how water is constantly being redistributed around our planet.
Image above: Illustration of the twin Gravity Recovery and Climate Experiment (GRACE) satellites in orbit. Image credits: NASA/JPL-Caltech.
"GRACE has provided paradigm-shifting insights into the interactions of our planet's ocean, atmosphere and solid Earth components," said Tapley. "It has advanced our understanding of the contribution of polar ice melt to global sea level rise and the amount of atmospheric heat absorbed by the ocean. Recent applications include monitoring and managing global water resources used for consumption, agriculture and industry; and assessing flood and earthquake hazards."
GRACE used a microwave ranging system to measure the change in distance between the twin satellites to within a fraction of the diameter of a human hair over 137 miles (220 kilometers). The ranging data were combined with GPS tracking for timing, star trackers for attitude information, and an accelerometer to account for non-gravitational effects, such as atmospheric drag and solar radiation. From these data, scientists calculated the planet's gravity field monthly and monitored its changes over time.
"GRACE was an excellent example of a research satellite mission that advanced science and also provided near-term societal benefits," said Michael Freilich, director of NASA's Earth Science Division at the agency's headquarters in Washington. "Using cutting-edge technology to make exquisitely precise distance measurements, GRACE improved our scientific understanding of our complex home planet, while at the same time providing information -- such as measurements related to groundwater, drought and aquifer water storage changes worldwide -- that was used in the U.S. and internationally to improve the accuracy of environmental monitoring and forecasts."
GRACE established that measuring the redistribution of mass around Earth is an essential observation for understanding the Earth system. GRACE's monthly maps of regional gravity variations have given scientists new insights into Earth system processes. Among its innovations, GRACE has monitored the loss of ice mass from Earth's ice sheets, improved understanding of the processes responsible for sea level rise and ocean circulation, provided insights into where global groundwater resources may be shrinking or growing and where dry soils are contributing to drought, and monitored changes in the solid Earth. Users in more than 100 countries routinely download GRACE data for analyses. For more on GRACE's science accomplishments, see:
"GRACE was a pioneering mission that advanced our understanding across the Earth system -- land, ocean and ice," said Michael Watkins, director of NASA's Jet Propulsion Laboratory in Pasadena, California, and the mission's original project scientist. "The entire mission team was creative and successful in its truly heroic efforts over the last few years, extending the science return of the mission to help minimize the gap between GRACE and its successor mission, GRACE Follow-On, scheduled to launch in early 2018."
Despite the loss of one of the twin GRACE satellites, the other satellite, GRACE-1, will continue operating through the end of 2017. "GRACE-1's remaining fuel will be used to complete previously planned maneuvers to calibrate and characterize its accelerometer to improve the final scientific return and insights from the 15-year GRACE record," said GRACE Project Scientist Carmen Boening of JPL.
Currently, GRACE-2's remaining fuel is being expended and the satellite has begun to slowly deorbit. Atmospheric reentry of GRACE-2 is expected sometime in December or January. Decommissioning and atmospheric reentry of GRACE-1 are expected in early 2018. NASA and the German Space Operations Center will jointly monitor the deorbit and reentry of both satellites.
GRACE Follow-On, a joint NASA/Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ) mission, will continue GRACE's legacy. It will also test a new laser-ranging interferometer developed by a joint German/U.S. collaboration for use in future generations of gravitational research satellites.
GRACE is a joint NASA/Deutsches Zentrum für Luft- und Raumfahrt (DLR, the German Aerospace Center) mission led by Tapley and Co-principal Investigator Frank Flechtner at GFZ. GRACE ground segment operations are co-funded by GFZ, DLR and the European Space Agency.JPL manages GRACE for NASA's Science Mission Directorate at the agency's headquarters in Washington. GRACE was the first mission launched under NASA's Earth System Science Pathfinder program, designed to develop new measurement technologies for studying the Earth system.
For more information on GRACE, visit:
http://www.csr.utexas.edu/grace and https://grace.jpl.nasa.gov
GRACE Follow-On: https://gracefo.jpl.nasa.gov/
Image (mentioned), Text, Credits: NASA/Steve Cole/JPL/Alan Buis.
Publié par Orbiter.ch à 09:34
jeudi 26 octobre 2017
Pope Francis and Expedition 53 Crew Exchange Thoughts About Humanity’s Deepest and Oldest Questions
ISS - Expedition 53 Mission patch.
October 26, 2017
In the middle of a workday where the Expedition 53 crew performed a routine emergency drill and additional ocular ultrasounds to map any eye changes, there was, most certainly, a higher (phone) call that actually came from more than 200 miles below the International Space Station at the Vatican: Pope Francis phoned in.
It was no ordinary ESA (European Space Agency) in-flight event. Though the Pope did ask the requisite question—what motivated them to become astronauts/cosmonauts—the conference delved quickly into deeper topics, like the crew’s thoughts of humankind’s place in the universe. Each crew member took turns speaking to Pope Francis through ESA astronaut Paolo Nespoli of Italy, who translated.
Image above: On a screen at right in NASA’s Mission Control Center in Houston, Pope Francis speaks to the crew aboard the International Space Station on Oct. 26. Image Credit: NASA.
Nespoli indicated that while he remains perplexed at humankind’s role, he feels their main objective is enriching the knowledge around us. The more we know, the more we realize we don’t. Part of space station’s ultimate mission is filling in those gaps and revealing the mysteries locked away in the cosmos.
Cosmonaut Alexander Misurkin of Roscosmos told the Pope that it was an honor to continue his grandfather’s legacy aboard the orbiting laboratory. Misurkin’s grandfather was a chief engineer of Sputnik, the world’s first satellite to launch to space. Misurkin said he is now part of the future of humanity, helping to open frontiers of new technology.
Commander Randy Bresnik of NASA spoke candidly to Pope Francis, saying that one cannot serve aboard the space station and not be touched to their soul. From Bresnik’s unique vantage orbiting Earth, it is obvious there are no borders. Also evident: a fragile band of atmosphere protecting billions of people below.
Space Station Crew Holds an Out of this World Audience with the Pope
Pope Francis said that while society is individualistic, we need collaboration—and there is no better example of international teamwork and cohesiveness than the space station. It is the ultimate human experiment, showing that people from diverse backgrounds can band together to solve some of the most daunting problems facing the world.
“The totality is greater than the sum of its parts,” Pope Francis observed.
At the end of the call, the Pope thanked his new friends, offered his blessings and asked that they, too, pray for him in return.
Expedition 53: https://www.nasa.gov/mission_pages/station/expeditions/expedition53/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Image (mentioned), Text, Credits: NASA/Catherine Williams.
Publié par Orbiter.ch à 17:45
Hubble Observes Exoplanet that Snows Sunscreen
NASA - Hubble Space Telescope patch.
Oct. 26, 2017
NASA's & ESA's Hubble Space Telescope has found a blistering hot planet outside our solar system where it "snows" sunscreen. The problem is the sunscreen (titanium oxide) precipitation only happens on the planet's permanent nighttime side. Any possible visitors to the exoplanet, called Kepler-13Ab, would need to bottle up some of that sunscreen, because they won't find it on the sizzling hot, daytime side, which always faces its host star.
Hubble astronomers suggest that powerful winds carry the titanium oxide gas around to the colder nighttime side, where it condenses into crystalline flakes, forms clouds, and precipitates as snow. Kepler-13Ab's strong surface gravity — six times greater than Jupiter's — pulls the titanium oxide snow out of the upper atmosphere and traps it in the lower atmosphere.
Image above: This illustration shows the seething hot planet Kepler-13Ab that circles very close to its host star, Kepler-13A. On the nighttime side the planet's immense gravity pulls down titanium oxide, which precipitates as snow. Seen in the background is the star's binary companion, Kepler-13B, and the third member of the multiple-star system is the orange dwarf star, Kepler-13C. Image Credits: NASA, ESA, and G. Bacon (STScI).
Astronomers using Hubble didn't look for titanium oxide specifically. Instead, they observed that the giant planet's atmosphere is cooler at higher altitudes, which is contrary to what was expected. This finding led the researchers to conclude that a light-absorbing gaseous form of titanium oxide, commonly found in this class of star-hugging, gas giant planet known as a "hot Jupiter," has been removed from the dayside's atmosphere.
The Hubble observations represent the first time astronomers have detected this precipitation process, called a "cold trap," on an exoplanet.
Without the titanium oxide gas to absorb incoming starlight on the daytime side, the atmospheric temperature grows colder with increasing altitude. Normally, titanium oxide in the atmospheres of hot Jupiters absorbs light and reradiates it as heat, making the atmosphere grow warmer at higher altitudes.
Image above: This is an artist’s impression of the gas giant planet Kepler-13Ab as compared in size to several of our solar system planets. The behemoth exoplanet is six times more massive than Jupiter. Kepler-13Ab is also one of the hottest known planets, with a dayside temperature of nearly 5,000 degrees Fahrenheit. It orbits very close to the star Kepler-13A, which lies at a distance of 1,730 light-years from Earth. Image Credits: NASA, ESA, and A. Feild (STScI).
These kinds of observations provide insight into the complexity of weather and atmospheric composition on exoplanets, and may someday be applicable to analyzing Earth-size planets for habitability.
"In many ways, the atmospheric studies we're doing on hot Jupiters now are testbeds for how we're going to do atmospheric studies on terrestrial, Earth-like planets," said lead researcher Thomas Beatty of Pennsylvania State University in University Park. "Hot Jupiters provide us with the best views of what climates on other worlds are like. Understanding the atmospheres on these planets and how they work, which is not understood in detail, will help us when we study these smaller planets that are harder to see and have more complicated features in their atmospheres."
Beatty's team selected Kepler-13Ab because it is one of the hottest of the known exoplanets, with a dayside temperature of nearly 5,000 degrees Fahrenheit. Past observations of other hot Jupiters have revealed that the upper atmospheres increase in temperature. Even at their much colder temperatures, most of our solar system's gas giants also exhibit this phenomenon.
Kepler-13Ab is so close to its parent star that it is tidally locked. One side of the planet always faces the star; the other side is in permanent darkness. (Similarly, our moon is tidally locked to Earth; only one hemisphere is permanently visible from Earth.)
The observations confirm a theory from several years ago that this kind of precipitation could occur on massive, hot planets with powerful gravity.
Hubble Space Telescope (HST). Animation Credits: NASA/ESA
"Presumably, this precipitation process is happening on most of the observed hot Jupiters, but those gas giants all have lower surface gravities than Kepler-13Ab," Beatty explained. "The titanium oxide snow doesn't fall far enough in those atmospheres, and then it gets swept back to the hotter dayside, revaporizes, and returns to a gaseous state."
The researchers used Hubble's Wide Field Camera 3 to conduct spectroscopic observations of the exoplanet's atmosphere in near-infrared light. Hubble made the observations as the distant world traveled behind its star, an event called a secondary eclipse. This type of eclipse yields information on the temperature of the constituents in the atmosphere of the exoplanet's dayside.
"These observations of Kepler-13Ab are telling us how condensates and clouds form in the atmospheres of very hot Jupiters, and how gravity will affect the composition of an atmosphere," Beatty explained. "When looking at these planets, you need to know not only how hot they are but what their gravity is like."
The Kepler-13 system resides 1,730 light-years from Earth.
The team's results appeared in The Astronomical Journal: http://iopscience.iop.org/article/10.3847/1538-3881/aa899b?fromSearchPage=true
The science paper by T. Beatty et al.: https://media.stsci.edu/preview/file/science_paper/file_attachment/292/Beatty_2017_AJ_154_158.pdf
NASA's Hubble Portal: http://www.nasa.gov/hubble
Images (mentioned), Animation (mentioned), Text, Credits: NASA/Karl Hille/Space Telescope Science Institute/Donna Weaver/Ray Villard/Pennsylvania State University/Thomas Beatty.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 17:20
Weekly Recap From the Expedition Lead Scientist, Week of October 16, 2017
ISS - Expedition 53 Mission patch.
Oct. 26, 2017
(Highlights: Week of October 16, 2017) - As the third round of spacewalks for October wrapped up last week, astronauts aboard the International Space Station conducted research that could contribute to better sleep in space and back on Earth, and set up a crystal growth experiment that could contribute to the development of better pharmaceuticals back on Earth.
Image above: ESA astronaut Paolo Nespoli made amateur radio contacts with students in Ireland, Sweden and Italy last week. He can be seen wearing the Drager Double Sensor, which measures core temperature and body chemistry to see how microgravity can alter the circadian rhythm. Image Credits: NASA.
A crew member completed a 36-hour session of data collection for the Circadian Rhythms investigation. Getting a good night’s sleep is important to the health of astronauts in space, as well as people on Earth. Circadian Rhythms studies how the “biological clock” of crew members changes during long-duration spaceflight. During missions, astronauts experience reduced physical activity, and changes in body composition and body temperature. Understanding how these phenomena affect the biological clock could improve performance and health for future crew members. Results could also help treat sleep disorders on Earth, and help people who do shift work or suffer from jet lag.
European Space Agency astronaut Paolo Nespoli installed canister bags as part of the JAXA Protein Crystallization Growth (JAXA PCG) investigation. The canisters contain protein samples prepared by Japanese and Russian researchers from universities, national research institutes, and the private sector in hopes of obtaining high quality protein crystals, and will return to Earth aboard Soyuz 51S after having run for about nine weeks.
Image above: NASA astronaut Joe Acaba captured photo documentation of the growth progress of the current crop of plants in the Veggie facility. This is the first time a mix variety of three leafy greens will be grown at the same time: mizuna, red romaine lettuce, and Wehldmon’s green lettuce. Image Credit: NASA.
Crystals grown on Earth are impacted by gravity, which may affect the way the molecules align on the surface of the crystal. Researchers have discovered that growing crystals aboard the space station allows for slower growth and higher quality crystals. Detailed analysis of high quality protein crystal structures is useful in designing new pharmaceuticals and catalysts for a wide range of industries.
During the week, Nespoli spoke with students in Ireland, Sweden and Italy via several amateur radio contacts. International Space Station Ham Radio also known as Amateur Radio on the International Space Station (ARISS)) allows groups of students in schools, camps, museums and planetariums to hold a conversation with the people living in space. As the orbiting laboratory passes overhead, students have between five and eight minutes to ask crew members 10 to 20 questions.
Space to Ground: Teacher On Board: 10/20/2017
Video above: NASA's Space to Ground is your weekly update on what's happening aboard the International Space Station. Video Credit: NASA.
Progress was also made on the following investigations last week: Veg-03, Meteor, Biochemical Profile, Fine Motor Skills, Space Headaches, ACE-T-6, Nano Step and MED-2.
Circadian Rhythms: https://www.nasa.gov/mission_pages/station/research/experiments/892.html
JAXA Protein Crystallization Growth (JAXA PCG): https://www.nasa.gov/mission_pages/station/research/experiments/157.html
Radio on the International Space Station (ARISS): https://www.nasa.gov/mission_pages/station/research/experiments/346.html
Biochemical Profile: https://www.nasa.gov/mission_pages/station/research/experiments/1008.html
Fine Motor Skills: https://www.nasa.gov/mission_pages/station/research/experiments/1767.html
Space Headaches: https://www.nasa.gov/mission_pages/station/research/experiments/181.html
Nano Step: https://www.nasa.gov/mission_pages/station/research/experiments/783.html
Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Images (mentioned), Video (mentioned), Text, Credits: NASA/Michael Johnson/John Love, Lead Increment Scientist Expeditions 53 & 54.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 16:59
Dawn Finds Possible Ancient Ocean Remnants at Ceres
NASA - Dawn Mission patch.
Oct. 26, 2017
Animation above: This animation shows dwarf planet Ceres as seen by NASA's Dawn. The map overlaid at right gives scientists hints about Ceres' internal structure from gravity measurements. Animation Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA's Dawn mission shed light on these questions.
The Dawn team found that Ceres' crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and that this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres' rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.
"More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground," said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA's Jet Propulsion Laboratory, Pasadena, California.
What's inside Ceres? Gravity will tell.
Landing on Ceres to investigate its interior would be technically challenging and would risk contaminating the dwarf planet. Instead, scientists use Dawn's observations in orbit to measure Ceres' gravity, in order to estimate its composition and interior structure.
The first of the two studies, led by Anton Ermakov, a postdoctoral researcher at JPL, used shape and gravity data measurements from the Dawn mission to determine the internal structure and composition of Ceres. The measurements came from observing the spacecraft's motions with NASA's Deep Space Network to track small changes in the spacecraft's orbit. This study is published in the Journal of Geophysical Research: Planets.
Image above: This artist concept shows NASA's Dawn spacecraft above dwarf planet Ceres, as seen in images from the mission. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
Ermakov and his colleagues' research supports the possibility that Ceres is geologically active -- if not now, then it may have been in the recent past. Three craters -- Occator, Kerwan and Yalode -- and Ceres' solitary tall mountain, Ahuna Mons, are all associated with "gravity anomalies." This means discrepancies between the scientists' models of Ceres' gravity and what Dawn observed in these four locations can be associated with subsurface structures.
"Ceres has an abundance of gravity anomalies associated with outstanding geologic features," Ermakov said. In the cases of Ahuna Mons and Occator, the anomalies can be used to better understand the origin of these features, which are believed to be different expressions of cryovolcanism.
The study found the crust's density to be relatively low, closer to that of ice than rocks. However, a study by Dawn guest investigator Michael Bland of the U.S. Geological Survey indicated that ice is too soft to be the dominant component of Ceres' strong crust. So, how can Ceres' crust be as light as ice in terms of density, but simultaneously much stronger? To answer this question, another team modeled how Ceres' surface evolved with time.
A 'Fossil' Ocean at Ceres
The second study, led by Roger Fu at Harvard University in Cambridge, Massachusetts, investigated the strength and composition of Ceres' crust and deeper interior by studying the dwarf planet's topography. This study is published in the journal Earth and Planetary Science Letters
By studying how topography evolves on a planetary body, scientists can understand the composition of its interior. A strong, rock-dominated crust can remain unchanged over the 4.5-billion-year-old age of the solar system, while a weak crust rich in ices and salts would deform over that time.
By modeling how Ceres' crust flows, Fu and colleagues found it is likely a mixture of ice, salts, rock and an additional component believed to be clathrate hydrate. A clathrate hydrate is a cage of water molecules surrounding a gas molecule. This structure is 100 to 1,000 times stronger than water ice, despite having nearly the same density.
The researchers believe Ceres once had more pronounced surface features, but they have smoothed out over time. This type of flattening of mountains and valleys requires a high-strength crust resting on a more deformable layer, which Fu and colleagues interpret to contain a little bit of liquid.
The team thinks most of Ceres' ancient ocean is now frozen and bound up in the crust, remaining in the form of ice, clathrate hydrates and salts. It has mostly been that way for more than 4 billion years. But if there is residual liquid underneath, that ocean is not yet entirely frozen. This is consistent with several thermal evolution models of Ceres published prior to Dawn's arrival there, supporting the idea that Ceres' deeper interior contains liquid left over from its ancient ocean.
Journal of Geophysical Research: Planets: http://onlinelibrary.wiley.com/doi/10.1002/2017JE005302/pdf
The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: https://dawn.jpl.nasa.gov/mission
More information about Dawn is available at the following sites:
Image (mentioned), Animation (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau/Written by Elyssia Widjaja.
Publié par Orbiter.ch à 16:35
Small Asteroid or Comet 'Visits' from Beyond the Solar System
Asteroid Watch logo.
Oct. 26, 2017
Animation above: This animation shows the path of A/2017 U1, which is an asteroid -- or perhaps a comet -- as it passed through our inner solar system in September and October 2017. From analysis of its motion, scientists calculate that it probably originated from outside of our solar system. Image Credits: NASA/JPL-Caltech.
A small, recently discovered asteroid -- or perhaps a comet -- appears to have originated from outside the solar system, coming from somewhere else in our galaxy. If so, it would be the first "interstellar object" to be observed and confirmed by astronomers.
This unusual object – for now designated A/2017 U1 – is less than a quarter-mile (400 meters) in diameter and is moving remarkably fast. Astronomers are urgently working to point telescopes around the world and in space at this notable object. Once these data are obtained and analyzed, astronomers may know more about the origin and possibly composition of the object.
A/2017 U1 was discovered Oct. 19 by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala, Hawaii, during the course of its nightly search for near-Earth objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy (IfA), was first to identify the moving object and submit it to the Minor Planet Center. Weryk subsequently searched the Pan-STARRS image archive and found it also was in images taken the previous night, but was not initially identified by the moving object processing.
How Does NASA Spot a Near-Earth Asteroid?
Video above: Did you ever wonder how NASA spots asteroids that maybe getting too close to Earth for comfort? Watch and learn. Find out more about NASA finds, studies and tracks near-Earth objects by visiting: https://www.nasa.gov/planetarydefense
Weryk immediately realized this was an unusual object. "Its motion could not be explained using either a normal solar system asteroid or comet orbit," he said. Weryk contacted IfA graduate Marco Micheli, who had the same realization using his own follow-up images taken at the European Space Agency's telescope on Tenerife in the Canary Islands. But with the combined data, everything made sense. Said Weryk, "This object came from outside our solar system."
"This is the most extreme orbit I have ever seen," said Davide Farnocchia, a scientist at NASA's Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California. "It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back."
The CNEOS team plotted the object's current trajectory and even looked into its future. A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.
Image above: A/2017 U1 is most likely of interstellar origin. Approaching from above, it was closest to the Sun on Sept. 9. Traveling at 27 miles per second (44 kilometers per second), the comet is headed away from the Earth and Sun on its way out of the solar system. Image Credits: NASA/JPL-Caltech.
The object approached our solar system from almost directly "above" the ecliptic, the approximate plane in space where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun. On Sept. 2, the small body crossed under the ecliptic plane just inside of Mercury's orbit and then made its closest approach to the Sun on Sept. 9. Pulled by the Sun's gravity, the object made a hairpin turn under our solar system, passing under Earth's orbit on Oct. 14 at a distance of about 15 million miles (24 million kilometers) -- about 60 times the distance to the Moon. It has now shot back up above the plane of the planets and, travelling at 27 miles per second (44 kilometers per second) with respect to the Sun, the object is speeding toward the constellation Pegasus.
"We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What's most surprising is that we've never seen interstellar objects pass through before," said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to solar system formation.
The small body has been assigned the temporary designation A/2017 U1 by the Minor Planet Center (MPC) in Cambridge, Massachusetts, where all observations on small bodies in our solar system -- and now those just passing through -- are collected. Said MPC Director Matt Holman, "This kind of discovery demonstrates the great scientific value of continual wide-field surveys of the sky, coupled with intensive follow-up observations, to find things we wouldn't otherwise know are there."
Since this is the first object of its type ever discovered, rules for naming this type of object will need to be established by the International Astronomical Union.
"We have been waiting for this day for decades," said CNEOS Manager Paul Chodas. "It's long been theorized that such objects exist -- asteroids or comets moving around between the stars and occasionally passing through our solar system -- but this is the first such detection. So far, everything indicates this is likely an interstellar object, but more data would help to confirm it."
The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is a wide-field survey observatory operated by the University of Hawaii Institute for Astronomy. The Minor Planet Center is hosted by the Harvard-Smithsonian Center for Astrophysics and is a sub-node of NASA's Planetary Data System Small Bodies Node at the University of Maryland (http://www.minorplanetcenter.net/ ). JPL hosts the Center for Near-Earth Object Studies (CNEOS). All are projects of NASA's Near-Earth Object Observations Program, and elements of the agency's Planetary Defense Coordination Office within NASA's Science Mission Directorate.
More information about asteroids and near-Earth objects can be found at:
For more information about NASA's Planetary Defense Coordination Office, visit:
For asteroid and comet news and updates, follow AsteroidWatch on Twitter:
Animation (mentioned), Image (mentioned), Video (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/JPL/DC Agle/University of Hawaii, Institute for Astronomy/Roy Gal.
Publié par Orbiter.ch à 16:15
Hubble discovers “wobbling galaxies”
ESA - Hubble Space Telescope logo.
26 October 2017
Observations may hint at nature of dark matter
Abell S1063, the final frontier
Using the NASA/ESA Hubble Space Telescope, astronomers have discovered that the brightest galaxies within galaxy clusters “wobble” relative to the cluster’s centre of mass. This unexpected result is inconsistent with predictions made by the current standard model of dark matter. With further analysis it may provide insights into the nature of dark matter, perhaps even indicating that new physics is at work.
Hubble image of galaxy cluster MACS J1206
Dark matter constitutes just over 25 percent of all matter in the Universe but cannot be directly observed, making it one of the biggest mysteries in modern astronomy. Invisible halos of elusive dark matter enclose galaxies and galaxy clusters alike. The latter are massive groupings of up to a thousand galaxies immersed in hot intergalactic gas. Such clusters have very dense cores, each containing a massive galaxy called the “brightest cluster galaxy” (BCG).
Lensing cluster Abell 383
The standard model of dark matter (cold dark matter model) predicts that once a galaxy cluster has returned to a “relaxed” state after experiencing the turbulence of a merging event, the BCG does not move from the cluster’s centre. It is held in place by the enormous gravitational influence of dark matter.
Brightest galaxy in Abell 2261
But now, a team of Swiss, French, and British astronomers have analysed ten galaxy clusters observed with the NASA/ESA Hubble Space Telescope, and found that their BCGs are not fixed at the centre as expected .
Galaxy cluster MACS J1720+35
The Hubble data indicate that they are “wobbling” around the centre of mass of each cluster long after the galaxy cluster has returned to a relaxed state following a merger. In other words, the centre of the visible parts of each galaxy cluster and the centre of the total mass of the cluster — including its dark matter halo — are offset, by as much as 40 000 light-years.
Wide-field image of Abell S1063 (ground-based image)
“We found that the BCGs wobble around centre of the halos,” explains David Harvey, astronomer at EPFL, Switzerland, and lead author of the paper. “This indicates that, rather than a dense region in the centre of the galaxy cluster, as predicted by the cold dark matter model, there is a much shallower central density. This is a striking signal of exotic forms of dark matter right at the heart of galaxy clusters.”
Wide field view of MACS 1206 (ground-based image)
The wobbling of the BCGs could only be analysed as the galaxy clusters studied also act as gravitational lenses. They are so massive that they warp spacetime enough to distort light from more distant objects behind them. This effect, called strong gravitational lensing, can be used to make a map of the dark matter associated with the cluster, enabling astronomers to work out the exact position of the centre of mass and then measure the offset of the BCG from this centre.
Pan across the galaxy cluster Abell S1063
If this “wobbling” is not an unknown astrophysical phenomenon and in fact the result of the behaviour of dark matter, then it is inconsistent with the standard model of dark matter and can only be explained if dark matter particles can interact with each other — a strong contradiction to the current understanding of dark matter. This may indicate that new fundamental physics is required to solve the mystery of dark matter.
Pan across Abell 383
Co-author Frederic Courbin, also at EPFL, concludes: “We’re looking forward to larger surveys — such as the Euclid survey — that will extend our dataset. Then we can determine whether the wobbling of BGCs is the result of a novel astrophysical phenomenon or new fundamental physics. Both of which would be exciting!”
Pan across MACS 1206
 The study was performed using archive data from Hubble. The observations were originally made for the CLASH and LoCuSS surveys.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
This research was presented in a paper entitled “A detection of wobbling Brightest Cluster Galaxies within massive galaxy clusters” by Harvey et al., which appeared in the Monthly Notices of the Royal Astronomical Society.
The international team of astronomers in this study consists of David Harvey (Laboratoire d’Astrophysique EPFL, Switzerland), F. Courbin (Laboratoire d’Astrophysique EPFL, Switzerland), J.P. Kneib (Laboratoire d’Astrophysique EPFL, Switzerland; CNRS, France), and Ian G. McCarthy (Liverpool John Moores University, UK).
Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/
Science paper: http://www.spacetelescope.org/static/archives/releases/science_papers/heic1718/heic1718a.pdf
ESA Hubble site: http://www.spacetelescope.org/
Image Credits: NASA, ESA, J. Lotz (STScI), M. Postman (STScI), J. Richard (CRAL) and J.-P. Kneib (LAM), T. Lauer (NOAO), S. Perlmutter (UC Berkeley, LBNL), A. Koekemoer (STScI), A. Riess (STScI/JHU), J. Nordin (LBNL, UC Berkeley), D. Rubin (Florida State), C. McCully (Rutgers University) and the CLASH Team/Digitized Sky Survey 2 (Acknowledgement: Davide De Martin)/Text Credits: ESA/Hubble/Mathias Jäger/Laboratoire d’Astrophysique EPFL/Jean-Paul Kneib/Frederic Courbin/David Harvey/Videos: ESA/NASA/Hubble/J. Richard (CRAL) and J.-P. Kneib. Acknowledgement: Marc Postman (STScI) and the CLASH Survey Team/Music: Johan B. Monell (http://www.johanmonell.com).
Best regards, Orbiter.ch
Publié par Orbiter.ch à 08:22
Rosetta finds comet plume powered from below
ESA - Rosetta Mission patch.
26 October 2017
Last year, a fountain of dust was spotted streaming from Rosetta’s comet, prompting the question: how was it powered? Scientists now suggest the outburst was driven from inside the comet, perhaps released from ancient gas vents or pockets of hidden ice.
The plume was seen by ESA’s Rosetta spacecraft on 3 July 2016, just a few months before the end of the mission and as Comet 67P/Churyumov–Gerasimenko was heading away from the Sun at a distance of almost 500 million km.
“We saw a bright plume of dust blowing away from the surface like a fountain,” explains Jessica Agarwal of the Max Planck Institute for Solar System Research in Göttingen, Germany, and lead author of the new paper.
“It lasted for roughly an hour, producing around 18 kg of dust every second.”
Alongside a steep increase in the number of dust particles flowing from the comet, Rosetta also detected tiny grains of water-ice.
The images showed the location of the outburst: a 10 m-high wall around a circular dip in the surface.
Previous plumes, collapsing cliffs and similar features have been seen on the comet, but spotting this one was especially fortunate: as well as imaging the location in detail, Rosetta also sampled the ejected material itself.
Comet plume in context
“This plume was really special. We have great data from five different instruments on how the surface changed and on the ejected material because Rosetta was, by chance, flying through the plume and looking at the right part of the surface when it happened,” adds Jessica.
“Rosetta hasn’t provided such detailed and comprehensive coverage of an event like this before.”
Initially, scientists thought that the plume might have been surface ice evaporating in the sunlight. However, Rosetta’s measurements showed there had to be something more energetic going on to fling that amount of dust into space.
“Energy must have been released from beneath the surface to power it,” says Jessica. “There are evidently processes in comets that we do not yet fully understand.”
How such energy was released remains unclear. Perhaps it was pressurised gas bubbles rising through underground cavities and bursting free via ancient vents, or stores of ice reacting violently when exposed to sunlight.
Water ice in Imhotep region
“One of Rosetta’s major goals was to understand how a comet works. For example, how does its gaseous envelope form and change over time?” says Matt Taylor, ESA’s Rosetta project scientist.
“Outbursts are interesting because of this, but we weren’t able to predict when or where they would occur – we had to be lucky to capture them.
“Having full, multi-instrument coverage of an outburst like this and its effect on the surface is really valuable for revealing how these events are driven.
“Rosetta scientists are now combining measurements from the comet with computer simulations and laboratory work to find out what drives such plumes on comets.”
Notes for Editors:
“Evidence of sub-surface energy storage in comet 67P from the outburst of 3 July 2016,” by J. Agarwal et al. is accepted for publication in Monthly Notices of the Royal Astronomical Society. https://academic.oup.com/mnras/article/469/Suppl_2/s606/4565550/Evidence-of-sub-surface-energy-storage-in-comet
Rosetta Mission: http://www.esa.int/Our_Activities/Space_Science/Rosetta
Rosetta at Astrium: http://www.astrium.eads.net/en/programme/rosetta-1go.html
Rosetta at DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10394/
Ground-based comet observation campaign: http://www.rosetta-campaign.net/home
End of mission FAQ: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_s_grand_finale_frequently_asked_questions
Images, Text, Credits: ESA/Markus Bauer/Matt Taylor/Max Planck Institute for Solar System Research/Jessica Agarwal/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/Comet image (left): ESA/Rosetta/NavCam, CC BY-SA 3.0 IGO; comet model: ESA; all others: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 07:46
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