вторник, 29 января 2019 г.

Warming Seas May Increase Frequency of Extreme Storms


NASA – EOS Aqua Mission logo.


Jan. 29, 2019


A new NASA study shows that warming of the tropical oceans due to climate change could lead to a substantial increase in the frequency of extreme rain storms by the end of the century.



Image above: An “anvil” storm cloud in the Midwestern U.S. Image Credit: UCAR.

The study team, led by Hartmut Aumann of NASA’s Jet Propulsion Laboratory in Pasadena, California, combed through 15 years of data acquired by NASA’s Atmospheric Infrared Sounder (AIRS) instrument over the tropical oceans to determine the relationship between the average sea surface temperature and the onset of severe storms.


They found that extreme storms — those producing at least 0.12 inches (3 millimeters) of rain per hour over a 16-mile (25-kilometer) area — formed when the sea surface temperature was higher than about 82 degrees Fahrenheit (28 degrees Celsius). They also found that, based on the data, 21 percent more storms form for every 1.8 degrees Fahrenheit (1 degree Celsius) that ocean surface temperatures rise.


“It is somewhat common sense that severe storms will increase in a warmer environment. Thunderstorms typically occur in the warmest season of the year,” Aumann explained. “But our data provide the first quantitative estimate of how much they are likely to increase, at least for the tropical oceans.”



Image above: A hurricane as seen by NASA’s Atmospheric Infrared Sounder (AIRS) instrument. A hurricane is a large collection of extremely severe thunderstorms — seen here in dark blue. Each square pixel represents the measurements from a 10-by-10-mile (16-by-16-kilometer) area. At the time this image was taken, there were 140 of these extreme thunderstorms rotating about the eye of the hurricane. Image Credits: NASA/JPL-Caltech.


Currently accepted climate models project that with a steady increase of carbon dioxide in the atmosphere (1 percent per year), tropical ocean surface temperatures may rise by as much as 4.8 degrees Fahrenheit (2.7 degrees Celsius) by the end of the century. The study team concludes that if this were to happen, we could expect the frequency of extreme storms to increase by as much as 60 percent by that time.



EOS Aqua satellite. Image Credit: NASA

Although climate models aren’t perfect, results like these can serve as a guideline for those looking to prepare for the potential effects a changing climate may have.


“Our results quantify and give a more visual meaning to the consequences of the predicted warming of the oceans,” Aumann said. “More storms mean more flooding, more structure damage, more crop damage and so on, unless mitigating measures are implemented.”


The peer-reviewed study was published in the December 2018 issue of the Geophysical Research Letters journal.


Aqua Satellite: https://www.nasa.gov/mission_pages/aqua/index.html


Climate: https://www.nasa.gov/subject/3127/climate


Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Esprit Smith.


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2019 January 29 Ultima Thule from New Horizons Image Credit:…


2019 January 29


Ultima Thule from New Horizons
Image Credit: NASA, JHU’s APL, SwRI; Color Processing: Thomas Appéré


Explanation: How do distant asteroids differ from those near the Sun? To help find out, NASA sent the robotic New Horizons spacecraft past the classical Kuiper belt object 2014 MU69, nicknamed Ultima Thule, the farthest asteroid yet visited by a human spacecraft. Zooming past the 30-km long space rock on January 1, the featured image is the highest resolution picture of Ultima Thule’s surface beamed back so far. Utima Thuli does look different than imaged asteroids of the inner Solar System, as it shows unusual surface texture, relatively few obvious craters, and nearly spherical lobes. Its shape is hypothesized to have formed from the coalescence of early Solar System rubble in into two objects – Ultima and Thule – which then spiraled together and stuck. Research will continue into understanding the origin of different surface regions on Ultima Thule, whether it has a thin atmosphere, how it obtained its red color, and what this new knowledge of the ancient Solar System tells us about the formation of our Earth.


∞ Source: apod.nasa.gov/apod/ap190129.html


New Horizons’ Newest and Best-Yet View of Ultima Thule


NASA – New Horizons Mission patch.


January 29, 2019



Image above: Best-Yet View of Ultima Thule. Image Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.


The wonders – and mysteries – of Kuiper Belt object 2014 MU69 continue to multiply as NASA’s New Horizons spacecraft beams home new images of its New Year’s Day 2019 flyby target.


This image, taken during the historic Jan. 1 flyby of what’s informally known as Ultima Thule, is the clearest view yet of this remarkable, ancient object in the far reaches of the solar system – and the first small “KBO” ever explored by a spacecraft.


Obtained with the wide-angle Multicolor Visible Imaging Camera (MVIC) component of New Horizons’ Ralph instrument, this image was taken when the KBO was 4,200 miles (6,700 kilometers) from the spacecraft, at 05:26 UT (12:26 a.m. EST) on Jan. 1 – just seven minutes before closest approach. With an original resolution of 440 feet (135 meters) per pixel, the image was stored in the spacecraft’s data memory and transmitted to Earth on Jan. 18-19. Scientists then sharpened the image to enhance fine detail. (This process – known as deconvolution – also amplifies the graininess of the image when viewed at high contrast.)


The oblique lighting of this image reveals new topographic details along the day/night boundary, or terminator, near the top. These details include numerous small pits up to about 0.4 miles (0.7 kilometers) in diameter. The large circular feature, about 4 miles (7 kilometers) across, on the smaller of the two lobes, also appears to be a deep depression. Not clear is whether these pits are impact craters or features resulting from other processes, such as “collapse pits” or the ancient venting of volatile materials.



Image above: Image above: Illustration of NASA’s New Horizons spacecraft encountering 2014 MU69 – nicknamed “Ultima Thule” – a Kuiper Belt object that orbits one billion miles beyond Pluto. New Horizons’ exploration of Ultima is the farthest space probe flyby in history. Image Credits: NASA/JHUAPL/SwRI.


Both lobes also show many intriguing light and dark patterns of unknown origin, which may reveal clues about how this body was assembled during the formation of the solar system 4.5 billion years ago. One of the most striking of these is the bright “collar” separating the two lobes.


“This new image is starting to reveal differences in the geologic character of the two lobes of Ultima Thule, and is presenting us with new mysteries as well,” said Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado. “Over the next month there will be better color and better resolution images that we hope will help unravel the many mysteries of Ultima Thule.”


New Horizons is approximately 4.13 billion miles (6.64 billion kilometers) from Earth, operating normally and speeding away from the Sun (and Ultima Thule) at more than 31,500 miles (50,700 kilometers) per hour. At that distance, a radio signal reaches Earth six hours and nine minutes after leaving the spacecraft.


Related article:


New Movie Shows Ultima Thule from an Approaching New Horizons
https://orbiterchspacenews.blogspot.com/2019/01/new-movie-shows-ultima-thule-from.html


New Horizons LORRI website: http://pluto.jhuapl.edu/soc/UltimaThule-Encounter/


For more information on the New Horizons mission, visit: https://www.nasa.gov/newhorizons


Images (mentioned), Text, Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.


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Active galaxies poin tto new physics of cosmic expansion



Active galaxies to measure cosmic expansion


Copyright ESA (artist’s impression and composition); 

NASA/ESA/Hubble (background galaxies); CC BY-SA 3.0 IGO



Investigating the history of our cosmos with a large sample of distant ‘active’ galaxies observed by ESA’s XMM-Newton, a team of astronomers found there might be more to the early expansion of the Universe than predicted by the standard model of cosmology. 


According to the leading scenario, our Universe contains only a few percent of ordinary matter. One quarter of the cosmos is made of the elusive dark matter, which we can feel gravitationally but not observe, and the rest consists of the even more mysterious dark energy that is driving the current acceleration of the Universe’s expansion. 


This model is based on a multitude of data collected over the last couple of decades, from the cosmic microwave background, or CMB – the first light in the history of the cosmos, released only 380 000 years after the big bang and observed in unprecedented detail by ESA’s Planck mission – to more ‘local’ observations. The latter include supernova explosions, galaxy clusters and the gravitational distortion imprinted by dark matter on distant galaxies, and can be used to trace cosmic expansion in recent epochs of cosmic history – across the past nine billion years.  


A new study, led by Guido Risaliti of Università di Firenze, Italy, and Elisabeta Lusso of Durham University, UK, points to another type of cosmic tracer – quasars – that would fill part of the gap between these observations, measuring the expansion of the Universe up to 12 billion years ago.


Quasars are the cores of galaxies where an active supermassive black hole is pulling in matter from its surroundings at very intense rates, shining brightly across the electromagnetic spectrum. As material falls onto the black hole, it forms a swirling disc that radiates in visible and ultraviolet light; this light, in turn, heats up nearby electrons, generating X-rays. 



Supermassive black hole

Copyright ESA–C. Carreau



Three years ago, Guido and Elisabeta realised that a well-known relation between the ultraviolet and X-ray brightness of quasars could be used to estimate the distance to these sources – something that is notoriously tricky in astronomy – and, ultimately, to probe the expansion history of the Universe. 


Astronomical sources whose properties allow us to gauge their distances are referred to as ‘standard candles’.


The most notable class, known as ‘type-Ia’ supernova, consists of the spectacular demise of white dwarf stars after they have over-filled on material from a companion star, generating explosions of predictable brightness that allows astronomers to pinpoint the distance. Observations of these supernovas in the late 1990s revealed the Universe’s accelerated expansion over the last few billion years.


“Using quasars as standard candles has great potential, since we can observe them out to much greater distances from us than type-Ia supernovas, and so use them to probe much earlier epochs in the history of the cosmos,” explains Elisabeta.


With a sizeable sample of quasars at hand, the astronomers have now put their method into practice, and the results are intriguing.






XMM-Newton

Copyright ESA-C. Carreau


Digging into the XMM-Newton archive, they collected X-ray data for over 7000 quasars, combining them with ultraviolet observations from the ground-based Sloan Digital Sky Survey. They also used a new set of data, specially obtained with XMM-Newton in 2017 to look at very distant quasars, observing them as they were when the Universe was only about two billion years old. Finally, they complemented the data with a small number of even more distant quasars and with some relatively nearby ones, observed with NASA’s Chandra and Swift X-ray observatories, respectively.


“Such a large sample enabled us to scrutinise the relation between X-ray and ultraviolet emission of quasars in painstaking detail, which greatly refined our technique to estimate their distance,” says Guido.


The new XMM-Newton observations of distant quasars are so good that the team even identified two different groups: 70 percent of the sources shine brightly in low-energy X-rays, while the remaining 30 percent emit lower amounts of X-rays that are characterised by higher energies. For the further analysis, they only kept the earlier group of sources, in which the relation between X-ray and ultraviolet emission appears clearer.


“It is quite remarkable that we can discern such level of detail in sources so distant from us that their light has been travelling for more than ten billion years before reaching us,” says Norbert Schartel, XMM-Newton project scientist at ESA.


After skimming through the data and bringing the sample down to about 1600 quasars, the astronomers were left with the very best observations, leading to robust estimates of the distance to these sources that they could use to investigate the Universe’s expansion.







Supernova and quasar data


Investigating the expansion of the Universe with type-Ia supernovas and quasars

Copyright Courtesy of Elisabeta Lusso & Guido Risaliti (2019) Description 



“When we combine the quasar sample, which spans almost 12 billion years of cosmic history, with the more local sample of type-Ia supernovas, covering only the past eight billion years or so, we find similar results in the overlapping epochs,” says Elisabeta.


“However, in the earlier phases that we can only probe with quasars, we find a discrepancy between the observed evolution of the Universe and what we would predict based on the standard cosmological model.”


Looking into this previously poorly explored period of cosmic history with the help of quasars, the astronomers have revealed a possible tension in the standard model of cosmology, which might require the addition of extra parameters to reconcile the data with theory.


“One of the possible solutions would be to invoke an evolving dark energy, with a density that increases as time goes by,” says Guido.


Incidentally, this particular model would also alleviate another tension that has kept cosmologists busy lately, concerning the Hubble constant – the current rate of cosmic expansion. This discrepancy was found between estimates of the Hubble constant in the local Universe, based on supernova data – and, independently, on galaxy clusters – and those based on Planck’s observations of the cosmic microwave background in the early Universe.


“This model is quite interesting because it might solve two puzzles at once, but the jury is definitely not out yet and we’ll have to look at many more models in great detail before we can solve this cosmic conundrum,” adds Guido.


The team is looking forward to observing even more quasars in the future to further refine their results. Additional clues will also come from ESA’s Euclid mission, scheduled for a 2022 launch to explore the past ten billion years of cosmic expansion and investigate the nature of dark energy.


“These are interesting times to investigate the history of our Universe, and it’s exciting that XMM-Newton can contribute by looking at a cosmic epoch that had remained largely unexplored so far,” concludes Norbert.



Notes for Editors


Cosmological constraints from the Hubble diagram of quasars at high redshifts” by G. Risaliti & E. Lusso is published in Nature Astronomy.




For further information, please contact:

Guido Risaliti
Università di Firenze
INAF – Osservatorio Astrofisico di Arcetri
Firenze, Italy
Email: risaliti@arcetri.inaf.it


Elisabeta Lusso
Centre for Extragalactic Astronomy
Durham University, UK
Email: elisabeta.lusso@durham.ac.uk


Norbert Schartel
XMM-Newton Project Scientist
European Space Agency
Email: norbert.schartel@sciops.esa.int


Markus Bauer








ESA Science Communication Officer









Tel: +31 71 565 6799









Mob: +31 61 594 3 954









Email: markus.bauer@esa.int








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Freshen Up To keep things healthy, most of our organs…


Freshen Up


To keep things healthy, most of our organs regularly refresh their component cells. Injured or aged cells are replaced with new recruits, produced from a stock of stem cells that multiply and develop into the required cell type. This routine maintenance occurs in animals of all shapes, including the fruit fly. Despite appearances, the fly’s midgut is comparable to our small intestine, and is a useful model system for studying both organ renewal and the problems that arise during disease and ageing. However, the insights provided by experiments have been limited by an inability to visualise changes over long periods of time. Now a new technique opens a window on the midgut for up to 16 hours (pictured). It reveals a new level of detail to researchers, shows that certain information can only be gleaned by direct observation over time, and provides new opportunities for investigating how organs stay healthy.


Written by Anthony Lewis



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Curiosity Says Farewell to Mars’ Vera Rubin Ridge


NASA – Mars Science Laboratory (MSL) logo.


Jan. 28, 2019



Image above: A selfie taken by NASA’s Curiosity Mars rover on Sol 2291 (January 15) at the “Rock Hall” drill site, located on Vera Rubin Ridge. Image Credits: NASA/JPL-Caltech/MSSS.


NASA’s Curiosity rover has taken its last selfie on Vera Rubin Ridge and descended toward a clay region of Mount Sharp. The twisting ridge on Mars has been the rover’s home for more than a year, providing scientists with new samples — and new questions — to puzzle over.


On Dec. 15, Curiosity drilled its 19th sample at a location on the ridge called Rock Hall. On Jan. 15, the spacecraft used its Mars Hand Lens Imager (MAHLI) camera on the end of its robotic arm to take a series of 57 pictures, which were stitched together into this selfie. The “Rock Hall” drill hole is visible to the lower left of the rover; the scene is dustier than usual at this time of year due to a regional dust storm.


Curiosity has been exploring the ridge since September of 2017. It’s now headed into the “clay-bearing unit,” which sits in a trough just south of the ridge. Clay minerals in this unit may hold more clues about the ancient lakes that helped form the lower levels on Mount Sharp.


For more information about NASA’s Curiosity Mars rover, visit: https://mars.nasa.gov/msl/


Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Andrew Good.


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Stone Forest | #Geology #GeologyPage #China #StoneForest The…


Stone Forest | #Geology #GeologyPage #China #StoneForest


The Stone Forest or Shilin is a notable set of limestone formations about 500 km2 located in Shilin Yi Autonomous County, Yunnan Province, People’s Republic of China, near Shilin approximately 90 km (56 mi) from the provincial capital Kunming.


The tall rocks seem to fall to the ground in the manner of stalagmites, with many looking like petrified trees thereby creating the illusion of a forest made of stone. Since 2007, two parts of the site, the Naigu Stone Forest and Suogeyi Village, have been UNESCO World Heritage Sites as part of the South China Karst.


GeologyPage

www.geologypage.com

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Space Station Highlights: Week of January 21, 2019


ISS – Expedition 58 Mission patch.


Jan. 28, 2019


Last week, Expedition 58 crew members continued conducting science aboard the International Space Station along with packing the NG-10 Cygnus resupply vehicle for its departure from the station. Upon undocking, Cygnus will boost to an altitude and inclination ideal for satellite deployment and release small satellites from the SlingShot small satellite deployment system. The cargo craft will then begin its descent toward Earth for a fiery but safe demise over the Pacific Ocean.



International Space Station (ISS). Image Credit: NASA

Here are details about some of the science conducted in space this week:


Ongoing work to protect astronauts’ eyes
After performing dilution measures last week, crew members continued collecting data for the Fluid Shifts investigation this week, performing a lower body negative pressure imaging session. This NASA investigation collects, at various intervals, dilution measurements and baseline imaging to help determine the causes for severe and lasting physical changes seen in the eyes of astronauts during spaceflight and to support development of preventive measures. A shift of fluids to the head may contribute to these changes, so one possible intervention could be reversing this fluid shift with a lower body negative pressure device.


A day in space station life



Animation above: NASA astronaut works within the Life Sciences Glovebox as a part of the Rodent Research-8 investigation. Animation Credit: NASA.


Crew members participated in a conference and ground uplinked the file needed for a firmware update for the ISS Experience. Filmed over multiple months, ISS Experience documents daily life aboard the space station using cinematic virtual reality (VR). Videos cover different aspects of crew life, execution of science aboard the station and the international partnerships involved. 


Testing solution convection for better crystal growth


The crew installed a Biophysics-5 plate into the Fluids Integrated Rack (FIR) and Light Microscopy Module (LMM). This investigation tests whether the movement of molecules through a fluid, known as solution convection, enhances or suppresses formation of the dense liquid clusters from which crystals form. This could answer the question of why protein crystallization investigations in microgravity often generate unexpectedly low or high numbers of crystals.



Image above: The Japanese Experiment Module (JEM) Exposed Facility (EF). The JEM-EF is continuously exposed to the space environment and can hold up to 10 experiments at a time. Image Credit: NASA.


The FIR is a complementary fluid physics research facility designed to host investigations involving colloids, gels, bubbles, capillary action, phase changes, and other phenomena. The LMM, a modified flexible and state-of-the-art commercial light imaging microscope facility, provides researchers with a powerful diagnostic hardware and software tool in space.


Other work was performed on these investigations:


– MISSE-10 hosts a suite of eight NASA investigations aboard the Materials International Space Station Flight Facility (MISSE-FF): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7929


– Lighting Effects examines whether changing from fluorescent light bulbs to solid-state light-emitting diodes (LEDs) with adjustable intensity and color can improve crew circadian rhythms, sleep, and cognitive performance: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013


– MSPR is a multi-purpose small payload rack in the Japanese Experiment Module (JEM) used for a variety of scientific experiments: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1090


– Polar Express is a Cold Stowage managed facility for transport and storage of science samples at cryogenic temperatures (-80ºC) to and from the space station: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1092


Related links:


Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html


SlingShot: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=7847


Fluid Shifts: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1126


ISS Experience: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7877


Biophysics-5: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7742


Fluids Integrated Rack (FIR): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=351


Light Microscopy Module (LMM): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=531


Spot the Station: https://spotthestation.nasa.gov/


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


Animation (mentioned), Images (mentioned), Text, Credits: NASA/Michael Johnson/Vic Cooley, Lead Increment Scientist Expeditions 57/58.


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All Systems Go As Parker Solar Probe Begins Second Sun Orbit


NASA – Parker Solar Probe Mission patch.


January 28, 2019


On Jan. 19, 2019, just 161 days after its launch from Cape Canaveral Air Force Station in Florida, NASA’s Parker Solar Probe completed its first orbit of the Sun, reaching the point in its orbit farthest from our star, called aphelion. The spacecraft has now begun the second of 24 planned orbits, on track for its second perihelion, or closest approach to the Sun, on April 4, 2019.



Parker Solar Probe closest approach to the Sun. Animation Credits: NASA/JHUAPL

Parker Solar Probe entered full operational status (known as Phase E) on Jan. 1, with all systems online and operating as designed. The spacecraft has been delivering data from its instruments to Earth via the Deep Space Network, and to date more than 17 gigabits of science data has been downloaded. The full dataset from the first orbit will be downloaded by April.


“It’s been an illuminating and fascinating first orbit,” said Parker Solar Probe Project Manager Andy Driesman, of the Johns Hopkins University Applied Physics Laboratory. “We’ve learned a lot about how the spacecraft operates and reacts to the solar environment, and I’m proud to say the team’s projections have been very accurate.” APL designed, built, and manages the mission for NASA.


“We’ve always said that we don’t know what to expect until we look at the data,” said Project Scientist Nour Raouafi, also of APL. “The data we have received hints at many new things that we’ve not seen before and at potential new discoveries. Parker Solar Probe is delivering on the mission’s promise of revealing the mysteries of our Sun.”



Image above: Parker Solar Probe’s position, speed and round-trip light time as of Jan. 28, 2019. Track the spacecraft online: http://parkersolarprobe.jhuapl.edu/The-Mission/index.php#Where-Is-PSP


The Parker Solar Probe team is not only focused on analyzing the science data but also preparing for the second solar encounter, which will take place in about two months.


In preparation for that next encounter, the spacecraft’s solid state recorder is being emptied of files that have already been delivered to Earth. In addition, the spacecraft is receiving updated positional and navigation information (called ephemeris) and is being loaded with a new automated command sequence, which contains about one month’s worth of instructions.


Like the mission’s first perihelion in November 2018, Parker Solar Probe’s second perihelion in April will bring the spacecraft to a distance of about 15 million miles from the Sun – just over half the previous close solar approach record of about 27 million miles set by Helios 2 in 1976.


The spacecraft’s four instrument suites will help scientists begin to answer outstanding questions about the Sun’s fundamental physics — including how particles and solar material are accelerated out into space at such high speeds and why the Sun’s atmosphere, the corona, is so much hotter than the surface below.


Parker Solar Probe: https://www.nasa.gov/content/goddard/parker-solar-probe


Animation (mentioned), Image (mentioned), Text, Credits: Johns Hopkins University Applied Physics Lab, by Geoff Brown.


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Crew Tests Time Perception in Space and Real-Time Vital Signs Monitoring


ISS – Expedition 58 Mission patch.


January 28, 2019


The Expedition 58 astronauts explored time perception and tested a wearable body monitor aboard the International Space Station today. The orbital residents also packed a U.S. space freighter and set up tiny satellites controlled by students on Earth.



Image above: NASA astronaut Anne McClain is pictured exercising aboard the International Space Station inside the U.S. Destiny laboratory module. Image Credit: NASA.


Astronauts Anne McClain and David Saint-Jacques started Monday in the Columbus lab module learning how microgravity affects time perception. During the experiment the crew judges time length with results compared to ground tests. Scientists hypothesize that astronauts experience time passing at a faster rate than those of us here on Earth.


McClain then spent the rest of the day with Commander Oleg Kononenko setting up and monitoring SPHERES satellites in the Kibo lab module. High school students compete to design the best algorithms that control the basketball-sized satellites to mimic spacecraft maneuvers and formation flying.



International Space Station (ISS). Animation Credit: NASA

Saint-Jacques set up a wearable device called the Bio-Monitor to test its ability to measure vital signs with minimum interference during a normal day in space. The Canadian astronaut also continued packing the Cygnus cargo craft from Northrop Grumman ahead of its Feb. 8 departure from the Unity module.


Related links:


Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html


Columbus lab module: https://www.nasa.gov/mission_pages/station/structure/elements/europe-columbus-laboratory


Time perception: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7504


SPHERES: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=679


Kibo lab module: https://www.nasa.gov/mission_pages/station/structure/elements/japan-kibo-laboratory


Bio-Monitor: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=7392


Cygnus cargo craft: https://www.nasa.gov/feature/northrop-grumman-cygnus-launches-arrivals-and-departures


Unity module: https://www.nasa.gov/mission_pages/station/structure/elements/unity


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


Image (mentioned), Animation (mentioned), Text, Credits: NASA/Mark Garcia.


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Temple of Mithras, Brocolitia, Hadrian’s Wall, Northumberland, 27.1.19.

Temple of Mithras, Brocolitia, Hadrian’s Wall, Northumberland, 27.1.19.











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Active galaxies point to new physics of cosmic expansion



ESA – Planck Mission patch / ESA – XMM-Newton Mission patch.


28 January 2019


Investigating the history of our cosmos with a large sample of distant ‘active’ galaxies observed by ESA’s XMM-Newton, a team of astronomers found there might be more to the early expansion of the Universe than predicted by the standard model of cosmology.


According to the leading scenario, our Universe contains only a few percent of ordinary matter. One quarter of the cosmos is made of the elusive dark matter, which we can feel gravitationally but not observe, and the rest consists of the even more mysterious dark energy that is driving the current acceleration of the Universe’s expansion.



Measuring the expansion of the Universe

This model is based on a multitude of data collected over the last couple of decades, from the cosmic microwave background, or CMB – the first light in the history of the cosmos, released only 380 000 years after the big bang and observed in unprecedented detail by ESA’s Planck mission – to more ‘local’ observations. The latter include supernova explosions, galaxy clusters and the gravitational distortion imprinted by dark matter on distant galaxies, and can be used to trace cosmic expansion in recent epochs of cosmic history – across the past nine billion years.


A new study, led by Guido Risaliti of Università di Firenze, Italy, and Elisabeta Lusso of Durham University, UK, points to another type of cosmic tracer – quasars – that would fill part of the gap between these observations, measuring the expansion of the Universe up to 12 billion years ago.


Quasars are the cores of galaxies where an active supermassive black hole is pulling in matter from its surroundings at very intense rates, shining brightly across the electromagnetic spectrum. As material falls onto the black hole, it forms a swirling disc that radiates in visible and ultraviolet light; this light, in turn, heats up nearby electrons, generating X-rays.



Supermassive black hole

Three years ago, Guido and Elisabeta realised that a well-known relation between the ultraviolet and X-ray brightness of quasars could be used to estimate the distance to these sources – something that is notoriously tricky in astronomy – and, ultimately, to probe the expansion history of the Universe.


Astronomical sources whose properties allow us to gauge their distances are referred to as ‘standard candles’.


The most notable class, known as ‘type-Ia’ supernova, consists of the spectacular demise of white dwarf stars after they have over-filled on material from a companion star, generating explosions of predictable brightness that allows astronomers to pinpoint the distance. Observations of these supernovas in the late 1990s revealed the Universe’s accelerated expansion over the last few billion years.


“Using quasars as standard candles has great potential, since we can observe them out to much greater distances from us than type-Ia supernovas, and so use them to probe much earlier epochs in the history of the cosmos,” explains Elisabeta.


With a sizeable sample of quasars at hand, the astronomers have now put their method into practice, and the results are intriguing.



XMM-Newton

Digging into the XMM-Newton archive, they collected X-ray data for over 7000 quasars, combining them with ultraviolet observations from the ground-based Sloan Digital Sky Survey. They also used a new set of data, specially obtained with XMM-Newton in 2017 to look at very distant quasars, observing them as they were when the Universe was only about two billion years old. Finally, they complemented the data with a small number of even more distant quasars and with some relatively nearby ones, observed with NASA’s Chandra and Swift X-ray observatories, respectively.


“Such a large sample enabled us to scrutinise the relation between X-ray and ultraviolet emission of quasars in painstaking detail, which greatly refined our technique to estimate their distance,” says Guido.


The new XMM-Newton observations of distant quasars are so good that the team even identified two different groups: 70 percent of the sources shine brightly in low-energy X-rays, while the remaining 30 percent emit lower amounts of X-rays that are characterised by higher energies. For the further analysis, they only kept the earlier group of sources, in which the relation between X-ray and ultraviolet emission appears clearer.


“It is quite remarkable that we can discern such level of detail in sources so distant from us that their light has been travelling for more than ten billion years before reaching us,” says Norbert Schartel, XMM-Newton project scientist at ESA.


After skimming through the data and bringing the sample down to about 1600 quasars, the astronomers were left with the very best observations, leading to robust estimates of the distance to these sources that they could use to investigate the Universe’s expansion.



Supernova and quasar data

“When we combine the quasar sample, which spans almost 12 billion years of cosmic history, with the more local sample of type-Ia supernovas, covering only the past eight billion years or so, we find similar results in the overlapping epochs,” says Elisabeta.


“However, in the earlier phases that we can only probe with quasars, we find a discrepancy between the observed evolution of the Universe and what we would predict based on the standard cosmological model.”


Looking into this previously poorly explored period of cosmic history with the help of quasars, the astronomers have revealed a possible tension in the standard model of cosmology, which might require the addition of extra parameters to reconcile the data with theory.


“One of the possible solutions would be to invoke an evolving dark energy, with a density that increases as time goes by,” says Guido.


Incidentally, this particular model would also alleviate another tension that has kept cosmologists busy lately, concerning the Hubble constant – the current rate of cosmic expansion. This discrepancy was found between estimates of the Hubble constant in the local Universe, based on supernova data – and, independently, on galaxy clusters – and those based on Planck’s observations of the cosmic microwave background in the early Universe.



Planck

“This model is quite interesting because it might solve two puzzles at once, but the jury is definitely not out yet and we’ll have to look at many more models in great detail before we can solve this cosmic conundrum,” adds Guido.


The team is looking forward to observing even more quasars in the future to further refine their results. Additional clues will also come from ESA’s Euclid mission, scheduled for a 2022 launch to explore the past ten billion years of cosmic expansion and investigate the nature of dark energy.


“These are interesting times to investigate the history of our Universe, and it’s exciting that XMM-Newton can contribute by looking at a cosmic epoch that had remained largely unexplored so far,” concludes Norbert.


Notes for editors:


“Cosmological constraints from the Hubble diagram of quasars at high redshifts” by G. Risaliti & E. Lusso is published in Nature Astronomy: https://www.nature.com/articles/s41550-018-0657-z


Related links:


ESA’s XMM-Newton: http://www.esa.int/Our_Activities/Space_Science/XMM-Newton_overview


ESA’s Planck: http://www.esa.int/Our_Activities/Space_Science/Planck


ESA’s Euclid: http://sci.esa.int/euclid/


Text, Credits: ESA/Markus Bauer/Norbert Schartel/Centre for Extragalactic Astronomy/Elisabeta Lusso/Università di Firenze/INAF – Osservatorio Astrofisico di Arcetri/Guido Risaliti/Images: ESA (artist’s impression and composition); NASA/ESA/Hubble (background galaxies); CC BY-SA 3.0 IGO/C. Carreau/Courtesy of Elisabeta Lusso & Guido Risaliti (2019).


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‘Limestone Corner’, Hadrian’s Wall, Northumberland, 27.1.19.This site...











‘Limestone Corner’, Hadrian’s Wall, Northumberland, 27.1.19.


This site is the famous location where the landscape frustrated the Roman Empire. Made from dolerite, the rocks were to be broken using metal wedges but they failed to do so, causing the forward fighting ditch of Hadrian’s Wall to be abandoned. Poignantly, the metal driver marks remain in the rock.


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