среда, 28 ноября 2018 г.

Behind the Scenes of Recovering NASA’s Hubble



DSF2237b


The first image captured by Hubble after returning to science on October 27, 2018, shows a field of galaxies in the constellation Pegasus. The observations were taken with the Wide Field Camera 3 to study very distant galaxies in the field. Image: NASA, ESA, and A. Shapley (UCLA)




In the early morning of October 27, 2018, the Hubble Space Telescope targeted a field of galaxies not far from the Great Square in the constellation Pegasus. Contained in the field were star-forming galaxies up to 11 billion light-years away. With the target in its sights, Hubble’s Wide Field Camera 3 recorded an image. It was the first picture captured by the telescope since it closed its eyes on the universe three weeks earlier, and it was the result of an entire team of engineers and experts working tirelessly to get the telescope exploring the cosmos once again.


“This has been an incredible saga, built upon the heroic efforts of the Hubble team,” stated Hubble senior project scientist, Jennifer Wiseman, at NASA Goddard. “Thanks to this work, the Hubble Space Telescope is back to full science capability that will benefit the astronomical community and the public for years to come.”


On the evening of Friday, October 5, the orbiting observatory had put itself into “safe mode” after one of its gyroscopes (or “gyros”) failed. Hubble stopped taking science observations, oriented its solar panels toward the Sun, and waited for further instructions from the ground.


It was the beginning of a three-day holiday weekend when members of the spacecraft’s operations team started receiving text messages on their phone, alerting them that something was wrong with Hubble. In less than an hour, more than a dozen team members had gathered in the control room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, to assess the situation. After unsuccessfully reviving the failed gyro, they activated a backup gyro on the spacecraft. However, the gyro soon began reporting impossibly high rotation rates — around 450 degrees per hour, when Hubble was actually turning less than a degree per hour.


“This is something we’ve never seen before on any other gyros — rates this high,” stated Dave Haskins, Hubble’s mission operations manager at Goddard.


Hubble has six gyros aboard, and it typically uses three at a time to collect the most science. However, two of its six gyros had previously failed. This was Hubble’s final backup gyro. The operations team either had to figure out how to get it working, or turn to a previously developed and tested “one-gyro mode,” which is proven to work but would limit Hubble’s efficiency and how much of the sky the telescope could observe at a given time of the year — something both the operations team and astronomers want to avoid until there is no other choice.


As they decided what to do next, team members stayed in the control center continuously to monitor the health and safety of the spacecraft. Because Hubble’s control center had switched to automated operations back in 2011, there were no longer people in place to monitor Hubble 24 hours a day.


“The team pulled together to staff around the clock, something we haven’t done in years,” Haskins shared. Team members stepped in to take shifts — several of Hubble’s systems engineers, others who help run tests and checkouts of Hubble’s ground systems, and some who used to staff Hubble’s control room but hadn’t in a long time. “It’s been years since they’ve been on console doing that kind of shift work,” Haskins said. “To me it was seamless. It shows the versatility of the team.”


Meanwhile, during the holiday weekend, Hubble’s Project Manager, Pat Crouse, was busy recruiting a team of experts from Goddard and around the country to analyze the backup gyro’s unusual behavior and determine whether it could be corrected. This anomaly review board met for the first time that Tuesday, October 9, and contributed valuable insight throughout Hubble’s recovery.


It took weeks of creative thinking, continued tests, and minor setbacks to solve the problem of the misbehaving gyro. Members of the operations team and the review board suspected there might be some sort of obstruction in the gyro affecting its readings. Attempting to dislodge such a blockage, the team repeatedly tried switching the gyro between different operational modes and rotating the spacecraft by large amounts. In response, the extremely high rotation rates from the gyro gradually fell until they were close to normal.


Encouraged but cautious, the team uploaded new software safeguards on Hubble to protect the telescope in case the gyro reports unduly high rates again, and then sent the telescope through some practice maneuvers to simulate real science observations. They kept a close watch to make sure everything on the spacecraft performed correctly. It did.


“Early on we had no idea whether we’d be able to resolve that issue or not,” Hubble’s deputy mission operations manager, Mike Myslinski, said about the high gyro rates.


In the background, other team members at Goddard and the Space Telescope Science Institute had begun preparing in case Hubble would have to switch to using just a single gyro, with the other working gyro held in reserve as a backup. Fortunately, the results of their efforts weren’t needed this time, but their work wasn’t for naught. “We know that we’ll have to go to one gyro someday, and we want to be as prepared as possible for that,” Myslinski explained. “We’d always said that once we got down to three gyros we would do as much up-front work as possible for one-gyro science. That day has come.”


For now, however, Hubble is back to exploring the universe with three working gyros, thanks to the hard work of a multitude of people on the ground.


“Many team members made personal sacrifices to work long shifts and off-shifts to ensure the health and safety of the observatory, while identifying a path forward that was both safe and effective,” Crouse said of the efforts to return to science. “The recovery of the gyro is not only vital for the life expectancy of the observatory, but Hubble is most productive in three-gyro mode, and extending this historic period of productivity is a main objective for the mission. Hubble will continue to make amazing discoveries when it is time to operate in one-gyro mode, but due to the tremendous effort and determination of the mission team, now is not the time.”


The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.




Related Links

This site is not responsible for content found on external links





Contact 


Vanessa Thomas
NASA Goddard Space Flight Center, Greenbelt, Maryland

vanessa.j.thomas@nasa.gov



Source:  HubbleSite/News



Archive link


2018 November 28 IC 1871: Inside the Soul Nebula Image Credit…


2018 November 28


IC 1871: Inside the Soul Nebula
Image Credit & Copyright: Mark Hanson


Explanation: This cosmic close-up looks deep inside the Soul Nebula. The dark and brooding dust clouds on the left, outlined by bright ridges of glowing gas, are cataloged as IC 1871. About 25 light-years across, the telescopic field of view spans only a small part of the much larger Heart and Soul nebulae. At an estimated distance of 6,500 light-years the star-forming complex lies within the Perseus spiral arm of our Milky Way Galaxy, seen in planet Earth’s skies toward the constellation Cassiopeia. An example of triggered star formation, the dense star-forming clouds of IC 1871 are themselves sculpted by the intense winds and radiation of the region’s massive young stars. The featured image appears mostly red due to the emission of a specific color of light emitted by excited hydrogen gas.


∞ Source: apod.nasa.gov/apod/ap181128.html


Ocean circulation in North Atlantic at its weakest since the past 1,500 years

The research co-led by Drs. Christelle Not and Benoit Thibodeau from the Department of Earth Sciences and the Swire Institute of Marine Science, The University of Hong Kong, highlights a dramatic weakening of the circulation during the 20th century that is interpreted to be a direct consequence of global warming and associated melt of the Greenland Ice-Sheet. This is important for near-future climate as slower circulation in the North Atlantic can yield profound change on both the North American and European climate but also on the African and Asian summer monsoon rainfall. The findings were recently published in the prestigious journal Geophysical Research Letters.











Ocean circulation in North Atlantic at its weakest since the past 1,500 years
This is a schematic of the circulation in the western North Atlantic during episode of strong (left) and weak (right) westward
transport of the Labrador Current (LC). The oceanography of this region is characterised by the interaction of water masses
formed in the Labrador and moving westward (LC and Labrador Sea Slope Water (LSSW)) and the water masses moving
eastward originating as the Gulf Stream (GS) and its Atlantic Temperate Slope Water (ATSW). The exact location where
these two water mass systems meet (yellow dashed lines) is determined by the strength of the northern recirculation
gyre (white arrows), which then control the temperature recorded by the foraminifers. The positions
of the sediments cores is indicated by the white dot [Credit: The University of Hong Kong]

The Atlantic Meridional Overturning Circulation (AMOC) is the branch of the North Atlantic circulation that brings warm surface water toward the Arctic and cold deep water toward the equator. This transfer of heat and energy not only has direct influence on climate over Europe and North American but can impact the African and Asian monsoon system through its effect on sea surface temperature, hydrological cycle, atmospheric circulation and variation in the intertropical convergence zone.
Many climate models predicted a weakening, or even a collapse of this branch of the circulation under global warming, partly due to the release of freshwater from Greenland Ice-Sheet. This freshwater has lower density than salty water and thus prevents the formation of deep water, slowing down the whole circulation. However, this weakening is still vigorously debated because of the scarcity of long-term record of the AMOC.


Drs. Not and Thibodeau used microfossils, called foraminifer, found in a sediment core to estimate the past temperature of the Ocean. The sediment core used is located in the Laurentian Channel, on the coast of Canada, where two important currents meet. Thus, the strength of these currents will control the temperature of the water at the coring site which implies that the temperature reconstructed from this core is indicative of the strength of the North Atlantic circulation. With their collaborators from the United-States of America, they validated their results using instrumental data and two numerical models that can simulate the climate and the ocean.











Ocean circulation in North Atlantic at its weakest since the past 1,500 years
This is a picture of the foraminifer specie used in this study
[Credit: The University of Hong Kong]

“The AMOC plays a crucial role in regulating global climate, but scientists are struggling to find reliable indicators of its intensity in the past. The discovery of this new record of AMOC will enhance our understanding of its drivers and ultimately help us better comprehend potential near-future change under global warming” said Dr. Thibodeau.
Interestingly, the research team also found a weak signal during a period called the Little Ice Age (a cold spell observed between about 1600 and 1850 AD). While not as pronounced as the 20th century trend, the signal might confirm that this period was also characterized by a weaker circulation in the North Atlantic, which implies a decrease in the transfer of heat toward Europe, contributing to the cold temperature of this period. However, more work is needed to validate this hypothesis.


“While we could ground-truth our temperature reconstruction for the 20th century against instrumental measurement it is not possible to do so for the Little Ice Age period. Therefore, we need to conduct more analysis to consolidate this hypothesis” said Dr. Not.


Source: The University of Hong Kong [November 23, 2018]



TANN



Archive


The origins of asymmetry: A protein that makes you do the twist

Asymmetry plays a major role in biology at every scale: think of DNA spirals, the fact that the human heart is positioned on the left, our preference to use our left or right hand … A team from the Institute of biology Valrose (CNRS/Inserm/Université Côte d’Azur), in collaboration with colleagues from the University of Pennsylvania, has shown how a single protein induces a spiral motion in another molecule. Through a domino effect, this causes cells, organs, and indeed the entire body to twist, triggering lateralized behaviour.











The origins of asymmetry: A protein that makes you do the twist
The molecular motor Myosin 1D creates asymmetry at all levels, from the movement of actin molecules
(red and green filaments) to respiratory trachea (white tube-like structures), to the organism itself
(here a Drosophila larva) [Credit: Gaëlle Lebreton/Stéphane Noselli/iBV/CNRS]

Our world is fundamentally asymmetrical: think of the double helix of DNA, the asymmetrical division of stem cells, or the fact that the human heart is positioned on the left … But how do these asymmetries emerge, and are they linked to one another?
At the Institute of biology Valrose, the team led by the CNRS researcher Stéphane Noselli, which also includes Inserm and Université Cote d’Azur researchers, has been studying right-left asymmetry for several years in order to solve these enigmas.


The biologists had identified the first gene controlling asymmetry in the common fruit fly (Drosophila), one of the biologists’ favoured model organisms. More recently, the team showed that this gene plays the same role in vertebrates: the protein that it produces, Myosin 1D, controls the coiling or rotation of organs in the same direction.


The movement of a normal larva (left) and a larva expressing Myosin 1D in its normally symmetrical epidermis. 


Whereas the normal larva crawls linearly, with its ventral side in contact with the liquid, the modified larva


 is twisted and moves via directional ‘barrel rolls’ [Credit: Gaëlle Lebreton/iBV/CNRS]


In this new study, the researchers induced the production of Myosin 1D in the normally symmetrical organs of Drosophila, such as the respiratory trachea. Quite spectacularly, this was enough to induce asymmetry at all levels: deformed cells, trachea coiling around themselves, the twisting of the whole body, and helicoidal locomotive behavior among fly larvae. Remarkably, these new asymmetries always develop in the same direction.


In order to identify the origin of these cascading effects, biochemists from the University of Pennsylvania contributed to the project too: on a glass coverslip, they brought Myosin 1D into contact with a component of cytoskeleton (the cell’s “backbone”), namely actin. They were able to observe that the interaction between the two proteins caused the actin to spiral.


Besides its role in right-left asymmetry among Drosophila and vertebrates, Myosin 1D appears to be a unique protein that is capable of inducing asymmetry in and of itself at all scales, first at the molecular level, then, through a domino effect, at the cell, tissue, and behavioral level.


These results suggest a possible mechanism for the sudden appearance of new morphological characteristics over the course of evolution, such as, for example, the twisting of snails’ bodies. Myosin 1D thus appears to have all the necessary characteristics for the emergence of this innovation, since its expression alone suffices to induce twisting at all scales.


The research is published in the journal Science.


Source: CNRS [November 23, 2018]



TANN



Archive


NASA InSight lander arrives on Martian surface

Mars has just received its newest robotic resident. NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander successfully touched down on the Red Planet after an almost seven-month, 300-million-mile (458-million-kilometer) journey from Earth.











NASA InSight lander arrives on Martian surface
An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations,
Geodesy and Heat Transport, is designed to give the Red Planet its first thorough check up since it formed 4.5 billion years
 ago. The mission will look for tectonic activity and meteorite impacts, study how much heat is still flowing through the
planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it’s more than a Mars mission.
InSight will help answer key questions about the formation of the rocky planets of the solar system
[Credit: NASA/JPL-Caltech]

InSight’s two-year mission will be to study the deep interior of Mars to learn how all celestial bodies with rocky surfaces, including Earth and the Moon, formed.


InSight launched from Vandenberg Air Force Base in California May 5. The lander touched down Monday, Nov. 26, near Mars’ equator on the western side of a flat, smooth expanse of lava called Elysium Planitia, with a signal affirming a completed landing sequence at 11:52:59 a.m. PST (2:52:59 p.m. EST).


“Today, we successfully landed on Mars for the eighth time in human history,” said NASA Administrator Jim Bridenstine. “InSight will study the interior of Mars and will teach us valuable science as we prepare to send astronauts to the Moon and later to Mars. This accomplishment represents the ingenuity of America and our international partners, and it serves as a testament to the dedication and perseverance of our team. The best of NASA is yet to come, and it is coming soon.”


The landing signal was relayed to NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, via NASA’s two small experimental Mars Cube One (MarCO) CubeSats, which launched on the same rocket as InSight and followed the lander to Mars. They are the first CubeSats sent into deep space. After successfully carrying out a number of communications and in-flight navigation experiments, the twin MarCOs were set in position to receive transmissions during InSight’s entry, descent and landing.


From Fast to Slow


“We hit the Martian atmosphere at 12,300 mph (19,800 kilometers per hour), and the whole sequence to touching down on the surface took only six-and-a-half minutes,” said InSight project manager Tom Hoffman at JPL. “During that short span of time, InSight had to autonomously perform dozens of operations and do them flawlessly — and by all indications that is exactly what our spacecraft did.”



Confirmation of a successful touchdown is not the end of the challenges of landing on the Red Planet. InSight’s surface-operations phase began a minute after touchdown. One of its first tasks is to deploy its two decagonal solar arrays, which will provide power. That process begins 16 minutes after landing and takes another 16 minutes to complete.


The InSight team expects a confirmation later Monday that the spacecraft’s solar panels successfully deployed. Verification will come from NASA’s Odyssey spacecraft, currently orbiting Mars. That signal is expected to reach InSight’s mission control at JPL about five-and-a-half hours after landing.


“We are solar powered, so getting the arrays out and operating is a big deal,” said Tom Hoffman at JPL. “With the arrays providing the energy we need to start the cool science operations, we are well on our way to thoroughly investigate what’s inside of Mars for the very first time.”


InSight will begin to collect science data within the first week after landing, though the teams will focus mainly on preparing to set InSight’s instruments on the Martian ground. At least two days after touchdown, the engineering team will begin to deploy InSight’s 5.9-foot-long (1.8-meter-long) robotic arm so that it can take images of the landscape.


“Landing was thrilling, but I’m looking forward to the drilling,” said InSight principal investigator Bruce Banerdt of JPL. “When the first images come down, our engineering and science teams will hit the ground running, beginning to plan where to deploy our science instruments. Within two or three months, the arm will deploy the mission’s main science instruments, the Seismic Experiment for Interior Structure (SEIS) and Heat Flow and Physical Properties Package(HP3) instruments.”


InSight will operate on the surface for one Martian year, plus 40 Martian days, or sols, until Nov. 24, 2020. The mission objectives of the two small MarCOs which relayed InSight’s telemetry was completed after their Martian flyby.


“That’s one giant leap for our intrepid, briefcase-sized robotic explorers,” said Joel Krajewski, MarCO project manager at JPL. “I think CubeSats have a big future beyond Earth’s orbit, and the MarCO team is happy to trailblaze the way.”


With InSight’s landing at Elysium Planitia, NASA has successfully soft-landed a vehicle on the Red Planet eight times.


“Every Mars landing is daunting, but now with InSight safely on the surface we get to do a unique kind of science on Mars,” said JPL director Michael Watkins. “The experimental MarCO CubeSats have also opened a new door to smaller planetary spacecraft. The success of these two unique missions is a tribute to the hundreds of talented engineers and scientists who put their genius and labor into making this a great day.”


Source: NASA/Jet Propulsion Laboratory [November 26, 2018]



TANN



Archive


Extreme heat increasing in both summer and winter

A new study shows extreme heat events both in the summer and in the winter are increasing across the U.S. and Canada, while extreme cold events in summer and winter are declining.











Extreme heat increasing in both summer and winter
Soybeans show the effect of the Texas drought near Navasota, TX on Aug. 21, 2013
[Credit: USDA]

A new study in the in Journal of Geophysical Research: Atmospheres, a publication of the American Geophysical Union, examined absolute extreme temperatures–high temperatures in summer and low temperatures in winter–but also looked at relative extreme temperature events–unusually cold temperatures and unusually warm temperatures throughout the year.


The new study found both relative and absolute extreme heat events have increased across the US and Canada since 1980. This upward trend is greatest across the southern US, especially in the Ozarks and southern Arizona, as well as northern Quebec. That means there are more extremely hot days during the summer as well as more days that are considered extremely hot for the time of year, like abnormally warm days in the winter.


The new research also found both relative and absolute extreme cold events are decreasing, most notably in Alaska and Northern Canada, along with patches along the US Atlantic coast. In these areas, there are fewer instances of temperatures that are extremely cold either compared to the normal range, like in winter, or for the time of year, like unusually cold days in the summer.


Global mean surface temperature, the most frequently cited indicator of climate change, has been steadily increasing since the 1970s. However, temperature extremes pose a greater ecological risk to many species than average warming, according to the study’s authors.


The new study is one of the first to explore relative extreme temperature events, which are changing more rapidly than absolute temperature extremes, and can have important implications for the environment, agriculture and human health, according to Scott Sheridan, professor in the department of geography at Kent State University and lead author of the new study.


“Typically for this kind of research we look at the highest temperatures in the summer and lowest temperatures in the winter. But we’ve also seen that extreme temperatures that are really anomalous for the time of year can have a high impact–these relative extremes are important and underappreciated,” he said.


Investigating temperature extremes


To investigate how extreme temperature events have been changing over time, Sheridan and his co-author conducted a climatology of cold and heat events, both absolute and relative, for North America, followed by an analysis of how they have changed from 1980-2016.











Extreme heat increasing in both summer and winter
Trends in Extreme Heat Events (EHE), Extreme Cold Events (ECE), Relative Extreme Heat Events (REHE),
and Relative Extreme Cold Events (RECE) in days per decade, 1980-2016. Dots indicate grid cells
 in which the trend is statistically significant (p<.05) [Credit: Scott Sheridan]

Relative extreme temperature events are changing faster than absolute extreme events, and often occur outside of seasonal norms, according to the new study. In the eastern half of the US, relative extreme heat events occur as early as mid-winter into early spring. Out-of-season extreme temperatures can cause early thaws in mild winters or catch vulnerable populations unprepared and unacclimated.


Across parts of the Arctic, extreme cold events have become almost entirely nonexistent and increasingly difficult to identify, according to the researchers.


“Relative temperature anomalies can trigger what are called phenological mismatches, where a mismatch in the temperature and the season can cause trees to bloom too early and birds and insects to migrate before there is appropriate food,” Sheridan said.


Most notable is the highly anomalous warm event in March 2012, which included persistent mid-summer warmth in multiple locations. The event produced a ‘false spring’ in which vegetation prematurely left dormancy, so that it was not prepared for subsequent frosts, leading to large agricultural losses in certain areas, according to the researchers.


There is some evidence that early-season heat events are more hazardous to humans than heat events later in the season. When people are not acclimatized to hotter temperatures, they are more vulnerable to negative health impacts, especially the elderly, infants, young children, and people with chronic health problems or disabilities, according to the researchers.


The study clearly underlines the importance of not just looking at high temperatures in the summer but also looking at relative temperatures, said Kristie Ebi, professor of Environmental and Occupational Health Sciences at the University of Washington, who was not involved in the study.


“Using information generated in the study on regional patterns in extreme weather events, particularly relative extremes in temperature, early warnings could be issued that include information on what people can do to protect themselves and to protect crops and ecosystems,” Ebi said.


Source: American Geophysical Union [November 26, 2018]



TANN



Archive


Behind the Scenes of Recovering Hubble Space Telescope


NASA – Hubble Space Telescope patch.


Nov. 27, 2018


In the early morning of October 27, the Hubble Space Telescope targeted a field of galaxies not far from the Great Square in the constellation Pegasus. Contained in the field were star-forming galaxies up to 11 billion light-years away. With the target in its sights, Hubble’s Wide Field Camera 3 recorded an image. It was the first picture captured by the telescope since it closed its eyes on the universe three weeks earlier, and it was the result of an entire team of engineers and experts working tirelessly to get the telescope exploring the cosmos once again.


“This has been an incredible saga, built upon the heroic efforts of the Hubble team,” said Hubble senior project scientist Jennifer Wiseman at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Thanks to this work, the Hubble Space Telescope is back to full science capability that will benefit the astronomical community and the public for years to come.”



Image above: The first image captured by Hubble after returning to science on October 27, 2018, shows a field of galaxies in the constellation Pegasus. The observations were taken with the Wide Field Camera 3 to study very distant galaxies in the field. Image Credits: NASA, ESA and A. Shapley (UCLA).


On the evening of Friday, October 5, the orbiting observatory had put itself into “safe mode” after one of its gyroscopes (or “gyros”) failed. Hubble stopped taking science observations, oriented its solar panels toward the Sun, and waited for further instructions from the ground.


It was the beginning of a three-day holiday weekend when members of the spacecraft’s operations team started receiving text messages on their phone, alerting them that something was wrong with Hubble. In less than an hour, more than a dozen team members had gathered in the control room at Goddard to assess the situation. After unsuccessfully reviving the failed gyro, they activated a backup gyro on the spacecraft. However, the gyro soon began reporting impossibly high rotation rates — around 450 degrees per hour, when Hubble was actually turning less than a degree per hour.


“This is something we’ve never seen before on any other gyros — rates this high,” said Dave Haskins, Hubble’s mission operations manager at Goddard.


Hubble has six gyros aboard, and it typically uses three at a time to collect the most science. However, two of its six gyros had previously failed. This was Hubble’s final backup gyro. The operations team either had to figure out how to get it working, or turn to a previously developed and tested “one-gyro mode,” which is proven to work but would limit Hubble’s efficiency and how much of the sky the telescope could observe at a given time of the year — something both the operations team and astronomers want to avoid until there is no other choice.


As they decided what to do next, team members stayed in the control center continuously to monitor the health and safety of the spacecraft. Because Hubble’s control center had switched to automated operations back in 2011, there were no longer people in place to monitor Hubble 24 hours a day.


“The team pulled together to staff around the clock, something we haven’t done in years,” Haskins said. Team members stepped in to take shifts — several of Hubble’s systems engineers, others who help run tests and checkouts of Hubble’s ground systems and some who used to staff Hubble’s control room but hadn’t in a long time. “It’s been years since they’ve been on console doing that kind of shift work. To me it was seamless. It shows the versatility of the team.”


Meanwhile, during the holiday weekend, Hubble Project Manager Pat Crouse was busy recruiting a team of experts from Goddard and around the country to analyze the backup gyro’s unusual behavior and determine whether it could be corrected. This anomaly review board met for the first time that Tuesday, October 9, and contributed valuable insight throughout Hubble’s recovery.



Image above: Astronauts captured this photo of the Hubble Space Telescope orbiting Earth in 2002 during STS-109, the fourth Hubble Telescope servicing mission.​ Image Credit: NASA.


It took weeks of creative thinking, continuous tests and minor setbacks to solve the problem of the misbehaving gyro. Members of the operations team and of the review board suspected there might be some sort of obstruction in the gyro affecting its readings. Attempting to dislodge such a blockage, the team repeatedly tried switching the gyro between different operational modes and rotating the spacecraft by large amounts. In response, the extremely high rotation rates from the gyro gradually fell until they were close to normal.


Encouraged but cautious, the team uploaded new software safeguards on Hubble to protect the telescope in case the gyro reports unduly high rates again, and then sent the telescope through some practice maneuvers to simulate real science observations. They kept a close watch to make sure everything on the spacecraft performed correctly. It did.


“Early on we had no idea whether we’d be able to resolve that issue or not,” Hubble’s deputy mission operations manager, Mike Myslinski, said about the high gyro rates.


In the background, other team members at Goddard and the Space Telescope Science Institute had begun preparing in case Hubble would have to switch to using just a single gyro, with the other working gyro held in reserve as a backup. Fortunately, the results of their efforts weren’t needed this time, but their work wasn’t for naught. “We know that we’ll have to go to one gyro someday, and we want to be as prepared as possible for that,” Myslinski said. “We’d always said that once we got down to three gyros we would do as much up-front work as possible for one-gyro science. That day has come.”


For now, however, Hubble is back to exploring the universe with three working gyros, thanks to the hard work of a multitude of people on the ground.


“Many team members made personal sacrifices to work long shifts and off-shifts to ensure the health and safety of the observatory, while identifying a path forward that was both safe and effective,” Crouse said of the efforts to return to science. “The recovery of the gyro is not only vital for the life expectancy of the observatory, but Hubble is most productive in three-gyro mode, and extending this historic period of productivity is a main objective for the mission. Hubble will continue to make amazing discoveries when it is time to operate in one-gyro mode, but due to the tremendous effort and determination of the mission team, now is not the time.”


Related articles:


Hubble Moving Closer to Normal Science Operations
https://orbiterchspacenews.blogspot.com/2018/10/hubble-moving-closer-to-normal-science.html


Update on the Hubble Space Telescope Safe Mode
https://orbiterchspacenews.blogspot.com/2018/10/update-on-hubble-space-telescope-safe.html


Hubble in Safe Mode as Gyro Issues are Diagnosed
https://orbiterchspacenews.blogspot.com/2018/10/hubble-in-safe-mode-as-gyro-issues-are.html


For more information about Hubble, visit:


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


Images (mentioned), Text, Credits: NASA/Karl Hille/Goddard Space Flight Center, by Vanessa Thomas.


Greetings, Orbiter.chArchive link


Russian, U.S. Spaceships Get Ready for Launch Ahead of Spacewalk


ISS – Expedition 57 Mission patch.


Nov. 27, 2018


In a replay similar to the weekend before Thanksgiving, two rockets on the opposite sides of the world are poised to launch one day after another to replenish the International Space Station with a new crew and cargo.


Three new Expedition 58 crew members are preparing to blast off to the space station on a Russian Soyuz crew ship early next week. The following day, SpaceX will launch its Dragon cargo craft to the orbital lab atop a Falcon 9 rocket.



Image above: In Baikonur, Kazakhstan, Expedition 58 crew members (from left) Anne McClain, Oleg Kononenko and David Saint-Jacques pose for pictures Nov. 27 as part of traditional pre-launch activities. Image Credit: ROSCOSMOS.


New astronauts Anne McClain and David Saint-Jacques with veteran cosmonaut Oleg Kononenko will take a six-hour ride to the station on Monday Dec. 3. The trio will lift off inside their Soyuz MS-11 spacecraft at 6:31 a.m. EST from the Baikonur Cosmodrome in Kazakhstan. About six hours later they will reach their new home in space and dock to the Poisk module beginning a six-and-a-half-month mission.


The SpaceX Dragon is targeted to begin its ascent to space from the launch pad at the Kennedy Space Center on Dec. 4. Dragon will orbit Earth for two days loaded with new science before it is captured with the station’s Canadarm2 and installed to the Harmony module.


Back in space, three Expedition 57 crew members are getting ready for the arrival of both spacecraft while staying focused on microgravity science and spacewalk preparations.



International Space Station (ISS). Animation Credit: NASA

Commander Alexander Gerst and Flight Engineer Serena Auñón-Chancellor trained for next week’s Dragon rendezvous and capture on a computer today. The duo also continued working on more life science and physics research. Gerst once again studied how protein crystals impact Parkinson’s disease to possibly improve treatments on Earth. Serena researched how cement hardens in space and continued setting up hardware for a semiconductor crystal experiment.


Cosmonaut Sergey Prokopyev is configuring the station’s Russian segment for a spacewalk targeted for Dec. 11. He and Kononenko will inspect the Soyuz MS-09 spacecraft docked to the Rassvet module before the Expedition 57 trio returns to Earth on Dec. 20.


Related links:


Expedition 57: https://www.nasa.gov/mission_pages/station/expeditions/expedition57/index.html


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


Protein crystals: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7855


Semiconductor crystal experiment: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=308


NASA TV: https://www.nasa.gov/multimedia/nasatv/index.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


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


Best regards, Orbiter.chArchive link


How the Atlantic Ocean became part of the global circulation at a climatic tipping point

The scientists made this discovery when they compared neodymium isotope signatures of deep sea sediment samples from both regions of the Atlantic. Their paper – ‘Major intensification of Atlantic overturning circulation at the onset of Paleogene greenhouse warmth’ – published in Nature Communications, reveals that the more vigorous circulation together with an increase in atmospheric CO2 led to a climatic tipping point. With a resulting more even distribution of heat over the earth, a long-term cooling phase ended and the world headed into a new greenhouse period.











How the Atlantic Ocean became part of the global circulation at a climatic tipping point
Collecting deep sea sediments which are valuable archives of ocean circulation and past climates
[Credit: Department of Earth Sciences]

Neodymium (Nd) isotopes are used as a tracer of water masses and their mixing. Surface waters acquire a Nd-isotope signature from surrounding land masses through rivers and wind-blown dust. When surface waters sink to form a deep-water mass, they carry their specific Nd-isotope signature with them. As a deep-water mass flows through the ocean and mixes with other water masses, its Nd-isotope signature is incorporated into sediments. Deep sea sediments are valuable archives of ocean circulation and past climates.
The story revealed in this paper begins at the end of the Cretaceous period (ending 66 million years ago), when the world was between two greenhouse states. Climate had been cooling for tens of millions of years since the peak hothouse conditions of the mid-Cretaceous, around 90 million years ago. Despite long-term cooling, temperatures and sea level at the end of the Cretaceous period were higher than at present day.


Dr Sietske Batenburg says: ‘Our study is the first to establish how and when a deep-water connection formed. At 59 million years ago, the Atlantic Ocean truly became part of the global thermohaline circulation, the flow that connects four of the five main oceans.’











How the Atlantic Ocean became part of the global circulation at a climatic tipping point
Deep sea sediments are valuable archives of ocean circulation and past climates
[Credit: Department of Earth Sciences]

The Atlantic Ocean was still young, and the North and South Atlantic basins were shallower and narrower than today. The equatorial gateway between South America and Africa only allowed a shallow, surface-water connection for much of the late Cretaceous period. Active volcanism formed underwater mountains and plateaus that blocked deep-water circulation. In the South Atlantic, the Walvis Ridge barrier formed above an active volcanic hotspot. This ridge was partially above sea level and formed a barrier for the flow of deep-water masses.
As the Atlantic Ocean continued to open, the oceanic crust cooled and subsided. Basins became deeper and wider, and submarine plateaus and ridges sank, along with the crust. At some point, deep water from the Southern Ocean was able to flow north across the Walvis Ridge and fill the deeper parts of the Atlantic basins.


From 59 million years ago onwards, Nd-isotope signatures from the North and South Atlantic were remarkably similar. This may indicate that one deep-water mass, likely originating from the south, made its way through the Atlantic Ocean and filled the basin from deep to intermediate depths. The enhanced deep water exchange, together with increasing atmospheric CO2, may have enabled a more efficient distribution of heat over the planet.











How the Atlantic Ocean became part of the global circulation at a climatic tipping point
This is a neodymium isotope ratio [Credit: Department of Earth Sciences]

This study shows that to understand the role of ocean circulation in past greenhouse climates, it is important to understand the different roles of geography and climate.


The current rate of climate change by CO2 emissions from human activity by far surpasses the rate of warming during past greenhouse climates. Studying ocean circulation during the most recent greenhouse interval in the geologic past may provide clues as to how ocean circulation might develop in the future, and how heat will be distributed over the planet by ocean currents.


This research is the result of an international collaboration with the Goethe-University Frankfurt; the Ruprecht-Karls-University of Heidelberg; the GEOMAR Helmholtz Centre for Ocean Research Kiel; the Federal Institute for Geosciences and Natural Resources in Hannover; the Royal Holloway University of London and the University of Oxford.


The sediments for this study were all taken from long ocean drill cores. The International Ocean Discovery Program (IODP) coordinates scientific expeditions to drill the ocean floor to recover these sediments, and stores the sediment cores so that they are available to the whole scientific community.


Source: University of Oxford [November 26, 2018]



TANN



Archive


How ancient viruses got cannabis high

THC and CBD, bioactive substances produced by cannabis and sought by medical patients and recreational users, sprung to life thanks to ancient colonization of the plant’s genome by viruses, U of T researchers have found.











How ancient viruses got cannabis high
Modern day hemp and marijuana evolved distinct chemistry thanks to ancient viruses that colonized
the ancestral cannabis genome millions of years ago [Credit: Michael Fischer]

The finding is only one of the insights revealed by the long-awaited cannabis genome map detailing gene arrangement on the chromosomes, published recently in the journal Genome Research. Among other revelations are discovery of a gene responsible for the production of cannabichromene, or CBC, a lesser known cannabinoid, as the active substances in cannabis are known, and new insights into how strain potency is determined.


“The chromosome map is an important foundational resource for further research which, despite cannabis’ widespread use, has lagged behind other crops due to restrictive legislation,” says Tim Hughes, a professor in the Donnelly Centre for Cellular and Biomolecular Research and co-leader of the study. Hughes is also a professor in the Department of Molecular Genetics and Senior Fellow at the Canadian Institute for Advancement of Research.


The researchers expect the map will speed up breeding efforts to create new strains with desired medical properties as well as varieties that can be grown more sustainably, or with increased resistance to diseases and pests.


The study was a three-part collaboration between Tim Hughes’ team and those of Jonathan Page, of Aurora Cannabis and the University of British Columbia , and Harm van Bakel, of the Icahn School of Medicine at Mt Sinai in New York.


Hughes, Page and van Bakel first got together in 2011 when they released the first draft of cannabis genome which was too fragmented to reveal gene position on chromosomes.


The new map reveals how hemp and marijuana, which belong to the same species Cannabis sativa, evolved as separate strains with distinct chemical properties. Cannabis plants grown for drug use (“marijuana”) are abundant in psychoactive tetrahydrocannabinol, or THC, whereas hemp produces cannabidiol, or CBD, popular of late for its medicinal potential. Some people use CBD to relieve pain and it is also being tested as a treatment for epilepsy, schizophrenia and Alzheimer’s.


The enzymes making THC and CBD are encoded by THCA and CBDA synthase genes, respectively. Both are found on chromosome 6 of the ten chromosomes the cannabis genome is packaged into. There, the enzyme genes are surrounded by vast swathes of garbled DNA which came from viruses that colonized the genome millions of years ago. This viral DNA, or retroelements as it is known, made copies of itself that spread across the genome by jumping into other sites in the host cell’s DNA.


“Plant genomes can contain millions of retroelement copies,” says van Bakel, an assistant professor in the Icahn Institute for Data Science and Genomic Technology in New York and in the department of Genetics and Genome Sciences. “This means that linking genes on chromosomes is analogous to assembling a huge puzzle where three quarters of the pieces are nearly the same color. The combination of a genetic map and PacBio sequencing technology allowed us to increase the size of the puzzle pieces and find enough distinguishing features to facilitate the assembly process and pinpoint the synthase genes.”


The researchers believe that gene duplication of the ancestral synthase gene and expanding retroelements drove ancient cannabis to split into chemically distinct types. Humans subsequently selected for plants containing desirable chemistry such as high THC.


The gene sequences for the THCA and CBDA synthases are nearly identical supporting the idea that they come from the same gene which was duplicated millions of years ago. Over time, one or both gene copies became scrambled by invading retroelements, and by evolving separately, they eventually came to produce two different enzymes – CBDA synthase found in hemp (fibre-type), and THCA synthase in drug-type (marijuana).


Because the enzymes are so similar at the DNA level, until this study it was not even clear if they are encoded by separate genes or by two versions of the same gene. Adding to the confusion was the fact that most strains produce both CBD and THC despite breeders’ efforts to grow hemp varieties free from the mind-altering THC for users looking to avoid it.


The chromosome map now clearly shows that two distinct genes are at play which should make it possible to separate them during breeding to grow plants without THC.


Some psychoactive effects in medical strains could be coming from CBC, a lesser known cannabinoid that has unusual pharmacology including anti-inflammatory properties. The discovery of the gene responsible for CBC synthesis will make it possible for breeders to tailor its content in future varieties.


“Mainstream science has still not done enough because of research restrictions,” says Page, of UBC and Chief Scientific Officer at Aurora, one of Canada’s largest producers of medical cannabis. “Legalization and looming ease of research regulation really provide for opportunities for more research to be done. And Canada is leading the way.”


Source: University of Toronto [November 26, 2018]



TANN



Archive


Effort clarifies major branch of insect tree of life

The insects known as Hemiptera are not a particularly glamorous bunch. This group includes stink bugs, bed bugs, litter bugs, scale insects and aphids. Their closest relatives are thrips, bark lice and parasitic lice. But with a massive number of species, two-thirds of which are still unknown to science, these insects together make up one of the twiggiest branches of the tree of life.











Effort clarifies major branch of insect tree of life
Philagra, a Chinese spittlebug [Credit: Christopher Dietrich]

A new study published in the Proceedings of the National Academy of Sciences collected a vast amount of molecular data on these insects and used the information to help tease out their family relationships and evolutionary history. The findings – and the data, which are now publicly available – will aid future research into some of the most abundant and economically important insects on the planet, the researchers said.


“There are 120,000 known species in this group, which is maybe a third of what’s actually out there,” said Illinois Natural History Survey entomologist Christopher Dietrich, who led the study with INHS ornithologist Kevin Johnson. “To put that in perspective, that’s more than all the vertebrates combined. It’s a massively diverse group. They cover the planet. They’re in every habitat.”


Many of these insects feed on plants and animals and can be seen as pests, Dietrich said. But they also provide food for birds, insectivorous mammals, reptiles, amphibians and other predacious insects.


“Many of them form the first link of the food chain, converting plant material into protein that can be used by other animals,” he said.


Among this group are many, like aphids and planthoppers, that afflict crops; others, such as body lice and certain assassin bugs, transmit disease, Dietrich said.











Effort clarifies major branch of insect tree of life
Bird louse [Credit: Stephany Virrueta Herrera]

To sort out these insects’ family relationships and history, the researchers analyzed nearly 2,400 protein-coding genes, their expression in the form of messenger RNA and the resulting amino-acid sequences. It was a massive effort involving collaborators in China, Europe, Japan and across the United States.


“We wanted to use newer sequencing technologies to address how all these major groups of hemipteroid insects related to each other,” Johnson said. “This is probably one of the largest data sets in existence for insects.”


The effort yielded several key findings. The most interesting of these had to do with the development of special mouthparts in some members of this group, the researchers said.


“The earliest, most primitive insects just had a pair of mandibles to chew, like ants do,” Dietrich said. “But some groups went off in a different direction.”


For those, the mandibles gradually evolved into sturdy narrow tubes that could pierce things and suck out the juices. “It was a major shift in feeding strategy,” Dietrich said. “All the insects to this point had just been chomping on things.”











Effort clarifies major branch of insect tree of life
Assassin bug of the family Reduviidae [Credit: Rachel Skinner]

The team’s molecular divergence estimate revealed that the evolution of piercing and sucking mouthparts likely occurred more than 350 million years ago. Similar mouthparts evolved independently in parasitic lice and other insects with the trait, such as mosquitoes.


“According to the fossil record, this group became the dominant group of insects on Earth in the Permian, 300 million years ago to 250 million years ago,” Dietrich said. “But at the end of the Permian they underwent a mass extinction, which was worse than the one that killed off the dinosaurs a couple hundred million years later.”


Eventually, the Hemiptera, along with the orders representing thrips and lice, were eclipsed by another group of insects, the Holometabola, which undergo complete metamorphosis and are even more diverse. Holometabola include butterflies, moths, ants, bees, flies and beetles.


Though more robust than other genetic studies of this group of insects, the new analysis has not fully resolved the relationship between the order that includes bark lice and parasitic lice, and the hemiptera and thrips, which likely belong to the same superorder, the researchers said. But the study sets the stage for future work, and an improved understanding of how some of the less charismatic, but ecologically essential, insects evolved.


Source: University of Illinois at Urbana-Champaign [November 26, 2018]



TANN



Archive


Oxygen could have been available to life as early as 3.5 billion years ago

Microbes could have performed oxygen-producing photosynthesis at least one billion years earlier in the history of the Earth than previously thought.











Oxygen could have been available to life as early as 3.5 billion years ago
Cyanobacteria in a river [Credit: Goran Cakmazovic/Shutterstock]

The finding could change ideas of how and when complex life evolved on Earth, and how likely it is that it could evolve on other planets.


Oxygen in the Earth’s atmosphere is necessary for complex forms of life, which use it during aerobic respiration to make energy.


The levels of oxygen dramatically rose in the atmosphere around 2.4 billion years ago, but why it happened then has been debated. Some scientists think that 2.4 billion years ago is when organisms called cyanobacteria first evolved, which could perform oxygen-producing (oxygenic) photosynthesis.


Other scientist think that cyanobacteria evolved long before 2.4 billion years ago but something prevented oxygen from accumulating in the air.


Cyanobacteria perform a relatively sophisticated form of oxygenic photosynthesis – the same type of photosynthesis that all plants do today. It has therefore been suggested that simpler forms of oxygenic photosynthesis could have existed earlier, before cyanobacteria, leading to low levels of oxygen being available to life.


Now, a research team led by Imperial College London have found that oxygenic photosynthesis arose at least one billion years before cyanobacteria evolved. Their results, published in the journal Geobiology, show that oxygenic photosynthesis could have evolved very early in Earth’s 4.5-billion-year history.


Lead author Dr Tanai Cardona, from the Department of Life Sciences at Imperial, said: “We know cyanobacteria are very ancient, but we don’t know exactly how ancient. If cyanobacteria are, for example, 2.5 billion years old that would mean oxygenic photosynthesis could have started as early as 3.5 billion years ago. It suggests that it might not take billions of years for a process like oxygenic photosynthesis to start after the origin of life.”


If oxygenic photosynthesis evolved early, it could mean it is a relatively simple process to evolve. The probability of complex life emerging in a distant exoplanet may then be quite high.


It is difficult for scientists to figure out when the first oxygen-producers evolved using the rock record on Earth. The older the rocks, the rarer they are, and the harder it is to prove conclusively that any fossil microbes found in these ancient rocks used or produced any amount of oxygen.











Oxygen could have been available to life as early as 3.5 billion years ago
Cyanobacteria up close [Credit: Dr. Norbert Lange/Shutterstock]

Instead, the team investigated the evolution of two of the main proteins involved in oxygenic photosynthesis.


In the first stage of photosynthesis, cyanobacteria use light energy to split water into protons, electrons and oxygen with the help of a protein complex called Photosystem II.


Photosystem II is made up of two proteins called D1 and D2. Originally, the two proteins were the same, but although they have very similar structures, their underlying genetic sequences are now different.


This shows that D1 and D2 have been evolving separately – in cyanobacteria and plants they only share 30 percent of their genetic sequence. Even in their original form, D1 and D2 would have been able to perform oxygenic photosynthesis, so knowing how long ago they were identical could reveal when this ability first evolved.


To find out the difference in time between D1 and D2 being 100 percent identical, and them being only 30 percent the same in cyanobacteria and plants, the team determined how fast the proteins were changing – their rate of evolution.


Using powerful statistics methods and known events in the evolution of photosynthesis, they determined that the D1 and D2 proteins in Photosystem II evolved extremely slowly – even slower than some of the oldest proteins in biology that are believed to be found in the earliest forms of life.


From this, they calculated that the time between the identical D1 and D2 proteins and the 30 percent similar versions in cyanobacteria and plants is at least a billion years, and could be more than that.


Dr Cardona said: “Usually, the appearance of oxygenic photosynthesis and cyanobacteria are considered to be the same thing. So, to find out when oxygen was being produced for the first time researchers have tried to find when cyanobacteria first evolved.


“Our study instead shows that oxygenic photosynthesis likely got started long before the most recent ancestor of cyanobacteria arose. This is in agreement with current geological data that suggests that whiffs of oxygen or localized accumulations of oxygen were possible before three billion years ago.


“Therefore, the origin of oxygenic photosynthesis and the ancestor of cyanobacteria do not represent the same thing. There could be a very large gap in time between one and the other. It is a massive change in perspective.”


Now, the team are trying to recreate what the photosystem looked like before D1 and D2 evolved in the first place. Using the known variation in photosystem genetic codes across all species alive today, they are trying to piece together the ancestral photosystem genetic code.


Author: Hayley Dunning | Source: Imperial College London [November 27, 2018]



TANN



Archive


Climate change wiped out the ‘Siberian unicorn’

New research has shed light on the origin and extinction of a giant, shaggy Ice Age rhinoceros known as the Siberian unicorn because of its extraordinary single horn.











Climate change wiped out the 'Siberian unicorn'
Australian scientists believe the Siberian unicorn was a victim of climate change
[Credit: WikiCommons]

An international team of researchers from Adelaide, Sydney, London, the Netherlands, and Russia, have settled a long-standing debate about the relationship of the Siberian unicorn to living rhinos, and revealed that it survived much later than previously believed, overlapping in time with modern humans.


Published in the journal Nature Ecology and Evolution and led by London’s Natural History Museum, the researchers say the Siberian unicorn became extinct around 36,000 years ago. This was most likely because of reduction in steppe grassland where it lived – due to climate change rather than the impact of humans.


Today there are just five surviving species of rhino, although in the past there have been as many as 250 species.


Weighing up to 3.5 tonnes with a single enormous horn, the Siberian unicorn (Elasmotherium sibiricum), which roamed the steppe of Russia, Kazakhstan, Mongolia, and Northern China, was undoubtedly one of the most impressive.











Climate change wiped out the 'Siberian unicorn'
Skeleton of the rhino at the Stavropol Museum [Credit: Igor Doronin]

Genetic analyses performed at the University of Adelaide’s Australian Centre for Ancient DNA (ACAD), however, have shown that the Siberian unicorn was the last surviving member of a unique family of rhinos.


“The ancestors of the Siberian unicorn split from the ancestors of all living rhinos over 40 million years ago,” says co-author and ACAD researcher Dr. Kieren Mitchell, who analysed the DNA of the Siberian unicorn. It is the first time DNA has ever been recovered from E. sibiricum.


“That makes the Siberian unicorn and the African white rhino even more distant cousins than humans are to monkeys.”


This new genetic evidence overturns previous studies that suggested the Siberian unicorn was a very close relative of the extinct woolly rhino and living Sumatran rhino.


It had long been assumed that the Siberian unicorn went extinct well before the last Ice Age, perhaps as much as 200,000 years ago.











Climate change wiped out the 'Siberian unicorn'
Artist’s impression of Elasmotherium [Credit: © W. S. Van der Merwe/Natural History Museum]

In this study 23 Siberian unicorn bone specimens were dated, confirming that the species survived until at least 39,000 years ago, and possibly as late as 35,000 years ago. The Siberian unicorn’s final days were shared with early modern humans and Neanderthals.


“It is unlikely that the presence of humans was the cause of extinction,” says co-author Professor Chris Turney, climate scientist at the University of New South Wales.


“The Siberian unicorn appears to have been badly hit by the start of the ice age in Eurasia when a precipitous fall in temperature led to an increase in the amount of frozen ground, reducing the tough, dry grasses it lived on and impacting populations over a vast region.”


Other species that shared the Siberian unicorn’s environment were either less reliant on grass – like the woolly rhino – or more flexible in their diet – like the saiga antelope – and escaped the Siberian unicorn’s fate, though the woolly rhino eventually became extinct 20,000 years later.


Author: Robyn Mills | Source: University of Adelaide [November 27, 2018]



TANN



Archive


Hidden history of Rome revealed under world’s first cathedral

Supported throughout by the British School at Rome the team – drawn from Newcastle University, UK, the universities of Florence and Amsterdam and the Vatican Museums – have been able to bring the splendour of successive transformations of the ancient city to life.











Hidden history of Rome revealed under world's first cathedral
Research beneath the Archbasilica of St John Lateran has revealed the appearance of world’s first cathedral and the
remarkable transformations that preceded its construction. A team of archaeologists from Newcastle University,UK,
the universities of Florence and Amsterdam and the Vatican Museums, have worked far beneath the streets of Rome
 to piece together a pivotal moment in the history of the eternal city [Credit: The Lateran Project]

The church, the Pope’s own cathedral, was originally built in the 4th century AD by Constantine – the first Roman emperor to convert to Christianity. Positioned on the Caelian Hill, the church would have dominated the Roman skyline at the time.


As research reveals, however, the site had already been in use for centuries. To build his magnificent cathedral, Constantine had swept away the Castra Nova (New Fort), the lavish headquarters of the imperial horseguard constructed over a century before by the Emperor Septimius Severus. In much the same way, Severus had previously destroyed the palatial houses of some of Rome’s most powerful residents to make way for the horseguards’ impressive new home.


This ongoing process of construction on the site meant that over hundreds of years layers of Roman history were laid down, much of it reflecting the changing fortunes and priorities of the Empire.


Working far beneath the modern streets of Rome, the team on the Lateran Project have brought to life the first ever holistic picture of hundreds of years of Roman history by using digital mapping, ground penetrating radar and 3D visualisation techniques.


Working with some of the world’s leading visualisation specialists, the team has reconstructed the splendour of the buildings. It is one of the first projects in the world to have used terrestrial laser-scanning over such a large area to drive archaeological research.











Hidden history of Rome revealed under world's first cathedral
Research beneath the Archbasilica of St John Lateran has revealed the hidden history of the world’s first cathedral
and the remarkable transformations that preceded its construction. A team of archaeologists from Newcastle University,
UK, the universities of Florence and Amsterdam and the Vatican Museums, have worked far beneath the streets of Rome
 to piece together a pivotal moment in the history of the eternal city. To build his 4th century cathedral, To build his
magnificent cathedral, Constantine swept away the Castra Nova (New Fort), the lavish headquarters of the imperial
horseguards constructed over a century before by the Emperor Septimius Severus [Credit: The Lateran Project]

The work has also permitted study of how the different buildings that occupied the site evolved, how different elements relate to one another and has given a sense of the scale the four-hectare site covers.


The work carried out by the Lateran Project is featured in the latest edition of Current World Archaeology. Talking exclusively to the publication, Professor Ian Haynes, Co-Director of the Lateran Project and Professor of Archaeology at Newcastle University, UK, said: “There is a large area of space underneath the Lateran that it is possible to walk or crawl through.


“The archaeology is at varying levels below – at the deepest we were 8.5m below modern ground surface. To access some of the spaces we worked with a group called Roma Sotteranea who specialise in working on buried sites and use exactly the same equipment and techniques as potholers. In some places, it was necessary to rotate the teams on a half hourly basis because otherwise it just becomes stifling.”


The construction of the cathedral was a pivotal moment marking the start of the major Christian buildings that came to define Rome and is a potent symbol of the military making way for religion.


In AD312 Constantine’s army fought the Battle of Milvian Bridge, after which the old Horse Guards base and several nearby buildings were destroyed. The land was given to the Church and provided the perfect spot for Constantine to set out his new vision for Rome.











Hidden history of Rome revealed under world's first cathedral
Research beneath the Archbasilica of St John Lateran has revealed the hidden history of the world’s first cathedral and
the remarkable transformations that preceded its construction. A team of archaeologists from Newcastle University, UK,
 the universities of Florence and Amsterdam and the Vatican Museums, have worked far beneath the streets of Rome to
 piece together a pivotal moment in the history of the eternal city. Using innovative 3D mapping and visualisation tools,
the Lateran Project team have brought to life the first ever holistic picture of hundreds of years of Roman history
[Credit: The Lateran Project]

Professor Haynes told Current World Archaeology: “The land may have been given to the Church within weeks of the battle. A decision was certainly taken pretty soon afterwards and work on the Lateran started some years before it did on St Peter’s.


“The cathedral was rebuilt in the 1650s but there is still original Constantine fabric in the walls, while the original foundations are exposed beneath the church.


“There have been various efforts to reconstruct it since then, so we wanted to pull together all of this information to create a digital cathedral that you can walk around.


“Working with colleagues at the University of Amsterdam and Newcastle-based visualisation specialists, New Visions, we’ve incorporated information from earlier excavations. We also created a simpler model to test the acoustics and to try to understand how sounds would have worked in the basilica.”


Source: Newcastle University [November 27, 2018]



TANN



Archive


HiPOD (27 November 2018): An Impact Crater with a Central…



HiPOD (27 November 2018): An Impact Crater with a Central Structure 


   – In a Context Camera image of the same crater, the ejecta does not look very fresh, so this crater might be extremely old. (Alt: 270 km. Black and white is less than 5 km across; enhanced color is less than 1 km.)


NASA/JPL/University of Arizona


Featured

    Солнечное затмение 14 декабря 2020 года  — полное  солнечное затмение  142  сароса , которое лучше всего будет видно в юго-восточной час...

Popular