пятница, 13 декабря 2019 г.

CryoSat maps ice shelf on the move

ESA - CRYOSAT Mission logo.

Dec. 13, 2019

It is now almost 10 years since ESA’s CryoSat was launched. Throughout its decade in orbit, this novel satellite, which carries a radar altimeter to measure changes in the height of the world’s ice, has returned a wealth of information about how ice sheets, sea ice and glaciers are responding to climate change. One of the most recent findings from this extraordinary mission shows how it can be used to map changes in the seaward edges of Antarctic ice shelves.

About three-quarters of the Antarctic coastline consists of ice shelves. They are permanent floating extensions of the ice sheet that are connected to and fed by huge ice streams draining the interior ice sheet. Ice shelves form as the ice sheet flows towards the ocean and detaches from the bedrock beneath. The advance or retreat of ice shelves is determined by a balance between mass gain from the flow of ice behind and snowfall on top, and mass loss through ocean melting at the base or iceberg calving at the edge.

Filchner-Ronne ice shelf advance 2011–18

Animation above: The animation shows the gradual advance of the Filchner-Ronne ice shelf in Antarctica. Applying a new method, called ‘elevation edge’, to CryoSat data and computational theory has revealed that the entire Filchner-Ronne ice shelf advanced by more than 800 sq km per year between 2011 and 2018. The growth of the ice shelf was only interrupted by the calving of a 120 sq km iceberg in 2012 and a few smaller-scale events.

Ice shelves are important for the stability of the ice sheet because they act as buttresses, holding back the glaciers that feed them and slowing the flow of land ice into the ocean that contributes to sea-level rise.

However, in recent years warming ocean waters and higher air temperatures are taking their toll on some of the ice shelves, causing them to thin, shrink or even collapse entirely. Therefore, mapping ice-shelf calving front locations is important for understanding and predicting future changes in the stability of the ice sheet.

A paper published recently describes how scientists have developed a novel approach of using CryoSat to generate a unique time series of ice front positions for the Filchner-Ronne ice shelf – the second largest ice shelf in Antarctica.

Jan Wuite, from ENVEO in Austria, said, “The detection of the calving front is based on the premise that the edge of an ice shelf is typically a steep ice cliff, with a drop of tens of metres to the ocean surface or sea-ice cover, which is clearly revealed by CryoSat.

“Applying a new method, called ‘elevation edge’, to CryoSat’s data has revealed that the entire Filchner-Ronne ice shelf advanced by more than 800 sq km per year between 2011 and 2018. The growth of the ice shelf was only interrupted by the calving of a 120 sq km iceberg in 2012 and a few smaller-scale events.”

Filchner-Ronne ice shelf

Image above: The Filchner-Ronne ice shelf in Antarctica. Applying a new method, called ‘elevation edge’, to CryoSat data has revealed that the entire Filchner-Ronne ice shelf advanced by more than 800 sq km per year between 2011 and 2018. The growth of the ice shelf was only interrupted by the calving of a 120 sq km iceberg in 2012 and a few smaller-scale events.

Eventually, the advancing ice front is expected to break off as part of the natural ice shelf cycle, but these are rather episodic events that only happen every few years or sometimes decades. Many questions still need to be answered as to what is driving these calving events.

Thomas Nagler, also from ENVEO, added, “Combining this new dataset with ice velocities derived from Copernicus Sentinel-1 data allows us to calculate changes in the thickness and area of the ice shelf, as well as the advance rates and iceberg calving rates, emphasising the value of combining data from both satellite missions.”

ESA’s Mark Drinkwater noted, “Understanding how the world’s ice shelves are changing is fundamental to assessing ice sheet stability, and the role of ice shelves in controlling ice-sheet contribution to sea-level rise.”

“Just this week a paper was published in Nature stating that the Greenland ice sheet mass loss closely follows the IPCC high-end climate warming scenario – and the research was based on measurements from a number of different satellites.

“Here, we see how using this innovative elevation edge method with CryoSat data is a welcome addition to standard calving front location detection techniques based on radar and optical satellite imagery. This is great news, as the more information we have the more confident we can be about what’s going on in the far reaches of the polar regions.”

ESA's ice mission

The new method provides calving front locations at regular intervals and can fill existing gaps in time and space. Moreover, it simultaneously provides ice-thickness measurements that are needed to calculate mass changes, and it also has a high degree of automation which removes the need for heavy manual intervention.

Dr Wuite added, “We fully expect that, in the future, altimetry data will deliver a systematic and continuous record of change in ice-shelf calving front positions around Antarctica.

“With CryoSat set to remain in service and the future CRISTAL Copernicus Polar Ice and Snow Topography Altimeter mission – one of the Copernicus high-priority candidate missions – on the table for development, there are certainly excellent opportunities for satellite radar altimetry to deliver valuable new calving front location datasets to monitor the effects of climate change in Antarctica.”

Related links:

Paper: https://www.mdpi.com/2072-4292/11/23/2761

CryoSat: http://www.esa.int/Applications/Observing_the_Earth/CryoSat

Observing the Earth: http://www.esa.int/Applications/Observing_the_Earth

Copernicus high-priority candidate missions: http://www.esa.int/Applications/Observing_the_Earth/Copernicus/Copernicus_High_Priority_Candidates

Animation, Images, Text, Credits; ESA/ENVEO/AOES Medialab.

Greetings, Orbiter.ch

* This article was originally published here

Sun's close-up reveals atmosphere hopping with highly energetic particles

Outbursts of energetic particles that hurtle out from the sun and can disrupt space communications may be even more varied and numerous than previously thought, according to results from the closest-ever flyby of the sun.

Sun's close-up reveals atmosphere hopping with highly energetic particles
On its first two flybys of the sun, the Princeton-led instrument ISOIS onboard the Parker Solar Probe detected a surprising
variety of activities by solar energetic particles -- the zippy electrons, protons and other ions that fly out in advance of the
 solar wind -- that can disrupt space travel and communications on Earth. The observations are just the beginning of
explorations of how these particle events form, findings that will shed light on broader questions about the sun, space
weather and cosmic rays. One of the greatest threats from the sun -- to astronauts and the satellites that provide GPS maps,
 cell phone service and internet access -- are high-energy particles that erupt from the sun in bursts. Top: On Nov. 17, 2018,
 the 321st day of that year, Parker Solar Probe's ISOIS observed a burst of high-energy protons, each with more than
1 million electron-volts of energy. The warmer colors (yellow, orange, red) represent an increase in the number

 of these high-energy particles hitting the ISOIS sensors [Credit: Jamey Szalay & David McComas;
Adapted with permission from D.J. McComas et al., 2019]
The new findings, which help us understand the sun's activity and ultimately could provide an early warning for solar storms, come from one of the four instrument suites aboard NASA's Parker Solar Probe, a spacecraft that has completed its first passes near the fiery orb. Results from all four suites appear today in a set of articles published in the journal Nature.

The finding that these energetic particle events are more varied and numerous than previously known was one of several discoveries made by the instrument suite known as the Integrated Science Investigation of the Sun (ISOIS), a project led by Princeton University that involves multiple institutions as well as NASA.

"This study marks a major milestone with humanity's reconnaissance of the near-sun environment," said David McComas, the principal investigator for the ISOIS instrument suite, a Princeton professor of astrophysical sciences and the vice president for the Princeton Plasma Physics Laboratory. "It provides the first direct observations of the energetic particle environment in the region just above the sun's upper atmosphere, the corona.

"Seeing these observations has been a continuous 'eureka moment,'" McComas said. "Whenever we receive new data from the spacecraft, we are witnessing something that no one has ever seen before. That is about as good as it gets!"

ISOIS seeks to find out how the particles become so fast moving, and what is pushing them to accelerate. The scientists searching for these answers includes ISOIS team members at the California Institute of Technology (Caltech), John Hopkins University Applied Physics Laboratory (APL), NASA Goddard Space Flight Center, NASA Jet Propulsion Laboratory, the University of New Hampshire, Southwest Research Institute, the University of Delaware and the University of Arizona, as well as collaborators at the University of California-Berkeley, Imperial College London, the University of Michigan, Smithsonian Astrophysical Observatory and the National Center for Scientific Research in France.

Highly energetic particles can disrupt communications and global positioning systems (GPS) satellites. These streams of particles, made up primarily of protons, have two sources. The first is from outside our solar system, generated when exploding stars release streams of particles known as cosmic rays. The other is our sun. Both can damage the electrical systems of spacecraft and are forms of radiation that can harm astronauts' health.

These energetic particles fly much faster than the solar wind, which is the roughly million mile-per-hour flow of hot electrically charged gas that whips off the sun. If the solar wind were a stream, the energetic particles would be fish that leap out and jump ahead of the flow. The particles travel along pathways -- called magnetic flux tubes -- that extend from the corona out into the solar wind.

Sun's close-up reveals atmosphere hopping with highly energetic particles
During Parker Solar Probe's first two orbits, ISOIS detected many small energetic particle events, solar bursts during which
 the rates of particles streaming out of the sun increased rapidly. On ISOIS, the Epi-Lo instrument measures particles in the
 tens of thousands of electron-volts, while Epi-Hi measures particles with millions to hundreds of millions of electron-volts.
(For reference, the electricity in your house is 120 volts.) Here, data from orbits 1 (left) and 2 (right) show the ISOIS
particle count rates overlaid as color strips along the black line that represents the trajectory of Parker Solar Probe.
The lower energy ("Lo") rates are on the inside of the track, while the higher energy ("Hi") rates run outside. Both the
 size and color correspond to the measured rates, such that large red bars indicate the biggest bursts, when the sun
released the most particles in a short amount of time [Credit: Jamey Szalay & David McComas;
Adapted with permission from D.J. McComas et al., 2019]
Understanding these particles could improve space weather forecasts and give early warning of the massive storms that can disrupt Earthly communications and space travel.

"The answer to questions about how energetic particles form and accelerate is incredibly important," said Ralph McNutt, who oversaw the building of the lower energy of the suite's two instruments and is chief scientist in the Space Exploration Sector at APL. "These particles affect our activities on Earth and our ability to get our astronauts out into space. We are making history with this mission."

Due to their speed, the particles act as an early warning signal for space weather, said Jamey Szalay, an associate research scholar in the Department of Astrophysical Sciences at Princeton who leads the data visualization efforts for ISOIS. "These particles are moving fast, so if there is a big solar storm on its way, these particles are the first indicators."

Most previous studies of solar energetic particles relied on detectors located in space about the same distance from the Sun as is the Earth -- 93 million miles from the sun. By the time the particles get to those detectors, it is hard to track where they came from, because the particles from various sources have interacted and intermixed.

"It's a bit like cars coming from crowded tunnels and bridges and spreading out onto interstate highways," McComas said. "They get faster as they move away, but they also get mixed and interact in ways that it is impossible to tell who came from where as you move farther and farther away from the sources."

In its first trips around the sun, the Parker Solar Probe travelled twice as close to the sun as any previous spacecraft has ever been. At its closest, the spacecraft was 14 million miles -- or 35 solar radii, which is 17.5 widths of the sun -- from the fiery surface.

Getting close to the sun is essential for unraveling how these particles form and gain high energies, said Eric Christian, the deputy principal investigator on ISOIS and a senior research scientist at NASA Goddard. "It is like trying to measure what is happening in a mountain by studying the base of the mountain. To know what is happening, you have to go where the action is: You have to go up on the mountain."

A potential concern of the researchers was that the sun's 11-year cycle of activity is presently at a low. But the low activity level turned out to be an advantage.

"The fact that the sun was quiet allowed us to analyze events that are extremely isolated," said Nathan Schwadron, a professor of physics and astronomy and the head of the ISOIS science operation center at the University of New Hampshire. "These are events that haven't been seen from farther away because they are just clobbered by the solar wind activity."

Sun's close-up reveals atmosphere hopping with highly energetic particles
The top panel shows a schematic of a Coronal Mass Ejection (CME), during which a burst of mass as big as Lake Michigan
is ejected from the sun. These can pose a hazard to astronauts and space satellites, but ISOIS scientists discovered that tiny
 energetic particles rush ahead of the ejected mass, providing advance warning of the incoming threat. The bottom panel
shows proton fluxes detected by ISOIS's EPI-Lo (top) and the magnetic field measurements (bottom) around the time
of an observed CME. The energetic particles reached Parker Solar Probe nearly a day before the ejected mass
[Credit: Jamey Szalay & David McComas; Adapted with permission from D.J. McComas et al., 2019]
During its first two orbits, ISOIS observed several fascinating phenomena. One was a burst of energetic particle activity that coincided with a coronal mass ejection, a violent eruption of energized and magnetized particles from the corona. Prior to the ejection, ISOIS detected a buildup of relatively low energetic particles, whereas after the ejection there was a buildup of high energetic particles. These events were small and not detectable from the Earth's orbit.

Another observation from ISOIS was particle activity indicating a sort of solar wind traffic jam, which happens when the solar wind suddenly slows down, causing fast-moving solar wind to pile up behind it and forming a compressed region of particles. This buildup, which astrophysicists call a co-rotating interaction region, occurred out beyond Earth's orbit and sent high energy particles back toward the sun where they were observed by ISOIS.

Researchers are eager to understand the mechanisms by which the sun accelerates particles to high speeds. ISOIS's detection of each particle's identity -- whether it is hydrogen, helium, carbon, oxygen, iron or another element -- will help researchers further explore this question.

"There are two kinds of acceleration mechanisms, one that occurs in solar flares when magnetic fields reconnect, and another that occurs when you get shocks and compressions of the solar wind, but the details of how they cause particle acceleration are not that well understood," said Mark Wiedenbeck, a principal scientist at NASA's Jet Propulsion Laboratory, who oversaw the development of the higher energy instrument in the ISOIS suite. "The composition of the particles is a key diagnostic to tell us the acceleration mechanism."

ISOIS made its third brush by the sun on Sept. 1, and will make its next on Jan. 29, 2020. As the mission continues, the satellite will make a total of 24 orbits, each time getting closer to the solar surface, until it is roughly five sun-widths from the star. The researchers hope that future flybys will reveal insights into the source of the energetic particles. Do they start as "seed particles" that go on to attain higher energies?

Jamie Sue Rankin, a postdoctoral researcher at Princeton working in the McComas group, began working on the higher energy ISOIS instrument as a graduate student at Caltech.

"It has been neat to see this whole process develop over the past decade," Rankin said. "It is like surfing a wave: We built these instruments, made sure they were working, made adjustments to make sure the calibrations were right -- and now comes the exciting part, answering the questions that we set out to address.

"With any spacecraft, when you go out into space, you think you know what to expect, but there are always wonderful surprises that complicate our lives in the best way," she said. "That is what keeps us doing what we do."

Source: Princeton Univerity [December 05, 2019]

* This article was originally published here

2019 December 13 Full Moon Geminids Image Credit &...

2019 December 13

Full Moon Geminids
Image Credit & Copyright: Juan Carlos Casado (TWAN)

Explanation: The dependable annual Geminid meteor shower will be near its peak tonight (December 13/14) and before tomorrow’s dawn. As Earth crosses through the dusty trail of active asteroid 3200 Phaethon the meteors will flash through the sky from the shower’s radiant in Gemini. Gemini will be pretty easy for skygazers to find too as it won’t be far from a nearly full waning gibbous Moon. You don’t have look at the shower’s radiant to see meteors though. The almost full moonlight won’t hide the brightest of the Geminids from view either, but it will substantially reduce the rate of visible meteors for those who are counting. In fact, the 2019 Geminids should look a lot like the 2016 meteor shower This composite image from the 2016 Geminids aligns individual short exposures to capture many of the brighter Geminid meteors, inspite of a Full Moon shining near the constellation of the Twins. Along the horizon are the Teide Observatory’s Solar Laboratory (right) and the Teide volcano on the Canary Island of Tenerife.

∞ Source: apod.nasa.gov/apod/ap191213.html

* This article was originally published here

Wildlife in tropics hardest hit by forests being broken up

Tropical species are six times more sensitive to forests being broken up for logging or farming than temperate species, says new research.

Wildlife in tropics hardest hit by forests being broken up
Sunbear (Helarctos malayanus) -- one of the tropical mammal species found to be negatively
affected by forest edge in Malaysian Borneo [Credit: Matt Betts]
A team led by Oregon State University and including Imperial College London scientists found that sensitivity to forest fragmentation - the breakup of forests by human activities like logging or farming - increased six-fold at low versus high latitudes, putting tropical species at greater risk of extinction.

The finding, published in Science, could allow researchers to design more effective conservation schemes, such as leaving larger areas of pristine forest intact in tropical areas.

Co-author Professor Rob Ewers, from the Department of Life Sciences at Imperial, led the data collection. He said: "Our research suggests that actions as simple as building roads through forests have far greater ecological impact in the tropics than they do in the temperate world. We need to tread very lightly in these sensitive ecosystems.

"It also provides important nuance in conservation planning. It explains why plans used in one place don't necessarily work in another, and gives us great insight into how we should be tailoring our plans to account for ecological history."

The researchers tested the 'extinction filter hypothesis', which suggests animals that evolved in environments that suffer regular disturbances - such as fires and hurricanes - should be more likely to cope with new disturbances like deforestation.

These disturbed conditions occur more regularly in temperate latitudes, so the species in those forests were expected to fare better under forest fragmentation.

The team gathered 73 datasets of forest species abundance around the world collected over the past decade and used modeling software to separate the effects of fragmentation from other factors. The datasets contained 4,489 species from four major taxa - arthropods (2,682); birds (1,260); reptiles and amphibians (282); and mammals (265).

Wildlife in tropics hardest hit by forests being broken up
Unfragmented tropical forest in Costa Rica. Species that evolved in landscapes with little
 large-scale disturbance -- like this one in the tropics -- tend to be more sensitive to
deforestation and edge effects than those that have persisted in landscapes with
 disturbances like fires and windstorms [Credit: Christian Ziegler]
They looked for 'edge avoidance' - animals that do not like living near the edges of forests, where conditions like light and moisture are markedly different from the dense core. Edges are created when forests are broken up by deforestation and other human activities like farming or roads, such that 70 percent of Earth's remaining forest is within one kilometre of the forest edge.

They found that in low-disturbance regions, nearer the equator, 51.3 percent of forest species tend to avoid edges compared to 18.1 percent in high-disturbance zones further from the equator.

First author Professor Matt Betts, from Oregon State University, said: "Biodiversity of vertebrates increases massively toward the equator, but even accounting for that, a greater proportion of species are more sensitive to fragmentation. Sensitivity increases six-fold at low versus high latitudes.

"That means that not only should we care about the tropics because so many species are found there that are found nowhere else on Earth, but those species are also more sensitive to how we treat the forests."

Although species at temperate latitudes are less sensitive to forest fragmentation, there are still some species that will be negatively impacted, and this is predicted to rise as species gradually move toward the poles in response to climate change.

Co-author Dr Cristina Banks-Leite, from the Department of Life Science at Imperial, said: "Tropical forests are at increasing danger from human activities. The results we obtained show how the expansion of roads and agriculture in the tropics can drive species extinction even when overall forest cover levels are maintained.

"These results allow us to better focus conservation and restoration activities depending on the history of disturbance of a region. In Brazil, for instance, the Atlantic Forest has a longer history of disturbance than the Amazon. So, in the Atlantic Forest we could expect that an increase in forest cover would lead to high gains of species, even if this new forest is fragmented. In the Amazon, on the other hand, either deforestation or simply the creation of a new road could lead to species losses."

Source: Imperial College London [December 05, 2019]

* This article was originally published here

U.S. Crew Ship Launch Plans Proceed; Mind and Body Research on Station

ISS - Expedition 61 Mission patch.

December 12, 2019

NASA and Boeing are proceeding with plans for Boeing’s Orbital Flight Test following a full day of briefings and a Flight Readiness Review that took place at the Kennedy Space Center.

Launch of the CST-100 Starliner spacecraft atop a United Launch Alliance Atlas V rocket is scheduled for 6:36 a.m. EST Friday, Dec. 20, from Florida. The uncrewed flight test will be Starliner’s maiden mission to the International Space Station for NASA’s Commercial Crew Program.

Image above: A United Launch Alliance Atlas V rocket, topped by the Boeing CST-100 Starliner spacecraft, stands at the launch pad in Florida. Image Credit: Boeing.

The Expedition 61 crew today is exploring how the brain, muscles and bones adapt to long-term exposure in weightlessness. The orbiting lab’s communications systems are also being continuously maintained.

Astronauts Andrew Morgan and Luca Parmitano were back in the Columbus lab module today investigating how the central nervous system manages hand-eye coordination in space. The duo wore virtual reality gear using real-time visual and audible displays while coordinating a variety of body motions. The GRASP study explores how the brain adapts to the lack of a traditional up and down reference in space to ensure mission success farther away from Earth.

The musculoskeletal system also adjusts rapidly to the microgravity environment and studying mice aboard the orbiting lab helps reveal the impacts. Flight Engineers Jessica Meir and Christina Koch continued scanning rodents today in a bone densitometer before placing them back in their habitats. The new Rodent Research-19 study is investigating two proteins that may prevent muscle and bone loss while living off the Earth.

International Space Station (ISS). Animation Credit: NASA

Cosmonauts Alexander Skvortsov and Oleg Skripochka ensured the upkeep of a variety of Russian space station systems. The duo connected a Progress cargo craft’s thrusters to the Zarya module’s fuel tanks. The veteran cosmonauts also checked out antenna gear, laptop computers and video recording equipment.

Japan’s new high-resolution spectral Earth imager has been installed and activated on the Kibo lab module. HISUI, or Hyperspectral Imagery Suite, is a technology demonstration that will send data to agricultural and environmental industries for improved resource management.

Related links:

Expedition 61: https://www.nasa.gov/mission_pages/station/expeditions/expedition61/index.html

CST-100 Starliner: https://www.boeing.com/space/starliner/

Boeing: https://www.boeing.com/

NASA: https://www.nasa.gov/

Commercial Crew Program: https://www.nasa.gov/exploration/commercial/crew/index.html

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

GRASP: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2038

Bone densitometer: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?

Rodent Research-19:

HISUI: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7476

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.

Best regards, Orbiter.ch

* This article was originally published here

How flowers adapt to their pollinators

Flowering plants are characterized by an astonishing diversity of flowers of different shapes and sizes. This diversity has arisen in adaptation to selection imposed by different pollinators including among others bees, flies, butterflies, hummingbirds, bats or rodents.

How flowers adapt to their pollinators
This is a flower of the bee-pollinated species Meriania hernandoi from
the Ecuadorian cloud forest [Credit: Agnes Dellinger]
Although several studies have documented that pollinators can impose strong selection pressures on flowers, our understanding of how flowers diversify remains fragmentary. For example, does the entire flower adapt to a pollinator, or do only some flower parts evolve to fit a pollinator while other flower parts may remain unchanged?

In a recent study published in Communications Biology, scientists around Agnes Dellinger from the Department of Botany and Biodiversity Research from the University of Vienna investigated flowers of 30 species of a tropical plant group (Merianieae) from the Andes.

How flowers adapt to their pollinators
This is a flower of a passerine-pollinated species of the genus Axinaea
[Credit: Agnes Dellinger]
"Each of these plant species has adapted to pollination by either bees, birds, bats or rodents", says Dellinger. Using High-Resolution X-ray computed tomography, the research team produced 3D-models of these flowers and used geometric-morphometric methods to analyse differences in flower shape among species with different pollinators.

The researchers could show that flower shapes have evolved in adaptation to the distinct pollinators, but that flower shape evolution was not homogeneous across the flower. In particular, the showy sterile organs of flowers (petals) adapted to the different pollinators more quickly than the rest of the flower: the reproductive organs have evolved more slowly.

How flowers adapt to their pollinators
This is a flower of the hummingbird- and bat-pollinated species Meriania radula
from the Ecuadorian paramo [Credit: Agnes Dellinger]
"This study is among the first to analyse the entire 3-dimensional flower shape, and it will be exciting to see whether similar evolutionary floral modularity exists in other plant groups", concludes Dellinger.

Source: University of Vienna [December 05, 2019]

* This article was originally published here

ISRO - PSLV-C48/RISAT-2BR1 launch success

ISRO - Indian Space Research Organisation logo.

Dec.12, 2019

PSLV-C48 Liftoff

ISRO’s PSLV-C48 mission, a Polar Satellite Launch Vehicle (PSLV) in “QL” configuration launched RISAT-2BR1 and 9 small satellites from the First Launch Pad (FLP) of Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota, on 11 December 2019, at 09:55 UTC (15:25 IST). PSLV-C48 is the second mission of PSLV-QL, a new variant of PSLV with 4 XL strap-on boosters.

India’s Polar Satellite Launch Vehicle, in its fiftieth flight (PSLV-C48), successfully launched RISAT-2BR1, an earth observation satellite, along with nine commercial satellites of Israel, Italy, Japan and USA from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota.

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Newfound Martian Aurora Actually the Most Common; Sheds Light on Mars’ Changing Climate

Conceptual image depicting the early Martian environment (right) – believed to contain liquid water and a thicker atmosphere – versus the cold, dry environment seen at Mars today (left). Credits: NASA’s Goddard Space Flight Center. Hi-res image

A type of Martian aurora first identified by NASA’s MAVEN spacecraft in 2016 is actually the most common form of aurora occurring on the Red Planet, according to new results from the mission. The aurora is known as a proton aurora and can help scientists track water loss from Mars’ atmosphere.

At Earth, aurora are commonly seen as colorful displays of light in the night sky near the polar regions, where they are also known as the northern and southern lights. However, the proton aurora on Mars happens during the day and gives off ultraviolet light, so it is invisible to the human eye but detectable to the Imaging UltraViolet Spectrograph (IUVS) instrument on the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft.

MAVEN’s mission is to investigate how the Red Planet lost much of its atmosphere and water, transforming its climate from one that might have supported life to one that is cold, dry, and inhospitable. Since the proton aurora is generated indirectly by hydrogen derived from Martian water that’s in the process of being lost to space, this aurora could be used to help track ongoing Martian water loss.

“In this new study using MAVEN/IUVS data from multiple Mars years, the team has found that periods of increased atmospheric escape correspond with increases in proton aurora occurrence and intensity,” said Andréa Hughes of Embry-Riddle Aeronautical University in Daytona Beach, Florida. Hughes is lead author of a paper on this research published December 12 in the Journal of Geophysical Research, Space Physics. “Perhaps one day, when interplanetary travel becomes commonplace, travelers arriving at Mars during southern summer will have front-row seats to observe Martian proton aurora majestically dancing across the dayside of the planet (while wearing ultraviolet-sensitive goggles, of course). These travelers will witness firsthand the final stages of Mars losing the remainder of its water to space.” Hughes is presenting the research on December 12 at the American Geophysical Union meeting in San Francisco. 

Different phenomena produce different kinds of aurora. However, all aurora at Earth and Mars are powered by solar activity, whether it be explosions of high-speed particles known as solar storms, eruptions of gas and magnetic fields known as coronal mass ejections, or gusts in the solar wind, a stream of electrically conducting gas that blows continuously into space at around a million miles per hour. For example, the northern and southern lights at Earth happen when violent solar activity disturbs Earth’s magnetosphere, causing high velocity electrons to slam into gas particles in Earth’s nightside upper atmosphere and make them glow. Similar processes generate Mars’ discrete and diffuse aurora – two types of aurora that were previously observed on the Martian nightside.

This animation shows a proton aurora at Mars. First, a solar wind proton approaches Mars at high speed and encounters a cloud of hydrogen surrounding the planet. The proton steals an electron from a Martian hydrogen atom, thereby becoming a neutral atom. The atom passes through the bowshock, a magnetic obstacle surrounding Mars, because neutral particles are not affected by magnetic fields. Finally, the hydrogen atom enters Mars' atmosphere and collides with gas molecules, causing the atom to emit ultraviolet light.Credits: NASA/MAVEN/Goddard Space Flight Center/Dan Gallagher. Download this graphic

Proton aurora form when solar wind protons (which are hydrogen atoms stripped of their lone electrons by intense heat) interact with the upper atmosphere on the dayside of Mars. As they approach Mars, the protons coming in with the solar wind transform into neutral atoms by stealing electrons from hydrogen atoms in the outer edge of the Martian hydrogen corona, a huge cloud of hydrogen surrounding the planet. When those high-speed incoming atoms hit the atmosphere, some of their energy is emitted as ultraviolet light.

Images of Mars proton aurora. MAVEN’s Imaging Ultraviolet Spectrograph observes the atmosphere of Mars, making images of neutral hydrogen and proton aurora simultaneously (left). Observations under normal conditions show hydrogen on the disk and in the extended atmosphere of the planet from a vantage point on the nightside (middle). Proton aurora is visible as a significant brightening on the limb and disk (right); with the contribution of neutral hydrogen subtracted, the distribution of proton aurora is revealed, showing that it peaks in brightness just off the Martian disk as energetic neutrals slam into the atmosphere. Credits: Embry-Riddle Aeronautical University/LASP, U. of Colorado

When the MAVEN team first observed the proton aurora, they thought it was a relatively unusual occurrence. “At first, we believed that these events were rather rare because we weren’t looking at the right times and places,” said Mike Chaffin, research scientist at the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics (LASP) and second author of the study. “But after a closer look, we found that proton aurora are occurring far more often in dayside southern summer observations than we initially expected.” The team has found proton aurora in about 14 percent of their dayside observations, which increases to more than 80 percent of the time when only dayside southern summer observations are considered. “By comparison, IUVS has detected diffuse aurora on Mars in a few percent of orbits with favorable geometry, and discrete aurora detections are rarer still in the dataset,” said Nick Schneider, coauthor and lead of the IUVS team at LASP.

The correlation with the southern summer gave a clue as to why proton aurora are so common and how they could be used to track water loss. During southern summer on Mars, the planet is also near its closest distance to the Sun in its orbit and huge dust storms can occur. Summer warming and dust activity appear to cause proton auroras by forcing water vapor high in the atmosphere. Solar extreme ultraviolet light breaks the water into its components, hydrogen and oxygen. The light hydrogen is weakly bound by Mars’ gravity and enhances the hydrogen corona surrounding Mars, increasing hydrogen loss to space. More hydrogen in the corona makes interactions with solar-wind protons more common, making proton aurora more frequent and brighter.div>

All the conditions necessary to create Martian proton aurora (e.g., solar wind protons, an extended hydrogen atmosphere, and the absence of a global dipole magnetic field) are more commonly available at Mars than those needed to create other types of aurora,” said Hughes. “Also, the connection between MAVEN’s observations of increased atmospheric escape and increases in proton aurora frequency and intensity means that proton aurora can actually be used as a proxy for what’s happening in the hydrogen corona surrounding Mars, and therefore, a proxy for times of increased atmospheric escape and water loss.”

This research was funded by the MAVEN mission. MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, Colorado, and NASA Goddard manages the MAVEN project. NASA is exploring our Solar System and beyond, uncovering worlds, stars, and cosmic mysteries near and far with our powerful fleet of space and ground-based missions.

Source: NASA/Mars

Bill Steigerwald / Nancy Jones
NASA Goddard Space Flight Center, Greenbelt, Md.
301-286-8955 / 301-286-0039
william.a.steigerwald@nasa.gov / nancy.n.jones@nasa.gov

Editor: Bill Steigerwald

* This article was originally published here

Prehistoric Projectiles, The National Museum of Scotland, Edinburgh, 24.11.19.

Prehistoric Projectiles, The National Museum of Scotland, Edinburgh, 24.11.19.

* This article was originally published here

Rhythmic perception in humans has strong evolutionary roots

Rhythm is a fundamental aspect of music, dance and language. However, we do not know to what extent our rhythmic skills depend on ancient evolutionary mechanisms that may be present in other animals.

Rhythmic perception in humans has strong evolutionary roots
"In our study, we explored whether other animals can detect an isochronous beat (in which all signals
 are separated by the same interval) and distinguish non-isochronous beats, regardless
of other irrelevant features such as tempo" [Credit: UPF]
"In our study, we explored whether other animals can detect an isochronous beat (in which all signals are separated by the same interval) and distinguish non-isochronous beats, regardless of other irrelevant features such as tempo", assert Alexandre Celma-Miralles and Juan Manuel Toro, ICREA research professor with the Department of Information and Communication Technologies (DTIC), and members of the Language and Comparative Cognition research group (LCC) at the Center for Brain and Cognition (CBC) at UPF.

The perception of temporal regularities is essential to synchronize to music and dance. The researchers explored the detection of isochrony in two mammal species for which they trained rats (Rattus norvegicus) and humans to discriminate sound sequences with regular intervals from sound sequences with irregular intervals. The researchers started from the assumption that that the detection of regularity may not rely on vocal learning skills and that both rats and humans distinguish regular from irregular stimuli.

The study used four different tempi in the training sessions and introduced two new tempi in the tests. They then compared the behavioural responses of the two species. They discovered that both rats and humans responded more to new, regular sequences than to irregular ones. Thus, as the authors point out: "In our experiments, we find that species that are very distant from humans, that do not produce complex vocalizations, like rats, have this ability". Therefore, the lack of difference between the responses of rats and those of humans may imply that the two species are able to detect regularity, regardless of the involvement of any vocal learning ability.

In summary, this study suggests that detecting temporal regularities in sequences of sounds may have ancient evolutionary roots and could rely on timing mechanisms present in distantly related mammals.

This suggests that rhythmic perception in humans has strong evolutionary roots that may be linked to more general mechanisms of temporal perception. This study represents a breakthrough in the understanding of the biological roots of rhythmic perception and opens the door to identifying the neural substrates, common across the species, that enhance musical cognition.

The findings are published in the Journal of Comparative Psychology.

Source: Universitat Pompeu Fabra - Barcelona [December 09, 2019]

* This article was originally published here


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