четверг, 19 июля 2018 г.

Attention to Detail Since the very first microscope revealed a…

Attention to Detail

Since the very first microscope revealed a hidden world, countless gradual improvements have exposed ever-deeper layers. This procession of progress eventually led to the electron microscope, able to show the very atoms of materials. But the electron beam – used in place of light – destroyed biological material, limiting its insights to the inert world. Determined to see not just matter, but life, at the finest detail, Richard Henderson – born on this day in 1945 – managed to expose a protein from a plant cell’s membrane to a reduced electron beam and picture its structure according to how the electrons bounced off (left, from 1975). With 15 years more work and the advent of cryo-electron microscopy, which freezes samples to shield from the electrons, he determined the structure at the ultimate resolution. In the process he gave the world a new viewpoint on life, and earned a share of a 2017 Nobel Prize.

Written by Anthony Lewis

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Calcite With Mottramite | #Geology #GeologyPage…

Calcite With Mottramite | #Geology #GeologyPage #Mineral

Locality: Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia, Africa

Dimensions: 7.2 × 7.2 × 4.3 cm

Photo Copyright © Crystal Classics

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HiPOD (19 July 2018): Layers in Noctis Labyrinthus   – One might…

HiPOD (19 July 2018): Layers in Noctis Labyrinthus

   – One might suppose that a place named “labyrinth of the night” would have layers of some kind, otherwise it would anticlimactic. (260 km above the surface. Black and white is less than 5 km across; enhanced color is less than 1 km.) 

NASA/JPL/University of Arizona


Aura | #Geology #GeologyPage #Mineral Geology…

Aura | #Geology #GeologyPage #Mineral

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Flysch Rock Formation, Zumaia Spain | #Geology #GeologyPage…

Flysch Rock Formation, Zumaia Spain | #Geology #GeologyPage #Spain

Flysch is a sequence of sedimentary rocks that is deposited in a deep marine facies in the foreland basin of a developing orogen.

More Photos : http://www.geologypage.com/2017/07/flysch-rock-formation-zumaia-spain.html

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Rhodonite | #Geology #GeologyPage #Mineral Locality: San Martín…

Rhodonite | #Geology #GeologyPage #Mineral

Locality: San Martín Mine, Chiurucu (Chiuruco), Huallanca, Bolognesi Province, Ancash Department, Peru

Dimensions: 7.2 × 4.8 × 4.0 cm

Photo Copyright © Crystal Classics

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Fluorite with Muscovite | #Geology #GeologyPage…

Fluorite with Muscovite | #Geology #GeologyPage #Mineral

Locality: Nagar, Hunza Valley, Gilgit District, Northern Areas, Pakistan, Asia

Dimensions: 11.0 × 6.3 × 6.5 cm

Photo Copyright © Crystal Classics

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Fluorite | #Geology #GeologyPage #Mineral Locality: Cambokeels…

Fluorite | #Geology #GeologyPage #Mineral

Locality: Cambokeels Mine, Weardale, Co Durham, England, Europe

Dimensions: 10.0 × 8.0 × 4.5 cm

Photo Copyright © Crystal Classics

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Elbaite Tourmaline | #Geology #GeologyPage #Mineral Locality:…

Elbaite Tourmaline | #Geology #GeologyPage #Mineral

Locality: Paprok, Kunar Province (Nuristan), Afghanistan, Asia

Dimensions: 3.5 × 3.5 × 2.7 cm

Photo Copyright © Crystal Classics

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An early Iranian, obviously

Today, the part of Asia between the Caspian Sea and the Altai Mountains, known as Turan, is largely a Turkic-speaking region. But during the Iron Age it was dominated by Iranian speakers. Throughout this period it was the home of a goodly number of attested and inferred early Iranic peoples, such as the Airyas, Dahae, Kangju, Massagetae, Saka and Sogdians.
Indeed, the early Iron Age Yaz II archaeological culture, located in southwestern Turan, is generally classified as an Iranian culture, and even posited to have been the Airyanem Vaejah, aka home of the Iranians, from ancient Avestan literature.
That’s not to say that Iranian speakers weren’t present in this part of the world much earlier. They probably were, and it’s likely that we already have their genomes (see here). But the point I’m making is that Turan can’t be reliably claimed to have been an Iranian realm until the Iron Age.
Ergo, any ancient DNA samples from Turan dating to the Iron Age, as opposed to, say, the Bronze Age, are very likely to be those of early Iranian speakers. One such sample is Zarafshan_IA (or Turkmenistan_IA) DA382 from Damgaard et al. 2018.
Below is a screen cap of the “time map” from homeland.ku.dk, with the slider moved to 847 BC, showing the location of the burial site where the remains of DA382 were excavated. The site is marked with the Z93 label because DA382 belongs to the Eastern European-derived Y-chromosome haplogroup R1a-Z93. Interestingly, his burial was located in close proximity to archaeological sites associated with the above mentioned and contemporaneous Yaz II culture.

DA382 didn’t get much of a run in the Damgaard et al. paper, and little wonder because the authors also analyzed 73 other ancient samples. So let’s take a close look at this individual’s genetic structure to see whether there’s anything particularly Iranian about it.
Damgaard et al. did mention that DA382 was partly of Middle to Late Bronze Age (MLBA) steppe origin. And indeed, my own mixture models using qpAdm confirm this finding with very consistent results and strong statistical fits. Here are a couple of simple, two-way examples…

Namazga_CA 0.528±0.040
Srubnaya_MLBA 0.472±0.040
P-value: 0.561330411
Full output
Dzharkutan1_BA 0.530±0.037
Srubnaya_MLBA 0.470±0.037
P-value: 0.485083377
Full output

The fact that the MLBA Srubnaya samples from the Pontic-Caspian steppe can be used to model DA382’s ancestry (alongside Bronze and Copper Age populations from Turan) with such ease shouldn’t be surprising, considering the he belongs to R1a-Z93, which is the dominant Y-haplogroup in the Srubnaya and all other closely related MLBA steppe peoples.
Now, Srubnaya is generally regarded to be the proto-Iranian archaeological culture. How awesome is that considering those qpAdm fits? But, admittedly, this is just an inference, even if a robust one, based on genetic, archaeological and historical linguistics data. So apart from the fact that DA382 comes from Iron Age Turan, an Iranian-speaking realm, is there any other way to link him directly to Iranians?
Well, he’s very similar in terms of overall genetic structure to some of the least Turkic-admixed Iranian-speakers still living in Turan, and might well be ancestral to them.
For instance, below is a Principal Component Analysis (PCA) featuring a wide range of ancient and present-day West Eurasian samples. Note that, in line with the qpAdm models, DA382 clusters about half-way between the populations of the MLBA steppe and pre-Kurgan expansion Turan, and amongst present-day Yaghnobi and Pamiri Tajiks. In fact, he clusters at the apex of a southeast > northwest cline made up of Tajiks that appears to be pulling towards Europeans.

Needless to say, Tajiks, especially Pamiri Tajiks, also pack a lot of Srubnaya-related ancestry. I’ve talked about this plenty of times on this blog (for instance, see here). But what happens if I try to model Pamiri Tajiks with DA382?

Zarafshan_IA 0.892±0.023
Han 0.108±0.023
P-value: 0.794566182
Full output

Wow, it’s an awesome fit! My mind’s made up: DA382 was probably an Iranian-speaker and, more specifically, an Eastern Iranian-speaker. Who disagrees and why? Feel free to let me know in the comments (unless you’re banned, in which case, f*ck off).
See also…
Late PIE ground zero now obvious; location of PIE homeland still uncertain, but…
Friendly Yeniseian steppe pastoralists
New PCA featuring Botai horse tamers, Hun and Saka warriors, and many more…



Quartz var Chalcedony | #Geology #GeologyPage…

Quartz var Chalcedony | #Geology #GeologyPage #Mineral

Locality: Jalgaon, Maharashtra, India, Asia

Dimensions: 9.0 × 6.6 × 6.0 cm

Photo Copyright © Crystal Classics

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Tourmaline with Albite | #Geology #GeologyPage…

Tourmaline with Albite | #Geology #GeologyPage #Mineral

Locality: Himalaya Mine, San Diego Co., California, USA, North America

Dimensions: 7.3 × 2.8 × 2.5 cm

Photo Copyright © Crystal Classics

Geology Page



Aquamarine with Fluorite and Muscovite | #Geology #GeologyPage…

Aquamarine with Fluorite and Muscovite | #Geology #GeologyPage #Mineral

Locality: Chumar Bakhoor, Hunza Valley, Gilgit District, Northern Areas, Pakistan, Asia

Dimensions: 11.3 × 8.0 × 5.6 cm

Photo Copyright © Crystal Classics

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Giant’s Causeway, Ireland | #Geology #GeologyPage…

Giant’s Causeway, Ireland | #Geology #GeologyPage #Ireland

The Giant’s Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption. It is also known as Clochán an Aifir or Clochán na bhFomhórach in Irish and tha Giant’s Causey in Ulster-Scots.

Read More & More Photos: http://www.geologypage.com/2018/07/giants-causeway-ireland.html

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Quartz Amethyst Sceptre | #Geology #GeologyPage…

Quartz Amethyst Sceptre | #Geology #GeologyPage #Mineral

Locality: Goboboseb Mountains, Brandberg, Erongo Region, Namibia, Africa

Dimensions: 8.8 × 2.2 × 1.9 cm

Photo Copyright © Crystal Classics

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Covellite with Pyrite | #Geology #GeologyPage…

Covellite with Pyrite | #Geology #GeologyPage #Mineral

Dimensions: 7.4 × 3.7 × 1.5 cm

Photo Copyright © Crystal Classics

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2018 July 19 Cerealia Facula Image Credit: NASA, JPL-Caltech,…

2018 July 19

Cerealia Facula
Image Credit: NASA, JPL-Caltech, UCLA, MPS/DLR/IDA

Explanation: Cerealia Facula, also known as the brightest spot on Ceres, is shown in this stunning mosaic close-up view. The high-resolution image data was recorded by the Dawn spacecraft, in a looping orbit, from altitudes as low as 34 kilometers (21 miles) above the dwarf planet’s surface. Cerealia Facula is about 15 kilometers wide, found in the center of 90 kilometer diameter Occator crater. Like the other bright spots (faculae) scattered around Ceres, Cerealia Facula is not ice, but an exposed salty residue with a reflectivity like dirty snow. The residue is thought to be mostly sodium carbonate and ammonium chloride from a slushy brine within or below the dwarf planet’s crust. Driven by advanced ion propulsion on an 11-year mission, Dawn explored main-belt asteriod Vesta before traveling on to Ceres. But sometime between this August and October, the interplanetary spacecraft is expected to finally run out of fuel for its hydrazine thrusters, with the subsequent loss of control of its orientation, losing power and the ability to communicate with Earth. Meanwhile Dawn will continue to explore Ceres in unprecedented detail, and ultimately retire in its orbit around the small world.

∞ Source: apod.nasa.gov/apod/ap180719.html


Corrimony Chambered Cairn, Inverness, Scotland

Corrimony Chambered Cairn, Inverness, Scotland

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NASA’s New Mini Satellite Will Study Milky Way’s Halo

ISS – International Space Station logo.

July 18, 2018

Astronomers keep coming up short when they survey “normal” matter, the material that makes up galaxies, stars and planets. A new NASA-sponsored CubeSat mission called HaloSat, deployed from the International Space Station on July 13, will help scientists search for the universe’s missing matter by studying X-rays from hot gas surrounding  our Milky Way galaxy.

The cosmic microwave background (CMB) is the oldest light in the universe, radiation from when it was 400,000 years old. Calculations based on CMB observations indicate the universe contains: 5 percent normal matter protons, neutrons and other subatomic particles; 25 percent dark matter, a substance that remains unknown; and 70 percent dark energy, a negative pressure accelerating the expansion of the universe.

Animation above: HaloSat, a new CubeSat mission to study the halo of hot gas surrounding the Milky Way, was released from the International Space Station over Australia on July 13. Animation Credits: NanoRacks/NASA.

As the universe expanded and cooled, normal matter coalesced into gas, dust, planets, stars and galaxies. But when astronomers tally the estimated masses of these objects, they account for only about half of what cosmologists say should be present.

“We should have all the matter today that we had back when the universe was 400,000 years old,” said Philip Kaaret, HaloSat’s principal investigator at the University of Iowa (UI), which leads the mission. “Where did it go? The answer to that question can help us learn how we got from the CMB’s uniform state to the large-scale structures we see today.”

Researchers think the missing matter may be in hot gas located either in the space between galaxies or in galactic halos, extended components surrounding individual galaxies.

Image above: HaloSat launched from NASA’s Wallops Flight Facility in Virginia on May 21, 2018, aboard a Cygnus spacecraft from Orbital ATK, now known as Northrop Grumman, on the company’s Antares rocket. HaloSat will study the halo of gas around the Milky Way as part of the search for the universe’s missing matter. Image Credits: NASA/Aubrey Gemignani.

HaloSat will study gas in the Milky Way’s halo that runs about 2 million degrees Celsius (3.6 million degrees Fahrenheit). At such high temperatures, oxygen sheds most of its eight electrons and produces the X-rays HaloSat will measure.

Other X-ray telescopes, like NASA’s Neutron star Interior Composition Explorer and the Chandra X-ray Observatory, study individual sources by looking at small patches of the sky. HaloSat will look at the whole sky, 100 square degrees at a time, which will help determine if the diffuse galactic halo is shaped more like a fried egg or a sphere.

“If you think of the galactic halo in the fried egg model, it will have a different distribution of brightness when you look straight up out of it from Earth than when you look at wider angles,” said Keith Jahoda, a HaloSat co-investigator and astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “If it’s in some quasi-spherical shape, compared to the dimensions of the galaxy, then you expect it to be more nearly the same brightness in all directions.”

Image above: The University of Iowa HaloSat team attended the satellite’s launch at NASA’s Wallops Flight Facility. From left to right: Daniel LaRocca, Anna Zajczjk, Philip Kaaret, William Fuelberth, Hannah Gulick and Emily Silich. Kay Hire (center) holds the University of Iowa’s tiki totem statue. Image Credits: Alexis Durow.

The halo’s shape will determine its mass, which will help scientists understand if the universe’s missing matter is in galactic halos or elsewhere.

HaloSat will be the first astrophysics mission that minimizes the effects of X-rays produced by solar wind charge exchange. This emission occurs when the solar wind, an outflow of highly charged particles from the Sun, interacts with uncharged atoms like those in Earth’s atmosphere. The solar wind particles grab electrons from the uncharged atoms and emit X-rays. These emissions exhibit a spectrum similar to what scientists expect to see from the galactic halo.

“Every observation we make has this solar wind emission in it to some degree, but it varies with time and solar wind conditions,” said Kip Kuntz, a HaloSat co-investigator at Johns Hopkins University in Baltimore. “The variations are so hard to calculate that many people just mention it and then ignore it in their observations.”

In order to minimize these solar wind X-rays, HaloSat will collect most of its data over 45 minutes on the nighttime half of its 90-minute orbit around Earth. On the daytime side, the satellite will recharge using its solar panels and transmit data to NASA’s Wallops Flight Facility in Virginia, which relays the data to the mission’s operations control center at Blue Canyon Technologies in Boulder, Colorado.

“HaloSat has been a wonderful opportunity to get my hands on an instrument, work on the intricacies of something that’s going into space, and plan for all of the problems that go with that, which is a lot of fun,” said Daniel LaRocca, a UI graduate student on the mission team.

International Space Station (ISS). Image Credit: NASA

HaloSat measures 4-by-8-by-12 inches (about 10-by-20-by-30 centimeters) and weighs about 26 pounds (12 kilograms). It is the first science-focused astrophysics CubeSat mission, but a CubeSat called the Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA), led by NASA’s Jet Propulsion Laboratory in Pasadena, California, launched in 2017 to demonstrate astrophysics technology. CubeSat missions usually take around three years to develop through launch and the start of data collection, the optimal amount of time for undergraduate or graduate students to be involved from start to finish.

“HaloSat has definitely shaped how I see my future playing out,” said Hannah Gulick, a UI undergraduate working on the mission. “I hope to be an astrophysicist who builds instruments and then uses the observations from those instruments to make my own discoveries.”

HaloSat is a NASA CubeSat mission led by the University of Iowa in Iowa City. Additional partners include NASA’s Goddard Space Flight Center in Greenbelt, Maryland, NASA’s Wallops Flight Facility on Wallops Island, Virginia, Blue Canyon Technologies in Boulder, Colorado, Johns Hopkins University in Baltimore and with important contributions from partners in France. HaloSat was selected through NASA’s CubeSat Launch Initiative as part of the 23rd installment of the Educational Launch of Nanosatellites missions.

Related links:

CubeSat: https://www.nasa.gov/directorates/heo/home/CubeSats_initiative

HaloSat: https://www.nasa.gov/mission_pages/station/research/experiments/2639.html

Small Satellite Missions: http://www.nasa.gov/mission_pages/smallsats

Neutron star Interior Composition Explorer (NICER): https://www.nasa.gov/nicer

Chandra X-ray Observatory: https://www.nasa.gov/mission_pages/chandra/main/index.html

Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA): https://www.jpl.nasa.gov/cubesat/missions/asteria.php

University of Iowa (UI): https://uiowa.edu/

Johns Hopkins University: https://www.jhu.edu/

Jet Propulsion Laboratory (JPL): https://www.jpl.nasa.gov/

Wallops Flight Facility: https://www.nasa.gov/centers/wallops/home/

Goddard Space Flight Center (GSFC): https://www.nasa.gov/centers/goddard/home/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Animation (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Jeanette Kazmierczak.

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Discovering Structure in the Outer Corona

NASA – STEREO Mission logo.

July 18, 2018

In 1610, Galileo redesigned the telescope and discovered Jupiter’s four largest moons. Nearly 400 years later, NASA’s Hubble Space Telescope used its powerful optics to look deep into space — enabling scientists to pin down the age of the universe.

Suffice it to say that getting a better look at things produces major scientific advances.

In a paper published on July 18 in The Astrophysical Journal, a team of scientists led by Craig DeForest — solar physicist at Southwest Research Institute’s branch in Boulder, Colorado — demonstrate that this historical trend still holds. Using advanced algorithms and data-cleaning techniques, the team discovered never-before-detected, fine-grained structures in the outer corona — the Sun’s million-degree atmosphere — by analyzing images taken by NASA’s STEREO spacecraft. The new results also provide foreshadowing of what might be seen by NASA’s Parker Solar Probe, which after its launch in the summer 2018 will orbit directly through that region.

STEREO spacecrafts. Image Credit: NASA

The outer corona is the source of the solar wind, the stream of charged particles that flow outward from the Sun in all directions. Measured near Earth, the magnetic fields embedded within the solar wind are intertwined and complex, but what causes this complexity remains unclear.

“In deep space, the solar wind is turbulent and gusty,” said DeForest. “But how did it get that way? Did it leave the Sun smooth, and become turbulent as it crossed the solar system, or are the gusts telling us about the Sun itself?”

Answering this question requires observing the outer corona — the source of the solar wind — in extreme detail. If the Sun itself causes the turbulence in the solar wind, then we should be able to see complex structures right from the beginning of the wind’s journey.

But existing data didn’t show such fine-grained structure — at least, until now.

“Previous images of the corona showed the region as a smooth, laminar structure,” said Nicki Viall, solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and coauthor of the study. “It turns out, that apparent smoothness was just due to limitations in our image resolution.”

The study

To understand the corona, DeForest and his colleagues started with coronagraph images — pictures of the Sun’s atmosphere produced by a special telescope that blocks out light from the (much brighter) surface.

How to Read a NASA STEREO Image

Video above: This video shows a coronagraph image taken by the STEREO spacecraft in 2012, highlighting coronal streamers, the solar wind and a coronal mass ejection (CME). Video Credits: NASA’s Goddard Space Flight Center/Joy Ng.

These images were generated by the COR2 coronagraph aboard NASA’s Solar and Terrestrial Relations Observatory-A, or STEREO-A, spacecraft, which circles the Sun between Earth and Venus.

In April 2014, STEREO-A would soon be passing behind the Sun, and scientists wanted to get some interesting data before communications were briefly interrupted.

So they ran a special three-day data collection campaign during which COR2 took longer and more frequent exposures of the corona than it usually does. These long exposures allow more time for light from faint sources to strike the instrument’s detector — allowing it to see details it would otherwise miss.

But the scientists didn’t just want longer-exposure images — they wanted them to be higher resolution. Options were limited. The instrument was already in space; unlike Galileo they couldn’t tinker with the hardware itself. Instead, they took a software approach, squeezing out the highest quality data possible by improving COR2’s signal-to-noise ratio.

What is signal-to-noise ratio?

The signal-to-noise ratio is an important concept in all scientific disciplines. It measures how well you can distinguish the thing you care about measuring — the signal — from the things you don’t — the noise.

For example, let’s say that you’re blessed with great hearing. You notice the tiniest of mouse-squeaks late at night; you can eavesdrop on the whispers of huddled schoolchildren twenty feet away. Your hearing is impeccable — when noise is low.

But it’s a whole different ball game when you’re standing in the front row of a rock concert. The other sounds in the environment are just too overpowering; no matter how carefully you listen, mouse-squeaks and whispers (the signal, in this case) can’t cut through the music (the noise).

The problem isn’t your hearing — it’s the poor signal-to-noise ratio.

COR2’s coronagraphs are like your hearing. The instrument is sensitive enough to image the corona in great detail, but in practice its measurements are polluted by noise — from the space environment and even the wiring of the instrument itself. DeForest and his colleagues’ key innovation was in identifying and separating out that noise, boosting the signal-to-noise ratio and revealing the outer corona in unprecedented detail.

The analysis

The first step towards improving signal-to-noise ratio had already been taken: longer-exposure images. Longer exposures allow more light into the detector and reduce the noise level — the team estimates noise reduction by a factor of 2.4 for each image, and a factor of 10 when combining them over a 20-minute period.

But the remaining steps were up to sophisticated algorithms, designed and tested to extract out the true corona from the noisy measurements.

They filtered out light from background stars (which create bright spots in the image that are not truly part of the corona). They corrected for small (few-millisecond) differences in how long the camera’s shutter was open. They removed the baseline brightness from all the images, and normalized it so brighter regions wouldn’t wash out dimmer ones.

But one of the most challenging obstacles is inherent to the corona: motion blur due to the solar wind. To overcome this source of noise, DeForest and colleagues ran a special algorithm to smooth their images in time.

Animations above: Views of the solar wind from NASA’s STEREO spacecraft (left) and after computer processing (right). Scientists used an algorithm to dim the appearance of bright stars and dust in images of the faint solar wind. Animations Credits: NASA’s Goddard Space Flight Center/Craig DeForest, SwRI.

Smoothing in time — with a twist

If you’ve ever done a “double-take,” you know a thing or two about smoothing in time. A double-take — taking a second glance, to verify your first one — is just a low-tech way of combining two “measurements” taken at different times, into one measurement that you can be more confident in.

Smoothing in time turns this idea into an algorithm. The principle is simple: take two (or more) images, overlap them, and average their pixel values together. Random differences between the images will eventually cancel out, leaving behind only what is consistent between them.

But when it comes to the corona, there’s a problem: it’s a dynamic, persistently moving and changing structure. Solar material is always moving away from the Sun to become the solar wind. Smoothing in time would create motion blur — the same kind of blurring you see in photographs of moving objects. That’s a problem if your goal is to see fine detail.

To undo motion blur from the solar wind, the scientists used a novel procedure: while they did their smoothing, they estimated the speed of the solar wind and shifted the images along with it.

To understand how this approach works, think about taking snapshots of the freeway as cars drive past. If you simply overlapped your images, the result would be a big blurry mess — too much has changed between each snapshot.

But if you could figure out the speed of traffic and shift your images to follow along with it, suddenly the details of specific cars would become visible.

For DeForest and his coauthors, the cars were the fine-scale structures of the corona, and the freeway traffic was the solar wind.

Of course there are no speed limit signs in the corona to tell you how fast things are moving. To figure out exactly how much to shift the images before averaging, they scooted the images pixel-by-pixel, correlating them with one another to compute how similar they were. Eventually they found the sweet spot, where the overlapping parts of the images were as similar as possible. The amount of shift corresponded to an average solar wind speed of about 136 miles per second. Shifting each image by that amount, they lined up the images and smoothed, or averaged them together.

“We smoothed, not just in space, not just in time, but in a moving coordinate system,” DeForest said. “That allowed us to create motion blur that was determined not by the speed of the wind, but by how rapidly the features changed in the wind.”

Now DeForest and his collaborators had high-quality images of the corona — and a way to tell how much it was changing over time.

The results

The most surprising finding wasn’t a specific physical structure — it was the simple presence of physical structure in and of itself.

Compared with the dynamic, turbulent inner corona, scientists had considered the outer corona to be smooth and homogenous. But that smoothness was just an artifact of poor signal-to-noise ratio:

“When we removed as much noise as possible, we realized that the corona is structured, all the way down to the optical resolution of the instrument,” DeForest said.

Like the individual blades of grass you see only when you’re up close, the corona’s complex physical structure was revealed in unprecedented detail. And from among that physical detail, three key findings emerged.

The structure of coronal streamers

Coronal streamers — also known as helmet streamers, because they resemble a knight’s pointy helmet — are bright structures that develop over regions of the Sun with enhanced magnetic activity. Readily observed during solar eclipses, magnetic loops on the Sun’s surface are stretched out to pointy tips by the solar wind and can erupt into coronal mass ejections, or CMEs, the large explosions of matter that eject parts of the Sun into surrounding space.

Image above: Coronal streamers observed by the Solar and Heliospheric Observatory (SOHO) spacecraft on Feb. 14, 2002. DeForest and his coauthors’ work indicates that these structures are actually composed of many individual fine strands. Image Credits: NASA/LASCO.

DeForest and his coauthors’ processing of STEREO observations reveals that streamers themselves are far more structured than previously thought.

“What we found is that there is no such thing as a single streamer,” DeForest said. “The streamers themselves are composed of myriad fine strands that together average to produce a brighter feature.”

The Alfvén zone

Where does the corona end and the solar wind begin? One definition points to the Alfvén surface, a theoretical boundary where the solar wind starts moving faster than waves can travel backward through it. At this boundary region, disturbances happening at a point farther away in the traveling solar material can never move backwards fast enough to reach the Sun.

“Material that flows out past the Alfvén surface is lost to the Sun forever,” DeForest said.

Physicists have long believed the Alfvén surface was just that — a surface, or sheet-like layer where the solar wind suddenly reached a critical speed. But that’s not what DeForest and colleagues found.

“What we conclude is that there isn’t a clean Alfvén surface,” DeForest said. “There’s a wide ‘no-man’s land’ or `Alfvén zone’ where the solar wind gradually disconnects from the Sun, rather than a single clear boundary.”

Animation above: A detailed view of the solar corona from the STEREO-A coronagraph after extensive data-cleaning. Animation Credits: Craig DeForest, SwRI.

The observations reveal a patchy framework where, at a given distance from the Sun, some plasma is moving fast enough to stop backward communication, and nearby streams are not. The streams are close enough, and fine enough, to jumble the natural boundary of the Alfvén surface to create a wide, partially-disconnected region between the corona and the solar wind.

Exploring the Unknown with Parker Solar Probe

The newly processed images from STEREO reveal evidence for a new, unsuspected “no-man’s land” between the corona and solar wind:  the so-called “Alfvén zone.”  This result arrives just in time for Parker Solar Probe, NASA’s mission to touch the Sun, which launches in August 2018. Parker Solar Probe will fly through this newly identified territory and directly explore the environment within it.

A mystery at 10 solar radii

But the close look at coronal structure also raised new questions.

The technique used to estimate the speed of the solar wind pinpointed the altitudes, or distances from the Sun’s surface, where things were changing rapidly. And that’s when the team noticed something funny.

“We found that there’s a correlation minimum around 10 solar radii,” DeForest said.

At a distance of 10 solar radii, even back-to-back images stopped matching up well. But they became more similar again at greater distances — meaning that it’s not just about getting farther away from the Sun. It’s as if things suddenly change once they hit 10 solar radii.

“The fact that the correlation is weaker at 10 solar radii means that some interesting physics is happening around there,” DeForest said. “We don’t know what it is yet, but we do know that it is going to be interesting.”

Where we go from here

The findings create headway in a long-standing debate over the source of the solar wind’s complexity. While the STEREO observations don’t settle the question, the team’s methodology opens up a missing link in the Sun-to-solar-wind chain.

“We see all of this variability in the solar wind just before it hits the Earth’s magnetosphere, and one of our goals was to ask if it was even possible that the variability was formed at the Sun. It turns out the answer is yes,” Viall said.

“It allows us for the first time to really probe the connectivity through the corona and adjust how tangled we think the magnetic field gets in the corona versus the solar wind,” DeForest added.

These first observations also provide key insight into what NASA’s upcoming Parker Solar Probe will find, as the first ever mission to gather measurements from within the outer solar corona. That spacecraft will travel to a distance of 8.86 solar radii, right into the region where interesting things may be found. DeForest and colleagues’ results allow them to make predictions of what Parker Solar Probe may observe in this region.

“We should expect steep fluctuations in density, magnetic fluctuations and reconnection everywhere, and no well-defined Alfvén surface,” DeForest said.

Complemented by Parker Solar Probe’s in situ measurements, long exposure imaging and noise reduction algorithms will become even more valuable to our understanding of our closest star.

The study was supported by a grant from NASA’s Living With a Star – Targeted Research and Technology program.

Related links:

Solar and Terrestrial Relations Observatory-A (STEREO-A): http://nasa.gov/stereo

Learn more about NASA’s STEREO mission: https://www.nasa.gov/mission_pages/stereo/mission/index.html

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

Sun: http://www.nasa.gov/sun

Images (mentioned), Animations (mentioned), Video (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Miles Hatfield.

Greetings, Orbiter.chArchive link


How glacial biomarkers can hone the search for extraterrestrial life

Detecting biomarkers in glacial lakes on Earth could pave the way for astrobiologists to detect evidence for life on other worlds, and also unravel the properties of the environments in which that life lived.

How glacial biomarkers can hone the search for extraterrestrial life
Laguna Negra in the Chilean Andes is a glacial lake that contains the remains of ancient life
and is exposed to ultraviolet light [Credit: Wamba Wambez/WikiCommons]

High in the Andes Mountains in Chile, unrelenting ultraviolet (UV) radiation blasts the nutrient-poor waters of Laguna Negra and Lo Encañado, two lakes fed by rapidly melting glaciers. In this hostile and remote environment, researchers are trialling life-detection technology to see if we can use it on other planets.

Understanding these lake systems will help scientists to interpret biomarkers in ancient lakes both on Earth or other planets. Although the organisms themselves are long dead, the traces and history of their deaths are encoded in the biomolecules that litter the lakes’ sediments.

The implications of these biomolecules extend far beyond the boundaries of these lakes: they could help scientists to recreate the evolutionary history of extraterrestrial life. The scientists’ findings were described in a recent article in Astrobiology.

“Once a microbe dies, different physiochemical factors – such as humidity, temperature, oxygen, or the presence of metals – affect the degradation or chemical alteration of its structures and molecular components,” says lead author Victor Parro, based at the Centro de Astrobiología, in Madrid, Spain.

Certain biomarkers are characteristic of certain groups of microbes and even particular metabolisms, he says. “From this information it is possible to infer what the environment where they developed was like.”

Crater lakes

In the Andes, this can tell us about the paleoclimate of the mountains and their rapidly thawing glaciers. But it could possibly unravel the geochemical and atmospheric histories of other worlds, such as Mars and Saturn’s moon Titan.

“These high-altitude lakes in the Andes mountains are interesting for astrobiology because they are exposed to high levels of ultraviolet radiation,” says Lewis Dartnell, an astrobiologist at the University of Westminster, in London, who was not involved in the research. “Understanding how microbial life in the lake copes with these UV levels is important for the search for life beyond Earth – on Mars, for example, where there are believed to have once been crater lakes but also very high UV levels. “

How glacial biomarkers can hone the search for extraterrestrial life
Gale Crater on Mars, which NASA’s Curiosity rover is exploring, used to contain a lake that was exposed to the
ultraviolet radiation incident on the surface of the red planet, and which may contain evidence for past life
[Credit: NASA/JPL–Caltech]

The researchers used a Life Detector Chip (LDChip) to hunt for these fragments of life. An LDChip is a biosensor that can detect the presence of life (recent or ancient) from protein fragments and other biomolecules.

“An LDChip doesn’t need entire living microbes, it just needs biological material, whether it is alive or dead, recent or ancient, free or as part of large polymers or even organo-mineral particles [which are mineral by-products of life],” Parro says. The chip needs between four and ten amino acids to identify the protein or family of proteins that the amino acids came from.

Testing for life in situ

The LDChip is the core of the Spanish Signs Of LIfe Detector (SOLID), an instrument that can liquidize up to two grams of solid rock, soil or ice, which can then be screened for biopolymers.

Importantly, especially when viewed through the lens of astrobiology, it can test for life in situ.

Researchers can treat these extreme environments as proxies for the remote and harsh conditions on other planets, allowing them to test their theories and technologies on Earth. Astrobiologists often view Laguna Negra as a stand-in for the lakes of Titan.

Understanding water, glaciers and ice is a fundamental part of astrobiology. “Ice and glaciers were and are common in other planetary bodies, such as Mars, and they must have played a critical role in the hydrogeology of those planets, the formation and behavior of ancient lakes, as well as in the development and evolution of potential Martian microbiology,” says Parro.

In their study, Parro’s team investigated the shallow sediments of the lakes. They reported the presence of sulphate-reducing bacteria, methanogenic (methane producing) archaea, and exopolymeric substances (polymers, such as biofilms, secreted by organisms) from Gammaproteobacteria.

Proof of life

Don Cowan, a professor of microbial ecology at the University of Pretoria, in South Africa, says that their presence is unsurprising and “just what one would expect in a glacial lake sediment”.

Asked if they were significant biomarkers, he says that “All are important, in a general sense, in that identification of any of these biomarkers (which are examples of many possible biomarkers) in an ‘astrobiological’ sample, such as from Mars, would be definitive evidence of life.”

A library of biomarkers is the next step in Parro’s research. “We need further studies and understanding of what biomarkers we can expect to find in different planetary environments,” he says. This involves identifying the most universal ones, discovering how they are preserved and how they respond to radiation and other environmental conditions, and then using that information to hone their tests for the presence of life.

The end game is to see the SOLID instrument with its LDChip on extraplanetary missions to test for biomarkers or assist astronauts in biohazard detection. Until then, the researchers plan to deploy it in as many terrestrial environments as they can, from extreme environments to the veterinary sector, Parro says.

Author: Sarah Wild | Source: Astrobiology Magazine [July 16, 2018]




Antimatter plasma reveals secrets of deep space signals

Mysterious radiation emitted from distant corners of the galaxy could finally be explained with efforts to recreate a unique state of matter that blinked into existence in the first moments after the Big Bang.

Antimatter plasma reveals secrets of deep space signals
Mysterious radiation emitted from pulsars – like this one shown leaving a long tail of debris as it races
through the Milky Way – have puzzled astronomers for decades [Credit: NASA]

For 50 years, astronomers have puzzled over strange radio waves and gamma rays thrown out from the spinning remnants of dead stars called pulsars.

Researchers believe that these enigmatic, highly-energetic pulses of radiation are produced by bursts of electrons and their antimatter twins, positrons. The universe was briefly filled with these superheated, electrically charged particles in the seconds that followed the Big Bang before all antimatter vanished, taking the positrons with it. But astrophysicists think the conditions needed to forge positrons may still exist in the powerful electric and magnetic fields generated around pulsars.

“These fields are so strong, and they twist and reconnect so violently, that they essentially apply Einstein’s equation of E = mc2 and create matter and antimatter out of energy,” said Professor Luis Silva at the Instituto Superior Técnico in Lisbon, Portugal. Together, the electrons and positrons are thought to form a super-heated form of matter known as a plasma around a pulsar.

But the exact conditions necessary to produce a plasma containing positrons remain unclear. Scientists also still do not understand why the radio waves emitted by the plasma around pulsars have properties similar to light in a laser beam – a wave structure known as coherence.

To find out, researchers are now turning to powerful computer simulations to model what might be going on. In the past, such simulations have struggled to mimic the staggering number of particles generated around pulsars. But Prof. Silva and his team, together with researchers at the University of California, Los Angeles in the United States, have adapted a computer model called OSIRIS so that it can run on supercomputers, allowing it to follow billions of particles simultaneously.

The updated model, which forms part of the InPairs project, has identified the astrophysical conditions necessary for pulsars to generate electrons and positrons when magnetic fields are torn apart and reattached to their neighbours in a process known as magnetic reconnection.

OSIRIS also predicted that the gamma rays released by electrons and positrons as they race across a magnetic field will shine in discontinuous spurts rather than smooth beams.

The findings have added weight to theories that the enigmatic signals coming from pulsars are produced by the destruction of electrons as they recombine with positrons in the magnetic fields around these dead stars.

Prof. Silva is now using the data from these simulations to search for similar burst signatures in past astronomical observations. The tell-tale patterns would reveal details on how magnetic fields evolve around pulsars, offering fresh clues about what is going on inside them. It will also help confirm the validity of the OSIRIS model for researchers trying to create antimatter in the laboratory.

Blasting lasers

Insights gained from the simulations are already being used to help design experiments that will use high-powered lasers to mimic the huge amounts of energy released by pulsars. The Extreme Light Infrastructure will blast targets no wider than a human hair with petawatts of laser power. Under this project, lasers are under construction at three facilities around Europe – in Măgurele in Romania, Szeged in Hungary, and Prague in the Czech Republic. If successful, the experiments could create billions of electron-positrons pairs.

Antimatter plasma reveals secrets of deep space signals
The OSIRIS computer model predicts how powerful magnetic fields around pulsars evolve, helping scientists
understand where matter and antimatter can be created out of the vacuum of space [Credit: Fabio Cruz]

“OSIRIS is helping researchers optimise laser properties to create matter and antimatter like pulsars do,” said Prof. Silva. “The model offers a road map for future experiments.”

But there are some who are attempting to wield matter-antimatter plasmas in even more controlled ways so they can study them.

Professor Thomas Sunn Pedersen, an applied physicist at the Max Planck Institute for Plasma Physics in Garching, Germany, is using charged metal plates to confine positrons alongside electrons as a first step towards creating a matter-antimatter plasma on a table top.

Although Prof. Sunn Pedersen works with the most intense beam of low-energy positrons in the world, concentrating enough particles to ignite a matter-antimatter plasma remains challenging. Researchers use electro-magnetic ‘cages’ generated under vacuum to confine antimatter, but these require openings for the particles to be injected inside. These same openings allow particles to leak back out, however, making it difficult to build up enough particles for a plasma to form.

Prof. Sunn Pedersen has invented an electro-magnetic field with a ‘trap door’ that can let positrons in before closing behind them. Last year, the new design was able to boost the time the antimatter particles remained confined in the field by a factor of 20, holding them in place for over a second.

“No one has ever achieved that in a fully magnetic trap,” said Prof. Sunn Pedersen. “We have proven that the idea works.”

But holding these elusive antimatter particles in place is only one milestone towards creating a matter-antimatter plasma in the laboratory. As part of the PAIRPLASMA project, Prof. Sunn Pedersen is now increasing the quality of the vacuum and generating the field with a levitating ring to confine positrons for over a minute. Studying the properties of plasmas ignited under these conditions will offer valuable insights to neighbouring fields.

In June, for example, Prof. Sunn Pedersen used a variation of this magnetic trap to set a new world record in nuclear fusion reactions ignited in conventional-matter plasmas.

“Collective phenomena like turbulence currently complicate control over big fusion plasmas,” said Prof. Sunn Pedersen. “A lot of that is driven by the fact that the ions are much heavier than the electrons in them.”

He hopes that by producing electron-positron plasmas like those created by the Big Bang, it may be possible to sidestep this complication because electrons and positrons have the exact same mass. If they can be controlled, such plasmas could help to validate complex models and recreate the conditions around pulsars so they can be studied up close in the laboratory for the first time.

If successful it may finally give astronomers the answers they have puzzled over for so long.

What is a pulsar?

First discovered by astronomer Jocelyn Bell in 1967, pulsars are the highly magnetised, rotating remains of stars that have collapsed at the end of their life. They emit beams of gamma rays and radio waves that spin much like the light from a lighthouse. When viewed from Earth, this gives the impression of the radiation arriving in pulses. It is thought that the intense magnetic fields around these dead stars generate clouds of charged particles known as plasmas, which in turn generate the radiation.

Author: Jude Gonzalez | Source: Horizon: The EU Research & Innovation Magazine [July 16, 2018]




A dozen new moons of Jupiter discovered, including one ‘oddball’

Twelve new moons orbiting Jupiter have been found–11 “normal” outer moons, and one that they’re calling an “oddball.” This brings Jupiter’s total number of known moons to a whopping 79–the most of any planet in our Solar System.

A dozen new moons of Jupiter discovered, including one 'oddball'
Various groupings of Jovian moons with the newly discovered ones shown in bold. The ‘oddball,’ called Valetudo
after the Roman god Jupiter’s great-granddaughter, has a prograde orbit that crosses the retrograde orbits
[Credit: By Roberto Molar-Candanosa/Carnegie Institution for Science]

A team led by Carnegie’s Scott S. Sheppard first spotted the moons in the spring of 2017 while they were looking for very distant Solar System objects as part of the hunt for a possible massive planet far beyond Pluto.

In 2014, this same team found the object with the most-distant known orbit in our Solar System and was the first to realize that an unknown massive planet at the fringes of our Solar System, far beyond Pluto, could explain the similarity of the orbits of several small extremely distant objects. This putative planet is now sometimes popularly called Planet X or Planet Nine. University of Hawaii’s Dave Tholen and Northern Arizona University’s Chad Trujillo are also part of the planet search team.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System,” said Sheppard.

Gareth Williams at the International Astronomical Union’s Minor Planet Center used the team’s observations to calculate orbits for the newly found moons.

“It takes several observations to confirm an object actually orbits around Jupiter,” Williams said. “So, the whole process took a year.”

A dozen new moons of Jupiter discovered, including one 'oddball'
May 2018 recovery images of Valetudo from Carnegie’s Magellan telescope’s at our Las Campanas Observatory
in Chile. The moon can be seen moving relative to the steady state background of distant stars.
Jupiter is not in the field but off to the upper left [Credit: Carnegie Institution for Science]

Nine of the new moons are part of a distant outer swarm of moons that orbit it in the retrograde, or opposite direction of Jupiter’s spin rotation. These distant retrograde moons are grouped into at least three distinct orbital groupings and are thought to be the remnants of three once-larger parent bodies that broke apart during collisions with asteroids, comets, or other moons. The newly discovered retrograde moons take about two years to orbit Jupiter.

Two of the new discoveries are part of a closer, inner group of moons that orbit in the prograde, or same direction as the planet’s rotation. These inner prograde moons all have similar orbital distances and angles of inclinations around Jupiter and so are thought to also be fragments of a larger moon that was broken apart. These two newly discovered moons take a little less than a year to travel around Jupiter.

“Our other discovery is a real oddball and has an orbit like no other known Jovian moon,” Sheppard explained. “It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter”.

This new “oddball” moon is more distant and more inclined than the prograde group of moons and takes about one and a half years to orbit Jupiter. So, unlike the closer-in prograde group of moons, this new oddball prograde moon has an orbit that crosses the outer retrograde moons.

As a result, head-on collisions are much more likely to occur between the “oddball” prograde and the retrograde moons, which are moving in opposite directions.

“This is an unstable situation,” said Sheppard. “Head-on collisions would quickly break apart and grind the objects down to dust.”

It’s possible the various orbital moon groupings we see today were formed in the distant past through this exact mechanism.

The team think this small “oddball” prograde moon could be the last-remaining remnant of a once-larger prograde-orbiting moon that formed some of the retrograde moon groupings during past head-on collisions. The name Valetudo has been proposed for it, after the Roman god Jupiter’s great-granddaughter, the goddess of health and hygiene.

Elucidating the complex influences that shaped a moon’s orbital history can teach scientists about our Solar System’s early years.

For example, the discovery that the smallest moons in Jupiter’s various orbital groups are still abundant suggests the collisions that created them occurred after the era of planet formation, when the Sun was still surrounded by a rotating disk of gas and dust from which the planets were born.

Because of their sizes–one to three kilometers–these moons are more influenced by surrounding gas and dust. If these raw materials had still been present when Jupiter’s first generation of moons collided to form its current clustered groupings of moons, the drag exerted by any remaining gas and dust on the smaller moons would have been sufficient to cause them to spiral inwards toward Jupiter. Their existence shows that they were likely formed after this gas and dust dissipated.

The initial discovery of most of the new moons were made on the Blanco 4-meter telescope at Cerro Tololo Inter-American in Chile and operated by the National Optical Astronomical Observatory of the United States. The telescope recently was upgraded with the Dark Energy Camera, making it a powerful tool for surveying the night sky for faint objects. Several telescopes were used to confirm the finds, including the 6.5-meter Magellan telescope at Carnegie’s Las Campanas Observatory in Chile; the 4-meter Discovery Channel Telescope at Lowell Observatory Arizona (thanks to Audrey Thirouin, Nick Moskovitz and Maxime Devogele); the 8-meter Subaru Telescope and the Univserity of Hawaii 2.2 meter telescope (thanks to Dave Tholen and Dora Fohring at the University of Hawaii); and 8-meter Gemini Telescope in Hawaii (thanks to Director’s Discretionary Time to recover Valetudo). Bob Jacobson and Marina Brozovic at NASA’s Jet Propulsion Laboratory confirmed the calculated orbit of the unusual oddball moon in 2017 in order to double check its location prediction during the 2018 recovery observations in order to make sure the new interesting moon was not lost.

Source: Carnegie Institution for Science [July 17, 2018]




New insight into Greenland’s melting glaciers

New research into Greenland’s glaciers will help bring accurate sea level rise forecasts – which are crucial in preparing for the impacts of climate change—a step closer.

New insight into Greenland's melting glaciers
Credit: University of St Andrews

The Greenland Ice Sheet, which contains enough water to raise sea levels by around seven metres if it melts completely, is expected to be a major source of sea level rise over the coming centuries.

However, predicting how quickly the ice sheet will shrink, as the climate warms, has proved difficult due to a poor understanding of the rapid changes where the ice sheet meets the ocean. Scientists, led by the University of St Andrews, have now taken an important step towards improving these predictions.

Their study, carried out in collaboration with the Universities of Sheffield, Edinburgh, Cambridge and California San Diego, examined the behaviour of ten large glaciers in east Greenland over a 20-year period (1993 –2012) using satellite imagery to track their retreat.

The resulting research, published in the Proceedings of the National Academy of Sciences found that, while the retreat of these glaciers could appear erratic and unpredictable when studied over just a few years, a clear relationship between the rate of retreat and climatic warming emerged when observed over longer timescales.

Crucially, the research (which was supported by the Natural Environment Research Council) discovered that variations in ocean temperature help to explain key discrepancies in glacier retreat along Greenland’s east coast.

In southeast Greenland, major glaciers retreated by several kilometres as regional air temperatures warmed rapidly between 2000 and 2005. Contrastingly, glaciers in the northeast remained much more stable despite air temperatures warming by a similar amount.

The team attributed this disparity to the presence of very cold ocean waters along the coast of northeast Greenland. Warmer ocean waters melted the submerged parts of marine-terminating glaciers, encouraging undermined blocks to tumble into the sea as icebergs. Colder waters suppress this process, which may then make the glaciers more resilient to the warming air temperatures.

These findings will be crucial in helping predict the rate of mass loss from the Greenland Ice Sheet over the coming century.

Dr. Tom Cowton of the School of Geography and Sustainable Development at the University of St Andrews, who led the study, said: “While we cannot predict the detailed retreat of individual glaciers, our findings enable us to approximate likely retreat rates based on air and ocean warming scenarios. This information can then be fed into the large scale ice sheet models that are used to predict sea level rise.”

Greenland is ringed by fast-flowing outlet glaciers, which drain from the slow-flowing interior of the ice sheet. The largest of these outlet glaciers reach the coast, where they discharge vast quantities of icebergs into the surrounding ocean.

In recent years, these marine-terminating outlet glaciers have attracted attention as hotspots of ice-loss around the ice sheet margin. However, their behaviour has proved difficult to explain, with some glaciers undergoing episodes of rapid retreat whilst others appear comparatively stable.

Source: University of St Andrews [July 17, 2018]




Looking toward earth’s future climate

A NASA scientist’s final scientific paper, published posthumously this month, reveals new insights into one of the most complex challenges of Earth’s climate: understanding and predicting future atmospheric levels of greenhouse gases and the role of the ocean and land in determining those levels.

Looking toward earth's future climate
From space, satellites can see Earth breathe. A new NASA visualization shows 20 years of continuous observations
of plant life on land and at the ocean’s surface, from September 1997 to September. 2017. On land, vegetation appears
on a scale from brown (low vegetation) to dark green (lots of vegetation); at the ocean surface, phytoplankton are
 indicated on a scale from purple (low) to yellow (high). This visualization was created with data from satellites
 including SeaWiFS, and instruments including the NASA/NOAA Visible Infrared Imaging Radiometer Suite
and the Moderate Resolution Imaging Spectroradiometer [Credit: NASA]

A paper published in the Proceedings of the National Academy of Sciences was led by Piers J. Sellers, former director of the Earth Sciences Division at NASA’s Goddard Space Flight Center, who died in December 2016. Sellers was an Earth scientist at NASA Goddard and later an astronaut who flew on three space shuttle missions.

The paper includes a significant overarching message: The current international fleet of satellites is making real improvements in accurately measuring greenhouse gases from space, but in the future a more sophisticated system of observations will be necessary to understand and predict Earth’s changing climate at the level of accuracy needed by society.

Sellers wrote the paper along with colleagues at NASA’s Jet Propulsion Laboratory and the University of Oklahoma. Work on the paper began in 2015, and Sellers continued working with his collaborators up until about six weeks before he died. They carried on the research and writing of the paper until its publication this week.

The paper focuses on the topic that was at the center of Sellers’ research career: Earth’s biosphere and its interactions with the planet’s climate. In the 1980s he helped pioneer computer modeling of Earth’s vegetation. In the new paper, Sellers and co-authors investigated “carbon cycle-climate feedbacks” – the potential response of natural systems to climate change caused by human emissions – and laid out a vision for how to best measure this response on a global scale from space.

The exchange of carbon between the land, ocean and air plays a huge role in determining the amount of greenhouse gases in the atmosphere, which will largely determine Earth’s future climate. But, there are complex interactions at play. While human-caused emissions of greenhouses gases are building up in the atmosphere, land ecosystems and the ocean still offset about 50 percent of all those emissions. As the climate warms scientists are unsure whether forests and the ocean will continue to absorb roughly half of the emissions – acting as a carbon sink – or if this offset becomes lower, or if the sinks become carbon sources.

Paper co-author David Schimel, a scientist at JPL and a longtime scientific collaborator of Sellers’, said the paper captured how he, Sellers and the other co-authors saw this scientific problem as one of the critical research targets for NASA Earth science.

“We all saw understanding the future of carbon cycle feedbacks as one of the grand challenges of climate change science,” Schimel said.

In a 2016 interview, Piers Sellers talked about his enthusiasm and appreciation for working 

at NASA’s Goddard Space Flight Center [Credit: NASA Goddard]

Scientists’ understanding of how Earth’s living systems interact with rising atmospheric levels of greenhouse gases has changed tremendously in recent decades, said co-author Berrien Moore III, of the University of Oklahoma. Moore has been a scientific collaborator with Sellers and Schimel since the 1980s. He said that back then, scientists thought the ocean absorbed about half of annual carbon emissions, while plants on land played a minimal role. Scientists now understand the ocean and land together absorb about half of all emissions, with the terrestrial system’s role being affected greatly by large-scale weather patterns such as El Niño and La Niña. Moore is also the principal investigator of a NASA mission called GeoCarb, scheduled to launch in 2022, that will monitor greenhouse gases over much of the Western Hemisphere from a geostationary orbit.

NASA launched the Orbiting Carbon Observatory-2 (OCO-2) in 2014, and with the advancement of measurement and computer modeling techniques, scientists are gaining a better understanding of how carbon moves through the land, ocean and atmosphere. This new paper builds on previous research and focuses on a curious chain of events in 2015. While human emissions of carbon dioxide leveled off for the first time in decades during that year, the growth rate in atmospheric concentrations of carbon dioxide actually spiked at the same time.

This was further evidence of what scientists had been piecing together for years – that a complex combination of factors, including weather, drought, fires and more, contributes to greenhouse gas levels in the atmosphere.

However, with the new combination of OCO-2 observations and space-based measurements of plant fluorescence (essentially a measure of photosynthesis), researchers have begun producing more accurate estimates of where carbon was absorbed and released around the planet during 2015, when an intense El Niño was in effect, compared to other years.

The paper follows a report from a 2015 workshop on the carbon cycle led by Sellers, Schimel, and Moore. Schimel and Moore both pointed out that every one of the more than 40 participants in the workshop contributed to a final scientific report from the meeting – a rare occurrence. They attributed this, in part, to the inspirational role Sellers played in spurring thought and action.

“When you have someone like Piers in the room, there’s a magnetic effect,” Moore said. “Piers had his shoulder to the wheel, so everyone had to have their shoulders to the wheel.”

Schimel and Moore said the workshop paper lays out a vision for what’s needed in a future space-based observing system to measure, understand, and predict carbon cycle feedbacks: active and passive instruments, and satellites both in low-Earth and geostationary orbits around the world. In the coming years, NASA and space agencies in Europe, Japan, and China, will all launch new greenhouse-gas monitoring missions.

“Piers thought it’s absolutely essential to get it right,” said Schimel, “and essential to more or less get it right the first time.”

The authors dedicated the paper’s publication to Sellers, and in their dedication referenced a Winston Churchill quote often cited by the British-born scientist. They wrote: “P.J.S. approached the challenge of carbon science in the spirt of a favorite Churchill quote, ‘Difficulties mastered are opportunities won,’ and he aimed to resolve the carbon-climate problem by rising to the difficulties and seizing the opportunities.”

Source: NASA/Goddard Space Flight Center [July 17, 2018]





https://t.co/hvL60wwELQ — XissUFOtoday Space (@xufospace) August 3, 2021 Жаждущий ежик наслаждается пресной водой после нескольких дней в о...