понедельник, 24 июня 2019 г.

Curiosity Detects Unusually High Methane Levels


NASA — Mars Science Laboratory (MSL) logo.


June 24, 2019



Image above: This image was taken by the left Navcam on NASA’s Curiosity Mars rover on June 18, 2019, the 2,440th Martian day, or sol, of the mission. It shows part of «Teal Ridge,» which the rover has been studying within a region called the «clay-bearing unit.» Image Credits: NASA/JPL-Caltech.


This week, NASA’s Curiosity Mars rover found a surprising result: the largest amount of methane ever measured during the mission — about 21 parts per billion units by volume (ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.


The finding came from the rover’s Sample Analysis at Mars (SAM) tunable laser spectrometer. It’s exciting because microbial life is an important source of methane on Earth, but methane can also be created through interactions between rocks and water.


Curiosity doesn’t have instruments that can definitively say what the source of the methane is, or even if it’s coming from a local source within Gale Crater or elsewhere on the planet.


«With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern,» said SAM Principal Investigator Paul Mahaffy of NASA’s Goddard Spaceflight Center in Greenbelt, Maryland.


The Curiosity team has detected methane many times over the course of the mission. Previous papers have documented how background levels of the gas seem to rise and fall seasonally. They’ve also noted sudden spikes of methane, but the science team knows very little about how long these transient plumes last or why they’re different from the seasonal patterns.


The SAM team organized a different experiment for this weekend to gather more information on what might be a transient plume. Whatever they find — even if it’s an absence of methane — will add context to the recent measurement.



Mars Science Laboratory (MSL) or Curiosity rover. Animation Credits: NASA/JPL

Curiosity’s scientists need time to analyze these clues and conduct many more methane observations. They also need time to collaborate with other science teams, including those with the European Space Agency’s Trace Gas Orbiter, which has been in its science orbit for a little over a year without detecting any methane. Combining observations from the surface and from orbit could help scientists locate sources of the gas on the planet and understand how long it lasts in the Martian atmosphere. That might explain why the Trace Gas Orbiter’s and Curiosity’s methane observations have been so different.


Related article:


NASA Finds Ancient Organic Material, Mysterious Methane on Mars
https://orbiterchspacenews.blogspot.com/2018/06/nasa-finds-ancient-organic-material.html


For more information about Curiosity, visit:


https://www.nasa.gov/mission_pages/msl/index.html


https://mars.nasa.gov/msl/


Image (mentioned), Animation (mentioned), Text, Credits: NASA/Alana Johnson/JPL/Andrew Good.


Greetings, Orbiter.chArchive link


Genetic substructures and adaptations in Lithuanians (Urnikyte et al. 2019)

Over at Scientific Reports at this LINK. Apparently, the genotype data from this paper will be available at figshare in just over three months (see here). Among other things, the paper makes some interesting points about the relationship between the genetic ancestry of Lithuanians and their language:



When combining the new data we generated with external datasets, we confirmed that Lithuanians locate within the expected European context, even though they also present particular genetic distinctiveness when compared to neighbouring populations. In addition, the inclusion of ancient individuals from different periods across western Eurasia in the analysis allowed us to distinguish the genetic signature of three main prehistorical sources shaping the distinctiveness of present-day Lithuanians: pre-Neolithic HG groups, the Early to Middle Bronze Age Steppe pastoralists and Late Neolithic Bronze Age (LNBA) Europeans. Moreover, up to three HG populations can be inferred to contribute to the main genetic component identified the Lithuanians being the contribution of the WHG and the Scandinavian HG greater than that of the EHG. On the contrary, earlier European Neolithic movements from Levant/Anatolia known to contribute to genetically differentiated populations in Europe such as Sardinians or Basques are not especially predominant in Lithuania.
Partial genetic isolation of the Lithuanians is a possible explanation for the structure results observed. Until the late Middle Ages, the eastern Baltic region was one of the most isolated corners of Europe [27]. Moreover, after the fall of the Roman Empire in the 5th century, the eastern Baltic region was spared by the subsequent population movements of the Migration Period [26,28], which allowed the most archaic of all the living speaking Indo-European languages [1] to survive. Thus, Lithuanians could retain their cultural identity.



Urnikyte et al., Patterns of genetic structure and adaptive positive selection in the Lithuanian population from high-density SNP data, Scientific Reports volume 9, Article number: 9163 (2019), DOI: https://doi.org/10.1038/s41598-019-45746-3
See also…
Fresh off the sledge
Uralic-specific genome-wide ancestry did make a signifcant impact in the East Baltic
It was always going to be this way
Inferring the linguistic affinity of long dead and non-literate peoples: a multidisciplinary approach

Source


2019 June 24 Anticrepuscular Rays Converge Opposite the Sun…


2019 June 24


Anticrepuscular Rays Converge Opposite the Sun
Image Credit & Copyright: Juraj Patekar


Explanation: Is there ever anything interesting to see in the direction opposite the Sun? Sometimes there is. Notable items include your own shadow, a shadow of the Moon during a total solar eclipse, a full moonin eclipse if the alignment’s good enough, a full earth, planets at opposition, glints from planets, the gegenschein from interplanetary dust, the center of a rainbow, hall-of-mountain fogbows, an airplane glory, and something yet again different if your timing, clouds and Sun position are just right. This different effect starts with clouds near the Sun that are causing common crepuscular rays to stream though. In the featured rare image taken from an airplane in mid-April, these beams were caught converging 180 degrees around, on the opposite side of the sky from the Sun, where they are called anticrepuscular rays. Therefore, it may look like something bright is shining at the antisolar point near the image center, but actually it is reverse-shining because, from your direction, light is streaming in, not out.


∞ Source: apod.nasa.gov/apod/ap190624.html


Zebra Schist | #Geology #GeologyPage #KangarooIsland…


Zebra Schist | #Geology #GeologyPage #KangarooIsland #Australia


Harvey’s Return Zebra rocks on Kangaroo Island.


The tightly folded, thinly bedded schists that are derived from sedimentary rocks that are exposed in Kangaroo Island are known as zebra schists. A quartz-rich and biotite-rich layering largely reflects original sedimentary layering rather than metamorphic differentiation as the secondary biotite preserves and outlines a variety of sedimentary structures.


More Info & Photos: http://www.geologypage.com/2019/05/zebra-schist.html


Geology Page

www.geologypage.com

https://www.instagram.com/p/BzESF0-AYXW/?igshid=sgg77itj1e5q


Subaru Telescope Identifies the Outermost Edge of our Milky Way System



Figure 1: The Milky Way and Halo component. 


Credit: Tohoku University


A team of researchers identified the outermost edge of the Milky Way Galaxy — the Galaxy that humans reside in. Using the Subaru Telescope, the researchers examined the boundary of the stellar system that makes up our Galaxy. The ultimate size of our Galaxy is 520,000 light years in radius, 20 times larger than the distance between the Galactic Center and our solar system (26,000 light years) (Figure 1). Stars that reach these outermost regions of the Galaxy during their orbital motions are ancient stellar populations with ages as old as 12 billion years. The spatial extent in which these ancient stars wonder is, therefore, important for our understanding of the Milky Way’s formation.


Our Galaxy holds a broadly extended halo component, in addition to the bright Milky Way in the form of the stellar disk component. The halo contains about a billion ancient stars and 150 globular clusters with ages as old as 12 billion years (Figure 1). The halo thus contains the remnants of long-lived stars and star clusters that formed in the first stage of the Galaxy. This suggests that the Galaxy was quite large in its beginning before the later formation of the younger, disk component.


Investigating the extent of this halo component in the Galaxy is similar to identifying the outer boundary of a forest whilst similarly being inside the forest and observing the trees. In other words, it is an arduous task. So called blue horizontal branch (BHB) stars as well as RR Lyr variables are ideal indicators for tracing the halo component. This is because they are naturally bright enough to determine the distance to and from them. However, the Galaxy is so large that it is impossible to identify the halo traces located at the outer boundary using 2.5 to 4 meter-diameter telescopes.


The team of researchers led by Tohoku University graduate student, Tetsuya Fukushima and his supervisor Masashi Chiba used the Hyper Suprime-Cam (HSC) digital camera on the 8.2 meter diameter Subaru Telescope. It enabled them to capture remote, very faint halo tracers at the outer edge of the Galaxy. The team carefully selected the BHB stars from the on-going survey program (SSP: Subaru Strategic Program) data against other contaminants having similar colors such as so-called blue straggler stars, white dwarfs, quasars and distant galaxies.


Using the data from HSC-SSP, the team derived the spatial density of the BHB stars over the Galaxy halo. While this density generally decreases the further you go from the Galactic center, the team discovered a sharp drop in density at around 520,000 light years away from the Galactic center. Thus, the team had finally reached the outermost edge of the Galaxy that we reside in. This is about 20 times larger than the distance between our Solar system and the Galaxy center.


Twelve billion years ago, successive merging of small galaxies confined by dark matter halos occurred. Key to understanding this is measuring the distribution of the halo component to ascertain the volume. This merging process differs from galaxy to galaxy. Our neighbor, the Andromeda Galaxy, is reported to have an extended halo component as large as 538,000 (at the very least) light years in its radius. It is, therefore, systematically larger when compared to the Galaxy halo. The researchers are planning to further map out this ancient component of the Galaxy after the final completion of the HSC-SSP.



These results were published in Publications of the Astronomical Society of Japan (Fukushima et al. 2019, «The stellar halo of the Milky Way traced by blue horizontal-branch stars in the Subaru Hyper Suprime-Cam Survey»). A preprint is available here. This research is supported by KAKENHI Grant Numbers Nos. JP25287062, JP16H01086, JP17H01101, JP18H04334, JP18H04359, JP18J00277, and JP18J11326.


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Hardknott Roman Fort, Hardknott Pass, Lake District, 22.6.19.In one of the most striking...


Hardknott Roman Fort, Hardknott Pass, Lake District, 22.6.19.


In one of the most striking but rugged locations of the lakes, this Roman Fort must have felt otherworldly to those posted here. Cold and windy winters must have made it a challenging place to defend the Roman empire.


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Hardknott Roman Fort Photoset 1, Hardknott Pass, Lake District, 22.6.19.

Hardknott Roman Fort Photoset 1, Hardknott Pass, Lake District, 22.6.19.












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Hardknott Roman Fort Photoset 2, Hardknott Pass, Lake District, 22.6.19.


Hardknott Roman Fort Photoset 2, Hardknott Pass, Lake District, 22.6.19.











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