вторник, 6 ноября 2018 г.

Researchers explain the origin of the mysterious periodicity of the genome

Scientists at the Institute for Research in Biomedicine (IRB Barcelona) have found an explanation for a periodicity in the sequence of the genomes of all eukaryotes, from yeast to humans. The results published in the journal Cell offer an alternative explanation to the one based on natural selection, which has been accepted by the scientific community to date.











Researchers explain the origin of the mysterious periodicity of the genome
The DNA molecule, formed by a double helix, winds around histone molecules twice, thus forming nucleosomes.
The pink regions indicate those enriched in Adenine/Thymine base pairs
[Credit: Iris Joval Granollers]

The researchers demonstrate that DNA damage and repair processes can play a role in the generation of sequence periodicity in the genomes of eukaryotic organisms. These processes are influenced by the orientation of the DNA structure when this molecule is packaged inside the cell nucleus, thus favouring a certain composition with a periodic nature in eukaryotic genomes.


“The answer we provide allows a better understanding of why our genome and that of other species have developed into what they are today,” says Nuria Lopez-Bigas, head of the study and leader of the Biomedical Genomics lab at IRB Barcelona.


The “mysterious” periodicity of the genome


Since the sequence of the human genome and that of other organisms such as the mouse and fruit fly became known at the beginning of the 21st century, some researchers have noted a marked periodicity in the proportion of base pairs comprising adenine (A) and thymine (T). Indeed, the proportion of A/T pairs has been observed to be greater every 10 base pairs.


This periodicity has been associated with how DNA winds around nucleosomes (the simplest compaction form of DNA, in which it envelopes proteins called histones). The explanation given has been that natural selection would favour the appearance of A/T bases as these bases would provide the DNA structure with a greater degree of flexibility, thus allowing it to wind around histones to form nucleosomes.


Tumour mutations provide the key


By studying the distribution of mutations in more than 3,000 human tumours, the team at IRB Barcelona observed that the mutations also accumulated every 10 DNA base pairs.


“By examining mutation distribution along the genomes in regions in which we ruled out the presence of selection, we found a marked periodicity of 10 base pairs in the DNA that forms part of nucleosomes,” explains Oriol Pich, PhD student and awardee of a fellowship from the Barcelona Institute of Science and Technology (BIST) and first author of the paper.



The periodicity of mutations occurs because the structure of the DNA packaged inside the nucleosome favours the appearance of regions that are prone to damage and to repair. Consequently, these regions are more susceptible to mutations.


Next, the researchers turned their attention to mutations that are passed from one generation to another, in both humans and plants. They found that these hereditary mutations also accumulated every 10 base pairs.


With this new discovery of how nucleosomes affect DNA mutations, the researchers deduced that it could also explain the development of the mysterious periodicity of the sequence of eukaryotic genomes.


Mutations over millions of years of evolution


The scientists at IRB Barcelona hypothesised that, as most mutations that we get are in cytosines (C) that convert into thymines (T), most of those regions most prone to mutating over millions of years have become A/T base pairs.


To test this notion, the researchers performed a mathematical simulation of genome evolution and demonstrated that the periodicity of the sequence of the human genome and that of other eukaryotes could have arisen from the periodic rate of mutations.


“We are really pleased to provide the scientific community with this alternative explanation regarding periodicity,” say Oriol Pich and Nuria Lopez-Bigas, who highlight the importance of this kind of research. “It is basic knowledge derived from curiosity-driven research that allows us to achieve a better understanding of nature.”


However, the results of the study are not only a breakthrough regarding current understanding of the human genome but they also explain how tumours acquire mutations. This knowledge is relevant for identifying mutations that are relevant for tumour development — another field of expertise of Lopez-Bigas’ group.


This study is an example of how basic research can bring about new scientific knowledge. The work has been funded by the European Research Council, through a Consolidator grant” awarded to Nuria Lopez-Bigas, by the Ministry of Science, through ERDFs, and by the Catalan Government.


Source: Institute for Research in Biomedicine (IRB Barcelona) [November 01, 2018]



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Guernsey’s medieval ‘Porpoise grave’ remains a mystery

The remains of a porpoise mysteriously buried on a small island have been dated to the medieval period. But experts remain baffled over why the sea creature seems to have been placed in a grave 600 years ago.











Guernsey's medieval 'Porpoise grave' remains a mystery
Extracts of bone from the porpoise’s skull are thought to date from the 15th Century
[Credit: Dr Philip de Jersey via BBC]

The porpoise was discovered during a dig on Chapelle Dom Hue, a tiny island off Guernsey’s west coast, last year. It is possible the mammal was butchered and preserved underground, according to the archaeologist who unearthed the animal.
Radiocarbon dating by a specialist lab in Florida has suggested the porpoise was buried between 1416 and 1490. The burial date fitted perfectly with the archaeology of the island, States of Guernsey Archaeologist Dr Philip de Jersey said.


However, he acknowledged some uncertainty remained over the exact date, owing to the uniqueness of the heavily decayed find. The porpoise was discovered during an archaeological dig in September 2017 to unearth a building that once stood on the island.











Guernsey's medieval 'Porpoise grave' remains a mystery
The porpoise bone is close to becoming soil after decaying in acidic soil, according to Dr de Jersey
[Credit: Dr Philip de Jersey via BBC]

The discovery quickly eclipsed any other finds, and prompted international intrigue as to why the porpoise was buried.
Dr de Jersey said he now believed the animal was butchered and placed underground, possibly in a salty brine, to be eaten, rather than being buried whole as a sign of respect by nearby Christian monks – one theory put forward.


“We have literary, textual, and historical evidence as well of the consumption of porpoise in the medieval period, and in fact specifically in Guernsey in the 13th and 14th Century,” he said.











Guernsey's medieval 'Porpoise grave' remains a mystery
The island of Chapelle Dom Hue, off Guernsey’s rugged west coast, can be reached over low tide [Credit: BBC]

Records from the 12th and 13th Century also showed disputes over porpoise meat which went on over “weeks, if not months” in the island, suggesting the remains were preserved over considerable time, he added.
A definitive answer as to why the porpoise was buried may, however, never be unearthed.


“There is not a lot left of Chapelle Dom Hue, and whoever was here didn’t leave particularly wealthy or precious items behind,” Dr de Jersey said. “I suspect we won’t find out.”


Source: BBC News Website [November 01, 2018]



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Unearthed Graeco-Roman statues unveiled in Jerash

After years of meticulous work, a French archaeological team that has been excavating the eastern Roman baths in Jerash, unearthed several intact sculptures from the Graeco-Roman period.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

An event to showcase the sculptures was held on Wednesday, at the Visitor Centre in Jerash and attracted a large number of local and foreign stakeholders, including the French Ambassador to Jordan David Bartolloti, and the head of the Jerash Department of Antiquities Ziyad Ghuneimat.
In his speech, on behalf of Tourism Minister Lina Annab, Issa Gammoh, the secretary general of the ministry, said that several projects will be implemented next year to promote tourism in Jerash, such as revamping the Swam Souk as part of a project to connect the modern and the ancient Jerash, adding that today Jerash has around 250 tourist facilities.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

The statues that were found together (27 of them in all), in a very small area of the Great Eastern Baths will “enrich visits to Jerash and enhance knowledge about the culture and heritage of Jordan for visitors, especially students”, Gammoh told The Jordan Times on the sidelines of the event.
“We worked from 2016 until 2018 with a German, French and Jordanian team, and it was impossible without help from the French ministry of foreign affairs and the Gerda Henkel Foundation,” said Professor Thomas Weber-Karyotakis, head of the French team in Jerash.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

The statues represent Greek-Roman gods Aphrodite, a god of love, and Zeus, the supreme god of the Olympian pantheon, as well as muses sitting on thrones. The colossal figure of Aphrodite is made of Pentelic marble from the region of Athens, while the sculpture of Zeus was forged with marble from northern Greece, said Weber-Karyotakis.


Weber-Karyotakis added that the work of the team, lead by French scholar Thomas Lepaon and himself, was the continuation of research conducted by veteran archaeologist Jacques Seigna, who spent decades studying the rich cultural heritage of Jerash.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

The statue of Aphrodite has a five-line Greek inscription on the plinth, which said the figure was donated by a local priest named Demetrios, according to the German expert, who noted that the inscription also indicates the unusually exact date of dedication, around March 20, 154 AD.


The names of the muses in Graeco-Roman mythology are: Caliope, the muse of epic poetry; Clio, the muse of history; Erato, the muse of lyric poetry; Euterpe, the muse of music; Melpomene, the muse of tragedy; Polyhymnia, the muse of sacred poetry; Terpischore, the muse of dance and chorus; Thalia, the muse of comedy and idyll; and Urania, the muse of astronomy.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

This monumental bathing complex — one of the largest and best preserved in the entire Orient — was built in the second half of the 2nd century AD in the valley of the Chrysorrhoas Brook, and then enlarged towards the end of that century or at the beginning of the following under the Severan emperors, the scholar elaborated.


He added that the construction work carried out in Severan period mainly concerned a pillared hall with exedra, which was built “attached to the north of the original core of the bathing complex”.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

The scholar said that this hall was reminiscent of the “imperial halls” of the Asia Minor, was decorated with sculptures according to numerous statue bases, most of which had Greek inscriptions.
The aims of three excavations were to establish architectural connections between the bathing complex and the pillared hall and to find out more about the sculptural decoration scheme, Weber –Karyotakis said.











Unearthed Graeco-Roman statues unveiled in Jerash
Credit: The Jordan Times

“An important member of the team was the Italian restoration expert, Franco Sciorilli, who spent 24 years working on different projects in Jordan and the region,” Weber-Karyotakis said, adding that although he is one of a few foreign experts, “after decades of work in Jordan, he feels like a real Jordanian”.


Authors: Saeb Rawashdeh & Ahmed Bani Mustafa | Source: The Jordan Times [November 02, 2018]



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Archaeologists probe the secrets of Sardis

Sardis, a two-millennia-old site in Turkey’s western province of Manisa, stands alone as one of the most prestigious and oldest archaeological excavations in the world, the Harvard Gazette said.











Archaeologists probe the secrets of Sardis
Scholars digging at Sardis, the capital of ancient Lydia later occupied by Greeks and Romans.
Sardis, in modern Turkey, was the fabled home of King Croesus, the richest man of his day,
according to lore [Credit: Archaeological Exploration of Sardis/Harvard University]

Sardis was the capital of the ancient kingdom of Lydia, one of the important cities of the Persian Empire, the seat of a proconsul under the Roman Empire, and the metropolis of the province Lydia in later Roman and Byzantine times.
The first large-scale scientific exploration of Sardis began in 1910 under the direction of Professor Howard Crosby Butler of Princeton with a staff of 300, Harvard Gazette said. However, the initial excavation stopped due to World War I and Butler died in 1922.




Excavations restarted when George M.A. Hanfmann, professor of archaeology at Harvard, arrived the site in 1958.
“Sardis combines a little bit of everything, or rather a lot of everything,” said Nicholas Cahill, field director of the Sardis expedition. “From monumental Roman arches, temples, and sculptures to religious transformations, from paganism to monotheism, Greek, and Latin inscriptions,” he said.




The new discoveries on the site continues to expand the knowledge of Sardis and its role in ancient times, said Cahill. The hard work of excavation have led to new directions and revealed even older material than previously known, he said.
“The work is not always glamorous or exciting,” said Cahill. “But it is always important.”


For more information visit the Sardis Expedition website.


Source: Ahval [November 03, 2018]



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Modern technology helping retrace ancient Czech roads

Czech scientists are using the latest technology to study the ancient roads of the Bohemian kingdom. Unlike Western Europe, the area of present-day Czechia was not colonized by the Romans, who developed a sophisticated network of paved routes or “via Romana”. This means the road system was developed without any earlier blueprints.











Modern technology helping retrace ancient Czech roads
Milestone by old Czech road [Credit: Vit Pohanka/Czech Radio]

Imagine a small village on a hill by a busy road. The name of the village is Strzanov and used to be Strazanov, from the Czech word strazit (in English to guard or to supervise). This fact led a local amateur 19th-century historian to conclude that the present-day road is simply a continuation of an ancient transport artery connecting Bohemia with Moravia.


The Libicka Road as it was called, is vaguely mentioned in one ancient chronicle. And the 19th-century amateur historian, from the nearby town of Zdar nad Sazavou, was sure that the local Cistercian Monastery was built here in the 13th century precisely because of the road.


But that was a rather hasty conclusion, says professional historian Miloslav Lopaur: “We have very little real evidence of archaeological nature as to where exactly the Libicka Road led. Historians in the 20th century concluded that the Zdar Monastery was more probably on a connection between the Libicka and Haberska roads. There is, however, no doubt that this major communication artery of the Bohemian kingdom passed somewhere in this area. It is just the exact passage that we cannot be quite sure about. There are several hypotheses, and it seems probable that the road changed its path as time went by and there could have been parallel sections. As the settlement was becoming denser here on the borderland of Bohemia and Moravia in the 12th and 13th centuries, the road could have led in two or even three directions.”


But there is not much more that we have known about most of the ancient Czech roads. Until recently, that is, with research in this field now gaining momentum.











Modern technology helping retrace ancient Czech roads
Laser scanner generated map of a bundle of trails [Credit: Centre for Transport Research]

The Czech Ministry of Culture finances the National and Cultural Identity program, which includes the project Moravian Crossroads. Experts from Palacky University, the Archaeological Centre and the Centre for Transport Research in Olomouc, eastern Czechia are cooperating in a unique way to find out more about the travels of our ancestors.
Jan Martinek is a researcher in geoinformatics and describes the way he and his colleagues work: “We try to project the old maps into modern relief or three-dimensional maps in relation to actual terrain and water streams and rivers. After assessing these projections, we designate polygons through which the historical roads most likely led and we send colleagues to do the actual field survey. When they can find some archaeological artefacts further confirming that there must have been some traffic in the Middle Ages we start an air survey. The plane is equipped with a laser scanner that creates a highly accurate terrain 3D map and that enables us to chart the ancient road in great detail. Or rather the bundles of paths that made up such a road.”


Yes, bundles. We usually see in historical films that people in the Middle Ages had roads similar to ours, only not so wide and paved. The picture we get with the help of laser scanners and 3D maps is different. The roads were more like bundles of many single paths. Rather than on a single road, people would travel in a sort of corridor that could be half a kilometre wide.











Modern technology helping retrace ancient Czech roads
Laser scanner generated map of a bundle of trails [Credit: Centre for Transport Research]

“That‘s the most common width of such a bundle. But they can further divide into two or three other bundles. It is not always easy to exactly pinpoint the main corridor of a historic road. It can be a kind of network of pathways crisscrossing each other, not just one clear line going in one direction. It is rather a system of trails in a corridor several hundred meters wide that usually converge into one point only occasionally.”


Jan Martinek explains that people in the Middle Ages naturally selected the easiest path depending on the time of year, the weather, what and how much they were carrying and whether they were on foot, on horseback or in a wagon.


This made sense: A person on a horse or on foot could often take shortcuts that were impassable for a wagon. Interestingly, most of the bundles of ancient roads already followed the general directions of today’s highways and motorways.


Doctor David Vich works for the Regional Museum of Vysoke Myto in Eastern Bohemia. For him as an archaeologist, modern technical gadgets mean completely new horizons: “The main road connecting Olomouc with Prague passed through our region. It was given the name Trstenicka Road by one of the historians in the 19th century. It is not a very good and certainly historically inaccurate title, but it has been used for so long that we continue to use it. Like in other cases, we were not able to say for sure where the road was. Now, thanks to modern technology, we are able to locate it much more precisely.”











Modern technology helping retrace ancient Czech roads
Cross by old Czech road [Credit: Vit Pohanka/Czech Radio]

This is all interesting and important for experts. But surveys by planes, laser scanners cost a lot of money and time. Is it worth it? Doctor David Vich: “The roads tell us something about the mobility of the society in those days, the way they travelled and where. Essentially, it informs us about the various cultural exchanges and influences that formed the society of our ancestors. It is not a complete picture but it is like an important piece of jigsaw puzzle that we put together with information that we know from the history of art, etc., etc.”


So ancient roads are now telling us more than just how our ancestors travelled and where. They are helping us to understand why they travelled and how that gradually transformed their lives.


Author: Vit Pohanka | Source: Radio Praha [November 03, 2018]



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Oldest evidence of dairying on the East Asian Steppe

Although dairy pastoralism once made Mongolian steppe herders successful enough to conquer most of Asia and Europe, the origins of this way of life on the East Asian steppe are still unclear. Now an international team of researchers led by the Max Planck Institute for the Science of Human History has uncovered evidence that dairying arrived in Mongolia as early as 1300 BC through a process of cultural transmission rather than population replacement or migration.











Oldest evidence of dairying on the East Asian Steppe
Many dairy livestock species, including cattle and yaks, were brought to Mongolia in prehistory
[Credit: Christina Warinner]

Two thousand years before the armies of Ghengis Khan, populations in Mongolia were already living a pastoralist, dairying lifestyle — similar to that which would enable future populations to conquer most of Asia and Europe. Although pastoralism has long been the primary means of subsistence on the East Asian steppe, the origins of this tradition have been unclear. Now, an international team of researchers has uncovered the earliest direct evidence to date of dairying in Mongolia — around 1300 BC — by tracking milk proteins preserved in tooth tartar.
The livestock that were milked — cattle, sheep and goats — are not native to the region and were likely introduced by Western Steppe herders. However, ancient DNA evidence from Bronze Age Mongolians indicates minimal genetic contributions from Western Steppe herders, suggesting that the livestock and dairying technologies were transferred by cultural processes rather than a major population migration, in contrast to the pattern seen in Europe. The findings are published in Proceedings of the National Academy of Sciences.


Cultural and technological transfer without population replacement


Researchers analyzed human remains from six sites in northern Mongolia associated with the Deer Stone-Khirigsuur Complex (DSKC). “The DSKC is well-known for their monumental architecture, including upright stones with deer and other motifs, and large stone mounds, often associated with one or more human burials,” explains co-first author Shevan Wilkin of the Max Planck Institute for the Science of Human History. “In some locations, these structures are highly conspicuous and visible from great distances.” The DSKC is the earliest culture associated archaeologically with pastoralism in Mongolia, with sites containing bones of sheep, goat, cattle and horse as early as the 13th century BC. However, to date no direct observations of dairy consumption had been made in this area.











Oldest evidence of dairying on the East Asian Steppe
Milk proteins preserved within tooth tartar have provided the earliest direct evidence
of dairy pastoralism in Mongolia [Credit: Christina Warinner]

The researchers conducted genome-wide analyses on 22 Bronze Age individuals, whose remains were radiocarbon dated to the late Bronze Age, ca. 1300-900 BC. Whole genome sequencing was further performed on two of these individuals. The results of these analyses showed that these Bronze Age Mongolians were genetically distinct from Western steppe herders of the same time period, indicating that the appearance of dairying in Mongolia was not the result of population migration and replacement.
“These findings suggest that neighbouring Western steppe herders directly or indirectly introduced dairy pastoralism to local indigenous populations primarily through a process of cultural exchange,” explains Choongwon Jeong, co-first and co-senior author, of the Max Planck Institute for the Science of Human History. “We don’t see evidence for the kind of large-scale population replacement by Western Steppe herders that has been observed in Bronze Age Europe or in the nearby Altai-Sayan region.”


Analysis of dental calculus shows clear evidence of dairy consumption


The researchers also analyzed the dental calculus of nine individuals using proteomics. Milk proteins were found in the calculus of seven individuals, confirming that dairy products were consumed as early as 1300 BC. Both whey and curd proteins were recovered, and could be identified as coming from sheep, goats and cattle. Interestingly, none of the individuals was lactase persistent — genetically capable of digesting the milk sugar lactose. Most Mongolians today are also not lactase persistent, despite consuming a large proportion of their diet as dairy products.











Oldest evidence of dairying on the East Asian Steppe
Late Bronze Age burial mounds known as khirigsuurs are associated with
early pastoralists in Mongolia [Credit: Bruno Frohlich]

“The 3,000-year legacy of dairy pastoralism in Mongolia poses challenging questions to grand narratives of human adaptation and natural selection,” explains Christina Warinner, senior author, of the Max Planck Institute for the Science of Human History. “As a non-lactase persistent dairying society with a rich prehistory, Mongolia can serve as a model for understanding how other adaptations, such as cultural practices or microbiome alterations, may be involved in enabling and maintaining dairy-based cuisines around the world.”


Source: Max Planck Society [November 05, 2018]



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ALMA and MUSE Detect Galactic Fountain





ALMA and MUSE Detect Galactic Fountain




Digitized Sky Survey image around Abell 2597




Abell 2597 in the Constellation of Aquarius





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ESOcast 182 Light: ALMA and MUSE Detect Galactic Fountain (4K UHD)


ESOcast 182 Light: ALMA and MUSE Detect Galactic Fountain (4K UHD)


Zooming in on a Galactic Fountain



Zooming in on a Galactic Fountain





Observations by ALMA and data from the MUSE spectrograph on ESO’s VLT have revealed a colossal fountain of molecular gas powered by a black hole in the brightest galaxy of the Abell 2597 cluster — the full galactic cycle of inflow and outflow powering this vast cosmic fountain has never before been observed in one system.


A mere one billion light-years away in the nearby galaxy cluster known as Abell 2597, there lies a gargantuan galactic fountain. A massive black hole at the heart of a distant galaxy has been observed pumping a vast spout of cold molecular gas into space, which then rains back onto the black hole as an intergalactic deluge .The in- and outflow of such a vast cosmic fountain has never before been observed in combination, and has its origin in the innermost 100 000 light-years of the brightest galaxy in the Abell 2597 cluster.


“This is possibly the first system in which we find clear evidence for both cold molecular gas inflow toward the black hole and outflow or uplift from the jets that the black hole launches,” explained Grant Tremblay of the Harvard-Smithsonian Center for Astrophysics and former ESO Fellow, who led this study. “The supermassive black hole at the centre of this giant galaxy acts like a mechanical pump in a fountain.”


Tremblay and his team used ALMA to track the position and motion of molecules of carbon monoxide within the nebula. These cold molecules, with temperatures as low as minus 250–260°C, were found to be falling inwards to the black hole. The team also used data from the MUSE instrument on ESO’s Very Large Telescope to track warmer gas — which is being launched out of the black hole in the form of jets.


“The unique aspect here is a very detailed coupled analysis of the source using data from ALMA and MUSE,” Tremblay explained. “The two facilities make for an incredibly powerful combination.”


Together these two sets of data form a complete picture of the process; cold gas falls towards the black hole, igniting the black hole and causing it to launch fast-moving jets of incandescent plasma into the void. These jets then spout from the black hole in a spectacular galactic fountain. With no hope of escaping the galaxy’s gravitational clutches, the plasma cools off, slows down, and eventually rains back down on the black hole, where the cycle begins anew.


This unprecedented observation could shed light on the life cycle of galaxies. The team speculates that this process may be not only common, but also essential to understanding galaxy formation. While the inflow and outflow of cold molecular gas have both previously been detected, this is the first time both have been detected within one system, and hence the first evidence that the two make up part of the same vast process.


Abell 2597 is found in the constellation Aquarius, and is named for its inclusion in the Abell catalogue of rich clusters of galaxies. The catalogue also includes such clusters as the Fornax cluster, the Hercules cluster, and Pandora’s cluster.




More information



This research was presented in a paper entitled “A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black Hole”, which appeared in The Astrophysical Journal.



The team was composed of G. R. Tremblay (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA; Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), F. Combes (LERMA, Observatoire de Paris, Sorbonne University, Paris, France), J. B. R. Oonk (ASTRON, Dwingeloo, the Netherlands; Leiden Observatory, the Netherlands), H. R. Russell (Institute of Astronomy, Cambridge University, UK), M. A. McDonald (Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, USA), M. Gaspari (Department of Astrophysical Sciences, Princeton University, USA), B. Husemann (Max-Planck-Institut für Astronomie, Heidelberg, Germany), P. E. J. Nulsen (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA; ICRAR, University of Western Australia, Crawley, Australia), B. R. McNamara (Physics & Astronomy Department, Waterloo University, Canada), S. L. Hamer (CRAL, Observatoire de Lyon, Université Lyon, France), C. P. O’Dea (Department of Physics & Astronomy, University of Manitoba, Winnipeg, Canada; School of Physics & Astronomy, Rochester Institute of Technology, USA), S. A. Baum (School of Physics & Astronomy, Rochester Institute of Technology, USA; Faculty of Science, University of Manitoba, Winnipeg, Canada), T. A. Davis (School of Physics & Astronomy, Cardiff University, UK), M. Donahue (Physics and Astronomy Department, Michigan State University, East Lansing, USA), G. M. Voit (Physics and Astronomy Department, Michigan State University, East Lansing, USA), A. C. Edge (Department of Physics, Durham University, UK), E. L. Blanton (Astronomy Department and Institute for Astrophysical Research, Boston University, USA), M. N. Bremer (H. W. Wills Physics Laboratory, University of Bristol, UK), E. Bulbul (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), T. E. Clarke (Naval Research Laboratory Remote Sensing Division, Washington, DC, USA), L. P. David (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), L. O. V. Edwards (Physics Department, California Polytechnic State University, San Luis Obispo, USA), D. Eggerman (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), A. C. Fabian (Institute of Astronomy, Cambridge University, UK), W. Forman (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), C. Jones (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), N. Kerman (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), R. P. Kraft (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), Y. Li (Center for Computational Astrophysics, Flatiron Institute, New York, USA; Department of Astronomy, University of Michigan, Ann Arbor, USA), M. Powell (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), S. W. Randall (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), P. Salomé (LERMA, Observatoire de Paris, Sorbonne University, Paris, France), A. Simionescu (Institute of Space and Astronautical Science [ISAS], Kanagawa, Japan), Y. Su (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), M. Sun (Department of Physics and Astronomy, University of Alabama in Huntsville, USA), C. M. Urry (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), A. N. Vantyghem (Physics & Astronomy Department, Waterloo University, Canada), B. J. Wilkes (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA) and J. A. ZuHone (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA).



ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.




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Contacts


Grant Tremblay

Harvard-Smithsonian Center for Astrophysics

Cambridge, USA

Tel: +1 207 504 4862



Francoise Combes

LERMA, Paris Observatory

Paris, France 



Calum Turner

ESO Public Information Officer

Garching bei München, Germany

Tel: +49 89 3200 6670



Source: ESO/News






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2018 November 6 NGC 1499: The California Nebula Image Credit…


2018 November 6


NGC 1499: The California Nebula
Image Credit & Copyright: Bray Falls


Explanation: There’s even a California in space. Drifting through the Orion Arm of the spiral Milky Way Galaxy, this cosmic cloud by chance echoes the outline of California on the west coast of the United States. Our own Sun also lies within the Milky Way’s Orion Arm, only about 1,500 light-years from the California Nebula. Also known as NGC 1499, the classic emission nebula is around 100 light-years long. On the featured image, the most prominent glow of the California Nebula is the red light characteristic of hydrogen atoms recombining with long lost electrons, stripped away (ionized) by energetic starlight. The star most likely providing the energetic starlight that ionizes much of the nebular gas is the bright, hot, bluish Xi Persei just to the right of the nebula. A regular target for astrophotographers, the California Nebula can be spotted with a wide-field telescope under a dark sky toward the constellation of Perseus, not far from the Pleiades.


∞ Source: apod.nasa.gov/apod/ap181106.html


On the spread of dairy pastoralism to East Asia (Jeong & Wilkin et al. 2018)

Over at PNAS at this LINK. Below is the abstract and a table with the uniparental haplogroups for the 20 ancient samples from the paper. Emphasis is mine.



Recent paleogenomic studies have shown that migrations of Western steppe herders (WSH) beginning in the Eneolithic (ca. 3300–2700 BCE) profoundly transformed the genes and cultures of Europe and central Asia. Compared with Europe, however, the eastern extent of this WSH expansion is not well defined. Here we present genomic and proteomic data from 22 directly dated Late Bronze Age burials putatively associated with early pastoralism in northern Mongolia (ca. 1380–975 BCE). Genome-wide analysis reveals that they are largely descended from a population represented by Early Bronze Age hunter-gatherers in the Baikal region, with only a limited contribution (∼7%) of WSH ancestry. At the same time, however, mass spectrometry analysis of dental calculus provides direct protein evidence of bovine, sheep, and goat milk consumption in seven of nine individuals. No individuals showed molecular evidence of lactase persistence, and only one individual exhibited evidence of >10% WSH ancestry, despite the presence of WSH populations in the nearby Altai-Sayan region for more than a millennium. Unlike the spread of Neolithic farming in Europe and the expansion of Bronze Age pastoralism on the Western steppe, our results indicate that ruminant dairy pastoralism was adopted on the Eastern steppe by local hunter-gatherers through a process of cultural transmission and minimal genetic exchange with outside groups.





Jeong & Wilkin et al., Bronze Age population dynamics and the rise of dairy pastoralism on the eastern Eurasian steppe, PNAS published ahead of print November 5, 2018 https://doi.org/10.1073/pnas.1813608115

Source


Laser battle that gave Europe our Aeolus wind-mapper


ESA – Aeolus Mission logo.


5 November 2018


It passes over at us at local dawn or dusk: among the most ambitious lasers ever flown in space, shining down to map Earth’s otherwise unknown global wind field. ESA’s Aeolus mission took more than two decades to reach this point. The laser was a key technology: in testing, the intensity of its beam was actually destroying the laser’s optical elements – the mission could not fly until this problem was fixed.



Aeolus in orbit

“Today Aeolus is returning more wind data than all ground-based measuring systems put together,” says Errico Armandillo, retired head of ESA’s Opto-electronics section. “But it took the sustained efforts of ESA labs and technical experts – in close cooperation with the Aeolus team – to make it fly.


“In the end we had to set up two new labs, call in additional DLR German Aerospace Center support and produce entire new technical standards, which are now being applied to all follow-on laser missions. The commercial space industry by itself could not have gone to the lengths we took.”



Lidar concept

At the heart of Aeolus – an ESA Earth Explorer mission that launched on 22 August – is the Atmospheric Laser Doppler Instrument, or Aladin. This is an ultraviolet lidar – ‘laser radar’ – whose 50 pulses per second are magnified by a 1.5-m-diameter telescope to shine through the entirety of the atmosphere from 320 km away in space.


Within three one-thousandths of a second, this same telescope then gathers up the resulting laser backscatter from aerosol droplets, water vapour and actual air molecules across different atmospheric layers. On the same basis as a police radar gun, this backscatter’s ‘Doppler shift’ is measured to derive wind velocities down to a few metres per second, taking a fresh sample every 200 km.



Aladin revealed

Making a laser this intense was not straightforward. When a prototype version of Aladin was run, its laser optics degraded by 50% in less than six hours of operations. This was bad news for a proposed three-year mission, but solving the problems created new technology to benefit a range of future missions.


Lining up laser technology


Attempts to understand and forecast the wind date back to Aristotle in the 4th century BC. Today, wind profiles sampled down through the atmosphere are an essential element of accurate medium- to long-term weather forecasting, as well a key input for modelling climate change.



Earth’s wind patterns

Previously, this information was simply not available: the best equivalent came from ground-based sensors, aircraft and balloon-based radiosondes giving localised point measurements, which were then extrapolated through cloud tracking or computer simulations. Aeolus in orbit changes that: for the first time in history, wind fields can be mapped globally, on a three-dimensional basis.


The idea of flying a wind-surveying lidar in orbit dated back to the early 1980s, considered at one time for the International Space Station. This lidar technology was later applied to spacecraft rendezvous and docking for ESA’s ISS-supplying ATV cargo spacecraft.



ESA laser testing

Following the 1989 recommendation of ESA’s space laser working group a high-energy carbon dioxide gas laser was developed, then demonstrated for aerial lidar. Later, in the mid 1990s, the development of spaceworthy laser-pumping diodes opened the way to a more compact solid-state version. The then ‘Aeolus Atmospheric Dynamics Mission’ was accordingly planned for a post-2000 flight.


“Aeolus’s Aladin runs on a synthetic crystal ‘ND: YAG’ laser, a common pulsed-laser ‘workhorse’,” explains ESA laser engineer Linda Mondin. “This crystal emits infrared laser light. A pair of what we call ‘non-linear crystals’ subsequently convert this first into the green region of the visible spectrum then to the shorter ultraviolet wavelength we require.”



Accelerated laser lifetime testing

Selecting high-energy ultraviolet was extremely ambitious, but essential to achieve a detectable level of backscatter from air molecules, along with lower-altitude aerosols and dust (it also prevented any eye damage risk from visible wavelengths). Ultraviolet is also the wavelength of greatest ‘Rayleigh scattering’ – the shifting of light by air that makes the sky blue.


So far, so good, recalls Errico: “We designed the UV laser to operate in vacuum, which simplified its thermomechanical design – considering we needed to maintain our lens alignment precisely. Except it was then our tears began.”


Laser light going out


The first inkling of trouble began with the early failure in orbit of NASA’s 2003-launched IceSAT, built around an ice-mapping lidar instrument. At the same time, Aladin ground testing hit parallel problems, dominated by laser-induced contamination.



Laser-induced contamination at nanometre scale

Organic contaminants from the Aladin laser equipment – akin to the fumes giving a new car its smell – were being carbonised by the UV laser, accumulating on its lenses. These growing deposits then absorbed the laser heat, distorting and eventually darkening the carefully crafted optics. ESA and wider European laser experts began to probe the phenomenon.


“The first solution was to take extreme precautions to remove all organics,” adds Errico. “But this did not prove entirely possible – even metal surfaces can act as a source. Even at just a few parts per billion of organics, contamination was still introduced.”



Laser-induced mirror coating damage

For clues the team reached out to terrestrial UV laser users, such as France’s Laser Mégajoule facility – employed to ignite nuclear fusion reactions – as well as the semiconductor industry.


“The answer?” says Linda. “Simply a pinch of air. Injecting a small amount of oxygen allows the contamination to burn up in the laser heat, cleaning the lens. In testing we saw this work in a matter of minutes.”


A breath of fresh air


Rather than redesigning Aladin to work on a fully pressurised basis, small wisps of oxygen are released from a pair of 30 litre tanks. This oxygen flows close to the optical surfaces that see the UV light, then gradually leaks out of the instrument enclosure.



Aeolus: ESA’s wind mission

“Just like us, the laser has to breathe,” adds Linda. “It’s very elegant because the burnt up contaminants flow out of the instrument along with this oxygen, in the form of carbon dioxide and water. We need roughly 25 Pascals of residual oxygen pressure – just one four-thousandth of standard atmospheric pressure.”


Contamination was only one of numerous challenges the instrument faced. The copious amounts of heat produced within the 30 litre volume of the laser transmitter demanded removal: this was done using ‘heat pipes’, which cool the laser by evaporating liquid and moving it to a space-facing radiator – analogous to human sweat glands. And Aladin’s electronics needed to operate on a steady, constant basis throughout their planned four billion laser shots.


“There were so many ways it could go wrong, we were worried,” adds Errico. “And then it worked! Those first wind profiles felt like Christmas coming early, a really amazing gift.”


Aladin’s development has given ESA its world-leading Optics and Opto-Electronics Labs, along with a set of ISO-certified laser development standards for other laser-based missions, starting with the EarthCARE mission for clouds and aerosol monitoring. These might also include further Aeolus satellites, favoured by the European Centre for Medium-Range Weather Forecasts, the mission’s main customer.



Winds imaged by Aeolus

“It’s proved an extremely complex mission, and we’ve learnt an awful lot about lasers,” concludes Linda. “Achieving success has really been a team effort, with the different ESA Directorates and industry rowing in the same direction against a really strong wind.”


“The fact we have a high-power UV laser instrument now working in space is testament to all of the hard work, ingenuity and inventiveness of many dedicated engineers both in industry, ESA and elsewhere,” comments Denny Wernham, Aeolus’s instrument manager.


“Within all this, the contribution of ESA’s Directorate of Technology, Engineering and Quality has been invaluable, setting up a dedicated laboratory to demonstrate the self-cleaning method we eventually utilised on the mission, and also proving the ability of Aladin’s optics to withstand its high-laser intensities for the mission lifetime.


“Aeolus is a world first mission that will hopefully lead to many active laser missions in the future and shows the true value of close collaboration between industry and ESA to find innovative solutions to very tough technical challenges.”


Related links:


1989 recommendation of ESA’s space laser working group: http://oa.upm.es/34897/1/Laser_sounding_from_space.pdf


Aeolus: http://www.esa.int/Our_Activities/Observing_the_Earth/Aeolus


ESA’s Optics and Opto-Electronics Laboratory: http://www.esa.int/Our_Activities/Space_Engineering_Technology/Space_Optics/About_Optics_Opto-Electronics_Laboratory_OOEL


Space Engineering & Technology: http://www.esa.int/Our_Activities/Space_Engineering_Technology


DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10002/


Images, Video, Text, Credits: ESA/Anneke Le Floc’h, CC BY-SA 3.0 IGO/ATG medialab/AOES Medialab/ECMWF.


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New Insights on Comet Tails Are Blowing in the Solar Wind



NASA – STEREO Mission logo / ESA & NASA – SOHO Mission patch.


Nov. 5, 2018


Engineers and scientists gathered around a screen in an operations room at the Naval Research Laboratory in Washington, D.C., eager to lay their eyes on the first data from NASA’s STEREO spacecraft. It was January 2007, and the twin STEREO satellites — short for Solar and Terrestrial Relations Observatory — which had launched just months before, were opening their instruments’ eyes for the first time. First up: STEREO-B. The screen blinked, but instead of the vast starfield they expected, a pearly white, feathery smear — like an angel’s wing — filled the frame. For a few panicky minutes, NRL astrophysicist Karl Battams worried something was wrong with the telescope. Then, he realized this bright object wasn’t a defect, but an apparition, and these were the first satellite images of Comet McNaught. Later that day, STEREO-A would return similar observations.


Comet C/2006 P1 — also known as Comet McNaught, named for astronomer Robert McNaught, who discovered it in August 2006 — was one of the brightest comets visible from Earth in the past 50 years. Throughout January 2007, the comet fanned across the Southern Hemisphere’s sky, so bright it was visible to the naked eye even during the day. McNaught belongs to a rarefied group of comets, dubbed the Great Comets and known for their exceptional brightness. Setting McNaught apart further still from its peers, however, was its highly structured tail, composed of many distinct dust bands called striae, or striations, that stretched more than 100 million miles behind the comet, longer than the distance between Earth and the Sun. One month later, in February 2007, an ESA (European Space Agency) and NASA spacecraft called Ulysses would encounter the comet’s long tail.


“McNaught was a huge deal when it came because it was so ridiculously bright and beautiful in the sky,” Battams said. “It had these striae — dusty fingers that extended across a huge expanse of the sky. Structurally, it’s one of the most beautiful comets we’ve seen for decades.”



Image above: Comet McNaught over the Pacific Ocean. Image taken from Paranal Observatory in January 2007. Image Credits: ESO/Sebastian Deiries.


How exactly the tail broke up in this manner, scientists didn’t know. It called to mind reports of another storied comet from long ago: the Great Comet of 1744, which was said to have dramatically fanned out in six tails over the horizon, a phenomenon astronomers then couldn’t explain. By untangling the mystery of McNaught’s tail, scientists hoped to learn something new about the nature of comets — and solve two cosmic mysteries in one.


A key difference between studying comets in 1744 and 2007 is, of course, our ability to do so from space. In addition to STEREO’s serendipitous sighting, another mission, ESA/NASA’s SOHO — the Solar and Heliospheric Observatory — made regular observations as McNaught flew by the Sun. Researchers hoped these images might contain their answers.


Now, years later, Oliver Price, a planetary science Ph.D. student at University College London’s Mullard Space Science Laboratory in the United Kingdom, has developed a new image-processing technique to mine through the wealth of data. Price’s findings — summarized in a recently published Icarus paper — offer the first observations of striations forming, and an unexpected revelation about the Sun’s effect on comet dust.





Image above: An illustration of the six-tailed Great Comet of 1744, observed before sunrise on March 9, 1744, from Les Comètes, by Amédée Guillemin. Image Credits: Paris Observatory.


Comets are cosmic crumbs of frozen gas, rock and dust left over from the formation of our solar system 4.6 billion years ago — and so they may contain important clues about our solar system’s early history. Those clues are unlocked, as if from a time capsule, every time a comet’s elliptical orbit brings it close to the Sun. Intense heat vaporizes the frozen gases and releases the dust within, which streams behind the comet, forming two distinct tails: an ion tail carried by the solar wind — the constant flow of charged particles from the Sun — and a dust tail.  


Understanding how dust behaves in the tail — how it fragments and clumps together — can teach scientists a great deal about similar processes that formed dust into asteroids, moons and even planets all those billions of years ago. Appearing as one of the biggest and most structurally complex comets in recent history, McNaught was a particularly good subject for this type of study. Its brightness and high dust production made it much easier to resolve the evolution of fine structures in its dust tail. 



Insights on Comet Tails Are Blowing in the Solar Wind

Video above: The first observations of striations forming have revealed new insights on the Sun’s effect on comet dust tails. Video Credits: NASA’s Goddard Space Flight Center/Genna Duberstein.


Price began his study focusing on something the scientists couldn’t explain. “My supervisor and I noticed weird goings-on in the images of these striations, a disruption in the otherwise clean lines,” he said. “I set out to investigate what might have happened to create this weird effect.”


The rift seemed to be located at the heliospheric current sheet, a boundary where the magnetic orientation, or polarity, of the electrified solar wind changes directions. This puzzled scientists because while they have long known a comet’s ion tail is affected by the solar wind, they had never seen the solar wind impact dust tails before.


Dust in McNaught’s tail — roughly the size of cigarette smoke — is too heavy, the scientists thought, for the solar wind to push around. On the other hand, an ion tail’s miniscule, electrically charged ions and electrons easily sail along the solar wind. But it was difficult to tell exactly what was going on with McNaught’s dust, and where, because at roughly 60 miles per second, the comet was rapidly traveling in and out of STEREO and SOHO’s view.


“We got really good data sets with this comet, but they were from different cameras on different spacecraft, which are all in different places,” Price said. “I was looking for a way to bring it all together to get a complete picture of what’s happening in the tail.”


His solution was a novel image-processing technique that compiles all the data from different spacecraft using a simulation of the tail, where the location of each tiny speck of dust is mapped by solar conditions and physical characteristics like its size and age, or how long it’d been since it’d flown off the head, or coma, of the comet. The end result is what Price dubbed a temporal map, which layers information from all the images taken at any given moment, allowing him to follow the dust’s movements.


The temporal maps meant Price could watch the striations form over time. His videos, which cover the span of two weeks, are the first to track the formation and evolution of these structures, showing how dust fragments topple off the comet head and collapse into long striations. 



Image above: The Sun’s magnetic field, which is embedded in the solar wind, permeates the entire solar system. The current sheet — where the magnetic field changes polarity —spirals out from near the solar equator like a wavy skirt around a ballet dancer’s waist. Image Credits: NASA’s Goddard Space Flight Center.


But the researchers were most excited to find that Price’s maps made it easier to explain the strange effect that drew their attention to the data in the first place. Indeed, the current sheet was the culprit behind the disruptions in the dust tail, breaking up each striation’s smooth, distinct lines. For the two days it took the full length of the comet to traverse the current sheet, whenever dust encountered the changing magnetic conditions there, it was jolted out of position, as if crossing some cosmic speed bump.


“It’s like the striation’s feathers are ruffled when it crosses the current sheet,” University College London planetary scientist Geraint Jones said. “If you picture a wing with lots of feathers, as the wing crosses the sheet, lighter ends of the feathers get bent out of shape. For us, this is strong evidence that the dust is electrically charged, and that the solar wind is affecting the motion of that dust.”


Scientists have long known the solar wind affects charged dust; missions like Galileo, Cassini and Ulysses watched it move electrically charged dust through the space near Jupiter and Saturn. But it was a surprise for them to see the solar wind affect larger dust grains like those in McNaught’s tail — about 100 times bigger than the dust seen ejected from around Jupiter and Saturn — because they’re that much heavier for the solar wind to push around.


With this study, scientists gain new insights into long-held mysteries. The work sheds light on the nature of striated comet tails from the past and provides a crucial lens for studying other comets in the future. But it also opens a new line of questioning: What role did the Sun have in our solar system’s formation and early history?


“Now that we see the solar wind changed the position of dust grains in McNaught’s tail, we can ask: Could it have been the case that early on in the solar system’s history, the solar wind played a role in organizing ancient dust as well?” Jones said.


Related:


A Solar Windsock Observed by NASA’s STEREO: https://www.nasa.gov/feature/goddard/comet-encke-a-solar-windsock-observed-by-nasa-s-stereo


STEREO (Solar TErrestrial RElations Observatory): http://www.nasa.gov/mission_pages/stereo/main/index.html


SOHO (Solar and Heliospheric Observatory): http://www.nasa.gov/mission_pages/soho/index.html


Images (mentioned), Video (mentioned), Text, Credits: NASA/Rob Garner/GSFC, by Lina Tran.


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HiPOD (5 November 2018): Layered Features in Brain Terrain in…



HiPOD (5 November 2018): Layered Features in Brain Terrain in Arabia Terra


   – The objective of this observation is to determine the nature of a group of light-toned, layered structures in a vast field of brain terrain. (300 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


The Mars InSight Landing Site Is Just Plain Perfect


NASA – InSight Mission logo.


Nov. 5, 2018


No doubt about it, NASA explores some of the most awe-inspiring locations in our solar system and beyond. Once seen, who can forget the majesty of astronaut Jim Irwin standing before the stark beauty of the Moon’s Hadley Apennine mountain range, of the Hubble Space Telescope’s gorgeous “Pillars of Creation” or Cassini’s magnificent mosaic of Saturn?


Mars also plays a part in this visually compelling equation, with the high-definition imagery from the Curiosity rover of the ridges and rounded buttes at the base of Mount Sharp bringing to mind the majesty of the American Southwest. That said, Elysium Planitia – the site chosen for the Nov. 26 landing of NASA’s InSight mission to Mars – will more than likely never be mentioned with those above because it is, well, plain.



Image above: This artist’s concept depicts the smooth, flat ground that dominates InSight’s landing ellipse in the Elysium Planitia region of Mars. Image Credits: NASA/JPL-Caltech.


“If Elysium Planitia were a salad, it would consist of romaine lettuce and kale – no dressing,” said InSight principal investigator Bruce Banerdt at NASA’s Jet Propulsion Laboratory in Pasadena, California. “If it were an ice cream, it would be vanilla.”


Yes, the landing site of NASA’s next Mars mission may very well look like a stadium parking lot, but that is the way the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) project likes it.


“Previous missions to the Red Planet have investigated its surface by studying its canyons, volcanoes, rocks and soil,” said Banerdt. “But the signatures of the planet’s formation processes can be found only by sensing and studying evidence buried far below the surface. It is InSight’s job to study the deep interior of Mars, taking the planet’s vital signs – its pulse, temperature and reflexes.”


Taking those vital signs will help the InSight science team look back to a time when the rocky planets of the solar system formed. The investigations will depend on three instruments:


A six-sensor seismometer called the Seismic Experiment for Interior Structure (SEIS) will record seismic waves traveling through the interior structure of the planet. Studying seismic waves will tell scientists what might be creating the waves. (On Mars, scientists suspect that the culprits may be marsquakes or meteorites striking the surface.)


The mission’s Heat Flow and Physical Properties Package (HP3) will burrow deeper than any other scoop, drill or probe on Mars before to gauge how much heat is flowing out of the planet. Its observations will shed light on whether Earth and Mars are made of the same stuff.


Finally, InSight’s Rotation and Interior Structure Experiment (RISE) experiment will use the lander’s radios to assess the wobble of Mars’ rotation axis, providing information about the planet’s core.


For InSight to do its work, the team needed a landing site that checked off several boxes, because as a three-legged lander – not a rover – InSight will remain wherever it touches down.



Image above: The landing site for InSight, in relation to landing sites for seven previous missions, is shown on a topographic map of Mars. Image Credits: NASA/JPL-Caltech.


“Picking a good landing site on Mars is a lot like picking a good home: It’s all about location, location, location,” said Tom Hoffman, InSight project manager at JPL. “And for the first time ever, the evaluation for a Mars landing site had to consider what lay below the surface of Mars. We needed not just a safe place to land, but also a workspace that’s penetrable by our 16-foot-long (5-meter) heat-flow probe.”


The site also needs to be bright enough and warm enough to power the solar cells while keeping its electronics within temperature limits for an entire Martian year (26 Earth months).


So the team focused on a band around the equator, where the lander’s solar array would have adequate sunlight to power its systems year-round. Finding an area that would be safe enough for InSight to land and then deploy its solar panels and instruments without obstructions took a little longer.


“The site has to be a low-enough elevation to have sufficient atmosphere above it for a safe landing, because the spacecraft will rely first on atmospheric friction with its heat shield and then on a parachute digging into Mars’ tenuous atmosphere for a large portion of its deceleration,” said Hoffman. “And after the chute has fallen away and the braking rockets have kicked in for final descent, there needs to be a flat expanse to land on – not too undulating and relatively free of rocks that could tip the tri-legged Mars lander.”


Of 22 sites considered, only Elysium Planitia, Isidis Planitia and Valles Marineris met the basic engineering constraints. To grade the three remaining contenders, reconnaissance images from NASA’s Mars orbiters were scoured and weather records searched. Eventually, Isidis Planitia and Valles Marineris were ruled out for being too rocky and windy.


That left the 81-mile long, 17-mile-wide (130-kilometer-long, 27-kilometer-wide) landing ellipse on the western edge of a flat, smooth expanse of lava plain.


“If you were a Martian coming to explore Earth’s interior like we are exploring Mars’ interior, it wouldn’t matter if you put down in the middle of Kansas or the beaches of Oahu,” said Banerdt. “While I’m looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads. The beauty of this mission is happening below the surface. Elysium Planitia is perfect.”



Image above: This map shows the single area under continuing evaluation as the InSight mission’s Mars landing site, as of a year before the mission’s May 2016 launch. The finalist ellipse marked is within the northern portion of flat-lying Elysium Planitia about four degrees north of Mars’ equator. Image Credits: NASA/JPL-Caltech.


After a 205-day journey that began on May 5, NASA’s InSight mission will touch down on Mars on Nov. 26 a little before 3 p.m. EST (12 p.m. PST). Its solar panels will unfurl within a few hours of touchdown. Mission engineers and scientists will take their time assessing their “workspace” prior to deploying SEIS and HP3 on the surface – about three months after landing – and begin the science in earnest.


InSight was the 12th selection in NASA’s series of Discovery-class missions. Created in 1992, the Discovery Program sponsors frequent, cost-capped solar system exploration missions with highly focused scientific goals.


JPL manages InSight for NASA’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.


A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), support the InSight mission. CNES provided the SEIS instrument, with significant contributions from the Max Planck Institute for Solar System Research (MPS) in Germany, the Swiss Institute of Technology (ETH) in Switzerland, Imperial College and Oxford University in the United Kingdom, and JPL. DLR provided the HP3 instrument.


Related article:


Five Things to Know About InSight’s Mars Landing:
https://orbiterchspacenews.blogspot.com/2018/10/five-things-to-know-about-insights-mars.html


For more information about InSight, visit: https://mars.nasa.gov/insight/


For more information about NASA’s Mars missions, go to: https://mars.nasa.gov


Images (mentioned), Text, Credits: NASA/Dwayne Brown/JoAnna Wendel/Tony Greicius/JPL/DC Agle.


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