Underwater ‘snow’ could be growing on Jupiter’s moon Europa Shri Radhe

 A study of Antarctic ice shelves suggests that the ice shell covering Jupiter’s moon Europa could contain a significant amount of underwater “snow”. This could have important implications for NASA’s upcoming Europa Clipper mission, which aims to use ground penetrating radar to study the ice shell and the ocean beneath.

The research was done by a team in the US led by Natalie Wolfenbarger at the University of Texas at Austin and focused on two processes by which Antarctic ice shelves grow from the bottom. The study also has implications for our understanding of whether life emerged in Europa’s ocean, which is encased in an ice shell some 15–25 km thick.

By examining the dynamic features that appear on the surface of Europa’s ice shell, scientists have found compelling evidence that the ocean beneath is constantly interacting with its ice shell. So far, however, the lower layers of this shell have proven more difficult to study.

Two mechanisms

To learn more about the processes which may be unfolding beneath Europa’s surface, Wolfenbarger and colleagues drew parallels with oceanic ice on our own planet. In Earth’s polar regions, ice shelves grow from the bottom through two possible mechanisms. One is congelation, whereby ice freezes at the interface between the ice and the water directly beneath it. The second mechanism involves the creation of frazil ice, which forms as millimetre-sized, randomly shaped crystals within columns of supercooled water. These columns are prevented from freezing more completely by turbulent currents. Under buoyant forces, these crystals travel upwards to rest on the underside of the ice, where they resemble underwater snow.

The researchers compared the contributions of each mechanism to ice formation by examining a variety of ice cores collected from ice shelves in Antarctica. They say that this environment is a close analogue to the temperature, pressure, and salinity of Europa’s ice sheet. Some of these samples were collected from features like rifts and glacier tongues, where the ice is thinner. Others were gathered from ancient ice shelves, which can reach several kilometres in thickness.

Their analysis revealed that congelation dominated the gradual thickening of older ice. On Europa, this process would be driven by the gradual cooling of the moon’s solid interior. In contrast, frazil ice is most likely to accumulate where the ice thins – either in small-scale rifts and fractures, or in warmer regions, often found at lower latitudes. On Europa, large sections of the ice shell are also warmed and thinned out through tidal heating, which is generated by Jupiter’s gravitational pull.

Low salinity

The team also found that these mechanisms create sea ice with very different salinities. While frazil ice retained just around 0.1% of the salinity of water from which it formed, congelation ice had a salt content of around 10% of the local water. Salinity strongly affects a variety of important properties of sea ice: including its strength, heat conduction, and its mechanical responses to ocean currents beneath..

Shri Radhe

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Want to be highly cited? Work with collaborators across multiple research fields, study finds Shri Radhe

Researchers who repeatedly collaborate with other scientists across multiple research disciplines produce papers that are more highly cited. That’s according to an analysis of more than 3000 scientists who publish in physical-science journals. But scientists who prefer to stick to single research topics tend, on average, to produce more papers than their peers (Proc. Natl Acad. Sci..

Carried out by a team led by Shlomo Havlin, a physicist at Bar-Ilan University in Israel, the study identified 3420 scientists who had published at least 50 papers in American Physical Society (APS) journals. For each of these “focal” scientists, the team picked out collaborators in the APS dataset who had co-authored at least two papers with them..

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Want to be highly cited? Work with collaborators across multiple research fields, study finds

24 Aug 2022

two people talking at a table

Getting together: Scientists with high citation rates are more likely to collaborate with peers who have many publications and high citations per paper (Courtesy: iStock/Weekend Images Inc).

Researchers who repeatedly collaborate with other scientists across multiple research disciplines produce papers that are more highly cited. That’s according to an analysis of more than 3000 scientists who publish in physical-science journals. But scientists who prefer to stick to single research topics tend, on average, to produce more papers than their peers (Proc. Natl Acad. Sci. 119 e2207436119).

Carried out by a team led by Shlomo Havlin, a physicist at Bar-Ilan University in Israel, the study identified 3420 scientists who had published at least 50 papers in American Physical Society (APS) journals. For each of these “focal” scientists, the team picked out collaborators in the APS dataset who had co-authored at least two papers with them.

When the researchers examined the topics covered by the collaboration networks, they discovered that scientists work with collaborators on a relatively limited number of different fields. On average, 63% of a scientist’s collaborators work with them on just a single research topic. A quarter of collaborations cover two research topics, while only 12% span three or more topics.

The team also examined how successful scientists work with their collaborators. Two metrics of success were used: productivity (measured by the total number of publications) and impact (average number of citations with two seconds...

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Want to be highly cited? Work with collaborators across multiple research fields, study finds

24 Aug 2022

two people talking at a table

Getting together: Scientists with high citation rates are more likely to collaborate with peers who have many publications and high citations per paper (Courtesy: iStock/Weekend Images Inc).

Researchers who repeatedly collaborate with other scientists across multiple research disciplines produce papers that are more highly cited. That’s according to an analysis of more than 3000 scientists who publish in physical-science journals. But scientists who prefer to stick to single research topics tend, on average, to produce more papers than their peers (Proc. Natl Acad. Sci. 119 e2207436119).

Carried out by a team led by Shlomo Havlin, a physicist at Bar-Ilan University in Israel, the study identified 3420 scientists who had published at least 50 papers in American Physical Society (APS) journals. For each of these “focal” scientists, the team picked out collaborators in the APS dataset who had co-authored at least two papers with them.

When the researchers examined the topics covered by the collaboration networks, they discovered that scientists work with collaborators on a relatively limited number of different fields. On average, 63% of a scientist’s collaborators work with them on just a single research topic. A quarter of collaborations cover two research topics, while only 12% span three or more topics.

The team also examined how successful scientists work with their collaborators. Two metrics of success were used: productivity (measured by the total number of publications) and impact (average number of citations per paper).

It turns out that the most productive scientists have a high proportion of single-topic collaborators, but only an average citation impact. Researchers with the highest impact, on the other hand, have more collaborators who they work with on multiple topics, yet are only as productive as the average scientist.

Keeping a balance

The study’s authors suggest that impactful scientists lean towards collaborators sharing similar research interests, while those who publish more papers select collaborators who specialize in a particular topic. Compared with more productive scientists, those researchers with high citation rates are more likely to collaborate with peers with many publications and high citations per paper.

Underwater ‘snow’ could be growing on Jupiter’s moon Europa Shri Radhe

Chilly worlds: mounds of snow-like frazil ice under the Antarctic ice shelf. According to this latest research, Europa’s ice shell could be made of the same stuff. (Courtesy: copyright Helen Glazer 2015/from the project "Walking in Antarctica".

A study of Antarctic ice shelves suggests that the ice shell covering Jupiter’s moon Europa could contain a significant amount of underwater “snow”. This could have important implications for NASA’s upcoming Europa Clipper mission, which aims to use ground penetrating radar to study the ice shell and the ocean beneath.

The research was done by a team in the US led by Natalie Wolfenbarger at the University of Texas at Austin and focused on two processes by which Antarctic ice shelves grow from the bottom. The study also has implications for our understanding of whether life emerged in Europa’s ocean, which is encased in an ice shell some 15–25 km thick.

By examining the dynamic features that appear on the surface of Europa’s ice shell, scientists have found compelling evidence that the ocean beneath is constantly interacting with its ice shell. So far, however, the lower layers of this shell have proven more difficult to study.

Two mechanisms

To learn more about the processes which may be unfolding beneath Europa’s surface, Wolfenbarger and colleagues drew parallels with oceanic ice on our own planet. In Earth’s polar regions, ice shelves grow from the bottom through two possible mechanisms. One is congelation, whereby ice freezes at the interface between the ice and the water directly beneath it. The second mechanism involves the creation of frazil ice, which forms as millimetre-sized, randomly shaped crystals within columns of supercooled water. These columns are prevented from freezing more completely by turbulent currents. Under buoyant forces, these crystals travel upwards to rest on the underside of the ice, where they resemble underwater snow.

The researchers compared the contributions of each mechanism to ice formation by examining a variety of ice cores collected from ice shelves in Antarctica. They say that this environment is a close analogue to the temperature, pressure, and salinity of Europa’s ice sheet. Some of these samples were collected from features like rifts and glacier tongues, where the ice is thinner. Others were gathered from ancient ice shelves, which can reach several kilometres in thickness.

Their analysis revealed that congelation dominated the gradual thickening of older ice. On Europa, this process would be driven by the gradual cooling of the moon’s solid interior. In contrast, frazil ice is most likely to accumulate where the ice thins – either in small-scale rifts and fractures, or in warmer regions, often found at lower latitudes. On Europa, large sections of the ice shell are also warmed and thinned out through tidal heating, which is generated by Jupiter’s gravitational pull.

Low salinity

The team also found that these mechanisms create sea ice with very different salinities. While frazil ice retained just around 0.1% of the salinity of water from which it formed, congelation ice had a salt content of around 10% of the local water. Salinity strongly affects a variety of important properties of sea ice: including its strength, heat conduction, and its mechanical responses to ocean currents beneath.

Madam President: On Droupadi Murmu’s election as India’s 15th President Shri Radhe Shri Radhe..

The election of Droupadi Murmu as India’s 15th President is rich in symbolism. In the 75th year of the country’s Independence, Ms. Murmu becomes the second woman to occupy the Rashtrapati Bhavan, and the first member of a tribal community to do so. Her membership of the Santhal tribe is in focus. She has risen through the ranks in the Bharatiya Janata Party (BJP), and has shown a mind of her own during her stint as Governor of Jharkhand. Her election to the highest office of the country comes 101 years after two tribespeople were elected to legislative bodies in colonial India. Founding figures of the Republic were acutely cognisant of the disadvantageous position of the tribespeople and made special provisions such as the Fifth and Sixth Schedules of the Constitution. Jaipal Singh Munda, sportsman and tribal leader, was a prominent member of the Constituent Assembly who forcefully articulated the fears and hopes of tribespeople. In 2000, two States, Jharkhand and Chhattisgarh, were formed to give more focused attention to the concentrated tribal population in these regions. The Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, was passed in 2006. Ms. Murmu’s election is a milestone in the journey of tribal empowerment, though she is by no means limited to her identity. It is a moment of pride for India......

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