3D images show what lies beneath Mars poles

January 4, 2017

Washington, Jan 4: Scientists using data from a NASA probe have unveiled 3D subsurface images of Mars polar ice caps, showing previously obscured layering, larger volume of frozen carbon dioxide and bowl-shaped features that may be buried impact craters.mars

The information will help scientists better understand Martian climate changes and may allow them to determine the age of the polar caps without using climate models.

The 3D data volumes were assembled from observations by the Shallow Radar (SHARAD) onboard NASA's Mars Reconnaissance Orbiter (MRO) during more than 2000 orbit passes over each Martian pole.

"We have applied industry-developed techniques in a very novel fashion to a martian dataset, producing 3D volumes that are each over 600 times larger than any terrestrial or planetary dataset of this kind," said Nathaniel E Putzig, a senior scientist at the Planetary Science Institute in the US.

"It is gratifying to see so plainly in the SHARAD volumes structures that took years of effort to characterise with the single-orbit profiles," Putzig said.

Layering seen at the surface of the martian polar caps has been studied for decades. It has long been thought to represent a record of climate changes on that planet.

The interior structures of the caps remained a mystery until the arrival of radar sounders at Mars in the last decade.

An early version of the north polar 3D volume helped to assess the quantity of water ice transferred to the polar caps in the most recent retreat from a martian ice age.

First looks at the south polar 3D volume indicate that previously mapped deposits of carbon dioxide ice are somewhat larger than reported.

In both polar 3D volumes, known impact craters in and near the polar caps that are partially filled with ice have distinctive bowl-shaped signatures in the radar data, and similar signatures are found elsewhere within the polar ices but without any surface expression.

Whether the latter structures truly are impact craters remains to be determined.
Age estimates of planetary surfaces throughout the solar system rely on statistical data for impact craters on the Moon's surface calibrated to radiometrically dated samples returned during the Apollo programme.

This method has been used to estimate the surface ages of the martian polar caps, but estimates for the ages of the caps themselves have had to rely on numerical models of past climate changes.

If a sufficient number of the bowl-shaped features found in the radar volumes are shown to be impact craters, scientists will be able to assess the age of the polar caps using cratering statistics alone.

The extent to which age estimates from this new volumetric method agree or disagree with those from climate models will have important implications for the accuracy of these dating techniques.

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Agencies
May 14,2020

Social media platform WhatsApp assured the Supreme Court on Wednesday that it will not roll out its payment services without complying with all payment regulations and norms in the country.

A bench headed by Chief Justice S.A. Bobde and comprising Justices Indu Malhotra and Hrishikesh Roy took up the matter through video conferencing. Senior advocate Kapil Sibal, representing the social media platform, said "WhatsApp Inc makes a statement on behalf of his client that they will not go ahead with the payments' scheme without complying with all the regulations in force."

The statement was made during the hearing of a petition seeking a ban on payment through WhatsApp, as it does not conform to the data localization norms. The top court took the assurance made by WhatsApp on record.

WhatsApp made the statement during the hearing of a plea seeking a ban on its payment service, for not being in line with data localization norms.

In 2018, WhatsApp was granted a beta licence to launch its payment service, but a dedicated and separate app is yet to be launched. A petition was moved in the apex court that WhatsApp's existing model for its payments service should be declared inconsistent with the Unified Payment Interface (UPI) Scheme, as a separate dedicated app has not been offered by the company.

The petitioner NGO, Good Governance Chambers, argued that the National Payments Corporation of India (NPCI) and the Reserve Bank of India (RBI) must change its model on the lines of the UPI payment scheme, and its operations may be suspended until these conditions are met.

The apex court today asked the Centre, Facebook and WhatsApp to file their replies within three weeks and it will take up the matter thereafter. The court noted that the government may process the applications filed by WhatsApp in accordance with the law and there is no stay on the same. Facebook was represented by senior advocate Arvind Datar.

The petitioner argued that lapses have been found in relation to WhatsApp's claims of having a secure and safe technological interface for securing sensitive user data.

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Agencies
June 27,2020

Mumbai, Jun 27: The Bombay High Court observed that COVID-19 patients from poor and indigent sections cannot be expected to produce documentary proof to avail subsidised or free treatment while getting admitted to hospitals.

The court on Friday was hearing a plea filed by seven residents of a slum rehabilitation building in Bandra, who had been charged ₹ 12.5 lakh by K J Somaiya Hospital for COVID-19 treatment between April 11 and April 28.

The bench of Justices Ramesh Dhanuka and Madhav Jamdar directed the hospital to deposit ₹10 lakh in the court.

The petitioners had borrowed money and managed to pay ₹10 lakh out of ₹12.5 lakh that the hospital had demanded, after threatening to halt their discharge if they failed to clear the bill, counsel Vivek Shukla informed the court.

According to the plea, the petitioners were also overcharged for PPE kits and unused services.

On June 13, the court had directed the state charity commissioner to probe if the hospital had reserved 20% beds for poor and indigent patients and provided free or subsidised treatment to them.

Last week, the joint charity commissioner had informed the court that although the hospital had reserved such beds, it had treated only three poor or indigent persons since the lockdown.

It was unfathomable that the hospital that claimed to have reserved 90 beds for poor and indigent patients had treated only three such persons during the pandemic, advocate Shukla said.

He further argued that COVID-19 patients, who are in distress, cannot be expected to produce income certificate and such documents as proof.

However, senior advocate Janak Dwarkadas, who represented the hospital, said the petitioners did not belong to economically weak or indigent categories and had not produced documents to prove the same.

A person who is suffering from a disease like COVID-19 cannot be expected to produce certificates from a tehsildar or social welfare officer before seeking admission in the hospital, the bench noted and asked the hospital to deposit ₹10 lakh in court within two weeks.

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Agencies
July 2,2020

Leiden, Jul 2: Astronomers have discovered a luminous galaxy caught in the act of reionizing its surrounding gas only 800 million years after the Big Bang.

The research, led by Romain Meyer, PhD student at UCL in London, UK, has been presented at the virtual annual meeting of the European Astronomical Society (EAS).

Studying the first galaxies that formed 13 billion years ago is essential to understanding our cosmic origins. One of the current hot topics in extragalactic astronomy is 'cosmic reionization,' the process in which the intergalactic gas was ionized (atoms stripped of their electrons).

Cosmic reionization is similar to an unsolved murder: We have clear evidence for it, but who did it, how and when? We now have strong evidence that hydrogen reionization was completed about 13 billion years ago, in the first billion years of the universe, with bubbles of ionized gas slowly growing and overlapping.

The objects capable of creating such ionized hydrogen bubbles have however remained mysterious until now: the discovery of a luminous galaxy in which 60-100 percent of ionizing photons escape, is likely responsible for ionizing its local bubble. This suggests the case is closer to being solved.

The two main suspects for cosmic reionization are usually 1) a population of numerous faint galaxies leaking ~10 percent of their energetic photons, and 2) an 'oligarchy' of luminous galaxies with a much larger percentage (>50 percent) of photons escaping each galaxy.

In either case, these first galaxies were very different from those today: galaxies in the local universe are very inefficient leakers, with only <2-3 percent of ionizing photons escaping their host. To understand which galaxies governed cosmic reionization, astronomers must measure the so-called escape fractions of galaxies in the reionization era.

The detection of light from excited hydrogen atoms (the so-called Lyman-alpha line) can be used to infer the fraction of escaping photons. On the one hand, such detections are rare because reionization-era galaxies are surrounded by neutral gas which absorbs that signature hydrogen emission.

On the other hand, if this hydrogen signal is detected it represents a 'smoking gun' for a large ionized bubble, meaning we have caught a galaxy reionizing its surroundings. The size of the bubble and the galaxy's luminosity determines whether it is solely responsible for creating this ionized bubble or if unseen accomplices are necessary.

The discovery of a luminous galaxy 800 million years after the Big Bang supports the scenario where an 'oligarchy' of bright leakers emits most of the ionizing photons.

"It is the first time we can point to an object responsible for creating an ionized bubble, without the need for a contribution from unseen galaxies.

Additional observations with the upcoming James Webb Space Telescope will enable us to study further what is likely one of the best suspects for the unsolved case of cosmic reionization," said Meyer.

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