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Groundwater depletion in India worst in world: NASA

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Washington: Groundwater is disappearing fast from the world and India is among the worst hit, shows data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites.3686365971_12107421e7_o

Among the world’s largest groundwater basins, the Indus Basin aquifer of India and Pakistan, which is a source of fresh water for millions of people, is the second-most overstressed with no natural replenishment to offset usage, said two new studies led by the University of California – Irvine (UCI), using data from GRACE satellites.

About a third of the Earth’s largest groundwater basins are being rapidly depleted by human consumption, the studies said.

Groundwater aquifers are typically located in soils or deeper rock layers beneath the Earth’s surface.

The most overburdened aquifers are in the world’s driest areas, where populations draw heavily on underground water. Climate change and population growth are expected to intensify the problem, the researchers warned.

“What happens when a highly stressed aquifer is located in a region with socioeconomic or political tensions that can’t supplement declining water supplies fast enough?” asked Alexandra Richey, the lead author on both studies, who conducted the research as a UCI doctoral student.

“We are trying to raise red flags now to pinpoint where active management today could protect future lives and livelihoods,” Richey said.

The Arabian Aquifer System, an important water source for more than 60 million people, is the most overstressed in the world, the findings showed.

The studies are the first to comprehensively characterise global groundwater losses with data from space, using readings generated by NASA’s twin GRACE satellites.

GRACE measures dips and bumps in the Earth’s gravity, which are affected by the mass of water.

In the first paper, researchers found that 13 of the planet’s 37 largest aquifers studied between 2003 and 2013 were being depleted while receiving little to no recharge.

Eight were classified as “overstressed”, with nearly no natural replenishment to offset usage.

Another five were found to be “extremely” or “highly” stressed, depending upon the level of replenishment in each.

Those aquifers were still being depleted but had some water flowing back into them.

“Given how quickly we are consuming the world’s groundwater reserves, we need a coordinated global effort to determine how much is left,” principal investigator Jay Famiglietti, who is also the senior water scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, said.

The findings appeared in the journal Water Resources Research. (IANS)

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NASA Probe Makes New Discoveries on Asteroid Bennu

As a result, Bennu's rotation period is decreasing by about a second every 100 years, the scientists explained

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Asteroid
This Nov. 16, 2018, image provide by NASA shows the asteroid Bennu. NASA

NASA’s first asteroid-sampling mission OSIRIS-REx has observed particle plumes erupting from the surface of Bennu, an asteroid the size of the pyramid at Giza.

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft, which began orbiting Bennu on December 31, first discovered the particle plumes on January 6, followed by additional particle plumes over the last two months.

While some of the particles were slow-moving, the others were found orbiting Bennu, like small satellites.

Bennu’s entire surface was also found to be rough and dense with boulders, contrary to the Earth-based observations, which showed a smooth surface with a few large boulders.

This means that the sample collection part of the mission will have to be adjusted to make sure that OSIRIS-REx can touch down and collect a sample, said NASA while presenting the discoveries at the 50th Lunar and Planetary Conference in Houston.

“The discovery of plumes is one of the biggest surprises of my scientific career,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

NASA
This artist’s rendering made available by NASA in July 2016 shows the mapping of the near-Earth asteroid Bennu by the OSIRIS-REx spacecraft. VOA

“And the rugged terrain went against all of our predictions. Bennu is already surprising us, and our exciting journey there is just getting started,” Lauretta added.

Further, the team observed a change in the spin rate of Bennu as a result of what is known as the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect.

The uneven heating and cooling of Bennu as it rotates in sunlight is causing the asteroid to increase its rotation speed.

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As a result, Bennu’s rotation period is decreasing by about a second every 100 years, the scientists explained.

OSIRIS-REx launched in 2016 to explore Bennu, the smallest body ever orbited by spacecraft, is expected to return a sample of the asteroid to Earth in 2023.

The findings will allow researchers to learn more about the origins of our solar system, the sources of water and organic molecules on Earth, the resources in near-Earth space, as well as improve our understanding of asteroids that could impact Earth. (IANS)