Thursday March 21, 2019

Vision deterioration in astronauts likely owing to lack of a day-night cycle in intracranial pressure: Scientists

Vision deterioration in astronauts is likely owing to the lack of a day-night cycle in intracranial pressure, say scientists

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Mars plans to send a manned mission to mars by 2030, Pixabay

New York, Jan 19, 2017: Vision deterioration in astronauts is likely owing to the lack of a day-night cycle in intracranial pressure, say scientists, adding that using a vacuum device to lower pressure for part of each day might prevent the problem.

To study how zero-gravity conditions affect intracranial pressure, researchers from University of Texas Southwestern Medical Centre recruited volunteer patients who had had a port permanently placed in their head as part of treatment for cancer.

The ports provided a way for researchers to measure intracranial pressure.

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NASA flights then flew the eight volunteers one by one on steep up-and-down maneuvers (parabolic flights) that created 20-second intervals of weightlessness.

The researchers measured intracranial pressure during the zero-gravity intervals and compared these with intracranial pressure during standard times of sitting, lying face upward (supine), and lying with head inclined downward.

The findings showed that intracranial pressure in zero-gravity conditions, such as exists in space, is higher than when people are standing or sitting on Earth, but lower than when people are sleeping on Earth.

“These challenging experiments were among the most ambitious human studies ever attempted and changed the way we think about the effect of gravity – and its absence – on pressure inside the brain,” said senior author Dr Benjamin Levine, Professor of Internal Medicine.

It suggests that the constancy of pressure on the back of the eye causes the vision problems astronauts experience over time.

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“The information from these studies is already leading to novel partnerships with companies to develop tools to simulate the upright posture in space while astronauts sleep, thereby normalising the circadian variability in intracranial pressure,” added Dr Levine.

“The idea is that the astronauts would wear negative pressure clothing or a negative pressure device while they sleep, creating lower intracranial pressure for part of each 24 hours,” noted first author Dr Justin Lawley in a paper appeared in the Journal of Physiology. (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)