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NASA probe flies past Pluto, world awaits historic images

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Applause by Nasa New Horizons team as countdown to the Pluto flyby ends. Picture sent on twitter by Nasa
Picture sent on twitter by NASA

Washington, In what may necessitate rewriting of science books, NASA’s New Horizons probe — after travelling over 4.8 billion km — on Tuesday flew past the mysterious dwarf planet Pluto on the outermost fringes of the solar system.

Flying past Pluto at a distance of about 12,500 km at around 5 p.m. (Indian standard Time), the probe, launched a decade ago, was expected to beam back key images of Pluto’s surface to Earth in about nine hours — the time it takes the communication to reach Earth from Pluto.

The images will also help scientists explore the mysterious Kuiper Belt — a huge band of planetary debris left over from the solar system’s formation 4.5 billion years ago.

The most dangerous hazards for the probe — flying at a speed of 45,000 km per hour — were dust particles trapped in orbit around Pluto and a strike can cripple the spacecraft, scientists said, but added that such a risk was very low.

The first images will debut on Facebook-owned photo-sharing website Instagram, NASA has announced.

“We made an editorial decision to give the world a sneak peek of the image on Instagram,” NASA social media manager John Yembrick told wired.com.

On board the New Horizons are seven sophisticated science instruments and the ashes of Clyde Tombaugh, the astronomer who discovered Pluto in 1930.

NASA was expecting a dark grey icy planet but the probe found it is red and appeared to be oxidized like Mars.

Earlier, the New Horizons probe settled one of the most basic questions about Pluto — its size. Mission scientists have found Pluto to be 2,370 km in diameter, somewhat larger than many prior estimates.

Images acquired with the Long Range Reconnaissance Imager (LORRI) on board the New Horizon probe were used to make this determination.

The result confirms that Pluto is larger than all other known solar system objects beyond the orbit of Neptune, the US space agency said in a statement.

“The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon from Washington University in St Louis.

Pluto’s newly-estimated size means that its density is slightly lower than previously thought, and the fraction of ice in its interior is slightly higher.

Measuring Pluto’s size has been a decades-long challenge due to complicating factors from its atmosphere.

Its largest moon Charon lacks a substantial atmosphere, and its diameter was easier to determine using ground-based telescopes.

New Horizons observations of Charon confirm its previous estimated size of 1,208 km across.

Two other moons – Nix and Hydra – were discovered using the Hubble Space Telescope in 2005. Nix is estimated to be about 35 km across while Hydra is roughly 45 km across.

These sizes lead mission scientists to conclude that their surfaces are quite bright, possibly due to the presence of ice.

Pluto’s two smallest moons, Kerberos and Styx, are smaller and fainter than Nix and Hydra and are harder to measure, the US space agency said.

(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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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)