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  • On July 4, 2015, a NASA spacecraft called New Horizons was 5 billion kilometers away from Earth.

  • It was only 10 days away from Pluto, after flying for 9.5 years when it suddenly dropped out of contact.

  • But let's back up a little.

  • As of 1989, mankind had successfully sent craft to every known planet in the solar system except onePluto.

  • You may have heard that astronomers don't consider Pluto or its brethren to be planets.

  • However, most planetary scientists still do, which is why we're using that terminology here.

  • There's a limited amount we can learn about Pluto from Earth because it's so far from us.

  • Pluto, however, is a scientific goldmine.

  • It's located in a region called the Kuiper Belt, home to many small planets, hundreds of thousands of ancient icy objects, and trillions of comets.

  • This mysterious region holds clues to the formation of our solar system, and it was long, tantalizingly beyond our reach.

  • Until New Horizons.

  • Its objectives: explore Pluto, collect as much scientific data as possible, transmit it back to Earth, then explore farther out in the Kuiper Belt.

  • To achieve this, the New Horizons team outfitted their craft with seven state-of-the-art scientific instruments.

  • Those included Ralph, a set of cameras powerful enough to capture features the size of city blocks in Manhattan from tens of thousands of kilometers away.

  • And REX, designed to use radio waves to measure Pluto's atmospheric pressure and temperature.

  • All of the onboard equipment had to be built to be both reliable and lightweight because New Horizons had an additional challenge; it had to reach its target as fast as possible.

  • Why?

  • Around 2020, Pluto will reach a point in its orbit where its atmosphere could freeze.

  • And due to the tilt of its axis, more and more of Pluto's surface is shrouded in darkness every year.

  • Pluto completes a full orbit once every 248 Earth years, so it would be a long wait for the next prime opportunity to visit.

  • To see how New Horizons got to Pluto in time, let's jump to its launch.

  • Its three rocket stages accelerated New Horizons to such great speeds that it crossed the 400,000 kilometers to the moon in just nine hours.

  • About a year later, the craft reached Jupiter and got what's called a gravity assist.

  • That's where it flies close enough to the gas giant to receive a gravitational slingshot effect.

  • New Horizons was then flying at around 50,000 kilometers per hour, as it would for the next eight years to cross the remaining gulf to Pluto.

  • Going at such an astonishing speed meant that slowing down to get into orbit or land would've been impossible.

  • That's why New Horizons was on a flyby mission, where it would get just one chance to scream by Pluto and make its observations.

  • The flyby would have to be fully automated, since at that distance, any signals to guide it from Earth would take 4.5 hours to reach it.

  • So the team loaded the ship's computer with a series of thousands of commands, called the core load, that would begin to execute when the craft was 6.5 days from Pluto.

  • But when New Horizons was just ten days out, disaster almost struck.

  • Ground control lost contact with the spacecraft.

  • After two nerve-wracking hours, New Horizons came back online,

  • but mission control discovered that its main computer had rebooted,

  • losing the entire core load and other critical data.

  • Without that, it would soon whizz by Pluto with virtually nothing to show for the mission.

  • Alice Bowman, the mission's Operations Manager,

  • led a team for 72 sleepless hours to get the instructions loaded back into New Horizons in time.

  • Without room for a single error, she and her team pulled it off, and New Horizons began taking and broadcasting breathtaking images.

  • Those observations have revealed a delightfully varied world,

  • with ground fogs,

  • high altitude hazes,

  • possible clouds,

  • canyons,

  • towering mountains,

  • faults,

  • craters,

  • polar caps,

  • glaciers,

  • apparent dune fields,

  • suspected ice volcanoes,

  • evidence for past flowing liquids, and more.

  • One of the most exciting discoveries is the 1000-kilometer-wide Sputnik Planitia glacier.

  • Sputnik Planitia is mainly composed of slowly churning frozen nitrogen, and we've never seen anything like it in our solar system.

  • The exploration of Pluto was a great success, but New Horizons isn't done yet.

  • On January 1, 2019,

  • it'll break its own record for furthest explored object when it visits a Kuiper Belt Object called 2014 MU69,

  • which is orbiting the sun another billion kilometers farther away than Pluto.

  • The world is holding its breath to see what it'll find there.

On July 4, 2015, a NASA spacecraft called New Horizons was 5 billion kilometers away from Earth.

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B1 US TED-Ed pluto kuiper kuiper belt craft solar system

The journey to Pluto, the farthest world ever explored - Alan Stern

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    Evangeline posted on 2021/06/19
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