Monday, October 7, 2019

Pluto and Beyond

Pluto and Beyond provides viewers with a fascinating look at our solar system's most enigmatic planet, the dwarf planet Pluto as well as a recently discovered feature, the Kuiper Belt.

Pluto and Beyond opens with the New Horizons mission scientists and their families waiting in anticipation for the spacecraft to fly by object 2014 MU69, now known as Ultima Thule, in the Kuiper Belt. The documentary then backtracks, giving viewers the backstory that has led the mission scientists to this historic moment.

It all began with the launch of the New Horizons spacecraft on a Lockheed Martin Atlas V rocket at Cape Canaveral on January 19, 2006. New Horizons flew past the planet Mars seventy-eight days later. A year after launch, New Horizons flew past Jupiter, capturing a volcanic eruption on Io, a Jupiter moon. Nine years after its launch, New Horizons began its approach to the Pluto system, having flown past Saturn, Uranus and Neptune.

From Earth, Pluto is nothing but a blur in the sky. But the New Horizons mission offers  scientists a first real look at this mysterious dwarf planet. Everything goes well until  July 4, 2015, when mission scientists inexplicably lose contact  with the spacecraft. Mission scientists eventually determined that the craft's computers had been overloaded. Alice Bowman, the Mission Operations Manager and her team managed to upload the necessary instructions to the spacecraft enabling it to function in time for the Pluto flyby.

The flyby reveals Pluto to be a planet of mountains made of ice and a massive glacier of methane and nitrogen ice. Planetary astronomers and astrophysicists now have more questions than answers as they speculate on Pluto's planetary geology and the possibility that conditions may be conducive for life.

The documentary then explores the history of our knowledge about Pluto beginning with its discovery  in 1930 by Clyde Tombaugh, a young American farm boy. Astronomers argued about Pluto's mass, eventually coming to the conclusion that it was smaller than Earth's moon. 

Beyond Pluto, the solar system was a mystery, an unknown. However, two astronomers, David Jewett and Jane Luu, discovered that there was much more than just empty space beyond Pluto. For six years, they searched the night sky, looking for evidence of something beyond Pluto. In 1992 they discovered an object located beyond Pluto and orbiting the Sun. They soon discovered many more objects in this region. Now known as the Kuiper Belt, is largely unknown to astronomers because it is so far away from Earth and therefore difficult to explore. Their discoveries led astronomers to theorize that Pluto was likely part of the Kuiper Belt.

The big unknown for the New Horizons mission was what to explore after Pluto. As New Horizons was approaching the Pluto system, astronomers began to search for an object in the Kuiper Belt that would be within the fuel capabilities of the spacecraft. In 2014, with the assistance of the Hubble Telescope, astronomers discovered an unknown object, designated 2014 MU69, eventually named Ultima Thule. However, finding an object was the first of many problems to solve.

The team needed to know more about Ultima Thule and one way to do that was to observe a stellar occultation which would help them determine the size and shape of the object. The astronomers needed two pieces of information: the exact location of Ultima Thule and a star that would be blocked out momentarily by the passage of Ultima Thule allowing observation of the object's shadow from Earth. The Hubble Telescope provided researchers with Ultima Thule's position. The Gaia Space Observatory, launched in 2013 was in the process of mapping the position, distances and motions of stars with precision. It could provide the data on a star that would be blinked out by Ultima Thule's passage in front of it.  Observing a stellar occultation is difficult because of the distance involved, the orbit pathway and many other factors.

After two failed attempts in 2017 to view occultations, Marc Buie and his team succeeded on July 17, 2017 in Patagonia, Argentina. With volunteers holding plywood to block the wind, the astronomers observed the star blink out for two seconds as Ultima Thule passed in front of it. In all, five different telescopes captured the occultation and provided the team with some interesting information. Ultima Thule is estimated to be about twenty miles across but even more interesting is the Kuiper Belt object's unusual shape. Scientists eventually settled on the theory that it is a "contact binary" object formed when the solar system formed.

Scientists believe that the planets formed due to a process called pebble accretion, where bits of dust, rock and gas clump together to form planetoids. It's possible that Ultima Thule is one such object that formed long ago when the solar system was beginning to form. In other words, it offers an opportunity to look back on the creation of our solar system.

On January 1, 2019, at 12:33am, New Horizons sails by Ultima Thule, a mere 2,200 km away. Telemetry from the spacecraft take six hours to travel the four billion miles from Ultima Thule to Earth. The results are breathtaking and enlightening. The New Horizons team is ecstatic as all of their hard work has paid off. The accomplishment, to view an object scientists did not even know existed when New Horizons was launched in 2006 is even more impressive.

Discussion

The New Horizons mission was tasked to explore the farthest regions of our solar system through the New Horizons mission, launched in January 16, 2006. The mandate of the mission was to explore the edge of our solar system, occupied by the dwarf planet Pluto as well as objects in the Kuiper Belt beyond Pluto. The journey to Pluto would take well over nine years.

The New Horizons spacecraft was designed, built and operated by the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. The science payload includes "an imaging spectrometer to probe atmospheric composition and planet structure, a visible and infrared camera to obtain high-resolution color maps and surface composition maps; a long-range telescopic camera for high-resolution surface images; particle spectrometers to measure charged particles in and around Pluto’s atmosphere; a detector to measure masses of space-dust particles; and two copies of a radio science experiment to examine atmospheric structure, surface thermal properties and planet mass." (1)

In February 2007, New Horizons flew past the planet Jupiter, and using its gravity to assist it on towards Pluto. In 2015, the spacecraft began a six month exploration of the Pluto system, culminating with a closest flyby on July 14. New Horizons gave scientists and the world a first close up look at Pluto. But it also allowed them to explore the Kuiper Belt, a region of the outer solar system that is similar to, but much larger than, the asteroid belt.

With a NOVA team embedded in the New Horizons mission team, Pluto and Beyond presents all the details, struggles and accomplishments in the exploration of the Pluto system. Viewers who haven't seen the photographs of Pluto from this mission will be understandably astonished. This mysterious planet that appears as a blurry image from Earth is revealed to look like an ice-covered Mars, with red hues.

While the impressive accomplishments of New Horizons Pluto mission and the beautiful photographs of Pluto are captivating, the most exciting part of the mission was the astronomer's struggle to work out all the details necessary to make the flyby of Ultima Thule a reality.  Pluto and Beyond captures the determination and persistence of astronomers as they work to capture the stellar occultation. Their dedication to science and the mission is obvious. In the end, we all are able to share in the fruits of their efforts as New Horizons flyby reveal Ultima Thule's unusual appearance. As of this time, New Horizons continues to send back data to Earth on the mission to Ultima Thule. Who knows what discoveries it might reveal in the remaining lifetime of the spacecraft as it makes its way into deep space.

For astronomy buffs, Pluto and Beyond is a documentary not to be missed. It is NOVA at its finest.

image credits:
Pluto and Charon: https://www.nasa.gov/sites/default/files/thumbnails/image/nh-pluto-charon-v2-10-1-15.jpg

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