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Pluto, underdog of the solar system, finally gets its day

Soon, some of the mystery surrounding Pluto, the distant dwarf planet, will be lifted. NASA’s New Horizons spacecraft, speeding through space for almost a decade on a mission to capture a myriad of data, is believed to have finally made a successful Pluto flyby. Science correspondent Miles O’Brien reports.

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    It's been a once-in-a-lifetime journey, and today NASA believes its New Horizons spacecraft finally made a successful flyby of Pluto.

    Once considered the ninth planet in our solar system, Pluto is billions of miles away. Confirmation of the spacecraft's arrival is expected tonight. But there were celebrations earlier today at mission control, as all signs pointed to success.

    Science correspondent Miles O'Brien fills in the picture of this mission.

    This story was done with help from the PBS program NOVA, which airs "Chasing Pluto" tomorrow night.


    Ready or not, it is finally time for Pluto's closeup. Once a full-fledged planet, now considered something less, it remains an intriguing mystery 85 years after its discovery, but not for long. The picture is growing clearer as a fast-moving spacecraft arrives at the solar system's underdog.

  • ALAN STERN, New Horizons Principal Investigator:

    It was always the planet with the little question marks everywhere. We didn't know anything. And because it's the last in the public mind, it takes a special place.


    Pluto has taken a special place in planetary scientist Alan Stern's mind since 1988. That's when he first began pushing NASA to send a spacecraft to what was then the ninth planet in our solar system.

    The three-billion-mile journey of the New Horizons spacecraft began in 2006. It left the Earth faster than any spacecraft ever, making a beeline for Pluto, getting a gravitational kick from Jupiter as it bulleted past, snapping pictures all the while. And now, after nearly a decade in space, New Horizons is finally there.

  • HAL WEAVER, New Horizons Project Scientist:

    I like to call this a mission of delayed gratification, because it takes nine-and-a-half years to get all the way out to Pluto, but we're almost there. And the opportunity to transform Pluto from a little pixelated blob into a world with complexity and diversity is just going to be amazing.


    Hal Weaver is the New Horizons project scientist. He admits to some nerves here in the home stretch.


    Oh, yes, I'm somewhat nervous because, in the space business, you're only as strong as your weakest link. And we have put so much effort into making sure that we squeeze as much as possible out of this mission scientifically.


    And that scientific to-do list is a long one. Despite what we may imagine, Pluto is no simple ice-covered rock, although, with a surface temperature of 387 below zero Fahrenheit, there is plenty of ice, ice made of carbon dioxide, methane, ethane and nitrogen, also the main ingredient of its atmosphere.

    Besides cold, the Pluto weather can be cloudy, hazy and windy. The sun is so distant that high noon on Pluto is like dusk here on Earth. It appears there are mountains and valleys. And, yes, it is red. Sorry, Mars, you're not as special as we once thought.


    So, we think that the color of the surface is a direct byproduct of a process called space weathering, where the radiation from the sun and cosmic rays generate trace constituents in the ices that have color.


    No less interesting than Pluto is its largest moon, Charon. It is covered with plain old water ice. They will be on the lookout for cracks in the surface, which could be telltale signs of liquid water below.


    So I would be surprised if we see evidence of some liquid water underneath Charon's surface, but I wouldn't say it's out of the question. If we see cracks on Charon's surface, and especially if we can see some venting from Charon's surface, that would be really cool.


    Clyde Tombaugh would heartily agree. In 1930, he discovered Pluto at the Percival Lowell Observatory in Flagstaff, Arizona.

    Tombaugh named his quarry Pluto for the Roman god of the underworld. Conveniently, the first two letters are Percival Lowell's initials. And, coincidentally, about that time, Disney's cartoon dog of the same name first appeared on the silver screen.

    Underdog indeed, and yet the ninth planet just the same. But the dogged march of scientific discovery set Pluto up for a cosmically unpopular demotion.

    MIKE BROWN, California Institute of Technology: As we had been discovering larger and larger and larger objects, that I — in my opinion, it made no sense that Pluto was called a planet, and it shouldn't be a planet.


    That's astronomer and Pluto killer Mike Brown, appearing in the PBS NOVA program "Chasing Pluto." Starting in 1992, he and his colleagues discovered a region of large, rocky, icy, planet-shaped debris at the outer edge of the solar system.

    It's called the Kuiper belt, leftovers from the formation of planets 4.6 billion years ago. But the debris really hit the fan for our beloved underdog in 2005, when Brown and his team discovered this object, Eris. It's more massive than Pluto.


    I had to make a decision, what we were going to call it. Is it a planet? Is it not a planet? Is it the 10th planet? Is it the 52nd planet? Is it — is Pluto not a planet? I knew that, that no matter what I said, it would be debated for a long time.


    Eventually, astronomers decided to call Pluto and the other big Kuiper belt objects dwarf planets.

    Whatever Pluto is called, New Horizons is well-poised to understand it much better. The grand piano-sized spacecraft is brimming with seven scientific instruments, spectrometers that measure infrared, ultraviolet, plasma and solar wind, a student-built dust counter, a radio device to characterize the atmosphere, and, of course, cameras, visible, infrared and the one that should make the Pluto screen savers, LORRI, short for Long Range Reconnaissance Imager.


    Ultimately, LORRI will allow us to map the surface of Pluto well enough that, if we flew over New York City at the same altitude and looked down with LORRI, we could count the ponds in Central Park and the wharfs on the Hudson. It's a very detailed imagery at closest approach.


    By and large, the spacecraft has run well these past nine-and-a-half years, despite a brief scare on July 4, when the computer crashed, causing the probe to go dark for a while. The team says it is ready regardless.

  • MARK HOLDRIDGE, New Horizons Encounter Mission Manager:

    We have done dozens of operational readiness tests.


    Mark Holdridge is the encounter mission manager for New Horizons at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. One of his key jobs has been to lead the team through numerous dress rehearsals, staying sharp for the big event.


    So, we have been really careful about timing the operational readiness tests to make sure that the last one doesn't happen too soon before the actual encounter, because we will forget things.


    They can't afford to forget, because New Horizons will not orbit Pluto. It is supposed to whiz by 18 times faster than a speeding bullet, 7,800 miles from the surface, taking pictures and Hoovering up data as quickly as it can.

    The spacecraft will not be transmitting while it gathers its science, leaving the team hanging for 13 hours before they even get a phone home. The postcards are supposed to come in the next day.


    We have no idea what we're going to see. We're going to be surprised. I'm positive of that.


    Assuming all goes well, NASA and APL will aim New Horizons toward another Kuiper belt object for a flyby in 2019. But for now, all eyes in the world of planetary science are focused on Pluto and the end of an era, as they finish the first forays of exploration into our celestial neighborhood.


    People will look back on this time, from the '60s to 2015, in future centuries, I think, and say, that is when the solar system was first explored.


    The underdog at the edge of our understanding may be the last, and the least, but perhaps that is why unlocking its mysteries seems so worthwhile.

    Miles O'Brien, the PBS NewsHour, Laurel, Maryland.


    And online, you can find more videos on Pluto and follow NOVA's live tweets on the flyby. That's on our home page, PBS.org/NewsHour.

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