For the first time in human history, a man-made object propelled from Earth and still under our control is about to touch the outer edges of our solar system — as the unmanned New Horizons spacecraft flies past Pluto and into the Kuiper Belt.
The craft is expected to come closest to Pluto, about 7,750 miles away, at 3 seconds before 6:50 a.m. CDT Tuesday.
It comes after a flight that has lasted more than nine years and covered almost 3 billion miles.
“Eight-thousand miles to normal people sounds like a whole lot,” said Tony Russo, a professor of physical sciences at Northwest Florida State College. “But getting within 8,000 miles after billions of miles of travel is definitely a close encounter.”
The New Horizons spacecraft is about the size and shape of a grand piano. Along with its scientific equipment, the ship carries an ounce of Clyde Tombaugh’s ashes — he discovered Pluto in 1930 — and a Florida state quarter.
As it passes Pluto, the spacecraft will point seven instruments at the surface to take pictures and collect all kinds of scientific data for transmission back to Earth — all while traveling 32,500 miles per hour.
“It’s like shooting a bullet past an object and having it take pictures as it flies by,” said Richard Millett, president of the Astronomical Society of Bay County.
The data should answer some of the questions scientists have pondered about one of the most mysterious objects in the solar system — what is now called a dwarf planet, which is smaller than our moon with an orbit unlike any other that circles the sun.
“It’s hard to say what we are going to learn,” Russo said. “Until now, Pluto is the only solar system object that has not been visited by a flyby.”
It’s been 15 years since a mission to Pluto was canceled because of budget cuts to NASA. But a year later, in 2001, the agency received a $650 million outlay to send a New Horizons spacecraft into space.
On a Thursday morning, Jan. 19, 2006, with mostly clear skies except for clouds drifting along the horizon, the craft was launched from Cape Canaveral headed toward Jupiter. On Feb. 28, 2007, New Horizons curled around Jupiter and, getting a gravity assist from that planet, picked up speed for the flight to Pluto.
For most of the next eight years, the craft hibernated as it hurtled through space. Once a week, it sent a radio transmission back to Earth, essentially telling flight controllers it was sleeping well. Once a year, New Horizons was awakened for systems checks.
On Dec. 6, 2014, it was brought back online. A little more than a month later, it began its approach path to Pluto.
On June 29, NASA burned thrusters on the craft for 23 seconds. It might not seem like much, but the burn sped up the ship by one-half of one mile per hour. Without the course correction, the craft would have been 20 seconds late and 114 miles off target on Tuesday.
A week later, during the Fourth of July weekend, the mission experienced a heart-stopping glitch, when flight controllers lost communication with New Horizons for 1 hour, 20 minutes. However, the spacecraft came back on line and, after a systems check, appeared to be functioning normally. Officials said the craft is still on a perfect course.
“We are really on the final path,” said Glen Fountain, New Horizons project manager at the Applied Physics Laboratory at Johns Hopkins University. “It just gets better and more exciting every day.”
New Horizons is expected to gather so much data that it will take a year and a half to transmit it all back to Earth.
There is growing anticipation as the spacecraft grows closer, and pictures being sent back are already revealing details of Pluto’s surface.
“This system is just amazing,” said Allen Stern, the New Horizons principal investigator at the Southwest Research Institute in Boulder, Colorado. “The science team is just ecstatic with what we see on Pluto’s close approach.”
Images received last week — transmissions take 4½ hours to reach Earth — showed lots of contrasts on Pluto’s surface.
“The unambiguous detection of bright and dark terrain units on both Pluto and Charon (Pluto’s largest moon) indicates a wide range of diverse landscapes across the pair,” said Jeff Moore from the NASA Ames Research Center in Mountain View, California.
After New Horizons passes Pluto it will continue into the Kuiper Belt, which is a ring of debris that orbits the sun beyond Pluto.
The Kuiper Belt has more than 100,000 objects of more than 100 kilometers in diameter. Astronomers discovered the first object in the belt in 1992, making it a part of the solar system that remains cloaked in mystery even more than Pluto.
For scientists, it’s a moment of discovery they have anticipated for almost a decade.
“It’s getting really exciting,” said Alice Bowman, operations manager for the mission “Every day is bringing new features into light.”
PLUTO: A closer look
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Pluto was discovered on Feb. 18, 1930, by 24-year-old Kansas native Clyde Tombaugh, who was working at the Lowell Observatory in Flagstaff, Arizona. He found Pluto by comparing photos using a device called a blink comparator, that allowed him to flip between photo plates looking for objects that had moved from one image to another. Astronomers had been looking for an object — dubbed Planet X — since the late 1800s because something yet discovered seemed to be affecting the orbit of Neptune, the seventh planet from the sun.
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The name (Pluto is the Roman god of the underworld) was suggested by 11-year-old English schoolgirl Venetia Burney, who was interested in classical mythology. When the name was selected, she received a $430 reward.
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lPluto was demoted as a planet by the International Astronomical Union in 2006 (after New Horizons had launched), and is now called a dwarf planet, a designation created for Pluto. Debate continues in the astronomical community about whether or not Pluto should be considered a planet.
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It orbits the sun once every 248 Earth years.
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Its orbit is the most elliptical of the eight-plus-Pluto planets and is tilted 17 degrees from the plane the other eight are on. Because of that, Pluto gets as close at 2.8 billion miles from the sun and as far as 4.6 billion. Its average distance from the sun is 3.7 billion miles — or 40 times the distance Earth is from the sun.
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Pluto’s diameter is estimated to be 1,466 miles, making it about two-thirds the size of our Moon.
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Its gravity is 6 percent that of Earth’s.
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The average surface temperature is minus-387 degrees Fahrenheit, although there are wide variations.
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It has five known moons — the largest being Charon, which is about half the size of Pluto.
ON THE NET
Here’s how to follow the New Horizons mission online:
Twitter: @NASANewHorizons
Facebook: www.facebook.com/new.horizons1?fref=ts
NASA website: nasa.gov/mission_pages/newhorizons/main/index.html
Applied Physics Laboratory: pluto.jhuapl.edu