After a decade-long, three-billion-mile journey through our solar system, NASA’s New Horizons spacecraft made its closest approach to Pluto on July 14, 2015.
The craft was a mere 7,750 miles above the surface — roughly the same distance from New York to Mumbai, India — making it the first-ever space mission to explore a world so far from Earth.
Three billion miles away, Pluto has sent a “love note” back to Earth, via NASA’s New Horizons spacecraft.
At about 4 p.m. EDT on July 13 — about 16 hours before closest approach — New Horizons captured this stunning image of one of Pluto’s most dazzling and dominant features. The “heart,” estimated to be 1,000 miles (1,600 kilometers) across at its widest point, rests just above the equator. (The angle of view displays mostly the northern hemisphere.) The heart’s diameter is about the same distance as from Denver to Chicago, in America’s heartland.
“Wow!” said New Horizons principal investigator Alan Stern, Southwest Research Institute, Boulder, Colorado, as the image was unveiled before the New Horizons science team at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “My prediction was that we would find something wonderful, and we did. This is proof that good things really do come in small packages.”
The newest image from the Long Range Reconnaissance Imager (LORRI) shows an almost perfectly shaped left half of a bright, heart-shaped feature centered just above Pluto’s equator, while the right side of the heart appears to be less defined.
The image shows for the first time that some surfaces on Pluto are peppered with impact craters and are therefore relatively ancient, perhaps several billion years old. Other regions, such as the interior of the heart, show no obvious craters and thus are probably younger, indicating that Pluto has experienced a long and complex geological history. Some craters appear partially destroyed, perhaps by erosion. There are also hints that parts of Pluto’s crust have been fractured, as indicated by the series of linear features to the left of the heart.
Below the heart are dark terrains along Pluto’s equator, including, on the left, the large dark feature informally known as the “whale.” Craters pockmark part of the whale’s head; areas that appear smooth and featureless may be a result of image compression.
Planet X = Pluto
“The exploration of Pluto and its moons by New Horizons represents the capstone event to 50 years of planetary exploration by NASA and the United States,” said NASA Administrator Charles Bolden. “Once again we have achieved a historic first. The United States is the first nation to reach Pluto, and with this mission has completed the initial survey of our solar system, a remarkable accomplishment that no other nation can match.”
The Pluto story began only a generation ago, when young Clyde Tombaugh was tasked to look for Planet X, theorized to exist beyond the orbit of Neptune. He discovered a faint point of light that we now see as a complex and fascinating world. (Read the original news story from 1930: Pluto: Kansas farm boy spots new planet.)
“Pluto was discovered just 85 years ago by a farmer’s son from Kansas, inspired by a visionary from Boston, using a telescope in Flagstaff, Arizona,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “Today, science takes a great leap observing the Pluto system up close and flying into a new frontier that will help us better understand the origins of the solar system.”
New Horizons’ flyby of the dwarf planet and its five known moons is providing an up-close introduction to the solar system’s Kuiper Belt, an outer region populated by icy objects ranging in size from boulders to dwarf planets. Kuiper Belt objects, such as Pluto, preserve evidence about the early formation of the solar system.
An almost 10-year, three-billion-mile journey
New Horizons principal investigator Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado, says the mission now is writing the textbook on Pluto.
“The New Horizons team is proud to have accomplished the first exploration of the Pluto system,” Stern said. “This mission has inspired people across the world with the excitement of exploration and what humankind can achieve.”
New Horizons’ almost 10-year, three-billion-mile journey to closest approach at Pluto took about one minute less than predicted when the craft was launched in January 2006. The spacecraft threaded the needle through a 36-by-57 mile (60 by 90 kilometers) window in space — the equivalent of a commercial airliner arriving no more off target than the width of a tennis ball.
Because New Horizons is the fastest spacecraft ever launched — hurtling through the Pluto system at more than 30,000 mph, a collision with a particle as small as a grain of rice could incapacitate the spacecraft. Once it reestablishes contact, it will take 16 months for New Horizons to send its cache of data — 10 years’ worth — back to Earth.
New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple rovers exploring the surface of Mars, the Cassini spacecraft that has revolutionized our understanding of Saturn and the Hubble Space Telescope, which recently celebrated its 25th anniversary. All of this scientific research and discovery is helping to inform the agency’s plan to send American astronauts to Mars in the 2030’s.
“After nearly 15 years of planning, building, and flying the New Horizons spacecraft across the solar system, we’ve reached our goal,” said project manager Glen Fountain at APL “The bounty of what we’ve collected is about to unfold.”