Throughout most of human history the worlds we share our solar system with were nothing more than points of light in the night sky, observed by astronomers for centuries as great minds worked to understand what they were, why they were there and what their significance was in nature’s puzzle of creation. In the last few decades some of the brightest minds alive, with the resources they needed, built some of the most robust vehicles ever made to go to these places on our behalf, to explore and study our celestial neighborhood up close and personal.
Over the last few decades these missions have changed the course of human understanding regarding our place among the stars, but one world remained elusive – Pluto. That is, until today.
July 14, 2015, marks the first day in a new world where humanity has officially completed the first reconnaissance of every planet in the solar system. At 7:49 a.m. EDT, NASA’s $728 million, piano-sized 1,000 pound New Horizons spacecraft made its closest approach to Pluto and its largest moon, Charon, cruising 7,750 miles over the surface of Pluto and putting its suite of seven high-tech science instruments into overdrive as it cruised by at 31,000 mph, fulfilling its destiny after a 9.5 year journey across a vast expanse of 3 billion miles – some 32 times further from the sun than the Earth is.
“I’m delighted at this latest accomplishment by NASA, another first that demonstrates once again how the United States leads the world in space,” said John Holdren, assistant to the President for Science and Technology and director of the White House Office of Science and Technology Policy. “New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple missions orbiting and exploring the surface of Mars in advance of human visits still to come; the remarkable Kepler mission to identify Earth-like planets around stars other than our own; and the DSCOVR satellite that soon will be beaming back images of the whole Earth in near real-time from a vantage point a million miles away. As New Horizons completes its flyby of Pluto and continues deeper into the Kuiper Belt, NASA’s multifaceted journey of discovery continues.”
In order to hit its target, on time and exactly where the science team wanted and when they wanted it, the spacecraft had to “thread 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.
“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 spacecraft last communicated with Earth on Monday night, July 13, before falling silent for 22 hours as it focused 100% on conducting science observations that could only be done during the flyby itself as it cruised through the Pluto system. At 8:53 p.m. EDT tonight, the “phone home” was received in mission control at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD, confirming that New Horizons’ flyby sequence worked and that it accomplished its primary mission. Everything from the spacecraft’s power supply to its propulsion and suite of science instruments reported back to Earth as alive and well.
But patience is the name of the game in planetary exploration, and the initial close-up images of Pluto are not expected to arrive home until tomorrow morning. At such distances round-trip radio communications between New Horizons and Earth takes nine hours—4.5 hours each way at the speed of light.
July 15th will mark the beginning of a 16-month “data waterfall” according to the mission’s Principal Investigator, Dr. Alan Stern from the Southwest Research Institute, in Boulder, Colo. The flyby may be over, but Wednesday the spacecraft will begin sending all of the information it collected to Earth, but at a transmission rate of only 2,000 bits per second.
The flyby imagery will be of such high-resolution that features as much as 230 feet wide will be crystal clear, and many times better than even the most recent image from July 13 on final approach, which showed Pluto at a resolution of nearly 8 miles per pixel. The flyby images will be so clear that if New Horizons was traveling over the Earth at the same distance, it would reveal detail as small as the ponds in New York’s Central Park.
“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.”
While the close up flyby imagery will take some time to be delivered home, the mission team has already seen Pluto’s geologic features during the spacecraft’s approach. Features such as its now-famous high-contrast terrain, which includes an intriguing region know as the “whale’s tail,” which is located at the hemisphere of Pluto that always faces its biggest moon, Charon.
“Among the structures tentatively identified are what appear to be polygonal features; a complex band of terrain stretching east-northeast across the planet, approximately 1,000 miles long; and a complex region where bright terrains meet the dark terrains of the whale,” said Stern. “After nine and a half years in flight, Pluto is well worth the wait.”
New Horizons has also showed Pluto has a methane-rich polar ice cap, and nitrogen has been confirmed escaping it’s thin atmosphere. It snows on Pluto, and there is strong evidence indicating that Charon may be catching some of Pluto’s thin atmosphere.
Clouds, geysers, perhaps signs of a liquid ocean beneath the surface, or maybe even liquid nitrogen on the surface might be present, we just do not know. But Pluto and Charon have come into very clear focus over the last couple weeks, offering tons of new information and insights into the worlds now known as the gatekeepers to the Kuiper Belt. Just yesterday Pluto’s true size was confirmed, and it’s bigger than was originally believed: 1,473 miles (2,370 kilometers) in diameter. Charon is 751 miles in diameter.
Pluto is now confirmed larger than all other known solar system objects beyond the orbit of Neptune.
“The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon, Washington University, St. Louis.
These latest observations also revealed the size of two of Pluto’s smaller moons: Nix is approximately 20 miles across, while Hydra is around 30 miles across.
“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.”
The collaborative work of several thousand people from over 50 organizations over the last decade seems to have paid off, and now humanity can begin writing the book on Pluto, thanks to New Horizons.
“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.”
Stay with AmericaSpace for regular updates and LIVE COVERAGE of New Horizons’ approach and flyby of the Pluto system.
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