The recent demotion of Pluto to “dwarf planet” by the International Astronomical Union has not diminished its interest to astronomers. New Horizon’s upcoming encounter with this dark, icy world will likely reveal many secrets about the formation of the solar system.
On January 19, 2006 the robotic spacecraft rumbled off the launch pad at Cape Canaveral, Florida atop an Atlas V rocket, embarking on its 3 billion mile journey. New Horizons left Earth traveling at 36,373 mph, setting a new record for the fastest launch for any human-made object. It zoomed past the moon in 9 hours.
It made its closest approach to Jupiter on February 28, 2007 moving at about 51,000 mph and received a gravity assist from the enormous gas giant, boosting its speed by about 8,900 mph. While at Jupiter, New Horizons made numerous scientific observations of the planet, its moons and rehearsed for its later flyby of Pluto.
The gravitational attraction of the Sun has slowed New Horizons to about 36,000 mph. This velocity is enough to eventually hurtle the spacecraft past Pluto, through the Kuiper Belt and beyond the influence of the Sun, sailing forever into interstellar space. At its current speed it will travel a distance equal to the nearest star in about 80,000 years.
On October 17, 2010 New Horizons passed the halfway point between Earth and Pluto. Even at this distance, from the perspective of the spacecraft, Pluto still cannot be seen by the naked eye.
New Horizons will make its closest approach to Pluto on July 14, 2015. It will study Pluto, its largest moon Charon and two additional moons, Nix and Hydra, that were discovered in 2005 using the Hubble Space Telescope.
Unfortunately, New Horizons will not orbit Pluto. The dwarf planet’s gravity is weak and the spacecraft cannot carry the tremendous amount of fuel necessary to slow it down. It will fly by the Pluto system and move on to study other objects in the Kuiper Belt, a region of the solar system similar to the asteroid belt, extending beyond Neptune. Thousands of objects have been discovered in the Kuiper Belt, some nearly the size of Pluto.
For those too young to remember NASA’s early Mariner and Voyager missions, New Horizons is very special. Ignoring planetary semantics for a moment, New Horizons could be the final time that any human will witness a physical encounter with an unexplored planet. Astronomers have discovered hundreds of extrasolar planets, but their distances are so vast that we cannot reach them within a human lifespan. Pluto seems to be our last chance to live planetary history.
So during the month of July, 2015 keep a close eye on national news and www.nasa.gov. Do not miss humanity’s first contact with the unimaginably cold, desolate and distant wanderer of the outer solar system, aptly named after the Roman god of the Underworld. Do not miss one of the most important astronomical encounters in history.