Launched in January 2006, the New Horizons probe will be the first to explore the binary system of Pluto-Charon, making it the fifth probe to traverse interplanetary space so far from the sun. After extensive study there, New Horizons will visit objects in the Kuiper Belt region beyond Neptune.
Pluto-Charon is described as a binary system since Charon, one of Pluto’s moons, is half the size of Pluto and the center of gravity which it orbits is outside of Pluto itself. Therefore, neither body truly orbits the other making them a binary system, meaning that each body orbits the same center of gravity. The New Horizons mission will mark the first opportunity to study such objects.
There are three zones that comprise the Solar System. First are the terrestrial planets, which are the four nearest to the sun, and are composed primarily of rock and metals. Second are the gas giants, which consist of the remaining four planets and are significantly more massive than the terrestrials. And the third is the Kuiper Belt, which is comprised of various celestial bodies that do not qualify as planets. This third region remains largely unexplored, but the New Horizons probe will be the first mission that’s been specifically designed to fill the knowledge gap regarding the Kuiper Belt.
The ice dwarfs in this region of the Solar System are “planetary embryos.” Their growth stopped at sizes much smaller than any of the other planets in the Solar System, which accumulated into these types of objects over long periods of time. The studies of New Horizons will provide much insight into planetary formation due to what is already known about the process.
It is also known that the Kuiper Belt is the source of many cometary impactors on Earth, most notably the impactor that caused the dinosaurs to go extinct. Through the study of craters on Pluto, its moons, and other Kuiper Belt objects, it will hopefully provide a better idea regarding how many threatening impactors currently exist.
New Horizons will also provide insights into Earth’s atmosphere in a unique way. Right now, the atmosphere on Pluto is escaping into space, and it is believed that Earth’s original atmosphere of hydrogen and helium was lost to space in a similar fashion. Therefore, whatever new information is learned about Pluto’s atmosphere will be enlightening about the evolution of Earth’s atmosphere.
Since 2005, four moons have been discovered aside from Charon that orbit Pluto. Two of these moons were discovered after New Horizons had already launched, and caused a great deal of initial fear. The Jet Propulsion Laboratory have been studying these discoveries, and have mostly completed their analysis: New Horizons should still be safe. The best models predict a 0.3 percent chance of critical impact, or a 1-in-300 chance.
New Horizons is expected to arrive at the Pluto-Charon system in July 2015. The overall cost of the mission is approximately $650 million, spread over 15 years, from 2001 to 2016.
JPL’s New Horizons “Why Go to Pluto?” page: http://pluto.jhuapl.edu/overview/whyGo.php
NASA’s New Horizons “Missions” page: http://www.nasa.gov/mission_pages/newhorizons/main/index.html
“New Horizons: Encounter Planning Accelerates”: http://www.planetary.org/blogs/guest-blogs/2013/20130520-new-horizons-encounter-planning-accelerates.html
“Pluto’s seasons and what New Horizons may find when it passes by”: http://www.planetary.org/blogs/emily-lakdawalla/2013/05021212-plutos-seasons-new-horizons.html
To learn why New Horizons will be able to view Pluto with better detail than Hubble: http://www.planetary.org/blogs/emily-lakdawalla/2013/02141014-hubble-galaxy-pluto.html