ABOUT NEW HORIZONS
(Courtesy of APL)

The Pluto-Kuiper Belt Mission will help us understand worlds at the edge of our solar system by making the first reconnaissance of Pluto and Charon – a "double planet" system and the last in our solar system to be visited by spacecraft. The mission will then visit one or more Kuiper Belt Objects, in the region beyond Neptune.

The Pluto-Kuiper Belt Mission will launch in 2006, fly by Pluto and Charon in 2016, and pass the Kuiper Belt Objects by 2026. Sending a spacecraft on this long journey will help us answer basic questions about these bodies’ surface properties, geology, interior makeup, and atmospheres.

Although we have never sent a spacecraft to Pluto or Charon, we’ll know what to do when it arrives, thanks to observations from ground-based, airborne, and Earth-orbiting telescopes and from analogy with other bodies in our solar system. We know Pluto has some of the most diverse surface markings in the solar system – with areas ranging from “darker than coal” to “brighter than snow” – so we expect to see evidence of complex geology in the mission’s high-resolution images of Pluto. We also know that frost on Pluto's surface should evaporate into the atmosphere as parts of the surface get more sunlight, and condense back onto the surface as the Sun fades away.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., will manage the Pluto-Kuiper Belt Mission, which Principal Investigator Dr. S. Alan Stern, of the Southwest Research Institute in Boulder, Colo., will lead. The mission team also includes Ball Aerospace Corp., Boulder; Stanford University, Palo Alto, Calif.; NASA's Goddard Space Flight Center, Greenbelt, Md.; and NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

Pluto's atmosphere was detected in 1988. We know that its surface pressure is about 100,000 times smaller than that on Earth but still large enough for us to expect weather, winds, haze, chemistry, and an ionosphere. At the same time, Pluto's weak gravity does not hold the atmosphere very tightly, and the upper portions of Pluto's atmosphere may resemble that of a comet. Finally, the Pluto-Kuiper Belt Mission will use lessons learned from the Voyager encounter of Triton, a moon of Neptune with size, mass, and composition similar to Pluto. Are Pluto and Triton sister worlds, or will a spacecraft mission to Pluto reveal fundamental differences between them?

Charon is difficult to observe against the glare from nearby Pluto, and only recently has this smaller member of the "double planet" been viewed as a world with its own personality and puzzles. Although Pluto and Charon were both formed in the outer solar system, they are very different. Charon is much more uniform, its surface mainly frozen water and its atmosphere very thin or nonexistent. Still, studies of Jovian satellites Europa and Ganymede assure us that icy moons can have fascinating geologic stories to tell.

Kuiper Belt Objects are very faint, and extremely hard to study from the Earth. Most of the detected “KBOs” are small, with diameters typically around 100 kilometers (62 miles). The first KBOs were discovered only in 1992, but already the Kuiper Belt is changing the way we think about the outer solar system and the formation of the outer planets and comets. Because KBOs are similar to the planetesimals that formed the cores of Jupiter, Saturn, Uranus, and Neptune, understanding the composition of the Kuiper Belt is the closest we will come to looking deep into the interior of a giant planet.

KBOs range in colors from gray to red, which may be clues to competing processes in the outer solar system. One possibility is that the frost on the surface of Kuiper Belt Objects gets darker and redder with exposure to energetic particles and photons from the Sun, and gray again if an impact throws up new, clean frost from below the reddened surface. The mission team wants to map the surfaces of the KBOs to understand why they show such diversity.

To study Pluto, Charon, and KBOs, the Pluto-Kuiper Belt Mission has a payload tailored to answer the most important questions about unexplored bodies in the outer solar system. How do they look? What are they made of? What are their atmospheres like? The mission will map surface appearance with visible-wavelength cameras; study surface composition by spectra in the near infrared; and probe the atmosphere with UV spectrometers and radio waves, studying the particles leaving the atmosphere, and the effect of the atmosphere on the solar wind.

New Horizons is currently funded for Fiscal Year 2002, and in development. The mission is not funded in the President's 2003 budget. Get involved to make sure Congress allocates funds for this ever important mission.

  A mission to Pluto became open for competition in 2001. NASA had opened the doors for Outer Planet Exploration, and accepted proposals from the space industry for a mission to Pluto. The New Horizons Mission was selected as the mission to go to Pluto, and funded for Fiscal Year 2002, after the President's Budget was amended by Congress  to include funding for a mission to Pluto. The Fiscal Year 2003 budget prepared by President Bush again cancels Outer Planets Exploration, as well as the New Horizons mission at the end of Fiscal Year 2002. New Horizons is going to shed light on these unexplored and new frontiers. Your help is needed to see more money is not wasted, and Pluto is explored.