The Hubble Space Telescope could begin the search for the next targets to be studied by the New Horizons spacecraft headed for Pluto.
New Horizons was launched in 2006, when Pluto was still classified as a planet. Although the body has since been reduced to a classification of an icy dwarf, the system contains at least five moons. One of these, Charon, is so large compared to its host world; it is considered a double-planet system by many astronomers.
The Hubble Space Telescope Time Allocation Committee has recommended the use of the orbiting observatory to search for the next destination for New Horizons.
"I am pleased that our science peer-review process arrived at a consensus as to how to effectively use Hubble's unique capabilities to support the science goals of the New Horizons mission," Matt Mountain, director of the Space Telescope Science Institute (STScI), said.
In July 2015, the spacecraft will reach the frozen system of worlds. After that, the next objects in the solar system are the Kuiper Belt Objects (KBO's). This collection of rocky and icy objects orbits the sun up to five billion miles away from our home star.
Kuiper Belt Objects have never been studied up close, due to their great distance from the Earth. Hubble could begin the search for KBO's that could be examined by the visiting spacecraft.
Hubble will search a small area of the sky, located near the constellation Sagittarius, examining some of the objects New Horizons could reach.
To find KBO's among the vast multitude of background stars, mission planners will employ a unique photographic trick. They will turn the telescope at the predicted rate the distant bodies should be orbiting the sun. Theoretically, KBO's should be seen in images as dots, while stars will be streaked. If two or more objects are seen with a given minimum brightness, mission planners believe there is a statistical chance a good target could be found. If this test is successful, the search area will be expanded to a region approximately half a degree across - roughly the size of a full moon as seen from Earth.
Objects in the Kuiper Belt were formed 4.6 billion years ago, during the creation of the solar system. Despite the remarkable capabilities of the Hubble Space Telescope, finding KBO's is a daunting task. Even objects large enough to warrant a study by New Horizons would be only a few miles in diameter, and could be as dark as charcoal.
Four of the five Moons of Pluto were discovered by astronomers using the Hubble observatory.