Pluto-bound Probe Crosses Saturn's Orbit

The Pluto-bound New Horizons spacecraft crossed the orbit of Saturn on June 8.

It is the first probe to cross that threshold since Voyager 2 passed the ringed planet nearly 27 years ago. In fact, Voyager 1 and 2, at the edge of the Sun’s heliosphere some 100 AU away, are the only spacecraft operating farther out than New Horizons, according to a statement released this week by mission managers.

New Horizons will reach Pluto in 2015. What it finds at Pluto and in the Kuiper Belt should help astronomers answer some fundamental questions about the origin of the solar system, astronomers say.

Spinning in healthy, electronic hibernation, New Horizons reached a distance of 10.06 astronomical units (about 935 million miles or 1.5 billion kilometers) from the Sun at 10:00 universal time Sunday.

New Horizons reached Saturn's distance two years and four months after launch -- by far a faster transit to Saturn than any previous spacecraft. (Voyager 1, the previous record holder, made the trip in approximately three years and two months.)

The craft used Jupiter for a gravity boost and took pictures and made some other observations as it passed that giant planet last year.

After a productive two-week series of system checks, maintenance activities, and software and command uploads,the spacecraft is humming through the outer solar system at 40,850 miles (65,740 kilometers) per hour, according to the statement. Managers expect to keep the spacecraft in hibernation until Sept. 2.

Applied Physics Laboratory at Johns Hopkins University in Maryland is overseeing the mission for NASA.

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• Gallery: Our New Solar System
• New Horizons Archive