September 8, 2009
New Horizons Hits Halfway Mark Between Saturn, Uranus Orbits
New Horizons sails silently today through another milestone on the way to its historic reconnaissance of the Pluto system, reaching the halfway point between the orbits of Saturn and Uranus.
The NASA spacecraft will reach 14.41 astronomical units from the Sun – 1.34 billion miles, or nearly 14½ times the distance between the Earth and Sun – between 6-7 p.m. EDT “Only five operating spacecraft have ever journeyed this far, and only one – the storied Voyager 2 mission – still had an encounter planned even farther out,” says New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. “New Horizons is on its way to the farthest planetary encounter ever, at just over 32 astronomical units, which is a quarter-billion miles beyond the current planetary encounter record set at Neptune back in 1989.”
Not that the spacecraft “sensed” today’s moment; New Horizons entered hibernation on Aug. 27 after its annual checkout and won’t be stirred again by the mission operations team until Nov. 9. New Horizons, launched more than 3½ years ago on Jan. 19, 2006, is approximately 1.3 billion miles (2.1 billion kilometers) from Earth, speeding away from the Sun at just over 37,000 miles per hour. The spacecraft will actually cross the orbit of Uranus on March 18, 2011.
New Horizons continues to cross the orbits of the outer planets, though it will not come close to Uranus (or Neptune, beyond) on the way to Pluto. Green denotes space New Horizons has covered; red marks its projected path toward the Pluto system. Click Image to Enlarge
Follow New Horizons’ journey at http://pluto.jhuapl.edu/Mission/Where-is-New-Horizons/index.php.