Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

NASA’s New Horizons spacecraft is chalking up interplanetary mileage en route to distant Pluto.

Few spacecraft travel 10 astronomical units (AU) during their entire mission.

But with New Horizons already logging more than twice that distance on its way to Pluto, coming to within 10 AU of its main target is akin to entering the home stretch.

Note: One AU is the average distance between Earth and the Sun: about 93 million miles or 149 million kilometers.

The piano-sized probe was launched in January 2006. The mission has entered the final three-year segment of its nine-plus year interplanetary trek from Earth to Pluto.

Mileage-plus mission

At around 4:55 Universal Time on Feb. 11 (or late tonight in the U.S.), New Horizons crosses to within 10 AU of the Pluto system. New Horizons space treks nearly a million miles of space a day.

The probe is racing outbound at 34,000 miles per hour. The voyage culminates in the historic flight past Pluto and its moons on July 14, 2015. However, encounter operations start several months earlier.

The NASA craft was built by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.- also the site of spacecraft operations.

New Horizons is currently in hibernation mode. Spacecraft operators will rouse the probe in late April for a comprehensive, two-month-long systems and instruments checkout.

By Leonard David