Credit: NASA/JHUAPL

NASA’s Pluto-bound New Horizons spacecraft is more than two billion miles from home.

Even at that distance, Earth controllers this month have woken up the probe from hibernation, as well as successfully test the New Horizons Radio Science Experiment (REX).

That test took advantage of an Earth-moon-spacecraft alignment to simulate atmospheric measurements “REX” will make at Pluto in 2015.

REX is integrated into the spacecraft communications system.

The operation team at the Johns Hopkins Applied Physics Lab in Maryland uploaded a new set of commands to the spacecraft’s computer; made sure its digital data recorders were in working order; primed the communications system for testing of the Radio Science Experiment (REX); refreshed the memory on one of the Guidance and Control processor memory banks; and prepped the Solar Wind at Pluto (SWAP) and Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instruments for more than three months of science-data collection.

Today, the team returned the spacecraft to hibernation.

Fortuitous alignment

The REX tests took place on Jan 21.

The team took advantage of a fortuitous Earth-moon-spacecraft alignment that allowed it to simulate the occultation technique New Horizons will use in 2015 to probe Pluto’s atmosphere and to search for an atmosphere around Pluto’s largest moon, Charon.

New Horizons is the first mission to Pluto and the Kuiper Belt of rocky, icy objects beyond.

The craft was launched on January 19, 2006 and is slated for the Pluto-Charon encounter in July 2015.

Since departure from Earth, the spacecraft is nearing 2,200 days of its cruise into the unknown.

For more information on this long-distance mission, go to:

http://pluto.jhuapl.edu/index.php

By Leonard David