Pluto Craft Reports for Duty

Science Fields

After covering nearly five billion kilometers in nine years, NASA’s “New Horizons” spacecraft was roused from the latest of its naps in preparation for the exploration of dwarf planet Pluto and its five moons.

Launched on January 19, 2006, the spacecraft will start observing the Pluto system on January 15, 2015, and make a flyby which will bring it virtually to a stone’s throw from the dwarf planet and its largest moon Charon on July 14. At its closest approach, it will be just 10.000 kilometers above the surface of Pluto, “close enough to photograph individual buildings, if it hovered at that height above the Earth” according to an earlier NASA ScienceCast.

After the flyby, the spacecraft will possibly be routed towards other Kuiper Belt Objects (KBOs) pending NASA’s decision.

To prevent the sensitive instruments on board from wear-and-tear of overuse and diminish the risk of system failures, New Horizons was put on 18 spells of “hibernation” of varying lengths, totaling 1873 days, or two-thirds of the voyage so far, woken in between for equipment tests and course corrections.

Following the latest activation, done with pre-loaded programs, the “I’m awake” signal the spacecraft sent took 4 hours and 26 minutes to reach the control center at Johns Hopkins University’s Applied Physics Laboratory, traveling with light speed. Mission controllers will make use of the remaining weeks before the commence of observations for calibrating and testing the spacecraft’s scientific payload which comprises of seven experiments and imaging instruments. New Horizons moves on a highly-eccentric orbit whose closest point is 4.4 billion, and farthest, 7.4 billion kilometers from the sun. Thus, its trajectory periodically takes it inside Neptune’s orbit.

Known for decades as the Solar System’s 9th planet after its discovery in 1930, Pluto was demoted to “dwarf planet” status in 2006 with a controversial decision of the International Astronomical Union which re-defined the prerequisites of being a planet. Believed to be hailing from the disc-shaped Kuiper Belt which houses the rocky and icy debris from the formation of the Solar System outside Neptune’s orbit, Pluto completes its orbit around the sun in 247.68 days. The 2306-kilometer-wide ( two-thirds the diameter of the Earth’s moon) dwarf planet is speculated to be formed of an icy mantle lying above a rocky core with a 1700 kilometer diameter. Its surface temperature is calculated to vary between -230 and -240 ⁰C depending on its distance to the sun. Its mass has been measured to be a quarter that of the Earth.

The  orbits of  minor moons orbiting Pluto and Charon system. The light from the latter were suppressed in order to make  small moons visible. So, the ilustration is out of scale.

The size of its largest moon, Charon, discovered in 1978, is about the half of Pluto’s. In recent years four other moons of the dwarf planet were discovered and named Nix, Hydra, Kerberos and Styx.

[Text Box: The orbits of minor moons orbiting Pluto and Charon system. The light from the latter were suppressed in order to make small moons visible. So, the ilustration is out of scale.] Because it’s too far from the Earth, Pluto cannot be resolved clearly even by the Hubble Space Telescope. But since light and dark patches covering its surface change shape and position in time, it is believed to have a “dynamic” surface in periodic interaction with an atmosphere composed of nitrogen, methane and carbon dioxide.

The data to be beamed back by New Horizon is expected to not only remove the shroud of mystery covering this system, but to expand our insight to other KBOs and cast a new and powerful light on the formation of our solar system. 


  • 1. “New Horizons Wakes Up on Pluto’s Doorstep”, NASA Science News, 7 November 2014
  • 2. “NASA ScienceCasts: One Year to Pluto”, https://www.youtube.com/watch?v=RDIsbN-e1qU