The transition from black-and-white filming to color during the mid-20th century was a pivotal event which fundamentally changed the entertainment industry and the way that cinema and television were perceived and experienced by the public at large. In similar fashion, NASA’s New Horizons mission, after beaming back hundreds of black-and-white images of Pluto and its largest moon Charon in recent months, has now returned the first color animations which depict the orbital motions of these two mysterious and fascinating worlds at the outskirts of the Solar System, while also elevating the quality of the science as well as the aesthetic appeal that is inherent in these images to new levels.
Ever since the New Horizons spacecraft began its long-range reconnaissance of Pluto and its system of moons in January, it has been constantly beaming back images as the day of its closest approach on July 14 approaches ever closer. Yet most of the imagery returned by the spacecraft so far had been taken with the onboard Long Range Reconnaissance Imager, or LORRI, which is a long focal length, telescopic high-resolution, panchromatic imaging system that can only record images in black-and-white. The second onboard visible-light camera is the Multispectral Visible Imaging Camera, or MVIC, which is part of the New Horizons ’ Pluto Exploration Remote Sensing Investigation, or PERSI, suite of science instruments that also includes an ultaviolet and a near-infrared spectrometer. The MVIC camera, which has been affectionately named “Ralph” by the mission’s science team, had previously showcased its unique capabilities during New Horizons’ gravity-assist flyby of Jupiter in 2007, returning spectacular images of the massive gas giant planet and its four largest moons. More recently, Ralph was used to take the spacecraft’s first-ever color image of both Pluto and Charon on April 14, from a distance of 115 million kilometers, which, while being a very low-resolution one, helped to showcase the distinctly different appearances of both celestial bodies.
Now, from less than half that distance away, New Horizons’ Ralph camera beamed back a series of near-true-color images of Pluto and Charon in blue, red, and near-infrared filters that were taken between May 29-June 3, which were then compiled into two color animations that show almost an entire orbital revolution of the double-planet system in a spectacular fashion. The first animation depicts this two-body orbital ballet from a Pluto-centric point of view, where the larger and much brighter Pluto has been digitally centered at the center of the frame, around which Charon revolves gracefully. In contrast, the second animation shows the real orbital tugging that takes place between Pluto and Charon, as both bodies revolve around their common center of mass every 6.8 days.
Even though these latest New Horizons images of Pluto and Charon are unfocused, due to the great distances between 55 and 49 million km from which they were taken, they nevertheless reveal clear brightness variations on Pluto which are indicative of the distant planet’s differentiated dark and bright terrain that have also been seen in previous monochromatic images taken with LORRI. Furthermore, in contrast to the previous black-and-white images, these latest color ones clearly showcase the different shades of both Pluto and Charon, which most probably are indicative of differences in chemical composition. “It’s exciting to see Pluto and Charon in motion and in color,” says Dr. Alan Stern, Principal Investigator for the New Horizons mission at the Southwest Research Institute, in Boulder, Colo. “Even at this low resolution, we can see that Pluto and Charon have different colors—Pluto is beige-orange, while Charon is grey. Exactly why they are so different is the subject of debate.”
Indeed, the exact nature of these color variations is very difficult to be established at this point, requiring a much closer and sharper view of Pluto and Charon system, which will come in the next three weeks as New Horizons gets close enough to image both in high-resolution. “Color observations are going to get much, much better, eventually resolving the surfaces of Charon and Pluto at scales of just kilometers,” said Cathy Olkin, a planetary scientist and deputy project scientist for New Horizons at the Southwest Research Institute. “This will help us unravel the nature of their surfaces and the way volatiles transport around their surfaces. I can’t wait; it’s just a few weeks away!”
For what these high-resolution images will reveal exactly has been the object of much speculation and debate, with hypotheses including that of a possible shared atmosphere between Pluto and Charon, to the possible existence of past liquid water oceans inside Charon billions of years ago. Whatever the case, Ralph’s sharp vision will help to distinguish fact from speculation, while revealing the never-before-seen alien vistas of the two mysterious distant worlds in the process during the next four weeks. “Ralph is the New Horizons mission’s main sense of sight,” says Stern. “Among other things, Ralph will make the maps that show us what Pluto, Charon and Kuiper Belt objects look like. And Pluto is so far from the Sun that Ralph must accomplish this at light levels 1,000 times fainter than daylight at Earth, or 300 times fainter than the conditions Mars probes face.”
It is a safe bet that the next four weeks won’t be lacking in surprises, drama, and excitement.
Stay with AmericaSpace for regular updates and LIVE COVERAGE of New Horizons’ approach and flyby of the Pluto system.