June 26, 2015 – NASA’s New Horizons spacecraft doesn’t pass Pluto until July 14 – but the mission team is making new discoveries as the piano-sized probe bears down on the Pluto system.
In a long series of images obtained by New Horizons’ telescopic Long Range Reconnaissance Imager (LORRI) May 29-June 19, Pluto and its largest moon, Charon, appear to more than double in size. From this rapidly improving imagery, scientists on the New Horizons team have found that the “close approach hemisphere” on Pluto that New Horizons will fly over has the greatest variety of terrain types seen on the planet so far. They have also discovered that Charon has a “dark pole” – a mysterious dark region that forms a kind of anti-polar cap.
“This system is just amazing,” said Alan Stern, New Horizons Principal Investigator, from the Southwest Research Institute, Boulder, Colorado. “The science team is just ecstatic with what we see on Pluto’s close approach hemisphere: Every terrain type we see on the planet—including both the brightest and darkest surface areas —are represented there, it’s a wonderland!
“And about Charon — wow — I don’t think anyone expected Charon to reveal a mystery like dark terrains at its pole,” he continued. “Who ordered that?”
New Horizons scientists use a technique called deconvolution to sharpen the raw, unprocessed pictures that the spacecraft beams back to Earth; the contrast in these latest images has also been stretched to bring out additional details. Deconvolution can occasionally produce artifacts, so the team will be carefully reviewing newer images taken from closer range to determine whether some of the tantalizing details seen in these images persist. Pluto’s non-spherical appearance in these images is not real; it results from a combination of the image-processing technique and Pluto’s large variations in surface brightness.
“The unambiguous detection of bright and dark terrain units on both Pluto and Charon indicates a wide range of diverse landscapes across the pair,” said science team co-investigator and imaging lead Jeff Moore, of NASA Ames Research Center, Mountain View, California. “For example, the bright fringe we see on Pluto may represent frost deposited from an evaporating polar cap, which is now in summer sun.”
New Horizons will make its closest approach to the Pluto system on July 14.
Ball Aerospace built the camera (Ralph) that will deliver details of Pluto and Charon we’ve never seen before. Students from the Laboratory for Atmospheric and Space Physics (LASP) in Boulder built the Student Dust Counter, the first student-built instrument to fly on a planetary mission.