New color images from NASA's New Horizons spacecraft show two very different faces of the mysterious dwarf planet, one with a series of intriguing spots along the equator that are evenly spaced. Each of the spots is about 300 miles in diameter, with a surface area that's roughly the size of the state of Missouri. The iamge above is a NASA artist’s conception of clouds in Pluto’s atmosphere.
"It's a real puzzle—we don't know what the spots are, and we can't wait to find out," said New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder. "Also puzzling is the longstanding and dramatic difference in the colors and appearance of Pluto compared to its darker and grayer moon Charon."
New Horizons team members combined black-and-white images of Pluto and Charon from the spacecraft's Long-Range Reconnaissance Imager (LORRI) with lower-resolution color data from the Ralph instrument to produce these views. We see the planet and its largest moon in approximately true color, that is, the way they would appear if you were riding on the New Horizons spacecraft. About half of Pluto is imaged, which means features shown near the bottom of the dwarf planet are at approximately at the equatorial line.
Images Pluto below shows two remarkably different sides in these color images of the planet and its largest moon Charon taken by New Horizons on June 25 and June 27. The images were made from black-and-white images combined with lower-resolution color data. The left image shows the side of Pluto that will be seen at highest resolution when New Horizons makes its close approach on July 14. The hemisphere is dominated by a very dark region that extends along the equator. The right image is of the side that faces Charon; the most dramatic feature on this side of Pluto is a row of dark spots arranged along the equator. (The equator appears near the bottom of the images, as only about half of the planet is shown.)
If Pluto has clouds, New Horizons can detect them. Both the high-resolution LORRI imager and the Ralph color imager will be used to look for clouds across the face of Pluto during its approach and departure from the planet. "We're looking for clouds in our images using a number of techniques," said science team postdoc Kelsi Singer of the Southwest Research Institute, "If we find clouds, their presence will allow us to track the speeds and directions of Pluto's winds."
For more than two decades, planetary scientists have raced to get a spacecraft to Pluto against predictions that its atmosphere would disappear—literally freezing onto the surface—before it could be explored. This week, planetary scientists using ground-based telescopes and NASA's SOFIA airborne observatory confirmed that "Pluto's atmosphere is alive and well, and has not frozen out on the surface," according to New Horizons deputy project scientist Leslie Young, Southwest Research Institute, Boulder. Added Young, "We're delighted!"
"The SOFIA observations will also be essential for linking ground-based studies to the results from the New Horizons Pluto encounter for decades to come", said Cathy Olkin, Southwest Research Institute, Boulder, co-investigator on NASA's New Horizons mission.
The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument aboard New Horizons is sending back data daily, sampling the space environment near Pluto. PEPSSI is designed to detect ions (atoms that have lost or gained one or more electrons) that have escaped from Pluto's atmosphere. As they depart, these atoms become caught up in the solar wind, the stream of subatomic particles that emanates from the Sun. PEPSSI's job is to tell scientists about the composition of Pluto's escaping atmosphere and how quickly the atmosphere is escaping.
New Horizons is now less than 9.5 million miles (15 million kilometers) from the Pluto system. The spacecraft is healthy and all systems are operating normally.
The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. The Southwest Research Institute, based in San Antonio, leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
The Daily Galaxy via NASA/New Horizons
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute and JHUAPL/NASA New Horizons