NASA’s nuclear-powered New Horizons spacecraft has turned Pluto from an astronomy object with just a pinpoint of light into a planetary body with surface features and a possible polar ice cap. For the first time, images from the Johns Hopkins Applied Physics Laboratory spacecraft, built near Baltimore, Md., are revealing bright and dark regions on the surface of faraway Pluto—the primary target of the New Horizons close flyby in mid-July.
“After traveling more than nine years through space, it’s stunning to see Pluto, literally a dot of light as seen from Earth, becoming a real place right before our eyes,” said Alan Stern, New Horizons principal investigator at Southwest Research Institute in Boulder, Colo.
“These incredible images are the first in which we can begin to see detail on Pluto, and they are already showing us that Pluto has a complex surface,” Stern said.
According to NASA, the images were captured in early- to mid-April from within 70 million miles (113 million km) of Pluto using the telescopic Long Range Reconnaissance Imager (LORRI) camera on the spacecraft.
ABOVE: These two “movies” show a series of LORRI images of Pluto and Charon taken at 13 different times spanning 6.5 days, from April 12 to April 18, 2015. During that time, the spacecraft’s distance from Pluto decreased from about 69 million miles (111 million kilometers) to 64 million miles (104 million kilometers). Pluto and Charon rotate around a center-of-mass (also called the “barycenter”) once every 6.4 Earth days, and these LORRI images capture one complete rotation of the system. The 3x-magnified view of Pluto highlights the changing brightness across the disk of Pluto as it rotates. Because Pluto is tipped on its side (like Uranus), when observing Pluto from the New Horizons spacecraft, one primarily sees one pole of Pluto, which appears to be brighter than the rest of the disk in all the images. Scientists suggest this brightening in Pluto’s polar region might be caused by a “cap” of highly reflective snow on the surface. The “snow” in this case is likely to be frozen molecular nitrogen ice. New Horizons observations in July will determine definitively whether or not this hypothesis is correct. In addition to the polar cap, these images reveal changing brightness patterns from place to place as Pluto rotates, presumably caused by large-scale dark and bright patches at different longitudes on Pluto’s surface.
A technique called image deconvolution was used to sharpen the raw, unprocessed images beamed back to Earth, the space agency said.
New Horizons scientists interpreted the data to reveal how the dwarf planet has broad surface markings—some bright, some dark—including a bright area at one pole that may be a polar cap.
“As we approach the Pluto system, we are starting to see intriguing features such as a bright region near Pluto’s visible pole, starting the great scientific adventure to understand this enigmatic celestial object,” says John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “As we get closer, the excitement is building in our quest to unravel the mysteries of Pluto using data from New Horizons.”
Also captured in the images is Pluto’s largest moon, Charon, rotating in its 6.4-day-long orbit. The exposure times used to create this image set (a tenth of a second) were too short for the camera to detect Pluto’s four much smaller and fainter moons, said NASA.
Images from the spacecraft will dramatically improve as New Horizons speeds closer to its July rendezvous with Pluto, says NASA. The overall mission cost is about $700 million.
“We can only imagine what surprises will be revealed when New Horizons passes approximately 7,800 miles (12,500 kilometers) above Pluto’s surface this summer,” said Hal Weaver, the mission’s project scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.
The science team believes the spacecraft’s instruments will reveal the composition of rocks even on the sides of craters. Pluto’s surface temperature is estimated to be -380 Fahrenheit, with a basic composition of nitrogen, methane, and carbon monoxide ice.
The National Academy of Sciences believes the New Horizons data will be important to understanding the earliest building blocks of the Solar System, as well as the planetary discs of debris around new stars spotted by the Hubble Space Telescope.
The new images mark the first time that the 1,054-lb spacecraft has returned images of Pluto exceeding the resolution that can be obtained by Hubble.
New Horizons, one of the most beautiful of all planetary spacecraft ever flown, has a 200-watt radioisotope thermoelectric generator (RTG) but uses only 28 watts to run its science instruments.
The instruments are the most compact high performance science devices ever flown on the first reconnaissance of a body in the Solar System, according to the Southwest Research Institute (SwRI) in San Antonio, Texas.
Instrument highlights include:
-LORRI: Developed by SwRI, the Long Range Reconnaissance Imager uses an 20.83-cm aperture telescope to return surface resolutions of about 25 meters. The instrument should reveal features the size of a basketball court.
-Ralph: The visible/infrared imaging spectrometer is to obtain 0.5 km monochromatic images and 1.5 km resolution color imagery and composition data with 7 km resolution. It was developed by Ball Aerospace, SwRI and the Goddard Space Flight Center to search for unknown moons or ring systems aiding navigation toward or away from them.
The main color and infrared camera suite on New Horizons is named after Ralph Kramden of the 1950s television series “The Honeymooners.” It is collocated on the spacecraft with his TV wife Alice.
-Alice: The Ultraviolet Imaging Spectrometer will obtain data on atmospheric composition. Developed by SwRI it is nearly identical to one flying on the European Rosetta comet mission.
-Swap: The SwRI solar wind instrument will measure when Pluto’s tenuous atmosphere begins to interact with the solar wind and characterize the rate which pluto is losing its atmosphere.
-Pepssi: The APL energetic particle detector will also help characterize Pluto’s atmosphere.
-Rex: The APL/Stanford University radio science instrument will use the spacecraft’s 83-inch diameter to obtain atmospheric data and terrain temperatures.
-SDC: The Student Dust Counter, managed by Univ. of Colorado students, has already provided years of educational space instrument experience to students. It will continue to do this for years into the future.
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