As NASA's New Horizons spacecraft careens through the solar system with Pluto in its cross-hairs, new detail in the dwarf planet's surface is popping into view at an ever increasing rate.
Any images acquired from here on in are the most detailed images humanity has ever seen of Pluto and, a little over a month from its historic flyby, New Horizons is already giving us tantalizing glimpses of what appears to be a rich and complex little world.
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Take, for example, this most recent series of observations captured by the mission's Long Range Reconnaissance Imager (LORRI), which were taken from May 29 to June 2. There appears to be large variations in surface albedo (reflectiveness), possibly indicating there are huge regions of varying composition.
In a recent blog post by Emily Lakdawalla of the Planetary Society, one of these intriguing features on Pluto evokes memories of the earliest days of Mars exploration. The first maps of the Martian surface sketched by astronomers Giovanni Schiaparelli and Percival Lowell in the late 1800′s and early 1900′s included Martian "canali" - features seen in blurry telescopic observations of Mars and interpreted as evidence for a Martian civilization. This speculation was incorrect of course, but it proved that even the earliest Mars observations revealed an alien world with a rich and varied surface.
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But these New Horizons images aren't of Mars, they're of a world nearly 30 times further away from the sun. This is a rocky world that likely has more in common with Neptune's strange moon Triton than anything we've experienced here in the inner solar system. This is pure discovery; we simply do not know what features or strange phenomena Pluto will have on its surface. But from less than 30 million miles, we can only guess, like Schiaparelli and Lowell did over a century ago, as to what these blurry features may be.
Could the dark features represent vast, mountainous regions? Are the bright areas dominated by ice? Can our current knowledge of planetary geology accurately interpret what we are seeing? For now, we have no clue, but we're going to find out soon.
"Even though the latest images were made from more than 30 million miles away, they show an increasingly complex surface with clear evidence of discrete equatorial bright and dark regions-some that may also have variations in brightness," said Alan Stern, New Horizons Principal Investigator of the Southwest Research Institute, Boulder, Colo. "We can also see that every face of Pluto is different and that Pluto's northern hemisphere displays substantial dark terrains, though both Pluto's darkest and its brightest known terrain units are just south of, or on, its equator. Why this is so is an emerging puzzle."
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"We're squeezing as much information as we can out of these images, and seeing details we've never seen before," added Hal Weaver, New Horizons Project Scientists at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We've seen evidence of light and dark spots in Hubble Space Telescope images and in previous New Horizons pictures, but these new images indicate an increasingly complex and nuanced surface. Now, we want to start to learn more about what these various surface units might be and what's causing them. By early July we will have spectroscopic data to help pinpoint that."
Sources: NASA, Planetary Society