“Pale Blue Dot” images could track cloud patterns on Uranus and Neptune. "We've got a lot of interesting observations coming up soon, starting in August, and they extend into astrophysics and heliophysics as well as planetary science," said Will Grundy, a New Horizons co-investigator from Lowell Observatory in Arizona. In the months and years ahead, New Horizons' science team plans to look back at Uranus and Neptune-and look ahead into the wide expanse beyond our solar system and our Milky Way galaxy.
"It seems like bladed terrain might be one of the most common landforms on Pluto," Mishra said. Mishra and his colleagues found that the properties associated with the bladed terrain imaged in detail by New Horizons during closest approach-for example, methane absorption and surface roughness-were also present in wider areas on Pluto's "far side." "On Earth, these are about a few meters tall, but on Pluto, these are hundreds of meters tall and form from methane deposits." "This is very reminiscent of 'penitente' on Earth … in the Atacama Desert in Chile, which are these landforms that are formed from sublimation of water-ice deposits," he said. Ishan Mishra, a science team contributor from NASA's Jet Propulsion Laboratory, concentrated on a swath of jagged landforms made almost entirely of methane ice, at the edge of the hemisphere visible to New Horizons at the time of closest approach. Lower image shows features known as penitentes. Upper image shows Pluto’s bladed terrain. "We suggest the possibility is that they formed when Pluto was oriented differently in its early history, and were then moved to their current location by true polar wander." "We're seeing signs of ancient landscapes that formed in places and in ways we can't really explain in Pluto's current orientation," he said in a news release. White pointed to an ancient system of ridges and troughs that might have been Pluto's original equator before true polar wander occurred. The New Horizons team analyzed the distribution of mass on Pluto-and determined that the formation of Sputnik Planitia, a sea of frozen nitrogen that forms part of the dwarf planet's distinctive heart-shaped feature, probably played a key role in the polar flip. But there is a lot we still don't know about true polar wander on Pluto." "The locations of the rotational axes moved hundreds if not thousands of miles-if you imagine, like San Francisco moving to New York on Earth. "Pluto essentially flipped on its side," said Oliver White, a New Horizons co-investigator from the SETI Institute. Planetary scientists say that Pluto's axis of rotation took on a substantial tilt early in its history, and that caused a shift in the latitudes and longitudes of surface features. Stern and his colleagues noted that Arrokoth seemed to have been built up from smaller mounds of icy material, as if a bunch of snowballs were stuck together to form a larger whole. And so, like its brethren across the Kuiper Belt, Arrokoth is very primitive, very unevolved in that deep freeze over all these billions of years." "The ultraviolet radiation out there is much lower than in the inner solar system, and so are the collisional rates. "Because this object is orbiting so far from the sun, it's always been in a deep freeze," Stern explained. It's been 17 years since the piano-sized New Horizons spacecraft was launched toward Pluto and the Kuiper Belt, The primary mission hit its peak in 2015 when the probe zoomed past Pluto, but the adventure moved on to a second act that focused on a smaller, two-lobed object called Arrokoth-a name derived from the Powhatan/Algonquin word for "sky."Īlan Stern, a planetary scientist at the Southwest Research Institute who serves as the mission's principal investigator, said that close study of Arrokoth's structure has yielded fresh insights about the early days of the solar system. Scientists on the New Horizons team shared their latest discoveries, and provided a preview of what's ahead, during this week's Lunar and Planetary Science Conference in The Woodlands, Texas.
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