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July 15, 2015

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New photos reveal “ice” mountains on Pluto, deep canyons on its moon

July 15, 2015
Courtesy of NASA
and World Science staff

Pluto (Image Credit: NASA-JHUAPL-SwRI)


Pho­tos just re­leased in con­nec­tion with a NASA space­craft’s fly­by of Plu­to show what sci­en­tists be­lieve to be moun­tains of ice on that frig­id, dark dwarf plan­et.

Mean­while, in sep­a­rate im­ages, its larg­est moon, Char­on, sports cliffs and can­yons es­ti­mat­ed as four times deeper than the Grand Can­yon.

Plu­to’s ge­ol­o­gy ap­pears quite un­ique—a patch­work of dif­fer­ent types of sur­faces whose na­ture will take a while to fully un­der­stand, agen­cy sci­en­tists said.

NASA’s New Hori­zons space­craft, the first to visit the Pluto system, passed with­in 7,800 miles (12,500 km) of Plu­to the morn­ing of July 14, but took these pho­tos shortly be­fore its clos­est ap­proach. Plans call for more pho­tos with much bet­ter de­tail to ar­rive in days ahead.

Close-ups of a re­gion near Plu­to’s equa­tor re­vealed a range of moun­tains as high as 11,000 feet (3,500 me­ters). The moun­tains likely formed no more than 100 mil­lion years ago—mere young­sters rel­a­tive to the 4.56-bil­lion-year age of the so­lar sys­tem—and may still be grow­ing, said Jeff Moore of New Hori­zons’ Ge­ol­o­gy, Geo­phys­ics and Im­ag­ing Team. 

Charon (Credit: NASA-JHUAPL-SwRI)


That sug­gests the re­gion in the close-up, which co­vers less than one per­cent of Plu­to’s sur­face, may still be ge­o­log­ic­ally ac­tive to­day, he added. 

Moore and his col­leagues base the youth­ful age es­ti­mate on the lack of craters. 

Like the rest of Plu­to, they rea­son, this re­gion would pre­sumably have been pum­meled by space de­bris for bil­lions of years and heavily cratered—un­less re­cent ac­ti­vity had giv­en the re­gion a facelift, eras­ing the pock­marks.

“This is one of the youngest sur­faces we’ve ev­er seen in the so­lar sys­tem,” said Moore. 

It’s un­cer­tain where the en­er­gy pow­er­ing this ge­o­log­ical ac­ti­vity comes from; un­like the icy moons of gi­ant plan­ets, Plu­to can’t gain heat from gravita­t­ional in­ter­ac­tions with a much larg­er plan­etary body, the sci­en­tists said.

“This may cause us to re­think what pow­ers ge­o­log­ical ac­ti­vity on many oth­er icy worlds,” said John Spen­cer of the South­west Re­search In­sti­tute in Boul­der, Co­lo., dep­u­ty team lead­er of the Ge­ol­o­gy, Geo­phys­ics and Im­ag­ing Team.

The moun­tains are probably made of Plu­to’s water-ice “bedrock,” the sci­en­tists added.

Al­though meth­ane and ni­tro­gen ice cov­er much of Plu­to, these ma­te­ri­als aren’t strong enough to build the moun­tains, and stiffer water-ice is thought to be their chief com­po­nent. “At Plu­to’s tem­per­a­tures, water-ice be­haves more like rock,” said Bill McK­in­non of Wash­ing­ton Uni­vers­ity, St. Lou­is, al­so a dep­u­ty lead­er of the team.

The close-up was tak­en about 1.5 hours be­fore New Hori­zons clos­est ap­proach to Plu­to, when the craft was 478,000 miles (770,000 kilome­ters) from the sur­face of the plan­et. The im­age easily re­solves struc­tures smaller than a mile across.

Mean­while, de­tails of Plu­to’s larg­est moon Char­on ap­pear in an im­age from New Hori­zons’ Long Range Re­con­nais­sance Im­ag­er cam­era, tak­en late on July 13 from a dis­tance of 289,000 miles (466,000 kilome­ters). Char­on is not cov­ered in water-ice like Plu­to, and it’s un­clear why it’s so dif­fer­ent, agen­cy sci­en­tists said.

A swath of cliffs and troughs stretches about 600 miles (1,000 kilome­ters) from left to right, sug­gest­ing wide­spread frac­tur­ing of Char­on’s crust, likely a re­sult of in­ter­nal pro­cesses, the sci­en­tists said. At up­per right, along the moon’s curv­ing edge, is a can­yon es­ti­mat­ed to be 4 to 6 miles (7 to 9 km) deep.

Mis­sion sci­en­tists said they were sur­prised by the ap­par­ent lack of craters on that moon. This again in­di­cates a rel­a­tively young sur­face re­shaped by ge­o­log­ic ac­ti­vity, they said. 

Near the north pole, a dark mark­ing has a blur­ry bound­a­ry, sug­gest­ing it’s a thin de­pos­it of dark ma­te­ri­al. Un­der­ly­ing it is a dis­tinct, sharply bound­ed, an­gu­lar fea­ture, mys­te­ri­ous for now. An “un­com­pressed” and thus more de­tailed ver­sion of the im­age still lies in New Hori­zons’ com­put­er mem­o­ry and should reach Earth at a lat­er date, bring­ing more in­forma­t­ion, re­search­ers said. The im­age was com­bined with col­or in­forma­t­ion ob­tained by New Hori­zons’ Ralph in­stru­ment on July 13.

The piano-sized New Hori­zons space­craft was launched in 2006 and trav­eled more than three bil­lion miles over nine-and-a-half years to reach the Plu­to sys­tem.


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Photos just released in connection with a NASA spacecraft’s flyby of Pluto show what scientists believe to be mountains of ice on that frigid, dark dwarf planet. Meanwhile, in separate images, its largest moon, Charon, sports cliffs and canyons estimated as four times deeper than the Grand Canyon. Pluto’s geology appears quite unique—a patchwork of different types of surfaces whose nature will take a while to fully understand, agency scientists said. NASA’s New Horizons spacecraft passed within 7,800 miles (12,500 km) of Pluto the morning of July 14, but took the photos shortly before its closest approach. Plans call for more photos with much better detail to arrive in days ahead. Close-ups of a region near Pluto’s equator revealed a range of mountains as high as 11,000 feet (3,500 meters). The mountains likely formed no more than 100 million years ago—mere youngsters relative to the 4.56-billion-year age of the solar system—and may still be growing, said Jeff Moore of New Horizons’ Geology, Geophysics and Imaging Team. That suggests the region in the close-up, which covers less than one percent of Pluto’s surface, may still be geologically active today, he added. Moore and his colleagues base the youthful age estimate on the lack of craters. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered—unless recent activity had given the region a facelift, erasing the pockmarks. “This is one of the youngest surfaces we’ve ever seen in the solar system,” said Moore. It’s uncertain where the energy powering this geological activity comes from; unlike the icy moons of giant planets, Pluto can’t gain heat from gravitational interactions with a much larger planetary body, the scientists said. “This may cause us to rethink what powers geological activity on many other icy worlds,” said John Spencer of the Southwest Research Institute in Boulder, Colo., deputy team leader of the Geology, Geophysics and Imaging Team. The mountains are probably made of Pluto’s water-ice “bedrock,” the scientists added. Although methane and nitrogen ice cover much of Pluto, these materials aren’t strong enough to build the mountains, and stiffer water-ice is thought to be their chief component. “At Pluto’s temperatures, water-ice behaves more like rock,” said Bill McKinnon of Washington University, St. Louis, also a deputy leader of the team. The close-up was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 478,000 miles (770,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across. Meanwhile, details of Pluto’s largest moon Charon appear in an image from New Horizons’ Long Range Reconnaissance Imager camera, taken late on July 13 from a distance of 289,000 miles (466,000 kilometers). Charon is not covered in water-ice like Pluto, and it’s unclear why it’s so different, agency scientists said. A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) from left to right, suggesting widespread fracturing of Charon’s crust, likely a result of internal processes, the scientists said. At upper right, along the moon’s curving edge, is a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep. Mission scientists said they were surprised by the apparent lack of craters on that moon. This again indicates a relatively young surface reshaped by geologic activity, they said. Near the north pole, a dark marking has a blurry boundary, suggesting it’s a thin deposit of dark material. Underlying it is a distinct, sharply bounded, angular feature, mysterious for now. An “uncompressed” and thus more detailed version of the image still lies in New Horizons’ computer memory and should reach Earth at a later date, bringing more information, researchers said. The image was combined with color information obtained by New Horizons’ Ralph instrument on July 13. The piano-sized New Horizons spacecraft was launched in 2006 and traveled more than three billion miles over nine-and-a-half years to reach the Pluto system.