iceメタンの山か？
冥王星、３千メートル級の山々
2015年7月16日(木)8時52分配信 共同通信 news.nifty.com
2015年7月16日(木)8時52分配信 共同通信 news.nifty.com
【ワシントン共同】
米航空宇宙局（ＮＡＳＡ）は１５日、無人探査機ニューホライズンズが冥王星への接近時に撮影した画像を発表した。
冥王星の地表にある氷でできた高さ約３５００メートルの山々や、衛星カロンに刻まれた長大な崖などが鮮明に捉えられている。
冥王星とカロンには無数の隕石が落下しているはずなのに、表面のクレーターが意外に少ないことも判明。
ＮＡＳＡのチームは
「熱を伴う何らかの地質学的な活動が内部で続いている可能性がある」
と指摘し、今後送られてくる観測データを使った謎の解明に意欲を見せた。
New Horizons Discovers Ice Mountains On Pluto
Posted on July 15, 2015 by Curtiss Thompson
NASA’s New Horizons spacecraft has revealed mountains of ice on Pluto’s surface.
NASA’s New Horizons spacecraft has revealed mountains of ice on Pluto’s surface.
penny4nasa.org/2015/07/15/new-horizons-discovers-ice-mountains-on-pluto/
NASA revealed the first detailed image of Pluto’s surface captured by the agency’s New Horizons spacecraft during a close flyby of the dwarf planet. The image shows a region free of impact craters with mountains of ice rising above its surface.
The surface seen in the first frame of Pluto revealed from New Horizons’ flyby of the dwarf planet shows mountains made of water ice that tower 11,000 feet high.
In addition, the frame shows a complete lack of impact craters on that region of Pluto, indicating a geologically young surface.
Pluto has presumably been impacted by other objects in the solar system for billions of years, causing craters to appear on its surface.
The fact that no craters are visible in this frame of Pluto, which represents less than one percent of the dwarf planet’s surface, indicates that geologic activity may have erased Pluto’s scars.
The first frame of Pluto returned from New Horizons’ closest approach to the dwarf planet shows mountains towering 11,000 feet above Pluto’s surface. Image Credit: NASA / JHUAPL / SwRI
The mountains likely formed within the last 100 million years and may still be building, making them extremely young in the context of the the solar system, which is 4.6 billion years old.
“This is one of the youngest surfaces we’ve ever seen in the solar system,”
said Jeff Moore, member of the New Horizons’ Geology, Geophysics and Imaging Team.
“Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape,” NASA said in a press release.
Methane and nitrogen ice covers much of the surface of Pluto, but according to the New Horizons team these materials are not strong enough to build mountains, leading the mission scientists to believe the mountains are created from a bedrock of water ice.
“At Pluto’s temperatures, water-ice behaves more like rock,”
said Bill McKinnon, deputy lead scientist with New Horizon’s Geology and Geophysics Imaging team.
This close-up image was captured by New Horizons at a distance of 478,000 miles from the surface of Pluto on July 14, approximately 1.5 hours before the spacecraft’s closest approach to the dwarf planet.
The image’s resolution can resolve surface features less than one mile wide.