A whole Black Beauty from Mars : 無料・フリー素材/写真
A whole Black Beauty from Mars / jurvetson
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | This as close to “unobtainium” as I have found on Earth.An exceptionally unusual shiny black meteorite find was recovered in 2011 in Morocco by Aziz Habibi (I bought it from him). Officially named NWA 7034, it was nicknamed “Black Beauty” by Dr. Carl Agee, Director of the Institute of Meteoritics. A team of scientists led by Agee found a number of marvels in this oldest and rarest of Martian meteorites: it contains the oldest Martian minerals ever dated (formed 4.48 billion years ago), it contains ~ 20x more water than any other Martian samples previously encountered (perhaps formed under an early Martian ocean), it is among the very few martian basalts that do not contain maskelynite (impact-melted plagioclase glass), and it is the only brecciated Martian (i.e., they are composed of angular fragments of different rock types fused together). Carl Agee did an hour-long talk on NWA 7034 here, with a short summary here: "this is a once in a career discovery."These rocks were so novel they were provided a new subtype "Martian (polymict breccia)" in the Met Bull. Moreover, in July 2022, it was determined that Black Beauty most likely originated from the Karratha Crater in Mars’s southern hemisphere; approximately 10 million years ago, the asteroid impact which formed the crater also ejected a large volume of Mars rock into space, some of which perturbed into an Earth-crossing orbit — and it took the long route, a journey of ~15,000 orbits around the Sun before penetrating Earth’s atmosphere.Black Beauty contains relatively large crystals of plagioclase (a calcium-aluminum silicate) and pyroxene (a calcium-magnesium-iron silicate). These large mineral grains are surrounded by fine-grained material that formed from rapidly cooling lava, most likely following a volcanic eruption. Rock and mineral fragments were incorporated into the flow during the eruption, giving the rock its brecciated appearance. Accessory minerals include chlorapatite, chromite, goethite, ilmenite, magnetite, maghemite, alkali feldspar and pyrite. A lay summary of the location news from Physical Org:"Scientists announced Tuesday they had found the crater from which the oldest known Martian meteorite was originally blasted towards Earth, a discovery that could provide clues into how our own planet was formed. The meteorite NWA 7034, nicknamed Black Beauty, has fascinated geologists since it was discovered in the Sahara Desert in 2011.It contains a mix of materials including zircons, which date back nearly 4.5 billion years. "That makes it one of the oldest rocks studied in the history of geology," Sylvain Bouley, a planetary scientist at France's Paris-Saclay University, told AFP.Its journey dates back to the solar system's infancy, "about 80 million years after the planets began forming", said Bouley, who co-authored a new study on the meteorite. Tectonic plates long ago covered up Earth's ancient crust, meaning that "we have lost this primitive history of our planet", Bouley said.But Black Beauty could offer "an open book on a planet's first moments", he added. By measuring Black Beauty's exposure to cosmic rays, they knew it was dislodged from its first home around five million years ago."So, we were looking for a crater that was very young and large," Lagain said. Another clue was that its composition showed it had suddenly heated up around 1.5 million years ago—likely by the impact of a second asteroid.The team then created an algorithm and used a supercomputer to trawl through images of 90 million craters taken by a NASA satellite. That narrowed it down to 19 craters, allowing the researchers to rule out the remaining suspects.They found that Black Beauty was dug up from its first home by an asteroid that struck around 1.5 billion years ago, forming the 40-kilometer Khujirt crater.Then a few million years ago, another asteroid hit not far away, creating the 10-kilometer Karratha crater and shooting the Black Beauty towards Earth.The region in Mars' southern hemisphere is rich in the elements potassium and thorium, just like Black Beauty. Another factor was that Black Beauty is the only Martian meteorite that is highly magnetized. "The region where Karratha was found is the most magnetized on Mars," Lagain said.Known as the Terra Cimmeria—Sirenum province, it is "a relic of the early crustal processes on Mars, and thus, a region of high interest for future missions," the study said."and Space,com summarized how the findings can prioritize the destination for future Mars landings:"The origin of Martian meteorites was an old enigma," Lagain said. Discovering the birthplace of one "is pretty much equivalent to a free sample-return mission," he noted."Now we know that the rock comes from the Terra Cimmeria-Sirenum province," Lagain said. "This region hosts the clues to understand[ing] the first stage of evolution and differentiation of the planet. If one wants to understand how Mars formed and evolved, then we need to analyze this province much more than we do right now."The findings suggest that sending a rover or drone to this region "would help us understand what happened 4.5 billion years ago on Mars," soon after the Red Planet, Earth and the solar system's other rocky worlds were born, Lagain said. This information, in turn, may help "fill the gap in knowledge for the same period of time on Earth."This black beauty is 61 x 33 x 19mm and 55 grams. |
| 撮影日 | 2023-04-02 15:06:02 |
| 撮影者 | jurvetson , Los Altos, USA |
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