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Oldest Known Rocks Evolved on Earth Are Result of Asteroids, Research Reveals

Meaning these rocks were rare survivors from a very different time on Earth

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Earth's oldest known evolved rocks result of asteroids. Pixabay
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The oldest evolved rocks on Earth are the consequence of asteroids colliding with the the planet 4 billion years ago, an Australian research released on Tuesday revealed.

The study by the Curtin University suggests that the rocks, part of the Acasta Gneiss Complex in northwest Canada, are the result of asteroids smashing into the Earth and melting its crust, allowing evolved, or granitic, rocks to form, reports Xinhua news agency.

What led scientists to suggest that they were formed in this way was firstly, the composition of the rocks is different from the those typical of the Earth’s ancient crust.

“The only known evolved rocks from the Hadean eon are those in northwest Canada, which have chemical compositions clearly distinct from those that dominate ancient continental crust worldwide, suggesting they were formed in a different way,” research co-author professor Phil Bland said.

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Meaning these rocks were rare survivors from a very different time on Earth. Pixabay

Secondly, the rocks were melted at very low pressures, equivalent to the uppermost few kilometres of crust, meaning the event happened closer to the Earth’s surface.

“The melting of these rocks at such shallow levels is most easily explained by meteorite impacts, which would have supplied the energy to attain the extreme temperatures required for melting,” lead researcher Tim Johnson said.

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This period, around 4 billion years ago, was dominated by a barrage of asteroid impacts that would have caused widespread melting and recycling of the Earth’s surface.

“Consequently, there are almost no rocks preserved from Earth’s formative Hadean eon,” Bland said.

Meaning these rocks were rare survivors from a very different time on Earth. (IANS)

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Earth’s Melting Ice Can Now Be Tracked By The Satellite That NASA Is Launching

The ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), completing an orbit around Earth in 90 minutes.

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NASA to launch satellite tracking Earth's melting ice on Saturday Pixabay

NASA is set to launch its Ice, Cloud and land Elevation Satellite-2, or ICESat-2 — that will track Earth’s melting poles and disappearing sea ice — on Saturday.

The satellite with a three-year mission is scheduled to launch at 8.46 a.m. EDT on September 15, with liftoff aboard a Satellite Delta II rocket from Space Launch Complex-2 (SLC-2), the US space agency said in a blog post late on Tuesday.

ICESat-2 is the NASA’s most advanced laser instrument — the Advanced Topographic Laser Altimeter System, or ATLAS.

It measures height by precisely timing how long it takes individual photons of light from a laser to leave the satellite, bounce off Earth and return to the satellite.

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ICESat-2 will measure the average annual elevation change of land ice covering Greenland and Antarctica. Flickr

The satellite will provide critical observations of how ice sheets, glaciers and sea ice are changing, leading to insights into how those changes impact people where they live, NASA said.

ICESat-2’s orbit will make 1,387 unique ground tracks around Earth in 91 days and then start the same ground pattern again at the beginning.

While the first ICESat satellite (2003-09) measured ice with a single laser beam, ICESat-2 splits its laser light into six beams making it better to cover more ground (or ice).

The arrangement of the beams into three pairs will also allow scientists to assess the slope of the surface they are measuring, NASA said.

NASA
ICESat-2 is the NASA’s most advanced laser instrument Pixabay

Further, the ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), completing an orbit around Earth in 90 minutes. The orbits have been set to converge at the 88-degree latitude lines around the poles, to focus the data coverage in the region where scientists expect to see the most changes.

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All of those height measurements result from timing the individual laser photons on their 600-mile roundtrip between the satellite and Earth’s surface – a journey that is timed to within 800 picoseconds, NASA said. (IANS)