Asteroid that illuminated the sky in 2008 “once contained water”

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An asteroid that exploded into Earth’s atmosphere in 2008 was part of a much larger space rock that once contained water, a new study shows.

The asteroid, named TC3 in 2008, illuminated Sudan’s sky in October 2008 and rained down the earth with 600 meteorites, collectively known as Almahata Sitta.

After analyzing a fragment of the Almahata Sitta, American researchers found evidence that it came from a large parent asteroid, rich in water, about the size of a dwarf planet – anywhere from 400 to 1,100 miles (640 to 1,800 kilometers) in diameter.

Experts believe that the parent body was formed in the presence of water at intermediate temperatures and pressures, based on the unexpected presence of a type of amphibole crystal.

Scientists in the United States have studied the composition of a small fragment of a meteoroid to determine that it probably came from a previously unknown parent asteroid. This false color micrograph of the meteoroid sample shows the unexpected amphibole crystals identified in orange

Scientists in the United States have studied the composition of a small fragment of a meteoroid to determine that it probably came from a previously unknown parent asteroid. This false color micrograph of the meteoroid sample shows the unexpected amphibole crystals identified in orange

DIFFERENT TYPES OF SPACE ROCKS

a asteroid it is a large piece of stone left over from collisions or the early solar system. Most are located between Mars and Jupiter in the main belt.

A comet it is a rock covered with ice, methane and other compounds. Their orbits take them much farther from the Solar System.

A meteor is what astronomers call a flash of light in the atmosphere when debris burns.

These residues themselves are known as meteoroid. Most are so small that they are vaporized in the atmosphere.

If any of these meteoroids reach Earth, it is called a meteorite.

Meteors, meteoroids and meteorites normally come from asteroids and comets.

Amphiboles have hydroxyl groups in their structure and are considered stable only in environments where water can be incorporated into the structure.

“Our surprising result suggests the existence of a large, water-rich parent body,” said study author Vicky Hamilton of the Southwest Research Institute in Boulder, Colorado.

“Some of these meteorites are dominated by minerals that provide evidence of exposure to water at low temperatures and pressures.

“The composition of other meteorites indicates heating in the absence of water.

“Evidence of metamorphism in the presence of water in intermediate conditions has been virtually absent so far.”

Asteroids – and meteors and meteorites that sometimes come from them – are remnants of the formation of our solar system 4.6 billion years ago.

Most live in the main asteroid belt between the orbits of Mars and Jupiter, but collisions and other events have broken them and expelled debris into the inner solar system.

Almahitta Sitta is named after the location in Sudan above which the space rock exploded in 2008.

The 9-ton asteroid, with a diameter of 13 feet, entered the Earth’s atmosphere and exploded in about 600 meteorites over Sudan.

Witnesses in the town of Wadi Halfa and at a railway station in the Nubian desert, known as “Station Six” or Almahata Sitta in Arabic, reported seeing a “rocket-like fireball” in the sky.

Almahitta Sitta, a type of carbonic chondrite (CC) stone, has been preserved at the University of Khartoum, Sudan since its discovery in 2008.

The diamonds found in the Almahata Sitta meteorite (fragment, pictured) come from a mysterious

The diamonds found in the Almahata Sitta meteorite (fragment, pictured) come from a mysterious “proto-planet” that was about 4.5 billion years ago, just a few million years after sunrise.

CC meteorites are valuable because they record geological activity in the early stages of the solar system and provide insight into the history of the parent body.

CC meteorites also account for only a small proportion – 4.6 percent – of meteorite falls.

“We were given a sample of 50 milligrams of AhS [Almahata Sitta] to study, Hamilton said.

“I mounted and polished the small fragment and used an infrared microscope to examine its composition.”

Spectral analysis identified a number of hydrated minerals, especially tremolite, a rock-forming mineral and a member of the hydrated crystal group called amphibole.

“In essence, this mineral is formed under conditions that these meteorites were not known to have previously experienced,” Hamilton said.

Animation of the 2008 TC3 asteroid that split over Sudan in 2008

‘[This] indicates intermediate temperatures and pressures and a prolonged period of aqueous alteration on a parent asteroid of at least 400 and up to 1,100 miles in diameter. “

Amphiboles are rare in CC meteorites, only previously identified as a trace component in the Allende meteorite – the largest CC ever found on Earth, which illuminated the Mexican sky in 1969.

“Almahata Sitta is a reliable source of information about early materials in the solar system that are not represented by CC meteorites in our collections,” said Hamilton.

The body from which the meteorite came will no longer exist, at least not in its shape with the size of a dwarf planet.

But the materials of asteroids arriving on Earth early may have differed significantly from what is represented by most meteorite collections.

The new study was published in Nature Astronomy.

WHAT IS ALMAHITTA SITTA?

The asteroid – first named TC3 2008 and later named Almahata Sitta after its location in Sudan, where witnesses saw it explode above Earth – was first seen on October 6 at 15:00 GMT.

It was only 20 hours away from the ground – although with an estimated diameter of only 16 feet, it had to disintegrate in the atmosphere and was not a threat.

The 83-ton asteroid was tracked traveling at an estimated speed of 27,739 mph until it disappeared into the shadow of the planet and was then observed exploding in a globe of light as a full moon.

The blast 23 miles above Sudan at 2.45am GMT on October 7 – exactly where and when scientists predicted – was seen by the crew of a KLM plane as flashing over the horizon and was also observed by various satellites .

Witnesses in Wadi Halfa and a railway station in the Nubian desert – “Station Six” or Almahata Sitta in Arabic – reported seeing a “rocket-like fireball”.

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