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 reveals.
The asteroid, named TC3 in 2008, illuminated the sky of Sudan in October 2008 and watered the earth with 600 meteorites, collectively known as Almahata Sitta.
After analyzing a fragment of Almahata Sitta, American researchers found evidence that it came from a large, water-rich parent asteroid the size of a dwarf planet, anywhere in diameter from 400 to 1,100 miles (640 to 1,800 kilometers).
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.
U.S. scientists studied the composition of a small fragment of a meteoroid to determine that it probably originated from an unknown parent asteroid. This false color micrograph of the meteoroid sample shows the unexpected amphibole crystals identified in orange
Amphiboles have hydroxyl groups in their structure and are considered stable only in environments where water can be incorporated into the structure.
“Our startling result suggests the existence of a large, water-rich mother body,” said study author Vicky Hamilton of Southwest Research Institute in Boulder, Colorado, USA.
“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 aims to heat up in the absence of water.
“Evidence of metamorphism in the presence of water in intermediate conditions has been virtually absent, so far.”
Asteroids – and the meteorites and meteorites that sometimes come from them – are remnants of the formation of our solar system 4.6 billion years ago.
Most reside in the main asteroid belt between the orbits of Mars and Jupiter, but collisions and other events have broken them and ejected debris into the inner solar system.
Almahitta Sitta is named after the location in Sudan on which the space rock exploded in 2008.
The 9-ton, 13-foot-diameter asteroid entered the Earth’s atmosphere and exploded about 600 meteorites over Sudan.
Witnesses from the city of Wadi Halfa and a train stop in the Nubian desert, known as “Station Six” or Almahata Sitta in Arabic, reported that they had seen a “rocket-like fireball” in the sky.
Almahitta Sitta, a type of carbonate chondrite stone (CC), 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 “proto-planet” that was about 4.5 billion years ago, just a few million years after the birth of ground.
CC meteorites are valuable because they record geological activity during the early stages of the solar system and provide information about the history of their parent bodies.
CC meteorites also account for only a small proportion (4.6%) of meteorite falls.
“We were assigned a 50 milligram sample of AHS [Almahata Sitta] study, ”Hamilton said.
“We assembled and polished the small fragment and used an infrared microscope to examine its composition.”
Spectral analysis identified a number of hydrated minerals, in particular tremolite, a rock-forming mineral, and a member of the group of hydrated crystals called amphiboles.
“Basically, this mineral is formed under conditions that were not known to have been experienced by these meteorites,” Hamilton said.
Animation of the 2008 TC3 asteroid that broke over Sudan in 2008
‘[This] indicates intermediate temperatures and pressures and a prolonged period of aqueous alteration in a parent asteroid of at least 400 and up to 1,100 miles in diameter. “
Amphiboles are rare in CC meteorites, as they had only previously been identified as a trace component of the Allende meteorite, the largest CC ever found on Earth, which illuminated the Mexican sky in 1969.
“Almahata Sitta is a source of information about the first materials in the solar system that are not represented by CC meteorites in our collections,” Hamilton said.
The body from which the meteorite came will no longer exist, at least not in its dwarf planet form.
But asteroid materials arriving on Earth early may have differed significantly from what most meteorite collections represent.
The new study has been published in Nature Astronomy.