Tag Archives: meteorites

Searchers find fragment of asteroid that hit Earth June 2nd

Researchers and local park volunteers in Botswana’s Central Kalahari Game Reserve on July 8 announced the discovery of a fragment from an asteroid that hit the Earth June 2 only eight hours after it was discovered.

“The biggest uncertainty we faced was to determine where exactly the meteorites fell,” says Peter Jenniskens a subject expert of the SETI Institute in California, who traveled to Botswana to assist in the search. He teamed up with Oliver Moses of the University of Botswana’s Okavango Research Institute (ORI), to gather security surveillance videos in Rakops and Maun to get better constraints on the position and altitude of the fireball’s explosion. Team member Tim Cooper of the Astronomical Society of Southern Africa calibrated videos to the south.

After disruption, the asteroid fragments scattered over a wide area, blown by the wind while falling down. Calculations of the landing area were done independently by the NASA-sponsored group headed by Jenniskens, as well as by Esko Lyytinen and Jarmo Moilanen of the Finnish Fireball Network. These calculations were defining the fall area well enough to warrant the deployment of a search expedition.

The first meteorite was found after five days of walking and scouring a landscape of sand, thick tall grass, shrubs and thorn bushes by a team of geoscientists from the Botswana International University of Science and Technology (BUIST), the Botswana Geoscience Institute (BGI) and from ORI, guided by Jenniskens. The Botswana Department of Wildlife and National Parks granted access and deployed their park rangers to provide protection and participate in the search. BUIST student Lesedi Seitshiro was first to spot the stone.

This is only the second time in history that a small asteroid observed in space was recovered following its impact on Earth.

I have amateur astronomer friends who attempted to do this exact thing, here in Tucson. We actually went out one day hunting for a meteorite they had tracked, but were unsuccessful in finding anything. To have had success we would have likely required more search time and a better constraint on the asteroid’s landing zone.

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Boulder-sized asteroid discovered just before it hit Earth

The Catalina Sky Survey, designed to find asteroid with the potential of hitting the Earth, discovered a boulder-sized such asteroid this past weekend just hours before it burned up in the atmosphere.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

The video at the link makes it appear that the asteroid has hit the ground, but that is not what happened.

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Tests confirm meteorite at India impact site

The uncertainty of science: Even as NASA officials poo-poo the suspected meteorite impact in India that killed a bus driver, India scientists have done a chemical analysis of one of the rocks found near the site and found it to be a meteorite fragment.

According to a preliminary report by National College Instrumentation Facility (NCIF) in Trichy, a Scanning Electron Microscope (SEM) study on samples retrieved from the campus in Vellore where the blast occurred shows the “presence of carbonaceous chondrites”.

“Carbonaceous denotes objects containing carbon or its compounds and chondrites refer to non-metallic meteorite parts containing mineral granules,” K Anbarasu, a geologist who is also principal of the Trichy-based National College, told The Indian Express.

There remains uncertainty because the fragments tested did not actually come from the impact crater itself.

Anbarasu said the preliminary SEM study was conducted on “small pieces of black material” found near the blast site. “The crater formed at the spot had been already disturbed by other investigators. So we inspected the entire campus as any meteor incident would scatter several objects across the area before landing. Finally, we spotted several small pieces of this black material, one the size of a paperweight, on the terrace of a building nearby,” Anbarasu said.

Nonetheless, I think it unprofessional and inappropriate for a NASA official to comment on this event half a globe away. There is no way that they can really determine anything from the available photos taken of the impact site, and thus they should shut up.

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Origin of Chelyabinsk meteorite remains unknown

The uncertainty of science: The origin of the Chelyabinsk meteorite that crashed over that Russian city two years ago remains murky to scientists.

Originally, astronomers thought that the Chelyabinsk meteor came from a 1.24-mile-wide (2 kilometers) near-Earth asteroid called 1999 NC43. But a closer look at the asteroid’s orbit and likely mineral composition, gained from spectroscopy, suggests few similarities between it and the Russian meteor.

The scientists noted in their paper that you really can’t use the similarity of orbits to link different asteroids, as their orbits are chaotic and change too much.

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Red tape appears to be preventing the U.S. military from releasing meteorite data obtained by its nuclear test monitoring system.

Red tape appears to be preventing the U.S. military from releasing meteorite data obtained by its nuclear test monitoring system.

Details of atmospheric meteor explosions, as recorded by U.S. military spacecraft sensors, were posted on a publicly accessible NASA website run by the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. In fact, the military-civil cooperation was spurred by the details of the February 2013 fireball explosion over Chelyabinsk, Russia — termed a “superbolide” event. The website postings are designed to assist the scientific community’s investigation of bolides, or exceptionally bright fireballs.

However, multiple scientists noted that the JPL website had not been updated recently. That presumably meant that there was some sort of delay, as some fairly big events were detected by infrasound in the last year. “Because of budget and personnel reductions on our military partner, they ran into workforce issues to accomplish this task,” said Lindley Johnson, NEO program executive within the Planetary Science Division of NASA’s Science Mission Directorate in Washington, D.C.

In other words, it looks like everyone in the military is saying “Ain’t my job, man!” so it doesn’t get done. They need to assign someone the job and be done with it.

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Most Mars meteorites found on Earth may have been blasted here from a single impact on Mars around 3 million years ago.

Most Mars meteorites found on Earth may have been blasted here from a single impact on Mars around 3 million years ago.

This is a great scientific detective story. It has a lot of uncertainties, should definitely be taken with a grain of salt, but is nonetheless very convincing.

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Tests have now shown that at least one bead from an Egyptian tomb was made from a meteorite.

Tests have now shown that at least one bead of jewelry from an Egyptian tomb was made from a meteorite.

The tube-shaped bead is one of nine found in 1911 in a cemetery at Gerzeh, around 70 kilometres south of Cairo. The cache dates from around 3,300 BC, making the beads the oldest known iron artefacts in Egypt.

An early study found that the iron in the beads had a high nickel content — a signature of iron meteorites — and led to the suggestion that it was of celestial origin2. But scholars argued in the 1980s that accidental early smelting efforts could have led to nickel-enriched iron3, while a more recent analysis of oxidised material on the surface of the beads showed low nickel content4.

To settle the argument, Diane Johnson, a meteorite scientist at the Open University in Milton Keynes, UK, and her colleagues used scanning electron microscopy and computed tomography to analyze one of the beads on loan from the Manchester Museum, UK. The researchers weren’t able to cut the precious artefact open, but they found areas where the weathered material on the surface of the bead had fallen away, providing what Johnson describes as “little windows” to the preserved metal beneath.

The nickel content of this original metal was high — 30% — suggesting that it did indeed come from a meteorite. To confirm the result, the team observed a distinctive crystallographic structure called a Widmanstätten pattern. It is only found in iron meteorites, which cooled extremely slowly inside their parent asteroids as the Solar System was forming.

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Planetary scientists reject meteorite fossil paper — without reading it

Richard Kerr of Science is attending the annual Lunar and Planetary Science Conference in Texas, and has written a short article describing the reaction of planetary scientists to the meteorite fossil paper by NASA scientist Richard Hoover. Their reaction, hostile and disinterested, isn’t pretty. These two quotes will give you the flavor:

Whether they have closely examined the paper by astrobiologist Richard Hoover of NASA’s Marshall Space Flight Center or only heard about it in the hallways, the reaction is the same: not again.

Rather than taking a look themselves, researchers have other things in mind. One leading scientist half-jokingly suggested hanging Hoover in effigy in the conference center lobby.

» Read more

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