Infrasonic Detection of Meteorites - Video

Infrasound arrays at an infrasound station at Qaanaaq, Greenland, part of the Nuclear Test Ban Treaty monitoring system 

Credits: CTBT Organization

In the early morning hours of November 17, 1998, a bright fireball was observed over northern New Mexico, about 150km away from Los Alamos.

The bolide was part of the annual Leonid meteor shower. Although the event did not produce any sonic boom reports, it was detected by an infrared radiometer and by an intensified camera located in the state.

Los Alamos National Laboratory (LANL) investigated the sighting in its role as a part of the International Monitoring System (IMS) created following the Comprehensive Test Ban Treaty (CTBT).

LANL found the presence of an infrasonic signal detected by six infrasound arrays. The signal matched the time and the direction of the fireball seen in the sky.

The infrasound recording indicated that the explosion occurred at 93.5 kilometer, matching the measurements from the camera.

The velocity obtained for the bolide from the signal was between 920 and 1150km/s. The meteorite was calculated to have a source energy equivalent to about 1.14 tons of TNT, where source energy is the kinetic energy when the shock wave is produced because of the passage through the atmosphere or the fragmentation of the meteoroid itself.

To detect nuclear explosions, IMS employs infrasound stations using microbarographs (acoustic pressure sensors) to detect very low frequency sound waves.

The investigation conducted by Douglas O. Revelle and Rodney W. Withaker at LANL showed that these detectors could also have been used to detect and measure objects entering the atmosphere.

According to Revelle, an array of low frequency sensors horizontally separated by a few hundred meters to a few kilometers can be used to determine both the direction and the elevation angle of the signals.

The determination uniquely locates the infrasound sources in a three-dimensional space within the atmosphere within certain errors.

Such data are also useful to estimate the frequency of occurrence of certain types of meteoroids. Revelle estimates that an event with the energy level of 10Mt, such as Tunguska, is likely to happen once every 120 years.

However, data from infrasound measurements reported that 30 ±9 large bolides with an energy level of 0.1kt are likely to enter Earth’s atmosphere every year.

The data shows that the number of entering debris increases as the source energy decreases and vice versa.

Historically, the primary source of data collection for reentering objects has always been visual or optical observations.

However, due to the extensive deployment of ILS infrasound sensors, this mode has shown its relevance along with radar and optical observation for the study of meteor physics.

The Los Alamos investigation was one of the first times that infrasound detection has been used to study objects reentering the atmosphere.

Revelle’s pioneering theoretical work on interaction between meteors and atmosphere led the way for future studies.

Vitamin B3: Made in space and delivered to Earth by meteorites

Karen Smith crushes meteorites with a mortar and pestle in Goddard's Astrobiology Analytical Laboratory to prepare them for analysis. Vitamin B3 was found in all eight meteorites analyzed in the study. 

Credit: Karen Smith

Ancient Earth might have had an extraterrestrial supply of vitamin B3 delivered by carbon-rich meteorites, according to a new analysis by NASA-funded researchers.

The result supports a theory that the origin of life may have been assisted by a supply of key molecules created in space and brought to Earth by comet and meteor impacts.

"It is always difficult to put a value on the connection between meteorites and the origin of life; for example, earlier work has shown that vitamin B3 could have been produced non-biologically on ancient Earth, but it's possible that an added source of vitamin B3 could have been helpful," said Karen Smith of Pennsylvania State University in University Park, Pa.

"Vitamin B3, also called nicotinic acid or niacin, is a precursor to NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and likely very ancient in origin."

Smith is lead author of a paper on this research, along with co-authors from NASA's Goddard Space Flight Center in Greenbelt, Md., now available online in the journal Geochimica et Cosmochimica Acta.

Sandra Pizzarello

This is not the first time vitamin B3 has been found in meteorites. In 2001 a team led by Sandra Pizzarello of Arizona State University, in Tempe discovered it along with related molecules called pyridine carboxylic acids in the Tagish Lake meteorite.

In the new work at Goddard's Astrobiology Analytical Laboratory, Smith and her team analyzed samples from eight different carbon-rich meteorites, called "CM-2 type carbonaceous chondrites" and found vitamin B3 at levels ranging from about 30 to 600 parts-per-billion.

They also found other pyridine carboxylic acids at similar concentrations and, for the first time, found pyridine dicarboxylic acids.

"We discovered a pattern – less vitamin B3 (and other pyridine carboxylic acids) was found in meteorites that came from asteroids that were more altered by liquid water. One possibility may be that these molecules were destroyed during the prolonged contact with liquid water," said Smith.

"We also performed preliminary laboratory experiments simulating conditions in interstellar space and showed that the synthesis of vitamin B3 and other pyridine carboxylic acids might be possible on ice grains."

Scientists think the solar system formed when a dense cloud of gas, dust, and ice grains collapsed under its own gravity.

Clumps of dust and ice aggregated into comets and asteroids, some of which collided together to form moon-sized objects or planetesimals, and some of those eventually merged to become planets.

Meteorites yield clues to Martian early atmosphere - Sulphur

A microscope reveals colorful augite crystals in this 1.3 billion-year-old meteorite from Mars, which researchers studied to understand the red planet's atmospheric history. 

Credit: James Day

Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks.

Their study, published April 17 in the journal Nature, shows that the atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year evolution of our solar system.

The results will help guide researchers' next steps in understanding whether life exists, or has ever existed, on Mars and how water—now absent from the Martian surface—flowed there in the past.

Heather Franz

Heather Franz, a former University of Maryland (UMD) research associate who now works on the Curiosity rover science team at the NASA Goddard Space Flight Center, led the study with James Farquhar, co-author and UMD geology professor.

The researchers measured the sulfur composition of 40 Mars meteorites—a much larger number than in previous analyses. Of more than 60,000 meteorites found on Earth, only 69 are believed to be pieces of rocks blasted off the Martian surface.

The meteorites are igneous rocks that formed on Mars, were ejected into space when an asteroid or comet slammed into the red planet, and landed on Earth.

James Farquhar

The oldest meteorite in the study is about 4.1 billion years old, formed when our solar system was in its infancy. The youngest are between 200 million and 500 million years old.

Studying Martian meteorites of different ages can help scientists investigate the chemical composition of the Martian atmosphere throughout history, and learn whether the planet has ever been hospitable to life.

Mars and Earth share the basic elements for life, but conditions on Mars are much less favourable, marked by an arid surface, cold temperatures, radioactive cosmic rays, and ultraviolet radiation from the Sun.

Still, some Martian geological features were evidently formed by water – a sign of milder conditions in the past.

Scientists are not sure what conditions made it possible for liquid water to exist on the surface, but greenhouse gases released by volcanoes likely played a role.

Sulphur, which is plentiful on Mars, may have been among the greenhouse gases that warmed the surface, and could have provided a food source for microbes.

Because meteorites are a rich source of information about Martian sulphur, the researchers analyzed sulfur atoms that were incorporated into the rocks.

In the Martian meteorites, some sulphur came from molten rock, or magma, which came to the surface during volcanic eruptions.

Volcanoes also vented sulphur dioxide into the atmosphere, where it interacted with light, reacted with other molecules, and settled on the surface.

The team's work has yielded the most comprehensive record of the distribution of sulphur isotopes on Mars.

In effect, they have compiled a database of atomic fingerprints that provide a standard of comparison for sulphur-containing samples collected by NASA's Curiosity rover and future Mars missions.

This information will make it much easier for researchers to zero in on any signs of biologically produced sulphur, Farquhar said.

More information: Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars, Nature, DOI: 10.1038/nature13175

Ancient Egyptians Crafted Jewelry From Meteorites

An analysis of this Gerzeh bead showed it was crafted from a space rock.

CREDIT: Open University

An ancient Egyptian iron bead found inside a 5,000-year-old tomb was crafted from a meteorite, new research shows.

The tube-shaped piece of jewelry was first discovered in 1911 at the Gerzeh cemetery, roughly 40 miles (70 kilometers) south of Cairo.

Dating between 3350 B.C. and 3600 B.C., beads found at the burial site represent the first known examples of iron use in ancient Egypt, thousands of years before Egypt's Iron Age and their cosmic origins were suspected from the start.

Soon after the beads were discovered, researchers showed that the metal jewelry was rich in nickel, a signature of iron meteorites but in the 1980s, academics cast doubt on the beads' celestial source, arguing that the high nickel content could have been the result of smelting.

Scientists from the Open University and the University of Manchester recently analyzed one of the beads with an electron microscope and an X-ray CT scanner.

They say the nickel-rich chemical composition of the bead's original metal confirms its meteorite origins.

What's more, the researchers say the bead had a Widmanstätten pattern, a distinctive crystal structure found only in meteorites that cooled at an extremely slow rate inside asteroids when the solar system was forming, according to Nature.

Further investigation also showed that the bead was not molded under heat, but rather hammered into shape by cold-working.

The first record of iron smelting in ancient Egypt comes from the sixth century B.C., and iron artifacts from before that time are quite rare, Nature reported.

"Today, we see iron first and foremost as a practical, rather dull metal," study researcher Joyce Tyldesley, an Egyptologist at the University of Manchester, said in a statement.

"To the ancient Egyptians, however, it was a rare and beautiful material which, as it fell from the sky, surely had some magical/religious properties."

The iron beads' inclusion in burials also suggests this material was deeply important to ancient Egyptians, Tyldesley added.

Strange as the find may seem, it's not the first time scientists have uncovered the cosmic origins of an ancient artifact.

Back in September, German researchers found that a heavy Buddha statue brought to Europe by the Nazis was carved from a meteorite between the eighth and 10th centuries.

They even linked it to a specific space rock — the Chinga meteorite, which scientists believe fell to Earth 10,000 to 20,000 years ago and left a scattering of space rocks around the Siberian and Mongolian border.

The new research on the Egyptian bead was detailed on May 20 in the journal Meteoritics and Planetary Science.

Avoid meteorite fragments: Russian Government tells citicens

Sutter's Mill Meteorite fragments

Russia's authorities on Friday cautioned residents of the Urals to stay away from any unidentified objects after a meteor dramatically burned up above the region, with a precious meteorite apparently plunging into a local lake.

"Russia's emergency ministry warns all residents of the Urals... not to approach unknown objects," the ministry said on its website, listing several numbers for people to use if they found something unusual.

The meteor spectacularly fell early Friday, causing blasts which blew out windows in the city of Chelyabinsk and left almost a thousand people injured.

Televised reports showed footage from the Chebarkul lake, about 60 kilometres from Chelyabinsk, where a circular hole was discovered in the ice, which regional police said was cut by a meteorite.

Local fishermen saw the falling meteor, which disintegrated into seven pieces. "One of them fell on the shore opposite of the (Chebarkul) town, whipping up a pillar of ice, water and steam," the police said in a statement.

"As a result, a giant circular ice hole eight meters (26 feet) in diameter was formed," the report said. Police secured the area and specialists measured radiation, which was normal, it said.

Pictures on the police website showed people standing around looking at the ice hole. One also showed a tiny rock about one centimetre in diameter, laying on ice next to a ruler.

Several such fragments, "hard, black pieces, which look like rock segments," have been recovered, police said.

Classified ad websites quickly had notices put up by enterprising or jestering Russians, offering pieces of the new meteorite for sale. "Two vans of the Chelyabinsk meteorite," said one notice, posted in the "jewelry" section of a Russian website Avito. "Price can be negotiated."

The regional emergency ministry said it had sent people to the Chebarkul area but could not confirm the hole in the ice was caused by an object from space. It also asked people not to panic and keep warm by closing shattered windows with plywood and plastic.

"It's a hole in ice, we have sent a team to inspect (look into) it, but I cannot confirm it's from a meteorite," spokesman of the Chelyabinsk branch of the emergency ministry Vyacheslav Ladonkin told AFP.

NASA Messenger: Mercury's Surface Resembles Rare Meteorites

These image of Mercury by NASA's Messenger probe show the distinctive colour of the planet's northern plains and their surrounding terrain. 

The top image is as Messenger saw the scene, with the bottom image enhanced to bring out features. Image released June 16, 2011. 

CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 

Mercury has a surface unlike any other planet's in the solar system, instead resembling a rare type of meteorite, researchers say.

The finding, based on an analysis of data from NASA's Messenger probe, sheds new light on the formation and history of the mysterious innermost planet, scientists add.

Mercury, the smallest planet in the solar system, is also one of the least understood, having received much less attention from scientific missions than Mars, Jupiter and Saturn.

NASA set out to change that when it launched the Messenger probe a little more than eight years ago. Messenger became the first spacecraft to orbit Mercury.

Past research based on Messenger data suggested a vast part of Mercury is covered with hardened lava, enough to bury the state of Texas under 4 miles (6.4 kilometers) of once-molten rock, scientists said.

All in all, these mammoth floods of lava cover 6 percent of the planet's surface, an area equal to nearly 60 percent of the continental United States.

They created Mercury's smooth northern plains between 3.5 billion to 4 billion years ago.

Credit: NASA/JHUAPL/CIW-DTM/GSFC/MIT/Brown University. Rendering by James Dickson and Jim Head.

Perspective view of ancient volcanic plains in the northern high latitudes of Mercury revealed by NASA's Messenger spacecraft.

Purple colours are low and white is high, spanning a range of about 2.3 km.

Width of area spans about 1200 km. Each line is 5 degrees in latitude and longitude.

Lava plains are common in the solar system.

For instance, young Mars spewed lava all across its surface, and it still has the largest volcano in the solar system: Olympus Mons is about 370 miles (600 km) in diameter, wide enough to cover the entire state of New Mexico, and 16 miles (25 km) high, three times taller than Mount Everest.

Now, 205 measurements of Mercury's surface composition, made by the X-ray spectrometer onboard Messenger, reveal how much Mercury's surface differs from those of other planets in the solar system.

"Being the closest planet to the sun does mean its formation history would be different and more extreme than the other terrestrial planets, with hotter temperatures and exposure to a stronger gravitational field," says lead study author Shoshana Weider, a planetary geologist at the Carnegie Institution of Washington.

The surface is dominated by minerals high in magnesium and enriched in sulfur, making it similar to partially melted versions of an enstatite chondrite, a rare type of meteorite that formed at high temperatures in low-oxygen conditions in the inner solar system.

"The similarity between the constituents of these meteorites and Mercury's surface leads us to believe that either Mercury formed via the accretion of materials somewhat like the enstatite chondrites, or that both enstatite chondrites and the Mercury precursors were built from common ancestors," Weider said.