Impact researcher: Austria needs cameras for meteor watching
The "FRIPON" (Fireball Recovery and InterPlanetary Observation Network) was founded in France a few years ago, said Köberl, who conducts research at the Department of Lithosphere Research at the University of Vienna and chairs the Geosciences Commission (GeoK) of the Austrian Academy of Sciences (ÖAW). There, more than 100 cameras connected to the Internet and recording 30 images per second are already observing the sky. In other European countries and in North Africa, another 50 cameras have been set up. In Austria, there is only one so far, on the roof of the Natural History Museum (NHM) in Vienna, which Köberl had installed there during his time as director general.
Only one camera in operation so far, but six to ten are needed
To cover the whole of Austria, however, six to ten such cameras would be needed, he explained. At a maximum of 2,000 euros, they are not very expensive, but you need electricity at the location, an Internet connection and on-site support. They could be set up, for example, at amateur astronomers or observatories, Köberl said. They would then be supervised by the curator of the NHM's meteorite collection, Ludovic Ferrière, who also looks after the camera at the museum in Vienna. In addition, the ÖAW is cooperating with the Austrian Central Institute for Meteorology and Geodynamics (ZAMG). The ZAMG is in charge of weather stations all over the country, where these conditions would be given. In addition, the ZAMG has infrasound stations for earthquake monitoring, with which the "sound" of larger meteors can be detected.
Not many fireballs have been seen from Austria, Köberl said: "Seven have been detected, four of them observed, and there have been three finds." In April 2020, a fireball was observed that was thought to have struck a small rock in the south of the Eastern Alps near Mürzzuschlag, Styria. However, nothing was found. "You had to search in the forest and in rough terrain, and there was snow right now, so the conditions were far from ideal," he said.
On the other hand, they were successful after a meteor observation in England over Winchcombe on Feb. 28, 2021, which was recorded by the FRIPON cameras (and other observing stations on the island). Eventually, fragments totaling one pound (about 450 grams) in mass were discovered in a meadow. "They ended up on private property, but thankfully were immediately turned over to a museum," Köberl said. Incidentally, as in many other countries, it would be unclear in Austria whether such a chunk of rock from space belongs to the landowners or the general public. "In some countries like Australia, this is clearly regulated by law, where it is very nicely said that it is 'property of the crown,'" the impact researcher said.
Camera records help to locate it
According to the report, camera records can be used to determine where a chunk of rock will land if it doesn't burn up in the atmosphere. "But to do that, you need two to three cameras to capture it so you can triangulate its trajectory," he explained. Admittedly, it's also possible to calculate where it's coming from. "This was first done in 1803 in L'Aigle, France, based on eyewitness accounts, when a meteor shower fell as a shower of stones," the expert said. This made it possible to calculate back that the rocks came from outside the Earth's atmosphere, which was not clear at the time. "People also considered eruptive material from distant volcanoes and accumulations of material in the Earth's atmosphere similar to hailstones until that time," Köberl said.
In addition, the observation of many small fireballs allows extrapolation of how many larger, sometimes dangerous, pieces of rock are floating around in the solar system. "We already know very well the really big objects that are more than half a kilometer in diameter, but we don't know much about those between one and a hundred meters," he explained. From about five meters in diameter, they would be potentially dangerous. "The fireball near Chelyabinsk in Russia on Feb. 15, 2013, was an object just under 20 meters in diameter that came out of the blue," Köberl said. There were 1,500 casualties in the town, just over 60 kilometers away, at the time and probably no fatalities only because the area is not densely populated.
"Observations at the lower end of the mass scale by such observational networks can greatly improve the statistics here, and if you know the small and large objects, you can interpolate how many there are in between," Köberl said, "Then I think we'll be horrified to find that we know only a fraction of them."
The symposium, "Meteors and Meteorites - The International FRIPON Network," is organized by ÖAW and ZAMG and will take place June 30. Click here for the event incl. live stream.