A team of researchers from the United Kingdom has rounded up a new figure for the number of space rocks that fall to Earth every year. The amounts are in excess of 16,000 kilograms (35,273 pounds) for a meteorite material of more than 50 grams (1.7 ounces) in mass.
“The vast, vast majority of objects to hit the Earth are really small,” explained Dr. Geoff Evatt, a mathematician at the University of Manchester. “We’re talking about objects for which, when they strike the ground, the fragments sum together to over 50g. So, typically, 50g-10kg in total. Objects bigger than this are very, very infrequent.”
Exploring the Stranding Zones for Meteorites
One of the results of the research, conducted in collaboration with fellow scientists from Cambridge University, Imperial College London, and the British Antarctic Survey, is that it makes it possible for a risk evaluation to be made globally.
This unveils that the number of falls at the extremities is around 60 percent of what we would get at the equator. It details why there’s the requirement to put any long-term contingency facilities at higher latitudes. For instance, The Global Seed Vault, which intends to get copies of Earth’s plants in case of a crisis, is located at 78 degrees North of the Svalbard archipelago.
The new figures, published in the journal Geology, came out of the project to carry out the first U.K.-dedicated meteorite quest in the Antarctic. Scientists involved in that program wanted to ensure that they would visit the most prolific areas to perform the hunt. Researchers usually go to regions where the movement of the ice sheet focuses on the meteoritic material, also known as stranding zones.
A Reliable Flux of Falls Per Year
Dr. Evatt and teammates figured how many objects should be in their selected area, a place named the Outer Recovery Ice Fields, which is close to the Shackleton range of mountains in East Antarctica. They found about 120 meteorites in two systematic hunts during 2019 and 2020.
However, figuring out a reliable flux for the number of falls in their chosen region, the team realized they could employ this knowledge to fix a global assessment. This included orbital mechanics, which involves the way Earth’s gravity will pull in nearby passing material, to understand how rates might differ by latitude. The model produced an overall total of about 17,000 falls per year.
“Satellites monitor these explosions in the sky, working out the energy of the events and also the longitude and latitude of where they happen. And from this, you can see how they vary across the globe with latitude, and very nicely, the curve you get from these fireballs fits with what we independently modeled using an applied mathematical approach,” explained Dr. Evatt.