Heavenly wanderers

Is it worth being afraid of asteroids?

In the history of the planet, catastrophes associated with boulders flying from space have occurred more than once

Stone guests

According to scientists, asteroids are quite large celestial bodies, smaller than planets, that do not have an atmosphere. Meteorites are even smaller bodies with a diameter of up to 30m and a weight of up to several tens of tonnes. Comets are somewhat similar to asteroids, but have elongated elliptical orbits, which allows them to stay away from the Sun for a long time.
A significant part of the stones flying to our planet from the depths of space burn up without a trace in the atmosphere. However, some still break through the Earth’s shield and end up on its surface. According to scientists’ estimates, every year, about 24,000 stone fragments with a total mass of more than 21 tonnes — and according to NASA, even 48 tonnes — fall on the Earth. Of these, only 800 are boulders weighing over 10kg. At the same time, only 10-20 meteorites are documented falling: most of them are either too small or sink into the oceans altogether, leaving no trace. Such luck — as in the case of the meteorite that fell near Berlin in January this year, when it was possible to film the fall and find the debris — is very rare.
The main components of a ‘successful’ asteroid include high speed, a large angle of entry into the atmosphere and a significant mass. The more impressive these indicators are, the more likely it is that a block of stone will reach the surface of the planet.  

From the darkness of ages

The problem is that occasionally, something much more deadly than a ten-kilogramme boulder falls to the Earth. There are marks on the surface of the planet — astroblemes — reminiscent of ancient catastrophes. 

Research conducted in Antarctica shows that there may potentially be a funnel under the ice shell on Wilkes Land that exceeds the Vredefort crater with a diameter of 300km, which appeared almost two billion years ago on the territory of present-day South Africa. According to scientists, the diameter of the Antarctic astrobleme can be up to 500km. The collision occurred around 250 million years ago, which corresponds to the largest Permian extinction on the Earth, during which 96 percent of all marine life and 73 percent of terrestrial vertebrates disappeared forever.

The Chicxulub asteroid is much more famous. According to many scientists, it was its fall 66 million years ago in the area of the Yucatán Peninsula in present-day Mexico that caused the extinction of dinosaurs. This catastrophe was extremely important for the history of the Earth, probably causing the transition from the Cretaceous to the Paleogene period, and left many traces all over the planet. The most essential of them is in a layer of rocks enriched with platinum group metals rare for the globe. A block of stone with a diameter of 10km collided with the surface at a steep angle of about 60 degrees. After the impact, fragments of rocks scattered for thousands of kilometres, the height of the tsunami waves reached 50-100m, a gigantic cloud of dust rose into the sky, accompanied with soot and carbon monoxide from burning forests. 
All this caused a mini nuclear winter, which could result in the extinction of dinosaurs and the disappearance of many species of flora.

FACT

The Fukang is one of the most beautiful meteorites in history. Found in China in 2000, it consists of an iron-stone mixture interspersed with precious peridot and olivine crystals.

Don’t look up

Messengers from the depths of space do not always appear in the form of gloomy murderers. There are enough examples of how boulders that have fallen to the Earth serve as sources of rare resources, help to better understand the universe, or simply give lucky people a chance to earn a good living.
A vibrant example is the history of the Sudbury Basin in the Canadian province of Ontario. It has become known recently that a great catastrophe occurred there 1.85 billion years ago. Nevertheless, since the end of the 19th century, nickel, copper, gold and platinum group metals have been mined around the crater.

For the sake of all mankind

As knowledge about celestial visitors accumulated and an understanding of the potential danger was formed, the opinion emerged that the Earth needs protection from asteroids.
The space air defence project has already passed its first tests: on September 27th, 2022, the NASA DART probe crashed into the Dimorphos asteroid at a speed of 22,500 km/h at a distance of about 11 million kilometres from the Earth. As a result, there was a successful correction of its trajectory.
Hitting an asteroid with an impact from the Earth is technically possible now, and even the cost of the venture is quite acceptable — the DART mission cost $330m. The main task is to detect the danger in time and give the correct co-ordinates for the kamikaze. 

On the one hand, we already know about many objects potentially hazardous for the Earth; on the other hand, an asteroid like the 111-metre 2018 GE3 was spotted just a few hours before it swept 193,000km away from us.

FACT

The Hoba is the biggest meteorite that has been preserved intact after falling to the Earth. It fell about 80,000 years ago on the territory of present-day Namibia, where it remains to this day. Weighing 66 tonnes, it is the largest piece of naturally occurring iron on the planet.

Asteroids with Belarusian registration

The largest specimen registered in Belarus weighing 303kg was found in 1954 by a tractor driver from the village of Gresk, Slutsk District. Approximately, it fell during the last glaciation of this territory. Today, the extraterrestrial object is located in the museum of the Belarusian Research Geological Exploration Institute (BRGEI).
The date when the Bragin meteorite visited Belarus is known for sure. In the Ipatiev Chronicle for 1144, an entry was found: ‘An omen occurred beyond the Dnieper and Kiev volost — a fireball fell from the sky, leaving a trace in the image of the great serpent’. Fortunately, it exploded five or six kilometres above the Earth and caused no damage. The first reports of the found parts of this iron-stone pallasite date back to 1803, and the last fragments were discovered in 1968. The total mass of the found fragments approximately exceeds 800kg.
Three more Belarusian meteorites were discovered in the villages of Zabrodye, Zhmen and Cherny Bor. The information about another one — the Ruzhany meteorite, which fell on December 7th, 1894 — periodically pops up, yet not a single particle of it has been preserved.
The recent recorded case of a celestial stone flying over the territory of Belarus dates back to May 1st of this year. However, it has not yet been possible to detect fragments of the Bobruisk meteorite.
Another Belarusian trace in meteorite history was left about 42 million years ago, when a seven-hundred-metre giant found its last resting place here, having left a crater with a diameter of 17km. However, during the glaciation, it was almost erased by a gigantic mass of ice and was discovered near the village of Malinovka in Logoisk District only in the mid-1970s when drilling wells. Scientists even assumed that the formation of diamonds could be one of the consequences of the disaster, but, alas, they were not found there.

The threat from outer space is an absolutely real phenomenon. Although disasters caused by a stone mountain that suddenly appeared out of the interplanetary darkness happen once in millions of years, our civilisation had better think about protection systems. Building a ‘planetary air defence system’ would certainly cost much less than is spent today on military preparations around the world, and could become a unifying factor for humanity — no less important than space exploration or the fight against deadly diseases.

By Anton Popov