This article examines objects related to the main asteroid belt, describes the history of its discovery, tells how it was formed, how astronomers study these celestial bodies, what attracts earthlings to distant "cold travelers". Relatively recently, the American scientific laboratory of the space department "NASA" reported that the Earth has a new satellite - the asteroid 2016 HO3. It was discovered by astronomer Paul Chodas using the Pan-StaRRs automatic telescope in Hawaii. But it is known that a small planet is too far from the Earth to be called its full satellite. For such asteroids, scientists have a special concept - a quasi-satellite. In 2016, HO3 has been near our planet for about a hundred years and, obviously, is not going to leave its post for several more centuries.
Characteristics of minor planets
At the beginning of the 21st century, astronomers know more than 285 thousand minor planets located in the Great Asteroid Belt. Moreover, a huge amount falls on asteroids with a diameter of 0.7 to 100 km.
The total mass of the asteroid belt in the solar system does not exceed 0.001 of the Earth's mass, most of which falls on 4 objects: Ceres (1, 5 by mass), Pallas, Vesta, Hygea. The volume of the occupied space, where the asteroid belt is located, is much larger than the volume of the Earth - approximately 16 thousand times in cubic kilometers.
As you might expect, such celestial bodies exist without an atmosphere. Studies of changes in regularly alternating brightness have proven that asteroids rotate on their axis. For example, Pallas makes a 360-degree turn in 7 hours 54 minutes.
The stereotype that emerged after watching blockbusters that the asteroid belt is almost impossible to overcome was destroyed by astrophysicists, who provided evidence of a loose concentration of these celestial bodies.
The method developed back in Soviet times for calculating the type of orbits along which meteoroids moved in space before falling to Earth proved that the meteorites came from the asteroid belt. Thus, it became clear that they are pieces of asteroids that broke off in collisions with each other.
It became possible to study in detail the chemical structure of such distant celestial objects without approaching them. Scientists have not identified new chemical elements that have not been discovered on Earth, mainly iron, silicon, oxygen, magnesium, nickel were present in their composition.
By 2014, more than 3000 meteorites, ranging in size from a few grams to ten tons, have been collected worldwide. The largest iron meteorite, Goba, weighing 60 tons, was discovered in Namibia in 1920.
The main types of asteroids
Scientists classify objects in the asteroid belt according to several criteria. The taxonometric classification is based on broadband spectrum and albedo analysis. According to this classification, all planetoids are divided into 3 groups and 14 types:
- First group … Also called primitive. Has changed little since its formation and is therefore rich in carbon and water. The composition of such celestial bodies includes serpintines, chondrites, etc. They are able to reflect up to 5% of sunlight. This group includes Hygea, Pallas.
- Second intermediate group … Includes silicon-bearing debris, accounting for about 17% of all asteroids. Basically, this group is located in the middle of the Main Belt and reflects more light coming from the Sun (about 10-25%).
- Third high temperature group … It includes minor planets, consisting mainly of metals. They are in orbits in the inner belt.
Asteroids are also distinguished by size: depending on the transverse diameter, they can be divided into large and small. The capabilities of modern scientific technology allow astronomers to observe celestial bodies only a few tens of meters in size.
The shapes of asteroids can be different and depend on their size: large - usually round, spherical; smaller ones, which are shapeless lumps. You can come across unique shapes, such as dumbbell-shaped.
Asteroids differ among themselves by the ability to form so-called families. At the beginning of the 20th century, it became known about the existence of a group of planetoids, densely grouped around Eos and moving in one orbit. Today this population includes 4,400 space objects. There are 75-100 such families in the big belt, according to various estimates.
There are asteroids who do not like big companies and prefer loneliness.
Research of the asteroid Vesta
In 1981, a group of scientists in Antarctica discovered a small fragment of an asteroid with unusual magnetic properties. Through paleomagnetic analysis, astronomers have estimated the magnitude of its primordial field. Next, it was necessary to establish the moment of formation of the mineral with the help of argon.
It turned out that this meteorite froze on the molten surface of Vesta. The existence of this "space guest" confirmed that Vesta is more similar to ordinary planets than to asteroids.
Vesta is the third largest asteroid, second only to Ceres and Pallas, and in terms of mass, this small planet is the second. It is only 525 km in diameter. It was only possible to obtain a reliable image of Vesta in 1990 using the latest Hubble telescope.
The chemical composition of the meteorite showed that immediately after its appearance on Vesta, its internal structure began to divide into two main parts: an iron-nickel alloy core and a stone (basalt) mantle.
Almost the entire asteroid is covered with large craters. The first, Reyasilvia, the largest in size, reaches a length of 505 km (the total diameter of Vesta is 525 km) and is named after the legendary mother of Remus and Romulus (founders of Rome).
The second crater resembles a snow woman, consisting of three craters, which are named after the priestesses of the Roman goddess Vesta: the largest is Marcia (diameter - 58 km), the middle one is Calpurnia (50 km); small - Minucia (22 km).
In 2011, NASA launched the DAWN spacecraft into orbit around the minor planet, which means Dawn. With the help of this miracle of technology, scientists managed to get the first photographs of Vesta, as well as calculate its mass by gravitational effects. On September 5, 2012, after completing work on the study of Vesta, the spacecraft left its orbit and was sent to study the largest asteroid - Ceres.
How asteroids can be useful
Everyone knows that the supply of minerals on Earth is not eternal. That is why many scientists around the world are developing devices for mining on asteroids.
Almost all demanded metals can be found on minor planets: gold, nickel, iron, molybdenum, ruthenium, manganese, and many rare earth elements. This arrangement will significantly reduce fuel consumption when delivering ore to the planet.
There are three main types of planetoid mining:
- Extraction of metals on an asteroid and subsequent processing at the nearest station;
- Extraction of minerals on a small planet and processing there;
- Transferring an asteroid to a safe orbit between the Moon and Earth.
A very important object of planned subsequent research for scientists is the asteroid belt itself in the solar system. Therefore, in 2018, Japan plans to implement the Hayabusa-2 project, the USA will launch OSIRIS-REX in 2019, Russia in 2024 - Phobos-Grunt 2.
The Luxembourg government is also keeping pace with the times. In June 2016, a decision was made at the state level to extract minerals and platinum ores located on asteroids. A tidy sum of 200 million euros is allocated for this large-scale project.
Watch a video about the asteroid belt:
Many large commercial firms are very interested in the prospects that extraterrestrial mining promises, because only on Psyche the reserves of iron-nickel ores will not be exhausted for several thousand years.
