Where a person appears, garbage will certainly appear, and space is no exception. According to the American (NORAD, NASA), European (DISCOS, ESA) and Russian (ASPOS OKP) catalogs of space debris, about 20 thousand registered space objects larger than 10 cm are observed in near-earth space. To observe and register smaller debris, it is necessary to create a special spacecraft to monitor fine fractions of space debris.
Space debris is of cosmogenic and technogenic origin. Cosmogenic is called the “building” material of the solar system, for example, micrometeorites, interplanetary or interstellar dust. Man-made is everything that man has created. Man-made space debris is classified into the following categories: small (less than 5 mm), medium (5 mm to 10 cm) and large debris (more than 10 cm).
The most contaminated orbits are: low orbits 300–400 km (space debris lives here for no more than three to four months), 800–1000 km and 1200–1500 km; sun-synchronous orbits, medium orbits (from 2000 km to 35 786 km) and geostationary orbit (35 786 km).
Space debris objects in near-earth space create a real danger of high-speed collisions of functioning vehicles with passive fragments. The reason for the early destruction of the object can be a collision with a particle smaller than 0.1 cm at a speed of 10 km / s. The probability of a collision of a spacecraft with an area of 6 m at an altitude of 900 km is 10 ^ –6 in 90 years. Of course, this probability is still very small, but it will grow every year, because the increase in space debris is 6-12% per year. The greatest likelihood of collisions of spacecraft with space debris exists in low orbits, at an altitude of about 500-1500 km.
Recently, there have been several collisions of cataloged space debris objects.
Collisions of space objects
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There are many ways to counteract space debris: from the most common, such as crushing large space debris, taking space debris out of orbit or taking a spacecraft out of space debris orbit, to less common ones – knocking down debris with a laser or converting it into fuel. It is impossible to use only one countermeasure for all types of space debris. For example, small space debris cannot be caught with a net, and large space debris is useless to stop with gas.
However, basically there are two directions:
– methods of crushing space debris directly in orbit;
– methods of deceleration and removal of large space debris from low orbits for subsequent combustion in the atmosphere or removal of space debris from a geostationary orbit to a disposal orbit.
Moreover, both methods have disadvantages associated with the formation of debris of a finer fraction, the fall of unburned debris to the Earth, and the clogging of higher orbits.
Why not develop a spacecraft that will absorb space debris? Such an apparatus exists. The idea of creating a space debris disposal apparatus is based on processing space debris into pseudo-liquid fuel, which is a mixture of powdered crushed space debris with oxygen and hydrogen. Space debris mainly consists of the materials shown in Fig. 2.
The robotic search system finds the location of the debris to be destroyed, as shown in Fig. 3.
The garbage collector spins the thrusters, folds the fan-shaped solar collector and propels through the debris accumulation, releasing a trap in the form of deformable nets on the tether system. It catches up debris in orbit at an altitude of 800 km and captures it with a net on ropes. The nets consist of triangular links, which, when the net is compressed, form a dense web. Such a structure of networks allows to avoid entanglement of space debris in them, and, consequently, breakdown of the SCM. When space debris is detected, the domed net is automatically released on cables from the telescopic guide beams of the cone-shaped net, capable of pulling the cables back inward. Connecting also by means of cables, the domed and cone-shaped networks form a closed cavity – a garbage collector, which shrinks as space debris enters for disposal. The recycling system consists of the following components: trap, two-roll chopper, drum-ball mill, membrane-electrode unit, water regenerator, control device, fuel tank and motors.
The space debris collector utilizes space debris, converting it into fuel, the use of which allows the spacecraft to gradually rise to higher orbits, up to the disposal orbit (over 40 thousand km), clearing space.
The easiest way to clear space from debris is to suspend space activity for ten years and wait for the Earth’s gravity to do its job, but then humanity will slide, at best, into the 19th century. If we do nothing, then at the current rate of growth of space activity, soon we will simply not be able to launch spacecraft (this phenomenon is called Kessler’s syndrome) and will slide into the same 19th century at best.
Now, in near-earth space, an ecosystem is emerging, in biological terms. In this ecosystem, as in any other, there are creatures that live, feed, perform their functions and, when dying, provide food to other creatures. In space activities, we must also imitate nature. Space debris collectors in the broadest sense of the word can and should become such creatures that “feed on carrion”. But so far 60 years of cosmic duration is a very short time to create a closed ecosystem called “outer space”.
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