In 1957, the Soviet Union launched the first artificial Earth satellite into space, thus opening a new era in the history of mankind - the era of space exploration. Over the past 50 years since then, man has sent into space a huge variety of satellites, rockets, scientific stations. All this led to the systematic pollution of outer space around our planet. According to NASA, as of July 2011, 16,094 objects of artificial origin were "spinning" around the Earth, including 3,396 functioning and already failed satellites, as well as 12,698 upper stages, spent stages of launch vehicles and their debris. The presented document states that in terms of the number of objects of artificial origin in low-earth orbit, Russia is in first place - 6075 objects, of which 4667 are space debris, followed by the United States, China, France, India and Japan.
The size of the debris that are in low-Earth orbit varies quite widely, from microparticles to the size of a school bus. The same can be said for the mass of this garbage. Large fragments can weigh up to 6 tons, while small particles weigh only a few grams. All these objects move in space in different orbits and at different speeds: from 10 thousand km / h to 25 thousand km / h. Moreover, in the event of a collision of such pieces of space debris with each other or with any satellite moving in opposite directions, their speed can reach 50 thousand km / h.
According to Alexander Bagrov, senior researcher at the Research Institute of Astronomy of the Russian Academy of Sciences, a paradoxical situation is emerging today. The more vehicles mankind launches into space, the less suitable it becomes for use. Spacecraft fail every year with enviable regularity, the result of which is that the amount of debris in Earth's orbit is increasing by 4% annually. At present, up to 150 thousand different objects with sizes from 1 to 10 cm rotate in the earth's orbit, while particles, the size of which is less than 1 cm in diameter, are simply millions. At the same time, if in low orbits up to 400 km, space debris is slowed down by the upper layers of the planet's atmosphere and after a certain time falls to the Earth, then it can be in geostationary orbits for an infinitely long amount of time.
Rocket boosters, which are used to launch satellites into Earth orbit, contribute to the increase in space debris. About 5-10% of the fuel remains in their tanks, which is very volatile and easily turns into steam, which often leads to quite powerful explosions. After a number of years in space, the rocket stages that have served their time explode into pieces, scattering around themselves a kind of "shrapnel" of small fragments. Over the past few years, about 182 such explosions have been recorded in near-Earth space. So only one explosion of a stage of an Indian rocket caused the formation of 300 large debris at once, as well as countless numbers of smaller, but no less dangerous space objects. Today, the world already has the first victims of space debris.
So in July 1996 at an altitude of about 660 km. the French satellite collided with a fragment of the 3rd stage of the French Arian launch vehicle, which was launched into space much earlier. The relative speed at the moment of collision was about 15 km / s or 50 thousand km / h. Needless to say, the French experts, who missed the approach of their own large object, bite their elbows for a long time after this story. This incident did not turn into a major international scandal, since both objects colliding in space were of French origin.
That is why the problem with space debris today does not need additional exaggeration. You just need to keep in mind the fact that at the current pace, in the near future, a significant part of the earth's orbit will not be the safest place for spacecraft. Realizing this, researcher Jonathan Missel, who is at the Texas Agricultural University, believes that all existing methods of cleaning up space debris have at least one of two diseases in common. They either involve carrying out missions "One piece of space debris - one scavenger" (which is very expensive), or they involve the creation of technologies, which will take more than a decade to fine-tune. Meanwhile, the number of victims of space debris is only growing.
Realizing this, Jonathan Missel proposes to upgrade the One Piece of Space Junk - One Scavenger concept to reusable. The TAMU Space Sweeper with the Sling-Sat satellite, developed by him together with his colleagues, is equipped with special customizable "arms". Such a satellite, after its approach to space debris, captures it with a special manipulator. At the same time, due to different motion vectors, the Sling-Sat begins to spin, but thanks to the adjustable tilt and length of the "arms", this maneuver is completely controlled, which allows, rotating like a soccer ball, meaningfully change its own trajectory, sending a "sling satellite" towards the next pieces space debris.
At the moment when the satellite is on the trajectory towards the second space object, the first element of space debris is released by it during rotation. Moreover, this will happen at such an angle that a sample of space debris is guaranteed to crash into the atmosphere of our planet, burning in it. Having reached the second object of space debris, this satellite will repeat the operation done and will do so every time, while receiving an additional charge of kinetic energy from space debris and at the same time, sending it back to Earth to the planet that gave rise to it.
It is worth noting that this concept is somewhat reminiscent of the method of the ancient Greek long jumpers, who did this with dropping dumbbells (for additional acceleration). True, in this particular case, space debris objects will have to be caught and thrown on the fly, whether TAMU Space Sweeper will cope with this is an open question.
TAMU Space Sweeper
The performed computer simulation shows that the proposed scheme has a high theoretical fuel efficiency. And this is understandable: in the case of a "sling satellite", the energy is supposed to be taken from pieces of satellites and rockets that have already been accelerated to the 1st cosmic speed for a long time, and not from the fuel that would have to be delivered to our garbage collector from the Earth.
Of course, the concept presented by Missel has some bottlenecks. It is worth noting that none of the pieces of space debris, naturally, is suitable for a manipulator trap and, most importantly, for high accelerations during intensive rotation. In the event that the piece is too large and heavy, its energy during rotation may be sufficient to destroy itself, as well as the manipulator. At the same time, the creation of a large number of others instead of one object of space debris is unlikely to lead to an improvement in the situation in space in low Earth orbits. At the same time, of course, the idea is seen as interesting, and in the case of adequate technical implementation - effective.
