Since mankind launched the first spacecraft into Earth's orbit, not much time has passed - only a little over sixty years, which is on the scale of our planet. But even in such a short time, we managed to leave many objects in space, large and small. All this is space debris that is in low-Earth orbit and within the solar system. The debris consists of spent stages of spacecraft and probes, spent satellites and their parts, as well as waste from astronauts on the ISS.
It would seem, what are these little things on the scale of space? Nevertheless, all of these objects in near space are of serious concern to scientists. The fact is that even now any space flights are associated with a serious risk: every unwanted object in the path of a spacecraft can cause its death.
The problem exists
Imagine a particle with a diameter of only 1 mm. In fact, this is a grain of sand, on Earth we are unlikely to notice it. In space with its tremendous speeds, such a grain of sand can be a serious problem: if the relative relative velocity of the ship and the particle is several kilometers per second, then in a collision such a seemingly small particle can penetrate the ship's hull to a depth of several millimeters or even centimeters. In 1983, a similar case already took place: a grain of sand less than 1 mm in diameter left a dangerous crack in the window of the American shuttle.
If the particle size exceeds a centimeter, then this is already a deadly weapon that can completely disable the ship. In fact, an object only a centimeter in size can cause damage that would be left on Earth by a grenade or projectile explosion. Moreover, when colliding with large objects, ships and satellites are scattered into fragments, generating even greater pollution of the orbit.
The first case of a large-scale accident due to space debris dates back to July 1996. Then the French satellite at an altitude of about 660 km collided with a fragment of the third stage of the Arian rocket, which, ironically, remained from an earlier French launch.
China is especially worth considering: in 2007, the country tested an anti-satellite missile, which successfully destroyed the Fengyun satellite at an altitude of 865 kilometers. As a result, about 2 thousand new fragments of several centimeters in size appeared in orbit.
According to the latest estimates, there are now about 220 - 300 thousand various man-made objects in the earth's orbit at an altitude of up to 2000 km, the total mass of which exceeds 5 thousand tons. More than 20 thousand objects, the size of which exceeds 5 cm, are constantly monitored. Another half a million smaller particles fly around our planet, but the number of microscopic particles that do not pose a significant danger to spacecraft is beyond counting.
Thus, the amount of debris in orbit is constantly increasing. Soon, experts predict significant difficulties in organizing flights due to the high risk of collisions with small objects in orbit. Well, in the event of a possible accident in outer space, there will be even more debris.
Despite the fact that in practice nobody removes space debris yet, it has been taken into account and tracked a long time ago.Only two countries can now track objects in orbit - Russia and the United States. Of course, everyone would like to see China also on this list - this country is the main polluter of the orbit, supplying about 40% of all garbage there. The second place is taken by the USA with 27.5%, the third - by Russia with 25.5%. The most clogged region of the orbit is closest to the planet. This is due to the fact that it is here that we manifest the most cosmic activity.
Back in 1985, the USSR, through the efforts of the Ministry of Defense and the Academy of Sciences, began to take an interest in space debris issues. Already by 1990, a mathematical model of the pollution of the near-earth space was obtained, as well as some practical data. In the United States, the Outer Space Observation Network deals with the problem. The organization tracks the trajectories of all objects in low-earth orbit more than a couple of centimeters in diameter.
Not so long ago, a group of scientists from the Federal Polytechnic School of Lausanne (Switzerland) announced the launch of a program to create space debris cleaners. The name for the program was chosen quite ambitious and with a claim to leadership - CleanSpace One.
Claude Nicollier, the only Swiss astronaut to have completed four flights so far, believes it is time for countries with space programs to clean up after themselves. CleanSpace One aims to create several models of low-cost, lightweight cleaning satellites. It is planned that the CleanSpace One devices will not exceed 300x100x100 mm in size, and their weight will be only a few hundred grams.
The first two objects to be de-orbited will be two Swiss small satellites. The first one is the Swisscube, launched in 2009 and currently has served its term. It is in orbit, the altitude of which ranges from 630 to 750 km, depending on its section. Another satellite to be de-orbited is the amateur TIsat-1, launched in 2010, orbiting slightly below Swisscube.
After reaching the required altitude, CleanSpace One must use the thrusters to approach one of the facilities selected for disposal. After that, he will put forward special grips that will wrap around him like the tentacles of an octopus. After that, both objects will be de-orbited and burn up in the atmosphere.
According to preliminary estimates, the program for the development and creation of the first examples of space cleaners will cost relatively inexpensively, just over $ 10 million. But do not delude yourself, each CleanSpace One device is capable of removing from orbit only an object comparable in size. So, according to the Swiss, space cleaning remains a rather expensive undertaking. However, scientists are rather optimistic and plan to sell their developments to other countries in the future.
The European Space Association (ESA) has existed for almost four decades, and its predecessor organizations have been around for about half a century. Initially, the association was founded by 10 European countries, but now its permanent members are 20 states. In addition, Canada is a regular contributor to ESA.
On the basis of the association, many different departments have been created, each of which deals with one or another problem related to space. Among them is the Department of Space Debris, which is headed by Heiner Klinkrad. At a recent conference dedicated to this problem, he made a report, according to which the countries that left it in orbit should remove space debris.
"Each country should keep track of the large objects that it puts into space, and be responsible for them after they run out of their resources," says Heiner Klinkrad. "Today ESA has two such problematic objects, and we are looking for opportunities to eliminate them."
By the problem objects Klinkrad meant two large European satellites - Envisat and ERS-1.The first of them was launched in 2002 and is the heaviest of the ESA satellites in history - 8211 kg. By comparison, the potential goals of CleanSpace One seem a little frivolous. For ten years, the satellite successfully performed the tasks assigned to it, until April 8, 2012, communication with it was lost. After unsuccessful attempts to restore it, on May 9 of the same year, the ESA leadership announced the termination of the mission. Since then, the satellite has been in its former sun-synchronous orbit with an average altitude of 790 km.
ERS-1 is a research satellite that was launched back in 1991. Its mass is 2400 kg, and the main task in a sun-synchronous orbit with an altitude of 758 km was to survey the Earth. During its operation, the satellite sent more than 1.5 million photographs and helped make several important scientific discoveries. In particular, it was he who helped discover the subglacial Lake Vostok in Antarctica. On March 10, 2000, the onboard attitude control system failed, after which ERS-1 continues to move in Earth orbit.
Now it is difficult to even approximately estimate how much it will cost to de-orbit such large objects. Nevertheless, ESA believes that the time for active action has already come. If in the near future countries with space programs do not begin to clean up after themselves, then in a couple of years it will become simply impossible to fly into space.
TAMU Space Sweeper
Jonathan Missel, a designer and scientist at the University of Texas, and his colleagues proposed their own way of cleaning near-earth space. The project was named TAMU Space Sweeper, and the developed satellite-cleaner - Sling-Sat. According to Missel, the project is designed to remove space debris from orbit as inexpensively as possible.
The uniqueness of the project is that the satellite will be reusable. Like the Swiss CleanSpace One, it will not have to go into the atmosphere with the garbage and burn there. A special manipulator arm will allow you to catch objects and change their trajectory so that they are sent to burn into the atmosphere, while the Sling-Sat itself will continue to hunt for new garbage. Another unique feature is that the satellite will receive most of its energy from debris, which will make it possible to do without bulky power sources, and, therefore, significantly reduce the cost of launching Sling-Sat from Earth.
The project looks very attractive. But so far there is no exact information about its cost and terms of practical implementation.
Russian view of the problem
The Russian rocket and space corporation Energia is developing its own solution for cleaning near space. At the same time, the project being created will allow not only cleaning the orbit of trash, but also repairing faulty spacecraft. And the approach proposed by Russian specialists is not at all similar to all those presented earlier.
For the project of the space cleaner Energia is developing a special manned spacecraft. The crew of the spacecraft will consist of two cosmonauts, and the maximum flight duration will be about two weeks. During the flight, the repair ship will be able to approach problematic meteorological satellites and Earth remote sensing devices, inspect them, and also carry out repairs. The equipment is expected to make it possible to replace satellite units, refuel them, repair solar panels, and even move satellites to other orbits.
For the repair, special robotic manipulators will be used, the positioning accuracy of which will not be inferior to human hands. In difficult situations, cosmonauts will carry out space walks for repairs. Well, and in the case when the repair is impractical, the ship will allow you to send a satellite to Earth, where it will burn up in the atmosphere.
According to the head of Energia, Vitaly Lopota, in the future it will be possible to provide services for the removal of inoperative satellites from orbit on a commercial basis, and this should be very profitable.Initially, testing will take place in unmanned mode. The first manned flight is scheduled for 2018.