In the next few days, “Kosmos-482” will fall to Earth. This is the name given to the descent capsule of the Soviet Venera 8 duplicate spacecraft launched in 1970. After the upper stage crashed, it remained in Earth orbit. And now, 55 years later, the spacecraft is returning to Earth.
The Kosmos-482 capsule is equipped with heat shielding, so it is very likely to survive re-entry into the atmosphere and reach the surface. Since its mass is about 500 kilograms, the fall of such an object is potentially dangerous. If Kosmos-482 were to fall in a populated area, it could cause damage and even loss of life.
Of course, the probability of such an outcome is low and is estimated at 1 in 10 thousand. But it is still different from zero. At the same time, because of many different factors, even now it is impossible to predict where exactly the device will fall. Any specific forecast will be possible only on the last turns before entering the atmosphere.
On the occasion of Kosmos-482’s imminent de-orbit, the editors of Universe Space Tech look back at the most famous cases of uncontrolled space debris falling out of orbit, from huge orbital stations to satellites with nuclear reactors.
Kosmos-482
Of all the cases of space debris falling to Earth, the story of Kosmos-954 has gone down in history as the most dangerous. The fact is that under this faceless name was a Soviet spy satellite of the US-A series, equipped with a nuclear reactor.
In a normal situation, after operation completion, such vehicles’ reactors would be separated and then taken to a disposal orbit. However, in the case of Kosmos-954, everything went quite differently. The apparatus failed only a month after launch, which made it impossible to bury the reactor. The altitude of its orbit began to decline rapidly, and where exactly “Kosmos-954” would fall was unknown. After the Western press became aware of what had happened, it dubbed the upcoming satellite fall “Russian roulette”.
Canada was not so lucky. On January 24, Kosmos-954 crashed in the sky over the north of the country: its debris fell on an area of about 124 thousand km2. Fortunately, it was a sparsely populated area. During the subsequent search operation, over a hundred fragments with a total mass of over 65 kg were collected. The radioactivity of some of them was up to 200 roentgens per hour.
A loud scandal erupted. As usual, the USSR did not want to take any responsibility for what had happened. But in the end, it still had to pay Canada 3 million Canadian dollars to compensate for the costs of eliminating the consequences of the fall of “Kosmos-954”. Also, the USSR had to give up launching such satellites for almost three years and seriously improve its radiation safety system.
Skylab
The Skylab orbital station was launched in 1973. It had a unique design. The fact is that Skylab was built based on the upper stage of the Saturn 1B rocket. Thanks to this, it had a huge internal volume, which the current inhabitants of the ISS. The length of Skylab was 24.6 meters, the diameter – 6.6 meters, mass – 77 tons.
In 1973-1974, the station received three expeditions, after which it was mothballed. It was assumed that after the beginning of the shuttle flight, its operation would be continued. NASA calculations showed that the Skylab orbit had sufficient altitude margin for the station to remain in space until the early 1980s.
These calculations turned out to be wrong. NASA seriously underestimated solar activity, which caused Skylab to lose altitude much faster than expected. At some point, it became clear that the station would fall before the shuttles start flying.
As in the case of Kosmos-954, the impending fall of Skylab was actively covered by the Western press. T-shirts with its image, “Skylab repellents” (with a money-back guarantee) were on sale, and the San Francisco Examiner newspaper offered a prize of 10,000 dollars for the first piece of debris delivered to its office.
On July 11, 1979, Skylab entered the atmosphere. NASA again miscalculated – it was assumed that the station would fall into the ocean 1300 km south of Cape Town. In reality, its wreckage fell in Western Australia. Fortunately, it was a sparsely populated area, so the fall did not hurt anyone. Local authorities even issued NASA a symbolic fine of 400 dollars for littering – it was paid only in 2009. As for the found wreckage of the station, they are now mostly exhibited in various museums.
Salyut 7
The history of Salyut 7 is somewhat similar to that of Skylab. The station was launched in 1982. It received several expeditions, was almost lost in an accident, and was then repaired.
In 1986, a decision was made to mothball Salyut 7. The plan was to study how a long stay in space would affect the orbital complex. In the future, it was planned to send a manned expedition to Salyut 7 on Buran, which would examine the station in detail and deliver the results of experiments to Earth.
However, as in the case of Skylab, Salyut 7 did not wait for the arrival of the cruise ships. The Buran programme was shut down shortly after the first flight in 1988. And, like their NASA colleagues, Soviet scientists underestimated solar activity. Because of it, the station’s altitude began to drop rapidly, and due to the depletion of fuel reserves, engineers had no way of controlling where it would fall.
“Salyut 7” fell out of orbit on the night of February 6-7, 1991. The wreckage of the 19-ton complex fell in sparsely populated areas of Chile and Argentina. Some of them were later found by residents.
Tiangong-1
Launched in 2011, Tiangong-1 was China’s first orbital station. It was used to develop technologies that were then used to build the larger, multi-module station that is now in orbit.
Source: Fraunhofer FHR
During its lifetime, Tiangong-1 received two visiting expeditions, after which it was used for data collection and technology testing. In 2016, the TsUP lost communication with it, making it impossible to control the station’s descent from orbit.
The 8.5-ton station re-entered the atmosphere on April 2, 2018. In a strange irony of fate, its wreckage fell exactly where it should have if China had been concerned in advance about the safe disposal of the complex: in a non-navigable area of the Pacific Ocean used as a graveyard for space equipment.
The stage of the Changzheng 5B rocket
As a rule, the central (first stages), which are the largest component of launch vehicles, do not reach the first space velocity and return to Earth immediately after launch. The approximate areas where they fall are closed in advance to air traffic and shipping.
However, China’s Changzheng 5B rocket (currently the most powerful carrier at Tianxia’s disposal) is an exception. In missions involving the launch of cargo into low-Earth orbit, its center stage gains enough speed to stay in space for a short time, which causes a lot of problems.
The fact is that the center stage of “Changzheng 5B” has very impressive dimensions. Its length is 30 meters, diameter – 5 meters, mass (without fuel) – about 21 tons. The latter figure is comparable to the mass of the same station, “Salyut 7”. At the same time, the engines of “Changzheng 5B” cannot re-ignite. And this means that engineers do not have the opportunity to take it out of orbit over a pre-selected area. As a result, the place where the stage falls turns into a kind of lottery.
So far, such situations have happened several times. Thus, on May 11, 2020, a 12-meter fragment of a step fell on a village in Ivory Coast. Fortunately, there were no casualties. The next time the Changzheng 5B central stage made an uncontrolled re-entry into the atmosphere was on July 31, 2022. It fell into the Pacific Ocean, so once again, everyone was only mildly frightened.
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These are just the best-known examples of space debris falling. They have happened hundreds of times. Most of the time, we have been lucky and the debris has fallen into the ocean or an unpopulated area. But there have also been situations where debris has fallen on houses and even people – fortunately, so far, there have been no serious injuries or damage. Sooner or later, however, the luck will run out, and a piece of metal falling from the sky will cause serious damage. We can only hope that the situation with the forthcoming fall of Kosmos-482 will once again remind us of this problem and the need to find more active ways to solve it.
