How satellites melt in the earth’s atmosphere
An experiment was conducted at the European Space Agency (ESA), during which part of the space satellite was melted in a plasma wind tunnel.
The purpose of the experiment is to simulate the combustion process of one of the most durable satellite elements in the atmosphere, in order to further minimize the possible risk of its debris falling to the Earth's surface with damage by analyzing the data.
Indeed, in theory, all the equipment and parts of the near-Earth satellite are developed taking into account the fact that when their useful life approaches the end, they should burn almost completely in the Earth’s atmosphere.
However, in practice, some parts of even small spacecraft still reach the surface of the Earth, and some of them may be large enough to cause serious damage to buildings or even people.
In their experiment, ESA engineers used:
- test site of the German Aerospace Center in Cologne to create conditions similar to the process of melting space debris during immersion in the atmosphere;
- a plasma wind tunnel to simulate the conditions of entry into the atmosphere and the melting process of the most durable satellite element;
- a rod of a magnetic orientation system (4 by 10 centimeters in size) made of a polymer composite material reinforced with an external carbon fiber, with copper coils and an internal cobalt core.
The state of the rod of the magnetic orientation system before melting:
Remains of the rod of the magnetic orientation system after heating to several thousand degrees Celsius:
Thus, the melting process of the most durable satellite element ended with its full spreading, however, some parts of the rod did not melt as planned, which may be associated either with improper production of rod parts, or with incorrect mathematical calculations of the destruction of satellite elements in the atmosphere.
It turns out that in addition to magnetic rods, other parts of satellites can not burn out in the Earth’s atmosphere and fly to its surface: tanks, optical instruments, flywheels of gyroscopes and drive mechanisms.
The most frequent “guests” of the Earth’s surface after launchings of launch vehicles and the fall of spacecraft are parts of fuel tanks.
As an example, a case in 1997 was cited in ESA in which just 50 meters from an apartment building on a Texas farm, a rocket-stage fuel tank that was not burnt in the atmosphere fell, weighing about 250 kg.
At the moment, according to the rules for the disposal of such space debris, the chance of being on the surface of the Earth at any element of a spent satellite that can cause injury to someone is 1 in 10,000.
As part of a global project called “CleanSat” , the European Space Agency is developing new technologies and methods for the production of spacecraft components that will ensure the development and production of future low-orbit satellites in accordance with the “D4D” (design for demise) concept - designed with complete destruction in mind.
Thus, thousands of tons of payload launched into outer space, thousands of satellites in Earth’s orbit, tens of thousands of elements of idle spacecraft (space debris) - this is such a significant trace Mankind has left in space outside the Earth.
But thousands more launches are planned, and space debris is considered the main risk for such new space missions.
It turns out that a small object in space measuring only about 1 cm in collision with a newly launched spacecraft can release energy equivalent to a military grenade explosion.
Which can lead to serious damage to the new spacecraft or even its destruction.