FCC: SpaceX satellites in orbit - a source of debris dangerous to Earth’s inhabitants
According to the analysis of the figures given by the FCC regarding the lifetime of SpaceX satellites (Starlink system) in Earth orbit, the probability of hitting someone on Earth with a satellite fragment will reach 45% every six years. It sounds a little difficult, literally it means that the fragments of satellites will fall to Earth every day, sometimes reach the surface of the planet, and sometimes kill someone from the people.
Ilon Musk plans to launch about 12,000 satellites into low orbit, which will eventually pass through half of all Internet traffic. To ensure fast communication and wide channel, satellites are equipped with laser installations and specific radio modules. All this is done in order to provide the planet with Internet connection, including the most remote and hard-to-reach regions.
This will not happen soon, because SpaceX initially plans to launch 1584 satellites into orbit. The height of the orbit will be about 550 kilometers. Then another 2825 satellites will be launched, already to higher orbits - 1100 and 1325 km. Finally, the last batch of 7,518 satellites will be sent to the lowest orbit of 340 km. If we calculate the total mass of all spaceX devices, then it will be 10 times the mass of the ISS.
Each of the 11927 satellites will be equipped with solar panels, batteries, radio and laser modules, the power of which will be sufficient to provide all regions of the Earth with reliable communications. The lifetime of one satellite is 6 years. At the expiration of this period, the fuel ends and the system falls to Earth. Most will burn in the atmosphere, since they are relatively small, but this will not happen with all systems.
Experts believe that the combustion will not always be complete, some satellites with a mass of several kilograms will remain from some satellites. Hitting such a wreck is more than enough to kill a person. “Surviving”, reaching the Earth, will be metal components, stainless steel flywheels, as well as silicon carbide mirrors.
When the company connected to the NASA system for calculating the likelihood of space debris falling to Earth, Debris Assessment Software , it turned out that every fragment of 17,400 has a chance to kill a person. In principle, the odds are very slim, the figure mentioned above is significantly below the safety threshold set by NASA (1: 10,000). But the FCC decided not to stop there and figure out other probabilities.
So, six years after launch, an average of five satellites per day will fall to Earth. For many, there is a non-zero chance of leaving a memory in the form of unburned debris that reaches the surface of the planet. As mentioned above, such debris can kill, the likelihood of this is 45% for every 6 years.
If we take into account that there are 7.5 billion people on Earth, then the probability of a satellite fragment falling into a person is very low. In 2011, NASA calculated the probabilities and got the number at 1: 3200 - this is just a chance that a fallen piece will kill a person. If you take personal risk, then the probability of hitting a satellite specifically for you is very low - about 1 to 22 trillion. More chances to win the lottery (much more).
SpaceX does not agree with the opinion that its satellites are a danger to people. The company cites statistics from NASA. The fact is that the Earth is constantly bombarded by many dozens or even hundreds of meteorites, some of which successfully reach the Earth’s surface. But at the same time getting into people or buildings are extremely rare. Thus, if some more fragments of satellites are added to this number, there should be no particular problems.
The FCC does not agree with this point of view. The regulator claims that within six years about half a million objects should fall to Earth - these are parts of satellites that have been decommissioned. On average, it turns out 228 objects per day - this is more than meteorites falling on Earth.
However, if we take into account that most people on Earth are constantly in any kind of shelter (house, car, school, parking, etc.), then the risk of hitting a person by a falling fragment of a satellite decreases many times - they say SpaceX, and the same point of view is supported by the company Iridium NEXT, which also deals with satellite communications.
Anyway, on November 19, the FCC proposed a draft regulatory documents on the regulation of space affairs related to space debris. Comments on the project can be left until the beginning of 2019.
So far, SpaceX has launched only two prototypes of the Starlink satellite network, so there is still time to regulate. But it is not so much, because in 2019 the launches will begin. All 11927 Starlink satellites should be sent into orbit before November 2024.