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Everything about the Starlink Satellite Internet project. Part 12. Starlink and space debris problems

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Starlink and space debris issues



Space debris issues have been discussed quite intensively after two incidents in space, which generated a huge amount of debris.







On January 11, China successfully tested an anti-satellite weapon: the FY-1C Fengyun meteorological satellite, in polar orbit at an altitude of 865 km, was hit by a direct hit from an anti-satellite missile. The rocket intercepted a satellite on a collision course. As a result of the destruction of the satellite and the interceptor, a cloud of debris was formed: ground tracking systems registered at least 2,317 fragments of space debris ranging in size from several centimeters or more.



The first known case of a collision in space occurred on February 10, 2009, when two artificial satellites, the Soviet Kosmos 2251, collided with the American Iridium-33 at an altitude of 788.6 km. The speeds of both satellites were approximately equal and amounted to about 7470 m / s, the relative speed was 11.7 km / s. The mass of the Iridium device was 600 kg, and the Russian Cosmos-2251 - 900 kg. As a result of their collision, about 600 debris was formed.



These two events, which occurred very close in time, turned the attention of experts to the prevention of collisions of satellites or their explosions (the second stages of missiles and upper stages are especially problematic in this respect). The plans announced by OneWeb for a network of 900 satellites did not attract much attention, as did the application of the Canadian company Telesat for a network of 300 satellites, but SpaceX's applications - first for a network of 4425 spacecraft, and then - with a short interval - for 7000 , changed the situation radically. The FCC has begun an in-depth analysis of the proposed SpaceX constellation in this direction.



One of the results of this work was probably SpaceX's decision to reduce the orbital altitude of its satellites from 1,100 km to 550 km, which ensured that the satellite would de-orbit and burn up in the atmosphere within five years, even if the satellite was completely unmanageable. For example, the lifetime of a Starlink satellite in an orbit with an inclination of 53 °, depending on its altitude, was calculated by SpaceX engineers:



Orbit inclination 53 degrees



Orbit altitude Satellite lifetime in orbit
200 km 22 days
250 km 100 days
> 300 <km 344 days
350km 2.0 years
400 km 2.9 years


In addition, SpaceX performed special calculations for the individual elements of its satellite in terms of which of them can reach the Earth's surface and what kind of "impact" energy they will have.



Orbit inclination 53 degrees



Composite element amount Material Weight (kg) DCA (sqm) Energy (J)
Shaft 1 Iron 1.66 0.47 2733
Body parts five Silicon carbide 1.50 2.79 961
Bearing five Stainless steel 0.07 2.45 eight
Bracket 12 Titanium 0.03 4.92 6




Note DCA (Debris Casualty Area) is the Predicted area of ​​debris damage on the Earth in square meters. Objects burned above the Earth's surface will have DCA = 0



After which, starting with the second batch of 60 spacecraft (Starlink version 1.0), SpaceX redesigned their satellites in such a way that no elements remain that may not completely burn out in the atmosphere and reach the surface of the Earth, having an impact force sufficient to injure a person.



In addition, SpaceX has developed a special program to monitor its satellites and their rapprochement with other spacecraft or their wreckage, and reports on the constant monitoring of such events.





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