SpaceX plans to launch up to 42,000 satellites for its Starlink constellation, and this is not the only megaconstellation project. With a large number of space debris already present in orbit, the risk of chain collisions is constantly increasing, and could make Earth’s orbit impassable.
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As more satellites are put into orbit, some scientists increasingly fear a chain reaction called Kessler syndrome. The idea is that the number of satellites and debris in orbit could reach a threshold where collisions become too frequent, creating new debris and therefore new collisions. This chain reaction could make it impossible to put new satellites into orbit, or even launch spacecraft, until the debris falls back to Earth.
Satellites avoid collisions with space debris using automated systems. However, even in low orbit, they are much less protected against solar flares and winds than devices on Earth. The sun reaches a peak of activity every 11 years, with the next expected in 2024 or 2025, and could potentially disrupt the operation of satellites or even create short circuits. They could then find themselves without an automatic guidance system and start a chain reaction of collisions with, each time, an increase in space debris.
A million pieces of space debris measuring more than a centimeter
Currently, there are a million pieces of debris larger than a centimeter, of which only 34,670 are tracked and cataloged. The total number of satellites launched at all times stands at 15,880, with approximately 8,600 still in operation. The Starlink constellation, in low orbit to provide Internet via satellite, alone currently has 4,519 satellites. SpaceX hopes to eventually create a megaconstellation of 42,000 satellites. And other companies like OneWeb and Amazon are building their own constellations.
One of the proposed solutions is a system of safe orbits planned in advance that maximizes the distance between satellites to avoid collisions. Currently, it is possible to detect solar flares using telescopes and observation satellites on Earth, in orbit around the sun or at the Lagrange point L1. Thus, scientists are warned between 5 p.m. and several days before the Earth is affected. It would then be possible to trigger the emergency solution and place all the satellites in their safe orbits in order to avoid a chain reaction. But for this, this system would have to be integrated into each satellite, which is not currently the case…
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