SpaceX warns of falling satellites
December 20, 2018
By Chris Forrester
The influential Institute of Electrical & Electronics Engineers (IEEE) says that the proposed mega-constellation of SpaceX’s ‘Starlink’ fleet of satellites will generate “hundreds of fragments” when one of the low-Earth orbiting craft fails in space.
The IEEE, in its ‘Spectrum’ report has calculated the risks of an injury or death as 45 per cent over a 6-year period. The IEEE is using data and analysis from SpaceX and submitted to the Federal Communications Commission (FCC).
Elon Musk is backing the Starlink constellation of an eventual 12,000 satellites which he hopes will eventually carry around half of the planet’s Internet traffic.
Musk’s plan will be achieved in three stages. First will be the launch of 1584 satellites each at 550 kms high. Another 2825 satellites will follow, but at orbits ranging from between 1100-1325 kms. Stage 3 will see a much larger group of satellites, numbering 7518 and operating in Very Low Earth Orbit at just 340 kms high.
The IEEE describes each satellite as being about the size of a Tesla Model 3, and comprising solar panels, batteries, communications kit and laser gear, plus fuel. Each satellite should last about 6 years, and then fall out of orbit and burn up in the Earth’s atmosphere.
“Except,” as the IEEE states, “some won’t”. SpaceX, in its FCC filing, says that several kilogrammes of each Starlink craft could hit the planet. Much of the plant is water, desert or other sparsely populated areas. But NASA’s Debris Assessment Software calculates that there is – at most – a 1 in 18,200 chance of a fragment hitting someone, and just 1 in 10,000 chance of a hit from the Very Low Earth Orbiting craft.
However, more worrying perhaps is that some 6 years after launch an average of 5 satellites a day will fall to Earth, says the FCC’s calculation. This equates, says the IEEE, to an injury or death about every 6 years.
SpaceX, in fairness, reminds us that between 62 and 242 meteorites larger than 10 grams – which is very small – make it to ground level on an average day – and few do any harm. Moreover, with 7.5 billion people on Earth the risk to any one individual is refreshingly low.