On 3 September, the European Space Agency announced that it had altered the trajectory of one of its active, orbiting Earth-observation satellites to prevent what could have been a collision with a satellite operated by SpaceX. The satellite was part of SpaceX's newly-launched Starlink constellation, a 12,000-strong planned constellation of internet broadband satellites offering hi-speed internet services globally.
"@ESA 's #Aeolus Earth observation satellite fired its thrusters, moving it off a collision course with a @SpaceX satellite in their #Starlink constellation," ESA's official Twitter account said. It added that ESA scientists decided the safest plan of action was to boost the altitude of the Aeolus satellite – this is the "first time ever" that a manoeuvre like this has been used to steer clear of another satellite's path.
For the first time ever, ESA has performed a 'collision avoidance manoeuvre' to protect one of its satellites from colliding with a 'mega constellation'#SpaceTraffic pic.twitter.com/kmXvAgpj1U
— ESA Operations (@esaoperations) September 2, 2019
This morning, @ESA's #Aeolus Earth observation satellite fired its thrusters, moving it off a collision course with a @SpaceX satellite in their #Starlink constellation pic.twitter.com/bn2GHnSoFI
— ESA Operations (@esaoperations) September 2, 2019
The manoeuvre took place about 1/2 an orbit before the potential collision. Not long after the collision was expected, #Aeolus called home as usual to send back its science data – proving the manoeuvre was successful and a collision was indeed avoided pic.twitter.com/flYGDwFQ57
— ESA Operations (@esaoperations) September 2, 2019
"The vast majority of ESA avoidance manoeuvres are the result of dead satellites or fragments from previous collisions, ESA added.
The Aelous satellite in orbit. Image: ESA
A bug in Starlink's on-call operating system prevented SpaceX from seeing the increased risk of a collision with the ESA satellite, a SpaceX spokesperson told AFP. "Had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine the best approach with their continuing with their manoeuvre or our performing a manoeuvre," the spokesperson added.
SpaceX, a leading space and launch vehicle company founded by Elon Musk in 2002, launched 60 demo broadband-beaming satellites under its Starlink project.
The initial launch prompted astronomers to raise the alarm over the risk of a possible collision and briefly threw up a spate of UFO sightings over the Netherlands.
A prototype Starlink satellite. The first two prototype Starlink satellites were launched by SpaceX in February 2018. Image: SpaceX
SpaceX says the Starlink constellation could eventually reach 12,000 satellites.
Faced with an increase of privately run craft, which currently number around 20,000 in Earth's atmosphere, the ESA will hold a meeting in November focussed on space security.
(Also read: Star Caravan: SpaceX Starlink satellites spark UFO frenzy among Dutch astronomers)
(Also read: First wave of SpaceX's Starlink satellites liftoff in a successful launch on 24 May)