International Space Station avoided three collision risks in 2022
The International Space Station (ISS) had to perform three Collision Avoidance Manoeuvres (CAMs) in 2022. During a collision avoidance maneuver, the orbiting space station fires its engines in order to move away and steer clear of incoming space objects. As of May 2021, the orbiting space lab has performed 29 debris avoidance maneuvers since its launch in 1999.
Why does this story matter?
The ISS orbits the Earth at an average altitude of 402km and completes an orbit every 90 minutes. Being docked in space also means that the orbiting station faces the constant threat of being bombarded by space debris, which could be cosmic objects of any size. Fortunately, there are surveillance systems that help the station swerve away when such hazards are imminent.
More than 47,000 pieces of space debris are being tracked
Dr. Jer Chyi Liou, NASA Chief Scientist for Orbital Debris, at an event in India, stated that NASA had executed or assisted 18 CAMs in 2022. He added that more than 47,000 pieces (each bigger than 10cm) of space debris were being monitored by the US Space Force and that their orbital paths were tracked for any impending collision risks.
The ISS is protected by 500 different shields
Millions of smaller chunks of space debris also pose a threat but they cannot be tracked. Dr. Liou mentioned that ISS is protected by 500 different shields, known as Micrometeroids and Orbital Debris (MMOD) impact protection shields. While the US module on ISS has protective shields against debris 1cm and smaller, the other modules are not guarded as much.
Space debris of different sizes is a serious concern
But why is space debris of varying sizes a concern? As per NASA, the average impact speed of orbital debris with another space object is approximately 10km/s and can go up to about 15km/s. For reference, that is more than ten times the speed of a bullet, and one can imagine the impact that such a collision might bring about.
ISS avoids space debris once a year on average
NASA in an official blog said that the space station has to evade space debris about once a year on average. "If another object is projected to come within a few kilometers of the International Space Station (ISS), the ISS will normally maneuver away from the object if the chance of a collision exceeds 1 in 10,000," explained the space agency.
