Scientists and observers are preparing for a potentially serious satellite collision later today as two defunct satellites are on course to pass dangerously close to one another. If a collision does occur it could spread debris which may seriously damage active satellites.
It’s not something we really give too much thought to, but satellite collisions pose a very real threat to much of the vital technology we use daily. Without GPS and satellite telecommunications, modern society would be in a tricky predicament.
Currently there are around 5000 satellites in Earth’s orbit, but many of them have reached the end of their lifecycles and are now effectively just space junk.
With so many satellites hurtling around Earth, there is a growing potential for collisions which could set off a catastrophic chain reaction.
Today’s potential collision
Scientists at LeoLabs, a service which monitors satellites in Low Earth Orbit, have raised the alarm about a potential collision which could take place over the US later today.
According to LeoLabs, two dead satellites are set to pass within 13 to 87 meters of each other at 18:39 EST. You can see the predicted paths of both satellites in the tweet below.
2/ On Jan 29 at 23:39:35 UTC, these two objects will pass close by one another at a relative velocity of 14.7 km/s (900km directly above Pittsburgh, PA). Our latest metrics on the event show a predicted miss distance of between 15-30 meters. pic.twitter.com/Hlb1KeQ50U
— LeoLabs, Inc. (@LeoLabs_Space) January 27, 2020
According to LeoLabs, the likelihood of a collision is 1 in 1,000. While these odds might sound tiny, experts in the field say it is quite the opposite.
Discussing the situation with CNN, Harvard astronomer Jonathan McDowell, said:
“We start getting worried when it’s 1 in 10,000, so 1 in 1,000 is unusual and it might actually be a lot worse than that.”
To put the potential collision in perspective, the satellites would impact each other at almost 33,000 miles per hour. McDowell says this collision would release 100,000 times more energy than a one-ton vehicle hitting a person at 100 miles per hour.
The real danger behind a collision
The satellites in question are no longer active, which means they wouldn’t be a loss. The larger of the two, the Infrared Astronomical Satellite (IRAS), was launched in January 1983 and only remained active for 9 months. The other satellite, GGSE-4 was launched way back in January 1967, and is also retired.
Although these satellites no longer serve a purpose, they do pose a significant risk to the thousands of other active satellites in Low Earth Orbit.
IRAS weighs in at more than one metric ton, whilst GGSE-4 weighs 84 kilograms. A collision between the two would spread debris far and wide, raising the very real possibility of a chain reaction which could affect hundreds of other satellites.
Ultimately, the real risk of today’s close call is much larger than the destruction of two old satellites. While LeoLabs maintains that the risk of a collision is just 1 in 1,000, it should also put into perspective the catastrophic knock-on effects which could arise as a result of satellite collisions.
With more and more satellites being launched every year, the risk of satellite collisions increases. Regardless of whether the collision between IRAS and GGSE-4 happens, it should act as a warning to the space industry.
Update 30/01/20: Reports from those observing the satellites say there has been no collision and no further debris added to the Earth’ surrounding space.