‘Dangerously Close’ - Two Satellites At Risk Of Collision Tomorrow Could Create Thousands Of New Pie

IRAS, one of the satellites at risk of colliding, was launched and later retired in 1983.


Two defunct satellites are at risk of colliding in orbit, potentially creating thousands of new pieces of orbiting space debris if they hit each other and highlighting the growing need for responsible operations in space.

Satellite-tracking company LeoLabs from California announced yesterday, January 27, that the Infrared Astronomical Satellite (IRAS) launched in 1983, and the GGSE-4 satellite, a US experimental payload launched in 1967, were set to make an unnervingly close pass at 6.39 P.M. Eastern Time tomorrow, January 29.

The two satellites were initially predicted to fly past each other at a distance of about 15 to 30 meters about 900 kilometers above Pittsburgh, U.S., traveling at a relative velocity of 14.7 kilometers per second, with LeoLabs estimating the probability of a collision was 1 in 100 or one percent.

They later revised this to 13 to 87 meters, with a collision risk of 1 in 1,000. However, The Aerospace Corporation predicted a collision risk of just 1 in 10, reported Business Insider, with a distance of the initial 15 to 30 meters.

“The big concern is if they collide, they could generate thousands of new pieces of debris and make space a lot more dangerous to operate in,” said LeoLabs CEO Dan Ceperley, who noted the conjunction was "dangerously close."

“And while this particular one is risky, there are also many other events like this that happen every year, and the world needs to know about it,” he added.

LeoLabs noted that the incident was “especially alarming” as IRAS was a particularly large satellite, measuring up to 3.6 meters across. “The combined size of both objects increases the computed probability of a collision,” they said.

The conjunction is expected to occur over Pittsburgh, U.S.

Under United Nations guidelines, satellite operators are told to remove their satellites from orbit 25 years after their mission ends, although there is no strict punishment for exceeding this guideline.

Both IRAS and GGSE-4 were launched before the guideline was introduced, meaning they do not have to adhere to it even though they exceed it - similar to NASA's Jason-2 satellite, which was decommissioned last year but will remain in orbit for centuries. However, events like this highlight why such guidelines are so important, with potentially disastrous consequences.

In 2009, the active US Iridium 33 satellite and the defunct Russian Kosmos-2251 satellite collided in orbit, producing more than 2,000 pieces of debris larger than 10 centimeters, and many thousands more smaller pieces. And debris from incidents like this causes a considerable collision risk to other satellites in orbit.

“Debris down to about an inch in size, if it hits a large satellite, it will shatter [it],” said Ceperley. “The best scientific estimates say there’s about 250,000 pieces of small debris that aren’t tracked.”

LeoLabs uses its own radar network to track debris in orbit, with three radar stations currently in operation around the world and three more planned. The goal is to track close approaches like this, and even with smaller bits of debris, to provide information for satellite operators to avoid such collisions.

To clean-up Earth orbit, several organizations are developing spacecraft that can remove dead satellites and burn them up in the atmosphere, including Japan-based Astroscale, which plans to launch a demonstration mission later this year.

Last month, the European Space Agency (ESA) announced it was supporting the ClearSpace-1 mission, which will attempt to perform the first deorbit of a large piece of space debris from orbit after launching in 2025.

ClearSpace-1 will use four arms to grab the upper stage of a spent Vega rocket.

Today there are 1,500 active satellites orbiting Earth, along with about 3,000 dead satellites, with about three collision avoidance maneuvers performed every day to avoid space debris.

However, in the coming years companies like SpaceX and OneWeb plan to add thousands of new satellites to orbit as part of new mega constellations to beam high-speed internet around the globe, increasing the number of such maneuvers to an estimated eight an hour.

Even if IRAS and GGSE-4 do not collide tomorrow, the incident highlights the need to responsibly manage satellites in Earth orbit. But if the worst comes to the worst, the implications could be enormous.

“If these things do collide tomorrow, we could see thousands of new pieces of debris that are going to be up there for centuries,” said Ceperley. “[It would] make operations in low Earth orbit a lot riskier.

“I’ve got my fingers crossed that we don’t have a collision tomorrow, and if we do then we need to rapidly have a discussion about how we prevent the next one after that.”


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