The experimental US satellite, GGSE-4, was launched by the US Air Force in 1967 and weighs just 85 kilograms (190 pounds) but has an unusual shape — just 60 centimeters (two feet) wide but 18 meters (60 feet) long, and it flies vertically.
LeoLabs, which uses radar to calculate collision risk, placed the probability of their making impact at between one and five percent, based on the uncertain orientation of the GGSE-4. This is considered a high risk among the space community.
If they do hit, they could create around a thousand pieces of debris larger than 10 centimeters, and more than 12,000 fragments bigger than one centimeter, astrodynamicist Dan Oltrogge told AFP.
“We will know because especially for low Earth orbit, there is much radar coverage, and we would see fragmentation happening, we would see objects separating off,” he said — though it won’t be visible to the naked eye.
The 900 kilometer altitude band is particularly crowded with satellites.
There are around 20,000 catalogued pieces of debris bigger than a softball orbiting the planet, traveling at speeds up to 17,500 miles (28,000 kilometers) per hour, and satellite operators have to frequently adjust their trajectory accordingly, which isn’t possible once a satellite dies.
Adding a few thousand more pieces would create significant extra workload and risk, said Oltrogge.
“There’s also the introduction of a lot of what we call lethal non trackable debris. It’s debris that’s big enough to kill your satellite, but not big enough to currently be tracked.”
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