Decommissioned Satellites Move Closer To Each Other Above Pittsburgh, Still No Collision Expected

Jan 29, 2020

Two retired satellites will cross paths this evening above Pittsburgh. At around 6:30 p.m., the IRAS telescope and GGSE-4 payload are expected to come within about 40 feet of each other during their orbits. But scientists say it’s unlikely the two will make contact.

According to Dan Seperley, CEO of LeoLabs — a company dedicated to tracking intruding spacecraft, satellites and space debris — there’s a 1-in-100 chance that these spacecraft collide this evening. He said in the space industry, a crash occurring at these odds is a red alert.

“A one in 10,000 event is considered noteworthy and satellites need to be moved,” Seperley said. “A one in a 1,000 event is considered an emergency, and if possible, satellites are definitely moved. One in 100 is an extreme emergency situation.”

Seperley said because this potential crash was not tracked earlier, the satellites can’t be moved.

Kathy Desantis, a part time instructor of space science and meteorology at Waynesburg University and an avid amateur astronomer, said a collision could cause debris from the crash to enter the atmosphere.

“There could be debris and that debris, when it would fall through the atmosphere, would heat up and would glow like a shooting star,” Desantis said.

LeoLabs currently tracks 40,000 pieces of this kind of debris in space, Seperley said, and he estimates there are 210,000 more pieces the company doesn’t track yet.

Seperley said debris from defunct satellites and satellite crashes harms the earth’s atmosphere because it interferes with active satellites transmitting information.

“That debris will stay in orbit for decades, probably centuries, and pose a threat to other spacecraft, either in the region or spacecraft going on to other destinations,” Seperley said.

Even if the satellites don’t collide tonight, Seperley said there’s a chance they could in the future as they continue to orbit.

Desantis said Pittsburgh expects 100 percent cloud coverage this evening, so if the two satellites do collide, the resulting debris wouldn’t be entirely visible. But Desantis said expectant viewers would not be completely disappointed.

“If we get a collision, we’re bound to see some of the debris, even with the cloud cover,” Desantis said.

The two decommissioned satellites were both launched before the turn of the century. The GGSE-4 is a U.S. experimental payload launched in 1967, and the IRAS is a NASA telescope launched in 1983.

Crash or no crash, Desantis said such celestial events can inspire people to think more deeply about science and space travel.

“It is neat to know what’s happening above us and there’s often a lot of neat things happening in the sky above us,” Desantis said, “all we need to do is just look up.”