Two satellites could collide over Pittsburgh Wednesday evening

Credit: DaytonDailyNews

Caption
What will happen if two satellites collide over Pittsburgh

Credit: DaytonDailyNews

It appears that two decommissioned satellites over Pittsburgh did not collide Wednesday evening.

Initially, scientists said there was a 1 in 100 chance of a collision, which was updated to a 1 in 20 chance, but Leolabs said its latest data shows “no evidence of new debris.”

Leolabs said it will continue to monitor data that comes in to be sure the two satellites did not collide in space.

Around 6 p.m., Leolabs released the final update and projections of what the satellites will do. It predicted that they would miss by approximately 47 meters (154 feet), but the actual distance is still unclear.

Leolabs said even though it’s unlikely the satellites collided, it has radars to schedule longer tracking on both of them to search for evidence of new debris.

One is an infrared telescope from NASA, and the other is an Air Force experimental satellite. Officials said they could have come within 40 feet of each other 560 miles directly over the city.

'LeoLabs' initially released the information Monday, which showed overlapping tracks between a decommissioned space telescope and an experimental government payload.

The older satellite, known as GGSE-4, was launched in 1967 by the U.S. military from Vandenberg Air Force Base in California. It is quite small and weighs only 10 pounds but is reported to be attached to a larger satellite, only recently declassified, called Poppy 5. Poppy 5 has 18-meter-long booms and an additional weight of 187 pounds, according to astronomer Jonathan McDowell.

Launched in 1983 from Vandenberg Air Force Base in California, the larger satellite is much larger and called IRAS. IRAS is the first infrared telescope in orbit. IRAS is credited with leading to the discoveries of six new comets, the core of the Milky Way galaxy and a deeper understanding of the stars Vega and Fomalhaut.

After a 10-month mission, IRAS exhausted its fuel supply and has been drifting in low Earth orbit ever since. IRAS is 11.8 by 10.6 by 6.7 feet and weighs nearly 2,400 pounds.

WPXI spoke with David Turnshek, director of the Allegheny Observatory. Turnshek said if a collision happened, it would be compared to a small shopping cart hitting a car and, if it were clear and you were away from light pollution, you could look overhead and possibly see a faint light to the unaided eye.

You might be able to hear a sonic boom, Turnshek said. Otherwise, the collision would result in debris in space.

The first and last time two satellites collided at a very high velocity was in 2009 over Siberia. Sonic booms were reported days later in Kentucky. Others in Texas reported a meteor, but it was deemed to be debris reentering the atmosphere.

Space archaeologist Alice Gorman, of Flinders University, told Science Alert there was no danger to anyone on the ground in the event the collision happens and any debris would burn up in the atmosphere during reentry.