The probability of a possible collision between the two satellites exceeds 10 percent at an altitude of 991 kilometers (616 miles) above the Weddell sea near the Antarctic Peninsula.
We are monitoring a very high risk conjunction between two large defunct objects in LEO. Multiple data points show miss distance <25m and Pc between 1% and 20%. Combined mass of both objects is ~2,800kg.— LeoLabs, Inc. (@LeoLabs_Space) October 13, 2020
Object 1: 19826
Object 2: 36123
TCA: Oct 16 00:56UTC
Event altitude: 991km pic.twitter.com/6yWDx7bziw
"This is probably one of the potentially worst accidental collisions that we've seen for a while," said space archaeologist Alice Gorman of Flinders University in Australia, according to ScienceAlert.
The Chinese rocket stage, which was part of a Long March 4B rocket launched on 10 May 1999, safely transported its payload, while the Soviet satellite called “Parus”, launched on 22 February 1989, was used by the military for communication and navigation.
Here's my own visualization of the encounter. Kosmos-2004 (red) is heading south towards the pole, CZ-4C-Y4 (purple) is heading north towards the Falklands pic.twitter.com/qem7ojlhcy— Jonathan McDowell (@planet4589) October 14, 2020
The objects are travelling in opposite directions with a relative velocity of about 14.7 kilometres per second and the total mass estimated at approximately 2,800 kilograms (6,170 pounds).
1/ This event continues to be very high risk and will likely stay this way through the time of closest approach. Our system generates new conjunction reports 6-8x per day on this event with new observation data each time. pic.twitter.com/d3tRbcV2P0— LeoLabs, Inc. (@LeoLabs_Space) October 14, 2020
The chance of collision is complicated by the shape of the spacecraft since the Parus satellite has a 17-metre (56-foot) boom that could close the projected gap between the objects.
"We're not yet in a position where we can actively remove any debris like this. So it'll be up there for a while. And because of the altitude of about 1,000 kilometres, this stuff isn't going to reenter within a matter of weeks or months. Some of it is likely to be up there for quite some time," Gorman added.
However, there is no risk for us here on Earth, even if a potential collision occurs. The concern is that these two objects will create a rain of small debris. It will burn up on re-entry, but is more likely to hover in low earth orbit, posing a danger to other objects above.
"My feeling about this is probably it's not going to happen, just to be optimistic. But we'll have to wait," Gorman told ScienceAlert. "Let's keep our fingers crossed."
Although the worst-case scenario, according to LeoLabs' probability calculations, is not likely to happen, it's only a matter of time before another collision in near-Earth space could occur. A similar situation occurred at the beginning of the year when observers feared a collision of two long-dead space objects that were planned to pass at a distance of 15 to 30 meters from each other with a one-in-100 chance of collision, but eventually sailed harmlessly past each other.
Later, LeoLabs said on Twitter that there was "no indication of collision".
No indication of collision. 👍— LeoLabs, Inc. (@LeoLabs_Space) October 16, 2020
CZ-4C R/B passed over LeoLabs Kiwi Space Radar 10 minutes after TCA. Our data shows only a single object as we'd hoped, with no signs of debris.
We will follow up in the coming days on Medium with a full in-depth risk assessment of this event!