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Oct 14, 2020 3 tweets 2 min read Read on X
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.
2/ Current risk metrics from our most recent CDMs:
Miss distance: 12 meters (+18/-12 meters)
Probability of Collision: >10%, scaled to account for large object sizes
Relative velocity: 14.7 km/s Image
3/ Shortly after TCA, we will have a direct pass of CZ-4C R/B over our Kiwi Space Radar in New Zealand. We have scheduled a search mode scan during this time to ensure we only see two objects as expected and hopefully confirm that no new debris is detected. Image

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More from @LeoLabs_Space

Feb 28
Too close for comfort. 😳

At ~06:30 UTC today we observed a conjunction at 608 km between two non-maneuverable spacecraft: a derelict Russian satellite and an operational NASA satellite.

Miss distance = <20 meters
Probability of collision = 3 to 8% at TCA Image
1/ Why does this event matter?

This event is notable because it is rare. In the last two years, there have been only 6 events with a miss distance of < 20 m between two intact, non-maneuverable objects.

Plus, it would've been dangerous...
2/ The resulting debris of a collision between these two objects, COSMOS 2221 and TIMED, would've created an increased collision risk on a large portion of LEO but especially on nearby lower orbits used by large constellations and human spaceflight.
Read 9 tweets
Sep 18, 2023
⚠️ On Sept 13, a derelict Soviet-era payload had a conjunction with a Chinese rocket body.

The miss distance was 36 m (± 13 m) and the probability of collision was 1E-3 (i.e., 0.1% or 1/1,000).

While we've seen more nail biting events, this one is notable — here's why.
1/ Cosmos 807 and CZ-4C had a combined hard body radius (HBR) of 5.6 m. This contributed to the relatively large probability of collision (PC) value.

If these two objects had collided, the number of resulting cataloged fragments would have likely been ~3,000. 🤯
2 / To put that into perspective, the 2021 Russian ASAT test resulted in ~1,800 total cataloged fragments over time.
Read 9 tweets
May 8, 2023
Update ➡️ The PRC Test Spacecraft 2 (NORAD ID 53357) landed in the early hours ET on Monday, 8 May 2023.

Based on our observation data and confirmed by reports, the landing window was likely between 0018 - 0020 UTC.
Members of our global operations team in the AIPAC region observed that the object missed a scheduled early morning pass over the LeoLabs Kiwi Space Radar on 8 May 2023 local time. Image
There were early indications that the spaceplane was likely to land.

After lowering its altitude by more than ~250 km on April 13, several smaller maneuvers were performed between 13 April – 08 May, including altitude changes and a small inclination change. Image
Read 7 tweets
Apr 21, 2023
On April 13, we detected a large maneuver by Object 53357, the PRC’s experimental spaceplane.

This maneuver resulted in a decrease in altitude from 613 - 355 km.

Shown below: the previous orbit is in orange and the new one is in blue. Image
This new mission phase could indicate preparations for landing of the reusable spaceplane — or something new entirely.
Since the spaceplane launched in August 2022, we’ve observed multiple large maneuvers raising the object’s altitude — as well as repeated deployments, formation flying, and docking of a sub-satellite OBJECT J (NORAD ID 54218).
Read 4 tweets
Jan 27, 2023
Too close for comfort... 😳

Two large, defunct objects in #LEO narrowly missed each other this morning — an SL-8 rocket body (16511) and Cosmos 2361 (25590) passed by one another at an altitude of 984km. 🚀⚠️ #SpaceDebris LeoLabs platform illustrati...
1/ Based on our radar tracking data, we computed a miss distance of only 6 meters with an error margin of only a few tens of meters.
2/ It's important to note that this conjunction occurred in one of the "bad neighborhoods" we've talked about before: 950 - 1050 km. 🏚️
Read 10 tweets
Jan 27, 2020
1/ We are monitoring a close approach event involving IRAS (13777), the decommissioned space telescope launched in 1983, and GGSE-4 (2828), an experimental US payload launched in 1967.

(IRAS image credit: NASA)
2/ On Jan 29 at 23:39:35 UTC, these two objects will pass close by one another at a relative velocity of 14.7 km/s (900km directly above Pittsburgh, PA). Our latest metrics on the event show a predicted miss distance of between 15-30 meters.
3/ These numbers are especially alarming considering the size of IRAS at 3.6m x 3.24m x 2.05m. The combined size of both objects increases the computed probability of a collision, which remains near 1 in 100.
Read 4 tweets

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