X Report 29 Aug 2025
SpaceX celebrates a record-breaking Falcon 9 launch while Starship demonstrates strong performance in its recent test flight, fueling excitement for upcoming projects.
SL-4 R/B (12831)
COSPAR: 1981-090B | Alt Name: Soyuz-U 39-416 Blok-I
DECAYED
Image
Additional Sources
Launch Details
Launch Date
September 15, 1981
Launch Site
PLMSC
Launch Pad
LC43/3
Launch Vehicle
Soyuz-U
Orbital Elements
NORAD ID
12831
International Designator
1981-090B
Decay Date
9/23/1981
Basic Satellite Info
Name
SL-4 R/B
Alternative Name
Soyuz-U 39-416 Blok-I
Type
Rocket Body
Status
Space Junk
Owner
RVSN
Country
USSR
Constellation
N/A
Related Satellites
Major Events
N/A
Summary
A rocket body, also commonly referred to as an upper stage or spent rocket stage, is the structural shell left behind after a rocket has delivered its payload to orbit. These large and often heavy pieces of space hardware can remain in orbit for years, posing significant collision hazards as part of the growing space debris problem. If left uncontrolled, rocket bodies have the potential to reenter Earth's atmosphere unpredictably, which can lead to falling debris in populated areas. Additionally, they risk colliding with operational satellites or the International Space Station, creating more debris and putting human life at risk.
Physical Characteristics
Length
6.7
Diameter
2.7
Span
6.7
Dry Mass
2350
Launch Mass
2350
Shape
Cyl
Radar Cross Section
Unknown
Visual Magnitude
Unknown
Color
Unknown
Material Composition
Unknown
Technical Details
Payload
11S510
Purpose
Unknown
Mission
Unknown
Manufacturer
PROG
Life Expectancy
Unknown
Bus
Blok-I
Configuration
Unknown
Motor
Unknown
Equipment
Unknown
Power System
Unknown
ADCS
Unknown
Transmitter Frequency
Unknown
Satellite Articles
View All Posts »Learn more about satellites and other related topics.
Starship Flight 12 Targets May 19 with Redesigned Ship | KeepTrack X Report
SpaceX targets May 19 for Starship Flight 12 debut, while CRS-34 delivers 6,500 lbs of cargo to ISS aboard a Falcon 9.
The End of Free Skies | FAA Starts Charging for Rocket Launches
On April 22, 2026, the FAA published a final rule implementing per-launch user fees for commercial space transportation — the first time the U.S. government has charged payload-based fees for rocket launches. Starting at 25 cents per pound with a $30,000 cap, the fees are modest today. By 2033, they won't be.
Space Brief 7 Jul 2025
Today's key topics include the halting of the U.S. Air Force's rocket landing pad plans, the Space Force's shift to a flexible satellite strategy, delays in Australia's Eris 1 rocket launch, and the controversial cut of satellite sea-ice data to climate scientists.
X Report 3 Nov 2025
SpaceX completed a successful Bandwagon rideshare mission, launching a private space station pathfinder along with multiple satellites, marking another significant milestone in 2025's launch schedule.
Space Brief 10 Dec 2024
Today's highlights include a new 5G demonstration launch on Firefly, potential supply chain interruptions in the defense sector, and updates on Artemis and ULA launches.
Space Brief 22 Nov 2024
Today's key topics include delays in Vulcan's national security launches, a significant network upgrade contract for the Space Force, and military interest in SpaceX's Starship.
Track the International Space Station
A look at how tracking the space station offers a unique view of space exploration.