X Report 19 Mar 2025
SpaceX safely returns Crew-9 from ISS, launches new Starlink satellites, and showcases its satellite kit production capabilities.
SL-4 R/B (21742)
COSPAR: 1991-071B | Alt Name: Soyuz-U2 No. 048 Blok-I
DECAYED
Image
Additional Sources
Launch Details
Launch Date
October 9, 1991
Launch Site
Launch Pad
LC1
Launch Vehicle
Soyuz-U2
Orbital Elements
NORAD ID
21742
International Designator
1991-071B
Decay Date
10/12/1991
Basic Satellite Info
Name
SL-4 R/B
Alternative Name
Soyuz-U2 No. 048 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
14.5
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.
X Report 21 Aug 2025
Today's brief highlights the upcoming X-37B military spaceplane launch, ongoing partnerships to protect radio astronomy, and West Virginia's minimal allocation of broadband subsidies to satellite providers like SpaceX.
X Report 10 Feb 2025
SpaceX prepares for Starship Flight 8 with successful booster static fire; Starlink continues its expansion.
Space Brief 28 Jun 2025
Today's brief covers a Pentagon review of satellite launch options, Kongsberg's completed maritime satellite network, York's new satellite launch, DARPA's project cancellation, and more.
Blue Origin's New Glenn Destroyed in Static Fire Test at Cape Canaveral | KeepTrack Space Brief
Blue Origin's fourth New Glenn rocket exploded during static fire at LC-36, Cape Canaveral, destroying the fully stacked vehicle and pad infrastructure. Amazon Leo launch postponed indefinitely.
Air Force One Gets Starlink, Astrobotic Acquired | KeepTrack Space Brief
Trump's interim Air Force One—a $400M Boeing 747-8—equipped with Starlink for presidential communications. First confirmed LEO constellation use for White House comms.
X Report 5 Dec 2025
SpaceX made significant strides with the launch of 28 Starlink satellites while navigating regulatory challenges regarding rural broadband funding. Additionally, developments on the Crew Dragon mission continue to evolve with a change in cosmonaut assignment.
X Report 12 Nov 2025
SpaceX breaks records with its 94th launch of the year while planning to ramp up Starship production to unprecedented levels.