Space Brief 18 Dec 2025
Today's updates cover Rocket Lab's launch for the U.S. Space Force, Digantara's major funding round, and discussions on national security in space.
NAVSTAR 18 (USA 50) (20452)
COSPAR: 1990-008A | Alt Name: GPS II-6
Image
Additional Sources
Launch Details
Launch Date
January 24, 1990
Launch Site
Launch Pad
LC17A
Launch Vehicle
Delta 6925
Orbital Elements
NORAD ID
20452
International Designator
1990-008A
Epoch
Fri, 03 Jul 2026 21:19:53 GMT
Apogee
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Perigee
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Inclination
54.87°
Right Ascension
133.06°
Eccentricity
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Argument of Perigee
283.47°
Period
759.50 min
Mean Motion
1.90 rev/day
Latitude
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Longitude
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Altitude
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Velocity
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Polar Plot
3D Visualization
Basic Satellite Info
Name
NAVSTAR 18 (USA 50)
Alternative Name
GPS II-6
Type
Payload
Status
Non-operational
Owner
AFSSD2
Country
United States
Constellation
N/A
Related Satellites
Major Events
N/A
Latest TLEs
1 20452U 90008A 26184.88881521 .00000048 00000-0 00000-0 0 9994
2 20452 54.8663 133.0642 0015633 283.4711 253.4086 1.89597821256742
Source: Celestrak
Summary
NAVSTAR 18 (USA 50), also known as GPS II-6, is a satellite that was launched on January 24, 1990, from Cape Canaveral Air Force Station using the Delta 6925 launch vehicle. The spacecraft measures 2.4 meters in length with a diameter of 1.8 meters and spans 5.3 meters when its solar arrays are deployed. It has a dry mass of 776 kilograms and is equipped with two deployable solar arrays for power, along with batteries as backup. Designed for navigation purposes, it operates within the GPS II series, featuring a 3-Axis stabilized configuration and was manufactured by RWISB. The satellite's mission lifetime expectancy was approximately 7.5 years, and its payload is identified as GPS SVN 18.
Physical Characteristics
Length
2.4
Diameter
1.8
Span
5.3
Dry Mass
776
Launch Mass
776
Shape
Box + 2 Pan
Radar Cross Section
1.5223
Visual Magnitude
Unknown
Color
Unknown
Material Composition
Unknown
Technical Details
Payload
GPS SVN 18
Purpose
Navigation
Mission
Navigation
Manufacturer
RWISB
Life Expectancy
7.5 years
Bus
GPS II
Configuration
3-Axis stabilized
Motor
Star 37F
Equipment
?
Power System
2 deployable solar arrays, batteries
ADCS
Unknown
Transmitter Frequency
Unknown
Map
Next Pass
Azimuth Elevation Time (Local)
Start Azimuth
Max Elevation
Stop Azimuth
Time Until
Pass Duration
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