Science
CALSPHERE 2
Radar Calibration Sphere · US Air Force
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Calsphere 2, one of a small family of passive aluminum calibration spheres launched in the early 1960s to give ground-based radar systems a fixed, known reference target. Like its sibling Calsphere 1, it carries no power and no instruments — its usefulness comes entirely from its unchanging, precisely measured shape.
Its orbit
- Orbit
- Low Earth Orbitcan appear as a fast-moving star at dawn or dusk
- Altitude
- 654–670 mi (1,053–1,078 km)
- Inclination
- 90.2°
- One orbit
- 106.4 minutes13.5 orbits a day
- NORAD ID
- 00902
- Int’l designator
- 1964-063E
- Launched
- 1964
Orbital elements from CelesTrak, as of 22 Sep 2026.
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