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RIGIDSPHERE 2 (LCS 4)

Radar Calibration Sphere · MIT Lincoln Laboratory

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Rigidsphere 2, also cataloged as LCS-4 — a sibling to the famous LCS-1, built by MIT's Lincoln Laboratory as a precisely machined radar calibration target. Like LCS-1, it has no power, no electronics, and no expiration date; it simply orbits, indefinitely, as a fixed point radar systems can check themselves against.

Its orbit

Orbit
Low Earth Orbitcan appear as a fast-moving star at dawn or dusk
Altitude
453–504 mi (728–810 km)
Inclination
87.6°
One orbit
100.1 minutes14.4 orbits a day
NORAD ID
05398
Int’l designator
1971-067E
Launched
1971

Orbital elements from CelesTrak, as of 22 Sep 2026.

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