LES 5
Country: United States · Also known as: Lincoln Experimental Satellite 5
Live Position
Ground Track · Last 90 Minutes
Upcoming Passes · Over Your Location
About This Satellite
LES-5 explored UHF satellite communications for small, mobile terminals on ships, aircraft, and land vehicles. The solar-powered, spinning spacecraft used a frequency-translating UHF transponder. It was a communications experiment aimed at practical user equipment, not a weather-observation mission or an ordinary broadcast television satellite.
The antennas switched as the spacecraft rotated
UHF antennas were arranged around the cylindrical body. An autonomous system selected the more Earth-facing antenna or antennas for connection to the transponder. This compensated for rotation without requiring the entire spacecraft to hold a fixed orientation toward an individual ground user.
Sharing the relay depended on terminal technology too
MIT credits LES-5 and LES-6 with demonstrating the Tactical Transmission System and demand-assigned Terminal Access Control System. These addressed robust signalling and access by multiple users. The experiments helped establish the usefulness of UHF links for size-constrained terminals; they were not simply tests of how much radio power a satellite could transmit.
Mission reference: MIT Lincoln Laboratory: LES-5 UHF communications, antenna switching and terminal access. Editorial review: .
The launch-day command problem nearly prevented the experiment
William Ward's firsthand account dates the launch to July 1, 1967. Preflight interference tests had led the team to launch with telemetry on and the communications transmitter off. A timing problem then blocked telecommands, preventing the planned switch. After seven hours of attempts, an acknowledged command allowed operators to activate the UHF transmitter, switch off telemetry, and begin in-orbit testing.
Reference: William W. Ward (2007): Saving a Satellite, LES-5 launch-day account.
The problem followed a daily geometry-dependent pattern
The subsequent investigation traced blocked command processing to sun-sensor signals during about seventeen hours of each day. The remaining five-hour interval was more favourable for commands. Ward reports that the experience led to more thorough prelaunch tests for LES-6 and later laboratory hardware. This historical operating window should not be read as a present-day contact schedule or evidence of an available communications service.
Reference: William W. Ward: sun-sensor interference and lessons for later spacecraft testing.
Reading this orbital snapshot
Based on TLE epoch: 2026-09-04. Estimated altitude ranges from 33,196 km at perigee to 33,606 km at apogee, a difference of 410 km. The orbital period is about 1316.0 minutes. Eccentricity 0.00516 indicates a nearly circular path. In a two-body approximation, perigee speed is 1.01 times apogee speed. These are mean-element estimates, not instantaneous measurements. Distance per orbit uses an ellipse approximation.
Saved build snapshot. If a valid TLE is retrieved, this explanation and the orbit panel update together. Otherwise this dated snapshot is retained.
Ground track is not sensor coverage
An inclination of 2.80 degrees implies approximate geocentric ground-track limits of 2.8 degrees north and south. This is a prograde orbit, moving in the same general direction as Earth rotation. The plotted line marks the point beneath the object. It does not represent camera coverage, radio reception, or a guaranteed visible pass.
Is it fixed above one longitude?
The snapshot period is 1316.0 minutes. A sidereal day is about 1,436.07 minutes. Height alone does not establish a geostationary orbit: the period must match Earth rotation and the path must be circular and equatorial. This catalog uses a five-minute period tolerance for near-geosynchronous labels; near-geostationary additionally requires inclination at most 1 degree and eccentricity at most 0.01. These are browsing categories, not evidence of station-keeping or a fixed longitude.
Accuracy and missing information
The introductory record describes the build snapshot. The orbital snapshot explanation and orbit panel share any successfully retrieved TLE; check the displayed epoch. Reentered objects retain historical data only. Mission history is not rewritten by TLE updates. TLE/SGP4 positions are predictions and can change after maneuvers or updated observations. The 14-day stale-data cutoff is a display safeguard, not an accuracy guarantee. Local passes are geometric predictions, not a visibility forecast. No verified operator or mission status means unknown, not active. Do not use this catalog for collision avoidance or operational flight decisions.
Catalog sources: CelesTrak SATCAT: NORAD 2866 · GCAT: S02866 (source update 2026 Sep 4 2345:57). Supplementary metadata: SatNOGS DB, retrieved 2026-09-05T12:57:25.375Z. Page assembled 2026-09-15. GCAT phase codes describe trajectory phases, not mission health.
Learn more: TLE data · Perigee and apogee · Ground tracks · JOT (Jewawud Live Orbital Map)