EXPLORER 22

About This Satellite

Explorer 22, also called Beacon Explorer B, combined ionospheric research with an early demonstration of satellite laser ranging. Its optical equipment was passive: reflectors returned light sent from a ground station. The satellite did not need to generate an answering laser pulse or broadcast its own GPS position for this experiment.

A returning flash measured distance, not a photograph

Nine panels carried forty cube-corner reflectors each, directing incoming light back toward its source. A ground telescope collected the return and a photomultiplier detected it. Timing the outward and return journey gave the station-to-satellite range. This is a line-of-sight distance, not simply altitude above the surface directly beneath the spacecraft.

Early precision belonged to a particular ground experiment

NASA's 1964 announcement reported roughly three-metre range accuracy. That historical result should not be replaced with the millimetre-level figures quoted for later laser-ranging systems. It also does not describe the accuracy of this catalog's TLE-based position: optical measurements and an orbital prediction are different products.

Mission reference: NASA Goddard: Explorer 22 and the first satellite laser-ranging experiments. Editorial review: 2026-09-14.

The plasma archive answers a different question

NASA's OMNIWeb archive provides electron temperature and density from the Cylindrical Electrostatic Probe experiment, with samples at one-to-five-minute resolution. Its selectable quantities include spacecraft position, satellite potential, magnetic coordinates, and solar and geomagnetic indices. These contextual variables help place a plasma measurement in its observing environment. They are not additional laser ranges, and a probe measurement near the spacecraft is not an image of the whole ionosphere.

Reference: NASA SPDF/OMNIWeb: Explorer 22 probe data, variables and sampling interval.

An archive endpoint is not the end of every experiment

The accessible probe dataset spans October 10, 1964 to August 26, 1967. That identifies the coverage of this particular archived product, not an independently established shutdown date for every instrument. When comparing observations, check that the requested time falls inside the dataset and retain its sample timing. A modern orbital snapshot cannot fill missing historical plasma measurements.

Reference: NASA SPDF/OMNIWeb: Explorer 22 archived time span.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 866 km at perigee to 1,040 km at apogee, a difference of 175 km. The orbital period is about 104.1 minutes. Eccentricity 0.01192 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 1.02 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 79.69 degrees implies approximate geocentric ground-track limits of 79.7 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.

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 899 · GCAT: S00899 (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)

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