EXPLORER 16

About This Satellite

Explorer 16 launched on December 16, 1962 to investigate the hazard posed by micrometeoroids to thin spacecraft surfaces. Its detectors recorded consequences of impacts, such as punctures and broken wires. These were physical exposure experiments, not a radar catalog locating individual pieces of orbital debris.

A new hole let sunlight reach a light-sensitive detector

One experiment placed an opaque, aluminium-coated Mylar film above a cadmium-sulfide photoconductor. A puncture admitted sunlight and changed the detector's electrical resistance. Vent openings allowed pressure equalization without illuminating the sensor directly. The resulting signal depended on the exposed opening and illumination, so it was not a photograph of the incoming particle.

A deliberately perforated reference checked the measurement system

The report describes two cells associated with separate telemetry channels. One film began opaque, while the other included a small calibration hole. That opening existed before orbital exposure and must not be counted as a newly observed impact. The reference response helped establish that the light-sensitive measurement chain was behaving as intended.

Mission reference: NASA: Secretan, Explorer 16 CdS and wire-grid dust-particle measurements. Editorial review: 2026-09-14.

Pressurized cells turned a puncture into a recorded event

A NASA-hosted assessment describes sealed beryllium-copper cells of different wall thicknesses. When a puncture released their pressure, a switch registered the event and retained its indication. Comparing exposed area, time, and wall thickness helped estimate penetrating-particle flux. The experiment measured how often a particular test surface was perforated, not a universal damage rate applying equally to all spacecraft structures.

Reference: NASA-hosted micrometeoroid assessment: Explorer XVI pressurized-cell detection.

Zero punctures did not establish zero risk

The final Langley supplement reports no punctures in the thickest, 0.005-inch beryllium-copper cells, but still gives a statistical upper rate limit with 95-percent confidence. A finite observation without events is a constraint, not proof of impossibility. The supplement identifies July 22, 1963 as its last usable experimental-data date; a later paper gives July 25 for telemetry B operation, so those archival descriptions are not collapsed into an unqualified exact mission-end date.

Reference: NASA Langley: Explorer XVI Supplement III, puncture limits and usable-data endpoint.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 742 km at perigee to 1,145 km at apogee, a difference of 404 km. The orbital period is about 103.9 minutes. Eccentricity 0.02756 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 1.06 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 52.00 degrees implies approximate geocentric ground-track limits of 52.0 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 506 · GCAT: S00506 (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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