VANGUARD 3

About This Satellite

Vanguard 3 launched on September 18, 1959, carrying experiments for the geomagnetic field, solar X-rays, and micrometeoroids. Its distinctive magnetometer housing extended from the spherical spacecraft. The satellite was an environmental laboratory, rather than a camera intended to photograph the land beneath its path.

The field measurement was a strength, not a compass arrow

Its proton-precession magnetometer measured the total magnetic field. That quantity is a scalar strength, not a complete three-axis direction measurement. A plot of these observations therefore needs to be read differently from a diagram showing the direction of magnetic field lines.

Do not turn a regional sample into a global survey

The original instrument report places observations between roughly 33.4 degrees north and south and links collection to the Minitrack station network. Those limits matter when interpreting the science. A map showing a complete Earth does not mean this particular experiment sampled every latitude or longitude equally.

Mission reference: NASA experiment catalog: Vanguard 3. Editorial review: 2026-09-12.

Eighty-five days of measurements

The instrument team reports that the magnetometer functioned throughout the 85-day battery life. Surface magnetic observatories at eight tracking stations supplied comparison measurements. Combining space and ground observations helped researchers interpret changes in the field rather than treating every change as a spacecraft effect.

Reference: NASA TN D-486: Vanguard magnetic-field instrumentation and measurements.

What the early analysis investigated

The technical report discusses calculated field accuracy, field stability in space, the Cape Town anomaly, and magnetic-storm effects. These are questions about the magnetic environment. The current orbital elements in this catalog locate the tracked hardware; they do not contain the magnetometer readings needed to reproduce that research.

Reference: NASA TN D-486: scope of the magnetic-field analysis.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 508 km at perigee to 3,203 km at apogee, a difference of 2,695 km. The orbital period is about 123.9 minutes. Eccentricity 0.16366 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 1.39 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 33.34 degrees implies approximate geocentric ground-track limits of 33.3 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 20 · GCAT: S00020 (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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