ATS 3

About This Satellite

ATS-3 carried the Multicolor Spin-Scan Cloudcover Camera, or MSSCC, which extended the monochrome imaging approach of ATS-1 to colour. Its telescope and red, green, and blue photomultiplier detectors viewed Earth through an opening in the side of the spinning spacecraft. The resulting cloud images were assembled by scanning, not by exposing an entire photographic frame at once.

The spacecraft spin supplied one direction of the scan

Rotation swept the view east to west, while a stepping mechanism advanced the telescope from pole to pole. SSEC describes 2,400 scan lines collected over about 24 minutes, followed by a retrace. A full-disc frame consequently combines observations made at different times; fast-changing cloud features should not be interpreted as a perfectly simultaneous view of the hemisphere.

Colour imaging did not last as long as the camera experiment

The red and blue channels failed approximately three months after launch, leaving black-and-white imaging. SSEC records daily pictures until December 11, 1974, then a reduced schedule, with the camera experiment ending on October 30, 1975. This instrument history is distinct from the operational history of the entire spacecraft.

Mission reference: University of Wisconsin SSEC: ATS-3 Multicolor Spin-Scan Cloudcover Camera. Editorial review: 2026-09-14.

Weather images and relayed weather products were different services

NASA dates the ATS-3 launch to November 5, 1967 and lists three meteorological experiments: the spin-scan camera, an electronically scanning Image Dissector Camera, and WEFAX. WEFAX relayed processed information from the ESSA ground facility to receiving stations, including spin-scan images. It was a distribution link, not another camera independently photographing the same clouds. Distinguishing acquisition from retransmission clarifies what a receiving station actually obtained.

Reference: NASA: ATS-3 launch, imaging experiments and WEFAX data relay.

Several spacecraft contributed different first views of Earth

NASA's history credits DODGE with a full-Earth colour image earlier in 1967. SSEC describes ATS-3's achievement specifically as operational multicolour Earth-cloud photography. These are different milestones. The famous ATS-3 imagery should not be described simply as the first colour photograph of Earth without qualifying the type of observation and distinguishing it from DODGE and earlier partial views.

Reference: NASA: historical Earth-image milestones, including DODGE.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 35,721 km at perigee to 35,852 km at apogee, a difference of 131 km. The orbital period is about 1436.1 minutes. Eccentricity 0.00155 indicates a nearly circular path. In a two-body approximation, perigee speed is 1.00 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 3.38 degrees implies approximate geocentric ground-track limits of 3.4 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 1436.1 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 3029 · GCAT: S03029 (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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