ESSA 2 (OT-2)

About This Satellite

ESSA-2 launched on February 28, 1966 to deliver cloud photographs directly to receiving stations through Automatic Picture Transmission, or APT. It complemented ESSA-1 rather than duplicating its ground-processing workflow. The practical benefit was access to local weather imagery during a satellite pass, without first routing every picture through a central analysis facility.

A rotating spacecraft provided discrete pictures, not live video

Two cameras were mounted on opposite sides of the spacecraft in the TIROS cartwheel configuration. As the spacecraft rotated, a camera faced Earth at the appropriate part of the cycle. NASA describes an APT image-transmission cycle of 352 seconds. That cadence should not be mistaken for continuous video or uninterrupted viewing of a fixed location.

The mission end is separate from continued catalog tracking

NASA records deactivation on October 16, 1970. A present-day catalog entry preserves the identity and orbit of the object; it does not imply that its cameras or APT transmitter still provide an operational weather service.

Mission reference: NASA Science: ESSA-2 direct-readout mission and deactivation. Editorial review: 2026-09-15.

Receiving stations brought the imagery closer to forecasters

The contemporary 1966 US space report describes APT pictures reaching comparatively simple ground stations within radio range. It reports more than 180 receiving stations in 45 countries, with roughly seven new stations being established per month at that time. These are historical network figures, not the number of terminals receiving any one pass simultaneously. Geographic access still depended on when the satellite was within view.

Reference: US space activities report 1966, page 93: ESSA-2 direct reception and station growth.

Control transferred before the rest of the early system

The same report records the National Environmental Satellite Center taking over ESSA-2 operations on March 15, 1966. Control of ESSA-1 and TIROS-9 followed on June 21. The dates distinguish launch from responsibility for routine operations, and show that the early weather-satellite system did not become operational through one simultaneous handover.

Reference: US space activities report 1966, page 91: ESSA satellite operational handovers.

APT and stored high-resolution imagery developed as complementary services

A NASA conference history describes ESSA-2 as the direct-readout member of the TIROS Operational System. Later ESSA-4, -6 and -8 continued APT service, while ESSA-3 and its successors used the Advanced Vidicon Camera System for a different imaging workflow. A family name alone therefore does not establish that every ESSA satellite used the same camera system or delivered pictures in the same way.

Reference: NASA CP-2227: the complementary APT and AVCS branches of the ESSA programme.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 1,354 km at perigee to 1,415 km at apogee, a difference of 61 km. The orbital period is about 113.4 minutes. Eccentricity 0.00393 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 101.22 degrees implies approximate geocentric ground-track limits of 78.8 degrees north and south. This is a retrograde orbit, moving against the direction of 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 2091 · GCAT: S02091 (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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