SENTINEL 1A

About This Satellite

Sentinel-1A was a Copernicus Earth-observation mission using C-band synthetic aperture radar. ESA lists its mission as ended in June 2026. Radar sends a signal toward Earth and measures the returned echo, enabling observations of land, ice, and oceans quite different from ordinary photographs.

A repeat orbit supports comparisons

The nominal mission orbit is near-polar and sun-synchronous, around 693 km high. Published revisit figures may describe a constellation rather than this one spacecraft. Do not read a six-day two-satellite figure as a guarantee that Sentinel-1A alone observes every place every six days.

This is Sentinel-1A, not every Sentinel-1

The later Sentinel-1C and Sentinel-1D carry ship Automatic Identification System capability. That feature must not be copied onto Sentinel-1A merely because the satellites share a family name. The same distinction applies to service availability and acquisition schedules: check the specific spacecraft and data product.

Mission reference: ESA: Sentinel-1 facts and figures. Editorial review: 2026-09-07.

The archive outlives the operating mission

ESA reports that Sentinel-1A's operational duties ended on June 29, 2026, after about twelve years of service. Its openly available radar archive remains useful for research and long-term comparisons. Retirement does not mean that the spacecraft has already reentered, and a fresh TLE does not restart its imaging mission. New acquisitions from other Sentinel-1 spacecraft belong to those separate records.

Reference: ESA: Sentinel-1A end of mission, June 2026.

How radar helps when skies are cloudy

The radar can observe by day or night and through cloud cover. That makes it useful where an optical image is unavailable, including cloudy tropical regions and polar darkness. Radar brightness describes the returned microwave signal; it is not natural surface colour. Surface structure, moisture, and viewing geometry all affect interpretation.

Reference: ESA: Sentinel-1 radar instrument.

Measuring deformation requires multiple acquisitions

Radar interferometry compares suitable images of the same area to investigate ground movement, including deformation associated with earthquakes or volcanic activity. A satellite marker passing nearby is not itself a deformation measurement. Processing must account for geometry and other effects before interpreting a change as motion; use the mission products, not a TLE trace, for that analysis.

Reference: ESA: radar interferometry and applications.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 693 km at perigee to 695 km at apogee, a difference of 2 km. The orbital period is about 98.6 minutes. Eccentricity 0.00014 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 98.16 degrees implies approximate geocentric ground-track limits of 81.8 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 39634 · GCAT: S39634 (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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