SENTINEL-1D
Country: European Union
Live Position
Ground Track · Last 90 Minutes
Upcoming Passes · Over Your Location
About This Satellite
Sentinel-1D completed its in-orbit commissioning and was announced fully operational by ESA on May 1, 2026. It is the fourth and final spacecraft of the first Sentinel-1 generation. Its arrival supports continuity of radar observations used for hazards, sea ice, land deformation, and environmental monitoring.
Four launches do not mean four operational partners
The mission was designed around two spacecraft in a shared orbit, separated by 180 degrees. The history includes the end of Sentinel-1B's mission and the later arrival of C and D. Counting all four catalog entries therefore does not establish that four radar satellites are currently contributing to the same operational constellation.
Commissioning is a milestone, not a live health feed
The May 2026 announcement establishes successful completion of a validation phase. It does not certify uninterrupted availability of every later scene. For a time-sensitive analysis, check the acquisition plan, product availability, and service notices alongside this historical mission record; orbital visibility alone cannot promise that an image was collected.
Mission reference: ESA: Sentinel-1D completion of commissioning, May 2026. Editorial review: .
Ariane 6 carried the replacement generation into orbit
The launch record dates Sentinel-1D's departure to November 4, 2025 aboard Ariane 6 from French Guiana. It identifies C-band radar and an Automatic Identification System receiver among its equipment. Launch, radar commissioning, and the availability of validated products should be kept separate when reconstructing the beginning of the mission.
Reference: ESA: Sentinel-1D launch record and onboard instruments.
A ship echo and a ship identity are different evidence
The AIS instrument receives vessel messages that can include identity, location, and direction of travel. Radar provides another kind of observation of the surface. Their combination can support maritime analysis, but a radar detection is not automatically a verified vessel identity. A catalog orbit contains neither the radar scene nor the received AIS messages needed for that association.
Reference: ESA: Sentinel-1D maritime radar and AIS capabilities.
Reading this orbital snapshot
Based on TLE epoch: 2026-09-04. Estimated altitude ranges from 695 km at perigee to 697 km at apogee, a difference of 2 km. The orbital period is about 98.7 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 98.18 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 66315 · GCAT: S66315 (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)