Orbital Imager Emulator
V0.5.1

The emulator simulates the orbit of a satellite using the Simplified Perturbation Model SGP4 through the use of the orb.js library linked below.

Images are captured during the satellite orbit at regular intervals. The images are captured pointing towards the ground (nadir pointing). Alternatively, a spinner mode can be used to simulate tumbling in which case images are only captured when all four corners of the camera frustum are facing the Earth.

The simulation makes use of several simplifications and assumptions, which will have an affect on the final result:

  • The Earth surface is treated as a smooth ellipsoid, with no digital elevation model.
  • The imager lens is assumed to be rectilinear (non-spatially-distorted).
  • Light refraction is ignored. Light is assumed to always move in a straight line.
  • Sampling and light-speed delay is ignored. The imager is assumed to capture instantaneous images of the ground.
  • The orbit from the SGP4 model rapidly loses accuracy over time elapsed since the reference date specified in the Two-Line Element epoch.
  • The imager is assumed to face perpendicular to the ground geodetically below the satellite. This may be an unrealistic assumption for simple satellites without gimbal control.

Javascript libraries:

GIS resources:

  • Geo-Maps - Coastlines and political borders licensed under the MIT License
  • Blue Marble by NASA
Simulation setup
Orbit

Input the Two-Line Element of the satellite to simulate (excluding the name line).
The simulation start time is at the epoch defined in the TLE.


Imager



Ground station

Documentation

  • Time scale

    The real-time scale factor. For example: A value of 10 means 10 seconds simulation time passes for each real-time second.

  • Attitude model

    The satellite attitude model.

  • Pitch/Yaw/Roll deg

    The satellite pitch/yaw/roll in the Earth-Centered, Earth-Fixed coordinate system.

  • Spin X/Y/Z in ECEF deg

    The satellite spin in degrees per second in the Earth-Centered, Earth-Fixed coordinate system.

  • Use downlink

    Whether to estimate downlink capacity above the ground station.

  • Min elevation angle

    The minimum angle between the ground station horizon plane and the satellite for a downlink to be active.

  • Bandwidth Mbps (bits)

    The downlink bandwidth in megabits per second.

  • Acquisition interval ms

    The acquisition interval in milliseconds. This is the interval between the beginnings of frame acqusitions.

  • Burst frame count

    The number of frames to capture inside each acquisition interval.

  • Frame acquisition time ms

    The imager frame acquisition time in milliseconds (0 = instantaneous sampling).

  • Limit acquisition area

    Whether to limit the satellite imager acquisition area to a spherical cap around the point of interest.

  • Sampling area radius km

    The minimum Haversine distance between the point of interest and the satellite ground track.

  • Grid count

    The number of pixel grids to visualize on the last captured images.

  • Unsubdivisons

    The number of subdivisions on the pixel grid (1 to half the number of pixels, 2 for 1/4 the number of pixels etc.)

Canvas is not supported