Aqua MODIS Near Real-Time Spacecraft Orbit Data

PM1EPHND files provide definitive daily spacecraft ephemeris data for NASA's Aqua satellite, processed by the ECS SDP Toolkit. This data is essential for determining the precise geolocation of Earth remote sensing observations collected by the MODIS instrument. The files are produced by the LANCEMODIS organization in a native binary format for near real-time applications.

Use Cases

• Calculate satellite position and velocity vectors from ephemeris data for geolocation algorithms.
• Time-sync Earth observation pixel coordinates using the Julian day and hour/minute timestamps encoded in filenames.
• Validate and correct orbital models by comparing definitive ephemeris data against predicted trajectories.
• Support atmospheric correction and data fusion pipelines that depend on accurate sensor positioning.

Strengths

• Data is processed to an internal standard supported by the ECS SDP Toolkit, ensuring format consistency.
• Files are generated for near real-time (NRT) applications, indicating low latency for operational use.
• Definitive ephemeris data provides a high-accuracy record of the spacecraft's orbit.

Limitations

• The dataset is provided in a proprietary native binary format requiring specific SDP Toolkit software to read.
• Specific data volume, temporal coverage, and update frequency details are not provided in the input.
• Lack of documented column structure makes direct analysis without the toolkit difficult.

Provenance

Source

NASA Earthdata (LANCEMODIS organization).

Collection Method

Preprocessed from PM1 Platform Attitude Data by the ECS (EOSDIS Core System) to an internal standard.

Time Range

Coverage is implied by daily files named with year and Julian day (Ayyyyddd).

Freshness

Near real-time (NRT) daily updates.

Geography

Global, as it tracks the orbit of the Aqua satellite.