Polar EFI: Spacecraft Potential and Plasma Density Measurements

Spin-resolution measurements of spacecraft potential and plasma density from the POLAR satellite's Electric Fields Instrument (EFI). The plasma density is derived from a function fitted to POLAR Hydra particle data for 2001/04/01, with relative accuracy estimated at 10-30% and absolute accuracy better than a factor of two for densities below ~20 particles/cm³. The dataset is provided by the National Aeronautics and Space Administration (NASA) and was last updated in March 2026.

Use Cases

• Calibrating plasma density models based on spacecraft potential measurements.
• Analyzing short-term plasma condition variability using the spin-resolution time series.
• Validating satellite instrument readings against the provided accuracy estimates for densities below 20 particles/cm³.
• Identifying data quality flags by detecting filler values (1.0e+20, 1.0e-20) in the plasma density column.

Strengths

• Provides explicit accuracy estimates: relative accuracy of 10-30% and absolute accuracy better than a factor of two for densities <20 particles/cm³.
• Includes clear data quality rules, specifying filler values for unreliable density readings (e.g., >1.0e+2 or <1.0e-4).
• All spacecraft potential values are noted as true values with no filler data.

Limitations

• Plasma density values greater than 30 particles/cm³ are described as inaccurate and are not plotted.
• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Data from the POLAR satellite's Electric Fields Instrument (EFI), with plasma density derived from a function fitted to POLAR Hydra particle data.

Time Range

The plasma density function is based on data from 2001/04/01; the full temporal coverage of the dataset is unspecified.

Freshness

Last updated 2026-03-13 07:39:03.433293; freshness should be verified.

Geography

Space-based measurements from the POLAR satellite orbit.