Measuring Earth-to-Space Contrast Transmittance from Ground Stations

Area of Science:

• Atmospheric optics and remote sensing.
• Earth observation and space science.

Background:

• Accurate measurement of atmospheric optical properties is crucial for Earth-to-space visibility studies.
• Ground-based measurements of inherent radiance, beam transmittance, and sky radiance are feasible.

Purpose of the Study:

• To demonstrate the computation of path radiance for orbital downward paths using ground-based measurements.
• To enable the calculation of apparent radiance, apparent contrast, and contrast transmittance from Earth to space using ground station data.

Main Methods:

• Utilized ground station measurements of sky radiance and beam transmittance.
• Calculated path radiance for downward orbital paths of sight in the visible spectrum.
• Conducted simultaneous in-flight and ground-based experiments to measure contrast transmittance.

Main Results:

• Demonstrated that apparent radiance, contrast, and contrast transmittance are measurable from a ground station.
• In-flight experiments yielded contrast transmittance measurements.
• Ground-based and in-flight measurements of contrast transmittance showed good agreement.

Conclusions:

• Ground-based measurements are sufficient for calculating key optical parameters for Earth-to-space observation.
• The study validates the use of ground-based atmospheric optical measurements for remote sensing applications.
• Confirms the reliability of ground-based methods for predicting atmospheric effects on Earth-to-space visibility.