Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

Area of Science:

• Space Physics
• Plasma Physics
• Aerospace Engineering

Background:

• Spacecraft charging is a significant concern for satellite operations in Earth's magnetosphere.
• Understanding the relationship between plasma environment and spacecraft potential is crucial for mission success.

Purpose of the Study:

• To investigate the correlation between electron energy fluxes and spacecraft surface charging.
• To analyze spacecraft charging phenomena within geosynchronous orbit using detailed plasma parameters.

Main Methods:

• Utilized data from the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments on the Van Allen Probes.
• Developed an algorithm to extract the H+ charging line from HOPE data for intense charging event analysis.
• Examined relationships between spacecraft potential and electron density, pressure, temperature, thermal electron current, and low-energy ion density.

Main Results:

• Identified that elevated electron energy fluxes and high electron pressures often coincide with spacecraft charging.
• Demonstrated that these conditions can also occur during non-charging periods, highlighting the complexity of charging events.
• Observed significant negative charging events on the Van Allen Probes, even during non-eclipse periods.

Conclusions:

• Both EFW potential measurements and HOPE instrument ion charging line data are essential for analyzing extreme spacecraft charging events.
• The study provides statistical insights into spacecraft charging based on L-shell and magnetic local time.
• Further research is needed to fully differentiate charging from non-charging conditions solely based on electron flux and pressure.