Plasma observations at venus with galileo.

Area of Science:

• Planetary Science
• Space Physics
• Plasma Physics

Background:

• Galileo spacecraft provided in-situ plasma measurements near Venus on February 10, 1990.
• The study focused on the Venusian bow shock and upstream solar wind environment.
• Instrument limitations (sunshade) affected ion observations in the magnetosheath.

Purpose of the Study:

• To analyze plasma conditions in the vicinity of Venus, including the bow shock and solar wind.
• To determine solar wind densities and bulk speeds using electron velocity distributions.
• To investigate the presence and density of pickup ions originating from Venus's planetary coronas.

Main Methods:

• Utilized plasma measurements from the Galileo spacecraft.
• Analyzed electron velocity distributions to derive solar wind parameters.
• Detected ions streaming from the bow shock and searched for pickup ions.

Main Results:

• Observed multiple crossings of the Venusian bow shock in the dawn sector.
• Determined solar wind densities and bulk speeds from electron data.
• Measured electron heating at the bow shock as less than or equal to 20%.
• Observed significant density increases (2-3x) at the dayside of the shock.
• Established an upper limit for pickup ion densities (10^-3 ion/cm^3).

Conclusions:

• Electron heating at the Venusian bow shock is minimal.
• Observed plasma density enhancements are consistent with bow shock dynamics.
• The upper limit for pickup ions aligns with theoretical models of Venus's neutral gas density.