Inflight performance of the Viking visual imaging subsystem

Area of Science:

• Planetary Science
• Space Mission Engineering
• Remote Sensing

Background:

• The Viking Orbiter mission provided crucial early imagery of Mars.
• Understanding the performance of onboard imaging systems is vital for data interpretation.

Purpose of the Study:

• To assess the performance of the Viking Orbiter Visual Imaging Subsystem cameras.
• To quantify camera stability, noise levels, photometric accuracy, and geometric distortion.

Main Methods:

• Analysis of photographic data acquired during the Viking Orbiter's journey to and orbit around Mars.
• Evaluation of image focus, noise characteristics, and geometric distortion parameters.
• Recalibration of instruments to determine photometric measurement accuracy.

Main Results:

• Camera focus remained consistently good throughout the mission.
• In-flight noise levels (random and coherent) matched pre-flight measurements.
• Photometric measurements achieved <3% relative and 9% absolute accuracy post-recalibration.
• Geometric distortion remained near pre-flight levels (4 pixels RMS, 11 pixels maximum).

Conclusions:

• The Viking Orbiter's imaging system demonstrated robust performance and stability.
• The cameras were reliable for scientific data acquisition throughout the Mars mission.
• Post-mission analysis confirmed the high quality and usability of Viking Orbiter imagery.