Why many GEO satellites serving a region are stationed slightly west of the service area Select the principal operational reason for placing geostationary satellites somewhat to the west of their primary service areas.

Introduction / Context:
Geostationary satellites experience seasonal eclipses (Earth’s shadow) near the equinoxes, causing brief daily outages of solar power. Mission planners choose orbital longitudes to minimize operational impact of these eclipses on target service time windows and to manage power system margins.

Given Data / Assumptions:

• Eclipse seasons occur near the equinoxes for GEO satellites.
• Even small schedule shifts of eclipse relative to local prime time can be valuable for broadcasters.
• Longitude placement affects the local time at which eclipses occur for a given service region.

Concept / Approach:

The daily timing of eclipse entry/exit depends on satellite longitude relative to the service area’s local time zone. By selecting a longitude slightly west of the region, operators can shift eclipse times away from peak viewing hours, effectively reducing perceived eclipse impact and the operational “period of concern.”

Step-by-Step Solution:

Verification / Alternative check:

Operations logs and mission planning documents often discuss eclipse season scheduling relative to service markets to mitigate customer impact, which aligns with choosing slightly western orbital slots.

Why Other Options Are Wrong:

Payload power loss, propellant mass, and scintillation are not directly mitigated by longitude choice. Battery size is set by maximum expected eclipse duration and load, not longitude alone (though time-of-day effects influence operations).

Common Pitfalls:

Assuming longitude changes eclipse duration; it mainly shifts the local occurrence time. Duration depends on orbital geometry common to all geostationary slots.

Final Answer:

To reduce eclipse period experienced during equinoxes