By Ron Faith
The rapid evolution of small satellite technology is transforming the landscape of satellite operations and ground station requirements. Traditionally, small satellites were primarily focused on Earth observation missions. However, their applications have expanded significantly to include communications, Internet of Things (IoT) services, and rendezvous and proximity operations (RPO) servicing. This proliferation of use cases is driving the adoption of diverse orbital regimes and creating new challenges and opportunities for ground station infrastructure.
Expanding Beyond Sun-Synchronous Orbits
Historically, many small satellite missions operated in Sun-synchronous orbit (SSO) due to its suitability for consistent lighting conditions essential for Earth observation. However, the growing diversity of mission objectives is pushing satellite deployments into new orbital domains:
- Medium Earth Orbit (MEO): Ideal for navigation and some communications missions due to its moderate altitude.
- Geostationary Orbit (GEO): Suitable for continuous coverage of specific areas, particularly for communications and IoT applications.
- Highly Elliptical Orbit (HEO): Allows for extended dwell times over specific regions, making it valuable for high-latitude coverage.
- Very Low Earth Orbit (VLEO): Provides high-resolution imaging and low-latency communications in a “self-cleaning” orbit due to atmospheric drag.
Ground Station Locations: Mid-Latitude and Equatorial Sites
The diversification of orbital regimes necessitates ground stations in strategic locations. While SSO missions primarily required polar or high-latitude ground stations, new mission profiles demand:
- Mid-latitude ground stations: Essential for MEO and some HEO missions to maximize tracking opportunities.
- Equatorial ground stations: Crucial for GEO RPO missions and certain equatorial HEO configurations.
Deploying antennas in these regions will enhance the ability to maintain consistent communication with satellites across various orbits.
Increasing Antenna Aperture Sizes
As satellites move into higher orbits like MEO and GEO, the increased distance from Earth requires ground station antennas with larger apertures to maintain sufficient signal strength. These larger antennas ensure adequate sensitivity and reliability for data transmission and reception, particularly for high-bandwidth applications such as communications and RPO servicing.
Need for Tracking Antennas
Unlike traditional GEO-focused antennas that are often fixed, supporting satellites in dynamic orbital regimes necessitates tracking antennas. This capability is vital for:
- Orbit raising and drifting phases: Satellites need constant monitoring and adjustments during these operations.
- Non-geostationary satellites: Continuous tracking ensures reliable communication as the satellites traverse the sky.
Advanced tracking systems enable ground stations to maintain precise alignment with satellites, even in challenging scenarios like HEO orbits with highly variable trajectories.
Ground Gateways and Intersatellite Links
While intersatellite links (ISLs) can facilitate data relay between satellites, ground gateways remain indispensable. These gateways provide the critical infrastructure needed to downlink data to Earth for processing and distribution. ISLs can reduce reliance on certain ground stations, but they cannot replace the foundational role of terrestrial gateways in ensuring robust data delivery and connectivity.