O3b

O3b is a MEO satellite network operated by SES that provides low-latency broadband connectivity and mobile backhaul, originally branded around serving the ‘other three billion’ people without high-speed access. The first-generation O3b MEO constellation comprises 20 Ka-band satellites in equatorial MEO at an altitude of about 8,063 km with an orbital period of about 288 minutes (five orbits per day). Because the constellation operates in an equatorial orbit, continuous service is primarily provided within approximately ±45° latitude. This reduced path length yields markedly lower latency than geostationary systems, with typical end-to-end round-trip latencies on the order of 120–150 ms, compared with approximately 500 ms for GEO systems.

The first four satellites were launched on 25 June 2013, and the final four were launched in April 2019, completing the 20-satellite constellation (including three in-orbit spares). Each satellite, with a mass of approximately 700 kg, is equipped with twelve steerable Ka-band antennas forming two gateway beams and ten user beams, each with a footprint of roughly 700 km. All beams are independently steerable within the coverage region and may be stacked to provide additional capacity where required. The payload supports up to ~1.6 Gbps per beam, giving an overall satellite throughput of approximately 16 Gbps, depending on beam allocation and modulation.

Each satellite supports two groups of gateway and user beams, with each gateway beam connected to five customer beams. Loopback configurations can also be established to provide localized connectivity between terminals within the same beam. Customer beams are implemented using 216 MHz Ka-band transponders in both the forward and return directions. The system operates primarily in the Ka-band, using approximately 17.8–19.3 GHz for downlinks and 27.6–29.1 GHz for uplinks.

Unlike geostationary satellites, O3b satellites move continuously across the sky relative to the user. Consequently, gateway and customer terminals typically employ two tracking antennas operating in a make-before-break configuration, allowing one antenna to acquire the next satellite before the current satellite moves out of view and ensuring uninterrupted connectivity.

The system was designed primarily for telecommunications operators, enterprise customers, governments, and mobile network operators rather than direct-to-consumer services. The O3b satellite constellation does not target the consumer market it is still considered to be a HTS. O3b is particularly well suited to cellular backhaul, trunk connectivity, maritime services, remote communities, and other applications requiring high throughput and low latency.

In September 2017, SES announced the next-generation O3b mPOWER system, designed to provide broadband connectivity from hundreds of megabits to 10 Gbps per link through tens of thousands of electronically steerable spot beams. The software-defined digital payload enables dynamic routing between the mPOWER MEO satellites and SES’s geostationary fleet. SES contracted Boeing to build 11 mPOWER satellites, of which six are required for global service. SpaceX was contracted for four Falcon 9 launches (2021–2024).

The first six O3b mPOWER satellites were launched in three pairs (16 December 2022; 28 April 2023; 12 November 2023), and the system entered commercial service in April 2024. Two additional upgraded satellites (7 and 8) launched on 17 December 2024 and began delivering services in June 2025. Two more satellites (9 and 10) launched on 22 July 2025, with the remaining three satellites scheduled for launch in 2026.