How Satellites Use Split Thrusters to Reach Orbit Faster

A method for satellites with electric engines to manage their power usage by staggering when they fire thrusters, allowing them to reach their final orbit more quickly.

What it covers

This patent describes a way to manage the limited electricity available to a satellite using electric propulsion. When a satellite emerges from the Earth's shadow (an eclipse), its solar arrays begin generating power. Instead of turning on all thrusters at once, which might drain the batteries or exceed the power budget, the system staggers the start times of different thrusters. By firing a second thruster after a calculated delay, the satellite balances the power needed for propulsion against the power required to recharge its batteries. This ensures the satellite maximizes its thrust time during the sunlight portion of its orbit, ultimately shortening the time it takes to reach its final destination.

What it doesn't cover

• —Does not cover chemical propulsion systems that do not rely on solar-powered electric thrusters.
• —Does not cover satellites that do not use batteries to store power for use during eclipse periods.
• —Does not cover thruster firing sequences that are not based on an electric power balance calculation.
• —Does not cover systems that fire all thrusters simultaneously regardless of power availability.

The clever bit

The innovation lies in the 'split thruster execution'—by intentionally delaying the second thruster, the system prevents a massive initial power spike, allowing the satellite to maintain a higher average thrust level throughout the entire sunlight portion of the orbit.

Why it matters

Electric orbit raising is a slow process that can take months. Every day spent moving to a final orbit is a day the satellite is not earning revenue for its operator. By optimizing the power cycle, Boeing's method allows satellites to reach their operational slots faster, which is critical for commercial telecommunications and military satellite constellations.

Real-world examples

• 1.Boeing 702 satellite bus series
• 2.Electric propulsion satellites in Geostationary Transfer Orbit (GTO)