Satellite Propulsion Segmentation for GEO Station Acquisition
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Solution Overview
Problem
Current methods for launching and positioning satellites in geostationary orbit using chemical propulsion systems result in a high propellant mass fraction, limiting the payload mass and mission duration, with no effective solution to significantly increase the dry mass share of the satellite while extending its operational life.
Innovation Solution
A method where a satellite is launched with a first quantity of propellant for initial positioning and an intermediate mission period, and a second quantity is transported by a tanker launched at a lower cost using more efficient electric propulsion, transferred in one go to extend the mission duration beyond the initial period, optimizing the total mass launched and reducing the number of rendezvous and unavailability of the satellite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a satellite uses chemical propulsion to circularize GTO orbit into GEO orbit, then positioning speed is improved, but propellant mass fraction increases significantly
Solution Approach 1:
The propulsion system is segmented into two distinct parts: a chemical propulsion system for high-speed positioning maneuvers, and an electric propulsion system for long-duration station-keeping. This segmentation allows each system to be optimized for its specific function, reducing the total propellant mass required while maintaining fast positioning capability.
Solution Approach 2:
The satellite dynamically switches between chemical and electric propulsion modes based on operational requirements. Chemical propulsion is used for rapid orbit circularization, then electric propulsion takes over for continuous station-keeping adjustments. This dynamic transition optimizes the balance between positioning speed and propellant consumption over the satellite's lifetime.
2Loss of energy
If electric propulsion is added to the satellite for station-keeping, then propellant efficiency is improved, but device complexity increases
Solution Approach 1:
The electric propulsion system serves multiple functions: it performs station-keeping maneuvers, extends the satellite's operational lifetime, and can supplement orbit raising if needed. This multi-functionality justifies the added complexity by providing versatile propulsion capabilities that benefit multiple aspects of satellite operation.
Solution Approach 2:
The satellite's control system acts as an intermediary that manages the complex interaction between chemical and electric propulsion systems. It determines when to switch between modes, coordinates propellant usage, and optimizes the overall propulsion strategy, thereby managing system complexity through intelligent control rather than mechanical complexity.
3Duration of action of moving object
If all propellant is launched on board the satellite, then mission duration is extended, but total mass launched increases
Solution Approach 1:
The satellite is preliminarily equipped with only the chemical propulsion system and minimal propellant needed for orbit circularization. The electric propulsion system is then activated to provide sustained thrust for station-keeping over the mission duration. This preliminary action allows the satellite to reach GEO orbit with reduced initial mass, while the electric propulsion extends operational life without requiring proportional increases in launch mass.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the dry mass fraction of the satellite, extends mission duration to over 15 years, and reduces the total mass launched, allowing for more complex payloads and longer operational lifetimes without increasing the satellite's dry mass, while minimizing risks and unavailability during refueling.
Implementation Method 1
Two types of propulsion are most generally used on board satellites: chemical propulsion (generally hydrazine or bi-liquid based on nitrogen peroxide and mono-methyl-hydrazine)
Implementation Method 2
Two types of propulsion are most generally used on board satellites: chemical propulsion and/or electric propulsion
Data Source
Figure 1~2
Figure 3
AI summary
The method involves transporting total quantity of propellant required for carrying out station acquisition of a satellite (1) e.g. earth observation satellite, in a geostationary orbit (GEO) (4) from a geostationary transfer orbit (GTO) (5) and station-keeping of the satellite, into two distinct units. A tanker (2) is launched on the GTO. Station acquisition of the tanker is carried out on a parking orbit near to the GEO using propulsion of propulsive efficiency higher than chemical propulsion of the satellite. An independent claim is also included for a system comprising a satellite and a tanker.