Satellite In-Orbit Testing During Electric Propulsion Transfer
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Solution Overview
Problem
The existing methods for positioning geostationary telecommunications satellites using electric or hybrid propulsion result in prolonged transfer and testing phases, often taking several weeks to months, due to the low thrust and high specific impulse of electric propulsion, leading to increased costs and time before the satellite can be delivered for In-Orbit Acceptance Review.
Innovation Solution
The method involves modifying the transfer phase to perform In-Orbit Testing during the transfer phase itself, by using electric or hybrid propulsion to gradually deform a geosynchronous elliptical orbit into a geostationary orbit, with thrust stopped during portions of the orbit for payload testing, allowing tests to be conducted 'in masked time' and avoiding the repositioning phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If electric propulsion is used to replace chemical propulsion, then the satellite mass can be significantly reduced, but the transfer phase duration increases from about a week to between 3 and 6 months
Solution Approach 1:
The patent applies preliminary action by performing payload testing during the transfer phase itself, before the satellite reaches geostationary orbit. The transfer trajectory is designed to include testing windows where the satellite can conduct payload tests while still in transit, utilizing the transfer orbit's characteristics to accommodate testing activities without requiring a separate dedicated testing phase after arrival at GEO.
2Adaptability or versatility
If the transfer phase is extended to perform payload testing, then In-Orbit Testing can be conducted during transfer, but the overall time from launch to In-Orbit Acceptance Review increases
Solution Approach 1:
The patent merges the transfer phase with the testing phase by conducting payload tests during the electric propulsion transfer orbit. Instead of completing transfer first and then performing tests separately, the methodology combines both operations into a single integrated phase, utilizing the transfer orbit's time window to accommodate testing activities alongside the propulsion maneuvers.
Solution Approach 2:
The patent employs periodic action by implementing thrust interruptions at specific intervals during the transfer phase to allow payload testing. The electric propulsion system applies thrust continuously except for designated testing windows, creating a periodic pattern of thrust application and testing. This periodic thrust interruption enables testing operations without completely halting the transfer process, maintaining progress toward geostationary orbit while accommodating test requirements.
3Ease of operation
If thrust is stopped during orbital revolutions for payload testing, then testing can be performed in masked time, but the transfer phase duration increases by a few days
Solution Approach 1:
The patent implements periodic action by stopping thrust during specific fractions of orbital periods to enable payload testing. The electric propulsion system operates continuously except for designated testing windows where thrust is interrupted. This periodic thrust interruption pattern allows testing operations to be conducted during the transfer phase while minimizing the impact on overall transfer duration, as the thrust resumption quickly restores the transfer trajectory.
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 reduces the overall time from launch to In-Orbit Acceptance Review, minimizing interference with operational satellites and reducing the need for repositioning, while also potentially reducing costs by allowing single-shift testing and shorter commissioning time.
Implementation Method 1
by electric or electric-chemical hybrid propulsion, applying to said satellite a thrust - which can be described as 'continuous' - suitable for gradually bringing said inclined geosynchronous elliptical orbit closer to a geostationary orbit
Implementation Method 2
a step of transferring the satellite to a geostationary orbit, during which the satellite moves in a geosynchronous elliptical orbit
Data Source
Figure 1~3
AI summary
Method of placing a satellite (SAT) into position comprising a transfer phase, during which said satellite moves on a geosynchronous elliptical orbit (GSO1, GS02), said orbit being progressively deformed by application of a thrust (P) by means of an electric or hybrid electric-chemical propulsion to bring it closer to a geostationary orbit (GEO), characterized in that said transfer step comprises a substep during which, during a plurality of revolutions of the satellite, said thrust is stopped for a fraction of the orbital period and tests of a telecommunications payload of said satellite are carried out in the absence of thrust.