Single-Axis Slit Sun Sensor Spacecraft Power Acquisition
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Solution Overview
Problem
Existing spacecraft power acquisition methods using wide field of view sun sensors require large clear fields of view and expensive hardware, while multi-axis slit sun sensors need multiple sensors to sweep a wide area, making them complex and costly. There is a need for a simpler and more robust method that avoids expensive hardware and reduces complexity.
Innovation Solution
A method utilizing a single-axis slit sun sensor to search for the sun by rotating the spacecraft about a search axis parallel to the sensor's field of view, monitoring for a time of arrival signal, and adjusting the spacecraft's orientation to align with the sun or move it away from a keyhole area if the signal is not detected, thereby simplifying the power acquisition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wide field of view sun sensor is used for sun acquisition, then the spacecraft can acquire the sun for power safety, but it requires a large clear field of view (120×120 degrees) which becomes difficult to find as spacecraft components (antenna, radiator, solar wing) are increased in size
Solution Approach 1:
The patent divides the sun acquisition process into multiple sequential phases (sun search phase, sun acquisition phase, power safe spin phase) instead of requiring a single wide field of view sensor to detect the sun in one step. This temporal segmentation allows the use of a narrow field of view sensor that sweeps through different angular positions to locate the sun.
Solution Approach 2:
The patent transforms the sun search problem from a two-dimensional wide field of view requirement into a one-dimensional sweeping motion along a search axis. By rotating the spacecraft about a search axis that is substantially parallel to the slit sun sensor field of view, the narrow FOV sensor can cover a large angular area over time, effectively adding the time dimension to the search space.
2Reliability
If a wide field of view sun sensor is used for sun acquisition, then the spacecraft can find the sun, but it involves angular measurement processing requiring expensive electronic hardware such as buffer channel hardware and hardware for angular measurement processing
Solution Approach 1:
The patent replaces complex electronic angular measurement processing hardware with a simpler mechanical approach. Instead of using expensive buffer channel hardware and angular measurement processing hardware, the system uses the spacecraft's rotation mechanism itself to perform the search, with the slit sun sensor providing simple on/off detection signals that require minimal electronic processing.
Solution Approach 2:
The patent uses a simple slit sun sensor that provides basic sun detection capability without requiring expensive, complex electronic hardware. The system trades the durability and precision of expensive hardware for a simpler, more cost-effective sensor combined with mechanical searching motion.
3Reliability
If NFOV slit sun sensors or multi-axis slit sun sensors are used for power acquisition, then sun detection is possible, but at least two slit sun sensors typically orthogonal to each other are needed to sweep a wide area of the sky to find the sun
Solution Approach 1:
The patent makes a single slit sun sensor perform multiple functions by utilizing three-dimensional spacecraft rotation about a search axis. Instead of requiring multiple sensors to cover different angular directions, the single sensor sweeps through a wide area of the sky as the spacecraft rotates, allowing one sensor to replace what would traditionally require two or more orthogonal sensors.
Solution Approach 2:
The patent introduces dynamic rotation of the spacecraft about a search axis to enable a single static slit sun sensor to dynamically scan a wide field of view over time. This dynamic approach allows one sensor to cover the same angular space that would require multiple static sensors positioned orthogonally to each other.
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 hardware requirements and complexity, allowing for efficient power acquisition with fewer phases compared to prior art methods, achieving improved time to power safety performance using a single-axis slit sun sensor.
Implementation Method 1
monitoring the slit sun sensor for a time of arrival signal
Implementation Method 2
a solar wing with concentrator
Data Source
AI summary
A method for spacecraft power acquisition is provided using single-axis slit sun sensors for both wing-stowed and wing-deployed spacecraft configurations. The method for wing-deployed spacecraft includes initializing a solar wing of the spacecraft to search for sun; rotating the spacecraft about a search axis substantially parallel to a slit sun sensor field of view; monitoring the slit sun sensor for a time of arrival signal; and wherein, if the time of arrival signal occurs, the spacecraft is rotated along the search axis to an orientation where the time of arrival signal occurred and the spacecraft is placed in stable rotation about an axis substantially parallel to a solar wing longitudinal axis; and for a non-occurrence of the time of arrival signal, the spacecraft is slewed about a keyhole axis substantially perpendicular to the search axis to move the sun away from a keyhole.