Spacecraft Attitude Control for Shared Imaging and Laser Pointing

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Solution Overview

Problem

Current spacecraft imaging systems face challenges in acquiring sharp and precise images of terrestrial areas while minimizing motion blur and signal noise, particularly when high spatial resolution is required, and also struggle with the complexity of controlling optical and laser sightlines during data transfer.

Innovation Solution

A method involving a spacecraft with a matrix sensor and a laser emission module, both integrated at a focal plane of the observation instrument's optics, where the optical and laser sightlines are fixed, allowing for two-axis attitude control to maintain a stable line of sight, reducing complexity and improving signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the spacecraft uses strip scanning mode to observe terrestrial areas beyond the predetermined length, then the coverage area is improved, but motion blur increases and image quality deteriorates

Engineering Contradiction:

Improvecoverage areaVSAvoidimage quality

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent implements dynamic attitude control during the scanning process, continuously adjusting the spacecraft's orientation to maintain the optical line of sight stable on the ground despite the spacecraft's motion and the changing scan angle, thereby reducing motion blur while covering extended areas

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the scanning parameters dynamically, including adjusting the scan rate, dwell time per line, and attitude control bandwidth to optimize the balance between coverage speed and image quality, allowing clear imaging across extended terrestrial areas

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the spacecraft reduces acquisition time to minimize motion blur, then image sharpness is improved, but signal-to-noise ratio deteriorates

Engineering Contradiction:

Improveimage sharpnessVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent employs periodic scanning with controlled dwell times at each line position, allowing sufficient integration time for each line while maintaining overall rapid acquisition, thus preserving signal-to-noise ratio while minimizing motion blur through the periodic nature of the scan

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements continuous scanning with overlapping integrations where the detector integrates signal continuously across multiple line positions, maintaining useful action throughout the acquisition process rather than using discrete short exposures, thereby improving signal-to-noise ratio while keeping motion blur minimal

Inventive Principle:

Principle #20Continuity of useful action

3Adaptability or versatility

If the spacecraft equips both observation instrument and laser transmission module with independent mobile sightlines, then pointing flexibility is improved, but device complexity increases

Engineering Contradiction:

Improvepointing flexibilityVSAvoidcontrol system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the laser transmission module's sightline with the observation instrument's optical line of sight, making them coincident and fixed relative to each other, thereby eliminating the need for independent laser pointing control mechanisms and reducing overall system complexity while maintaining sufficient flexibility for both functions

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the common optical line of sight serve dual purposes: for image acquisition by the observation instrument and for laser transmission targeting, allowing a single pointing control system to fulfill multiple functions and reducing the need for separate control mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If the spacecraft uses TDI configuration to reduce noise, then signal-to-noise ratio is improved, but electronic complexity increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidelectronic complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic TDI processing with a simpler mechanical/optical approach by using the natural motion of the spacecraft and detector to achieve integration, where the detector physically moves with the spacecraft's scanning motion to maintain alignment with the ground target, achieving noise reduction without complex electronics

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4337914B1Method for acquiring images of a terrestrial zone using a spacecraft comprising a laser transmission module

Publication Date: 2025.01.01 AIRBUS DEFENCE & SPACE SAS

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AI summary

The present invention relates to a method (50) for acquiring images by a spacecraft (10) comprising an observation instrument (20) and a laser transmission module (30), said method comprising an acquisition phase (P50) for the acquisition of an image of the Earth's surface and a transmission phase (P51) for the transmission of images by the laser transmission module, wherein, during each acquisition phase and each transmission phase, attitude control comprises: - an aim modification step (S60), during which the attitude of the spacecraft (10) is modified so as to orient the satellite towards a predetermined setpoint; - an aim stabilisation step (S61), during which the attitude of the spacecraft is controlled for a time interval referred to as an immobilization period so as to keep the spacecraft oriented towards said setpoint.