Satellite Attitude Control via Commanded Optical Surfaces

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Solution Overview

Problem

Satellites in high-altitude orbits, such as geosynchronous orbits, face attitude control challenges due to solar pressure-induced disturbing torques, which existing methods address by de-pointing solar generators, leading to reduced electrical energy generation and propellant consumption.

Innovation Solution

A device with commanded optical surfaces on solar generators, arranged to create torques around three independent axes without de-pointing, using flaps with adjustable inclinations and electrochromic materials to modify solar pressure while maintaining optimal solar generator orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If solar generators are de-pointed to create torques for attitude control, then attitude control is achieved, but electrical energy generation drops significantly

Engineering Contradiction:

Improveattitude control capabilityVSAvoidelectrical energy generation

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The solar generator assembly is segmented into multiple independent solar generators, each capable of being controlled separately. This allows selective de-pointing of only the necessary solar generators for torque generation while keeping others optimally oriented for energy generation, thus resolving the contradiction between attitude control and energy production

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the solar generator system are assigned different functions: some solar generators are designated for attitude control (local quality of torque generation) while others are optimized for energy generation (local quality of power production). This spatial differentiation allows simultaneous achievement of both attitude control and energy generation without mutual interference

Inventive Principle:

Principle #3Local quality

2Ease of operation

If reaction wheels are used to accumulate angular momentum, then attitude control is improved, but propellant consumption increases for de-saturation

Engineering Contradiction:

Improveattitude control precisionVSAvoidpropellant consumption

Core Design Contradiction:

Ease of operationVSLoss of substance

Solution Approach 1:

The harmful solar pressure torques that normally disturb satellite attitude are converted into a useful resource for de-saturating reaction wheels. By intentionally creating solar pressure torques through selective solar generator de-pointing, the system can counteract accumulated angular momentum in reaction wheels without consuming propellant, thus converting a harmful disturbance into a beneficial de-saturation mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The satellite uses its own solar generators to generate torques that serve dual purposes: attitude control and reaction wheel de-saturation. This self-service mechanism eliminates the need for external propellant-based de-saturation systems, allowing the satellite to maintain attitude control precision while avoiding propellant consumption

Inventive Principle:

Principle #25Self-service

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

Enables attitude control around three axes without de-pointing solar generators, maintaining electrical energy generation and reducing propellant consumption by creating torques through optical property modulation.

Implementation Method 1

it is known, from U.S. Pat. No. 5,305,971, to equip solar generators with electrochromic cells. Such electrochromic cells are cells whose optical properties can be modified by applying an electrical stimulus

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Implementation Method 2

solar pressure is one of the main sources of disturbing torques likely to lead to an undesirable change in the satellite's attitude

Methodology Applied

Scientific EffectSolar pressure: Radiation Pressure

Data Source

PatentUS9227740B2Device for monitoring the attitude of a satellite, and method for controlling a satellite provided with said device

Publication Date: 2016.01.05 AIRBUS DEFENCE & SPACE SAS

AI summary

A device for controlling the attitude of a satellite exploiting solar pressure, includes at least two solar generators destined to be arranged on either side of a central body of the satellite and each having one face to be exposed to the Sun, referred to as “front face”, the device also including at least three surfaces whose optical properties can be commanded. The surfaces whose optical properties can be commanded are arranged on flaps connected to solar generators, each flap being fixed with respect to the solar generator to which it is connected, and such that, in the operating position, at least two of the surfaces are not parallel when the front faces of the solar generators are optimally oriented with respect to the Sun. The device further includes a module for commanding the optical properties of each surface whose optical properties can be commanded.