Electric Sail Propulsion Using Radial Wires and Solar Wind

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Solution Overview

Problem

Current spacecraft propulsion systems, such as chemical rockets and electric propulsion, fail to achieve high enough delta-v values for efficient travel to outer solar system targets in a reasonable time, leading to high mission costs and limited payload capacity.

Innovation Solution

A spacecraft propulsion system utilizing an electric sail with radially extending multifilament wires, held tight by centrifugal force, which are electrically conductive and maintained at a positive potential to interact with the solar wind, allowing momentum transfer and steering capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional propulsion systems (chemical rockets or electric propulsion) are used, then the spacecraft can achieve propulsion, but the delta-v values are insufficient for efficient travel to outer solar system targets

Engineering Contradiction:
Improvedelta-vVSAvoidtravel time to outer solar system
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent replaces conventional chemical or electric propulsion systems with an electric sail that utilizes electromagnetic interaction with solar wind particles. The conductive wires held at positive potential create an electric field that repels solar wind protons, transferring momentum to the spacecraft without mechanical propellant expenditure, thereby achieving higher delta-v values and reduced travel times.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If higher delta-v values are generated by reducing the payload mass fraction to a minimum, then delta-v increases, but the initial mass and mission cost increase exponentially

Engineering Contradiction:
Improvedelta-vVSAvoidinitial mass
Core Design Contradiction:
SpeedVSWeight of stationary object

Solution Approach 1:

The electric sail eliminates the need for large amounts of propellant mass by using electromagnetic forces to accelerate the spacecraft. The conductive wires interact with solar wind particles to generate thrust without consuming onboard propellant, dramatically reducing the initial mass required to achieve high delta-v values while maintaining payload mass fraction.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Force

If a continuous sheet membrane is used for solar sail, then momentum can be extracted from solar radiation, but the structure becomes complex and vulnerable to space hazards

Engineering Contradiction:
Improvepropulsive forceVSAvoidstructure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent divides the continuous membrane structure into discrete radially extending conductive wires. This segmentation simplifies the structure by eliminating the need for a continuous sheet while maintaining the ability to interact with solar wind particles. The wires are held at positive potential and spaced apart, creating a simplified yet effective propulsion structure that is more tolerant of space hazards.

Inventive Principle:
Principle #1Segmentation

4Force

If the electric sail uses a mesh of wires with spacing less than or equal to Debye length, then propulsion can be achieved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvepropulsive forceVSAvoidwire spacing precision
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The patent changes the operational parameters of the electric sail by holding the conductive wires at a positive electric potential rather than relying solely on precise geometric spacing. This parameter change allows the system to achieve effective propulsion with more relaxed wire spacing requirements, as the electric field extends beyond the immediate wire positions, reducing manufacturing precision requirements while maintaining propulsive force.

Inventive Principle:
Principle #35Parameter changes

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 efficient and reliable propulsion with the ability to steer the spacecraft, tolerance against space hazards, and reduced mission costs by leveraging solar wind momentum for higher delta-v values without the need for continuous membranes.

Implementation Method 1

An electric sail is an electrically conductive structure that is held at a positive potential with respect to the solar wind plasma... The positive potential of the wires causes an electrostatic Coulomb force interaction with the protons of the solar wind, which in turn transfers momentum from the solar wind to the wires

Methodology Applied
Scientific EffectElectrostatic repulsion: Electrostatics

Implementation Method 2

The positive potential of the wires causes an electrostatic Coulomb force interaction with the protons of the solar wind, which in turn transfers momentum from the solar wind to the wires and therethrough to the whole spacecraft

Methodology Applied
Scientific EffectMomentum transfer: Conservation of Momentum

Implementation Method 3

the electric sail comprise a number of radially extending multifilament wires that are held tight by the centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP1989114B1Electric sail for producing spacecraft propulsion
Publication Date: 2010.11.24 JANHUNEN PEKKA
  • EP1989114B1 patent drawingFigure 1~2b
  • EP1989114B1 patent drawingFigure 3~4
  • EP1989114B1 patent drawingFigure 5a~6

AI summary

A spacecraft propulsion system comprises a plurality of wires (102) or other electrically conductive elongated members deployed from a main body (101) into respective radial directions. An electric potential generator (605) generates an electric potential on board said main body (101). The electric coupling between the electric potential generator (605) and the elongated members is controlled (604) so that all or some of the elongated members (102) assume a high positive potential. An auxiliary propulsion system (203) rotates said main body around a rotational axis (502) that is perpendicular to said radial directions, thus creating a centrifugal supporting force to the elongated members.