Micropropulsion

The Basics of Micropropulsion

At its core, micropropulsion involves generating forces and moments to control spacecraft motion. These systems are characterised by their low thrust output, usually in the range of microNewtons to milliNewtons, which suffices for the fine control and adjustments needed by small spacecraft. Micropropulsion systems draw their appeal from their ability to enable long-duration space missions, contribute to spacecraft attitude control, and provide orbital maintenance capabilities with minimal propellant consumption.Key technologies in the domain of micropropulsion include:

• Electric Propulsion: Utilises electric power to accelerate propellant at high speeds.
• Cold Gas Thrusters: Uses pressurised inert gases as propellant.
• Pulsed Plasma Thrusters: Employs electrical energy to produce plasma from a solid or liquid propellant.
• Micro ElectroMechanical Systems (MEMS)-based Thrusters: Integrates propulsion components on a micro scale using semiconductor manufacturing techniques.

How Micropropulsion is Revolutionising Space Exploration

Micropropulsion is playing a pivotal role in the new era of space exploration, particularly in the deployment and management of small satellite constellations. These systems make it feasible to undertake complex missions with smaller, more cost-effective spacecraft.Examples of micropropulsion's impact on space exploration include:

• Enhanced capabilities for CubeSats, allowing for more ambitious missions beyond low Earth orbit.
• Enabling the formation flying of satellite constellations, which can drastically improve Earth monitoring and data collection efforts.
• Facilitating deep space exploration by smaller probes, capable of manoeuvring and adjusting trajectories with fine control.

Different Types of Micropropulsion Systems

Micropropulsion systems are integral to the functioning and operation of modern small spacecraft. These systems offer precise control capabilities, enabling satellites and probes to perform complex manoeuvres with high accuracy and efficiency. The development of various micropropulsion technologies allows for tailored applications, suiting different mission requirements and objectives.

Electric Micropropulsion for Small Spacecraft

Electric micropropulsion systems use electrical energy to generate thrust. This method contrasts with traditional chemical propulsion by offering higher efficiency and lower propellant consumption. Electric propulsion is especially suitable for small spacecraft, including CubeSats, because of its compact size and the ability to provide precise thrust control without adding significant weight to the spacecraft.There are several types of electric propulsion systems, each with unique mechanisms and advantages:

• Ion Thrusters: Accelerate ions using electricity to create thrust.
• Hall Effect Thrusters: Use a magnetic field to ionise and accelerate propellant.
• Electrospray Thrusters: Generate thrust through the electrostatic acceleration of charged liquid droplets.

Cold-Gas Micropropulsion Explained

Cold-gas micropropulsion represents one of the simplest forms of thrust generation available for small spacecraft. This system utilises a pressurised tank of inert gas, such as nitrogen or helium, which is released through a nozzle to create thrust. The absence of combustion or complex reactions makes cold-gas systems highly reliable and easy to control.Key features of cold-gas micropropulsion include its simplicity, reliability, and the capacity for rapid thrust modulation. Despite their lower efficiency compared to electric propulsion systems, cold-gas thrusters are often preferred for missions requiring uncomplicated and robust control mechanisms.

The Role of Cubesat Micropropulsion in Modern Space Missions

CubeSats have revolutionised access to space by providing an affordable and scalable platform for a wide range of missions, from Earth observation to fundamental scientific research. Micropropulsion systems play a vital role in extending the capabilities of CubeSats, enabling them to undertake more complex missions that require precise positioning and propulsion capabilities.Micropropulsion allows CubeSats to perform tasks such as orbital adjustments, formation flying, and deorbiting manoeuvres efficiently. This technology supports the sustainability of space operations by enabling small satellites to avoid collisions and reduce space debris through controlled deorbiting.

Advancements in Liquid Water Micropropulsion System for Small Satellites

The advent of liquid water micropropulsion systems marks a significant leap forward in the field of aerospace engineering, particularly for small satellites. This technology harnesses the unique properties of water as a propellant, offering an eco-friendly and efficient propulsion solution. As space missions grow more ambitious, the need for advanced and sustainable propulsion methods has never been clearer.Liquid water micropropulsion systems provide a compelling alternative to traditional propulsion methods, enabling precise control and manoeuvrability of small satellites with minimal environmental impact.

Benefits of Using Liquid Water Micropropulsion

Liquid water micropropulsion systems offer several benefits for small satellite operations, making them an attractive option for a wide range of missions. Some of these advantages include:

• Sustainability: Water is a non-toxic and readily available propellant, reducing the environmental risks associated with chemical propellants.
• Efficiency: The use of water as propellant can be highly efficient, especially when coupled with innovative propulsion technologies such as electrolysis.
• Safety: The inherent safety of water compared to traditional propellants simplifies handling and reduces risks during ground operations.
• Cost-effectiveness: Utilising water as a propellant can lower mission costs due to its availability and the simplicity of the propulsion system's architecture.

Engineering Challenges in Liquid Water Micropropulsion Systems

While the benefits of liquid water micropropulsion systems are substantial, they also present unique engineering challenges. Overcoming these hurdles is essential for maximising the potential of this technology in small satellites applications:

• Electrolysis Efficiency: Efficiently splitting water into hydrogen and oxygen in a compact, low-energy system remains a technical challenge.
• Thermal Management: Managing the heat generated during propulsion operations without compromising the small satellite's limited payload capacity.
• Micro Nozzle Design: Developing nozzles that can effectively handle the low thrust levels and ensure precise control of the satellite.
• System Integration: Integrating the propulsion system within the limited space of small satellites without compromising other vital systems.

Future of Space Micropropulsion Technologies

The arena of space exploration and satellite technology is presently witnessing an unprecedented evolution, thanks to advancements in micropropulsion technologies. These innovations are not just enhancing the capabilities of small spacecraft but are also redefining their roles in both near-Earth and deep space missions. The future of space micropropulsion promises more efficient, reliable, and cost-effective solutions, significantly impacting the strategic planning of upcoming space expeditions and satellite deployments.

Innovations in Micropropulsion for Small Spacecraft

Small spacecraft, particularly CubeSats, have become indispensable tools for scientific research, communication, and Earth observation. The advent of advanced micropropulsion technologies is pivotal in maximising their operational capabilities and extending their mission lifespans. Innovations in this sphere are focusing on miniaturisation, fuel efficiency, and reducing the environmental footprint of propulsion systems.

Emerging technologies include:

• Electrospray propulsion, leveraging the acceleration of charged particles.
• Ion thrusters, providing high efficiency through ionised gas propulsion.
• MEMS-based thrusters, integrating propulsion elements at a micro scale.

The Potential of Micropropulsion in Deep Space Missions

The scope of micropropulsion is rapidly expanding beyond Earth's orbit, venturing into the realm of deep space missions. This advancement heralds a new era in which smaller and more cost-effective spacecraft can participate in interplanetary exploration, asteroid mining, and beyond.

Deep space missions benefit from micropropulsion in several key ways:

• Extended mission durations through efficient fuel usage.
• Enhanced payload capacities by reducing the space and weight allocated for propulsion systems.
• Improved mission flexibility and trajectory correction capabilities.