What are the best applications and missions for electric propulsion in spacecraft?

2 Drawbacks of EP

EP also has some drawbacks for spacecraft, such as lower thrust, higher power requirements, complex subsystems, and environmental effects. Thrust is the force that propels a spacecraft forward. EP has much lower thrust than chemical propulsion, which means it takes longer to accelerate and change orbits. EP is not suitable for missions that require high thrust, such as launch, landing, or rapid maneuvers. EP also requires more electric power than chemical propulsion, which means the spacecraft needs larger solar arrays or nuclear reactors, adding to the mass and complexity. EP also has more complex subsystems, such as thrusters, cathodes, power processors, and propellant tanks, which can increase the risk of failure or degradation. EP can also be affected by environmental factors, such as magnetic fields, plasma, or collisions with micrometeoroids.

3 Types of EP

There are several types of EP, each with different characteristics and performance. The main types are electrothermal, electrostatic, and electromagnetic. Electrothermal propulsion uses electric energy to heat propellant and expel it through a nozzle. Examples of electrothermal propulsion are resistojets and arcjets. Electrothermal propulsion has low to moderate specific impulse and thrust. Electrostatic propulsion uses electric energy to ionize propellant and accelerate it with electric fields. Examples of electrostatic propulsion are gridded ion thrusters and Hall effect thrusters. Electrostatic propulsion has high specific impulse and low thrust. Electromagnetic propulsion uses electric energy to generate magnetic fields and accelerate propellant with electromagnetic forces. Examples of electromagnetic propulsion are pulsed plasma thrusters and magnetoplasmadynamic thrusters. Electromagnetic propulsion has very high specific impulse and moderate thrust.

4 Applications of EP

EP can be used for various applications and missions for spacecraft, depending on the type and requirements. Some of the most common applications are orbit transfer, station-keeping, drag compensation, and interplanetary exploration. Orbit transfer is the process of changing the orbit of a spacecraft, such as from low Earth orbit to geostationary orbit. EP can perform orbit transfer more efficiently and with less propellant than chemical propulsion, but it takes longer and requires more power. Station-keeping is the process of maintaining the orbit of a spacecraft, such as a satellite or a space station. EP can perform station-keeping with minimal propellant consumption and long operational lifetime, but it requires continuous power and control. Drag compensation is the process of counteracting the atmospheric drag that slows down a spacecraft in low Earth orbit. EP can perform drag compensation with low thrust and high specific impulse, but it requires large solar arrays and may encounter plasma interactions. Interplanetary exploration is the process of sending a spacecraft to another planet or celestial body. EP can perform interplanetary exploration with high delta-v and large payload mass fraction, but it requires nuclear power and long transit time.

5 Challenges of EP

EP faces some challenges and limitations for spacecraft, such as technology readiness, system integration, testing, and regulation. Technology readiness is the degree of maturity and reliability of a technology for a specific application or mission. EP has varying levels of technology readiness, depending on the type and complexity. Some EP systems, such as gridded ion thrusters and Hall effect thrusters, have been proven and flown on several spacecraft, while others, such as magnetoplasmadynamic thrusters and nuclear electric propulsion, are still in development and demonstration. System integration is the process of combining and coordinating different subsystems into a functioning whole. EP requires careful system integration, as it involves multiple components and interfaces, such as power sources, thrusters, propellant tanks, valves, regulators, sensors, controllers, and wiring. Testing is the process of verifying and validating the performance and functionality of a system under simulated or actual conditions. EP requires extensive testing, as it involves high voltages, currents, temperatures, pressures, and speeds, which can pose safety hazards and technical challenges. Regulation is the process of establishing and enforcing rules and standards for a system or activity. EP requires regulation, as it involves the use of hazardous materials, such as propellants and radioactive sources, which can pose environmental and security risks.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?