Consider a spacecraft/space platform that does not have onboard fuel but instead breathes while orbiting around the Earth. These platforms breathe (in other words ‘collect’) the residuals of the thin atmosphere while operating at a range of altitude between 150 km to 400 km, which is called the Very Low Earth Orbit (VLEO). It is not very accustomed and sounds like science fiction, but it is not. This is the vision behind Air-Breathing Electric Propulsion (ABEP) systems, as demonstrated in Figure 1.
What does the operation in VLEO promise? Orbiting at lower altitudes provides better resolution of satellite imaging and the lower latency in communication and internet. This is crucial for applications like Earth observation, disaster monitoring, and global connectivity. But there is a great challenge: Drag force caused by the atmosphere. This can quickly de-orbit the satellite without the help of drag elimination by a thruster system.
Why are new technologies necessary? As space missions are dramatically being increased, our knowledge about the space is increasing along with providing advanced solutions from daily life and national security to space exploration. However, this brings additional challenges such as pollution, space debris, high launching costs, and more. Furthermore, traditional electric propulsion systems rely on onboard fuel, typically xenon gas, which limits their operational lifetime and adds significant weight and cost to missions.
This is where ABEP comes in.
There is growing interest in sustainable, efficient, and low-cost propulsion alternatives for space operations. ABEP systems redefine the conventional approach of propulsion in three stages, as presented in Figure 2: Gathering (intake), thermalising (compression), and ionisation (propulsion).
These systems collect atmospheric gases like oxygen and nitrogen and compress them in a chamber. Then, the collected gas is ionised using an electric source, such as solar panels, and accelerated to generate thrust force. The result? Continuous propulsion without carrying any fuel. It is like gliding through space on a solar-powered breath of air. Thus, the weight and cost of onboard fuel, limitations in operational life based on the amount of onboard fuel as well as emission as a result of propulsion are eliminated.
Space debris is also an arising risk. By 2035 (within 10 years) and without effective mitigation strategies, the collision rate around the Earth could increase to several events per year, as shown in Figure 3.
However, ABEP provides a solution for the space debris as well. Once their operational lifespan ends, they can be de-orbited and demised (burned) in the atmosphere, which is a concept known as design for demise (D4D), to mitigate space debris, as illustrated in Figure 4. In this way, inactive satellites and their collision probabilities are removed.
Operation at Other Planets: ABEP systems are designed to collect atmospheric gases from a planet and employ them as propellant in electric thrusters, as discussed above. This means that these systems can be used in the atmosphere of other planets such as Mars. Although the composition of the Martian atmosphere is different than Earth’s, the propulsion concepts/stages are the same.
ABEP could revolutionise long-duration Martian missions by enabling in-situ resource utilisation for propulsion, provided engineering challenges are adequately addressed through advanced system design and testing.
Design and Engineering: From an engineering standpoint, ABEP is elegant, but its design process is not easy. The atmosphere is quite thin at these operational altitudes, even collecting enough gas to keep the thruster running is a serious design challenge. The intake system needs to be incredibly efficient, and materials should be selected to withstand harsh operational environments that include atomic oxygen erosion. Plus, the propulsion system has to work reliably over long periods to keep the satellite from decaying into the atmosphere.
Despite the challenges, early-stage experiments have been conducted at various research institutions around the world, including the UK, Germany, Japan, and Italy.
Concluding Remarks: What makes this technology so exciting is not just its potential to extend satellite lifetimes or reduce launch weights. ABEP also offers a promising path toward cleaner and more sustainable spaceflight. By eliminating the need for heavy propellant tanks, these systems can reduce launch emissions and space debris. Furthermore, D4D minimises the impact of ABEPs on the growing problem of space debris.
As the space sector continues to grow, technologies like ABEP could redefine the limits of what is possible in VLEO. We are entering an era with more sustainable and advanced platforms in space operations -all by taking a breath of the atmosphere they are orbiting in.
[1] The European Space Agency (2018, March 5). World-first firing of air-breathing electric thruster. https://www.esa.int/Enabling_Support/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster. Accessed on 22/05/2025.
[2] The European Space Agency (2008, April 10). Debris objects in low-Earth orbit (LEO). https://www.esa.int/Enabling_Support/Space_Engineering_Technology/The_Kessler_Effect_and_how_to_stop_it. Accessed on 22/05/2025.
[3] The European Space Agency (2024, September 24). Draco mission made for destruction. https://www.esa.int/Space_Safety/Draco_mission_made_for_destruction. Accessed on 22/05/2025.
[4] Dobrijevic, D. (2023, September 2023). Mars’ atmosphere: Facts about composition and climate. Space.com. https://www.space.com/16903-mars-atmosphere-climate-weather.html. Accessed on 22/05/2025.
[5] Crisp, N. H., Roberts, P. C.E., Romano, F., Smith, K. L., Oiko, V. T. A., Sulliotti-Linner, V., Hanessian, V., Herdrich, G.H., García-Almiñana, D., Kataria, D., & Seminari, S. (2021). System modelling of very low Earth orbit satellites for Earth observation. Acta Astronautica, 187, 475-491.