Speaker
Description
State-of-the-art satellite chemical propulsion systems are based on conventional toxic propellants such as Hydrazine or its derivatives, which are environmentally harmful and therefore very extensive in handling.
Although, harmless to the environment, cold gas thrusters cannot reach the performance of chemical combustion technology, requiring big and high pressure gas tanks.
Electric propulsion technology offers very high specific impulse, which is required for highly efficient orbital manoeuvres, but due to the low thrust provided, no debris mitigation manoeuvres can be performed. Here, usually thrust of multiple magnitudes higher than EP can provide is required, to change orbit quickly for collision avoidance. Furthermore, the gases used as propellant are usually quite costly.
ArianeGroup is developing the Water Propulsion System as the ultimate green technology. Pure water is used as propellant, which is decomposed via electrolysis to generate hydrogen and oxygen, once the spacecraft is in orbit. The combination of hydrogen and oxygen offers 50% higher specific impulse compared to Hydrazine based thrusters. The gases are generated and stored under pressure until thrust is required. Then, the gases are pressure fed to one or several chemical thrusters to be recombined and expelled.
Not only is water green in every sense – no harm to the environment, easy handling, high performance, low cost – but it is also a convenient way to store hydrogen in space.
Furthermore, water offers many synergetic effects by combining multiple spacecraft subsystems, such as the life support system (drinking water, respiratory oxygen generation) or the power supply system (regenerative fuel cell).
