Singapore: Sustainable spaceflight – powering satellites with water

In a decisive step towards sustainable space exploration, Singaporean company Aliena has developed Hydrocat, a versatile satellite thruster powered by water. Traditional propulsion methods involve trade-offs: chemical propulsion delivers high thrust but poor fuel efficiency, whilst electric propulsion provides high efficiency but limited thrust and typically relies on xenon, a scarce and costly fuel.

Seeking a way to exploit in-situ resources for satellite propulsion, Aliena launched the Eureka project WET-HET in collaboration with United Kingdom partners Imperial College London and URA Thrusters. The project team soon pioneered the world’s first electric Hall-effect thruster fuelled by hydrogen and oxygen derived from water electrolysis, an abundant, low-cost and potentially space-sourced propellant.

Eureka was instrumental in transforming our shared vision into reality. By fostering global partnerships, providing funding and opening access to world-class facilities, Eureka enabled the consortium to achieve the world’s first hydrogen-oxygen Hall thruster. This milestone not only advanced our technology but also accelerated new products, collaborations and visibility globally.

Mark Lim Jian Wei – co-founder and Chief Executive Officer at Aliena

Central to this breakthrough is Aliena’s Hydrocat cathode, a critical component of dual-mode chemical and electric satellite propulsion systems, which enables ignition and steady-state operation using electrolysed water byproducts. Aliena developed Hydrocat “in the blind,” unable to test it with hydrogen in Singapore. Even so, at Imperial College London, ignition succeeded on the first attempt weeks ahead of schedule. This feat was later shared with the Prince of Wales during his 2023 Earthshot visit, where he remarked, “you’ve blown my mind.” Validation followed at the European Space Agency’s European Space Technology and Research Centre laboratory, where the full cycle of in-situ water electrolysis and thruster operation was demonstrated.

Support from Eureka and Enterprise Singapore was pivotal, providing funding, facilitating early exchanges, building trust and enabling cross-continent access to world-class facilities. The collaboration has also delivered substantial research impact, with six acclaimed technical papers, including two award-winners, validating the technical innovation, improving visibility with prospective clients and driving commercial success.

The WET-HET project has propelled Aliena from a domestic Singaporean startup to a global space propulsion leader, achieving breakthrough technical and commercial milestones. Aliena now has new product lines, including advanced cathodes and higher-power Hall thrusters, and infrastructure to match.

With these lucrative new revenue streams, Aliena saw a remarkable 328% revenue surge in 2024 and a 210% compound annual growth rate through 2023-2025. The partnership unlocked four new international markets for the Singaporean company across the United Kingdom, Spain, Belgium and Middle East and North Africa regions.

The WET-HET project achievements have captured public imagination: water, one of Earth’s most abundant resources, can power spacecraft. More broadly, water-based propulsion paves the way for manoeuvrable, sustainable satellites that enhance communications, navigation, disaster response and environmental monitoring.