Will Mitsubishi’s Water-Powered Satellites Green Telecoms?

Mitsubishi is backing Pale Blue, a Tokyo start-up developing water-powered propulsion systems that could transform satellite-based telecommunications, from broadband and broadcasting to connectivity in remote regions.

The company has secured an investment from the Mitsubishi Electric Innovation Fund, which was launched in 2022 to support emerging technology ventures.

By replacing hydrazine, a toxic and hazardous propellant widely used in satellite operations, with water, Pale Blue’s systems aim to cut environmental impact and reduce the safety risks faced by engineers handling conventional fuels.

Using advanced propulsion that vaporises water at ambient temperature and low pressure, Pale Blue generates plasma without oxidation.

In plain terms, this allows satellites to manoeuvre in space with water as the only propellant, producing emissions that are non-reactive and safe.

For the telecommunications sector, this means a cleaner, more reliable method to maintain and reposition satellites that deliver essential services to rural and hard-to-reach communities.

Founded in 2020 as a spinout from the University of Tokyo, Pale Blue has already completed in-orbit demonstrations using small satellites.

These tests show that the propulsion systems are reliable, helping to attract major investors, including Sony before Mitsubishi.

The funding will support scaling up production to meet industry demand.

Why sustainable propulsion matters to satellite telecoms

Satellite communications rely on constellations, groups of satellites working together, to deliver broadband, broadcasting and mobile connectivity.

Every satellite requires propulsion to adjust its orbit, perform station-keeping or avoid debris.

Traditionally, these manoeuvres depend on costly propellants, hazardous to store and handle and produce harmful by-products.

By switching to water as a propellant, the industry could reduce operational risks and environmental impact while lowering costs.

Water is safer to transport, easier to handle and cheaper to source.

For telecommunications providers operating in remote regions where fibre connections are not viable, these advantages could mean faster, safer satellite deployment and lower maintenance expenses over a satellite’s lifespan.

"Pale Blue possesses the potential to realise safety, efficiency and environmental compatibility in space transportation through its innovative water-based propulsion technology," says Komi Matsubara, Executive Officer at Mitsubishi Electric.

"Such sustainable propulsion solutions are essential for the future of space infrastructure and are closely aligned with the direction of our space business."

In the telecoms context, this mobility translates to maintaining network coverage without service interruptions, repositioning satellites to meet changing demand and extending mission lifetimes without costly fuel resupply.

Mitsubishi’s role in commercialising the technology

Mitsubishi Electric’s space business already spans satellite manufacturing, ground systems and related technologies.

By investing in Pale Blue, the company gains access to propulsion systems that align with global priorities for sustainability in space infrastructure.

Partnerships like this may help address growing concerns over orbital debris.

With more satellites entering service to meet telecoms demand, manoeuvrability becomes vital for collision avoidance.

Safer, cleaner propulsion could make it easier to deorbit satellites at the end of their operational life, freeing up valuable orbital slots and reducing debris hazards for future telecoms missions.

The collaboration also combines Mitsubishi’s manufacturing scale and integration expertise with Pale Blue’s propulsion innovation, improving the prospects for market adoption.

However, water-based systems currently produce less thrust than chemical alternatives, which may limit their use for large-scale orbital changes.

They are particularly well-suited for small satellites needing precise adjustments, such as those used in low Earth orbit telecoms constellations.

Commercial prospects for sustainable satellite operations

The satellite industry has expanded rapidly over the past decade, driven by demand for global broadband, high-definition broadcasting and resilient communications in disaster zones.

This growth has increased the need for safe, cost-effective propulsion that meets both performance and sustainability criteria.

While water-based systems face technical constraints, their advantages may outweigh these for operators prioritising safety, environmental compliance and operational efficiency. Lower handling costs and the ability to avoid toxic chemicals can improve project economics, especially for high-volume constellations serving telecoms markets.

"Through collaboration with Mitsubishi Electric, we will further enhance the reliability of our technology and work toward realising our vision of establishing mobility as a core element of the space industry," concludes Jun Asakawa, Co-Founder and CEO of Pale Blue.