TAMPA, Fla. — Japanese water propulsion startup Pale Blue is exploring jointly developing systems with Japan’s Mitsubishi Electric, after the satellite maker joined the University of Tokyo spin-off’s $10 million Series C funding round.
An investment from Mitsubishi Electric’s corporate venture capital fund helped bring Pale Blue’s total equity raised to around 4.5 billion yen ($30 million) since its founding in 2020, co-founder and CEO Jun Asakawa told SpaceNews Aug. 11 during the Small Satellite Conference in Salt Lake City.
He said the latest funding will help strengthen production and quality control systems to meet rising demand for small satellite propulsion.
Pale Blue currently offers a thruster called Resistojet, which uses jets of steam to move satellites weighing less than 100 kilograms and has secured several undisclosed customers since its 2023 in-orbit debut.
The company expects to soon demonstrate a water-based ion thruster following its deployment to low Earth orbit in June.
In 2027, Pale Blue plans to demonstrate a water-based Hall-effect thruster as part of efforts to meet demand for larger, more capable spacecraft of up to 700 kilograms.
Diversifying water propulsion lineup
“Resistojet and ion thrusters are designed for nanosats and microsats,” Asakawa continued, “where Resistojet is best aligned with satellites with limited power budget, while ion thruster is designed for high delta-V, high efficiency missions.”
The first-of-its-kind Hall-effect thruster, which Asakawa said would be the first to use water as a propellant, is designed to strike an ideal balance of thrust and propulsion efficiency for small satellites.
According to Asakawa, water-based propulsion offers a cost advantage over xenon and krypton systems because the propellant is inexpensive and can be shipped preloaded, eliminating launch-site fueling operations.
Water’s abundance and ease of sourcing also reduce supply chain risks, he added, while aligning with emerging sustainability requirements for collision avoidance and rapid deorbiting.
Building partnerships for growth
Komi Matsubara, Mitsubishi Electric vice president of business innovation, said sustainable propulsion technology is a crucial element that aligns with the direction of the company’s space business.
“We are confident that this investment will be a catalyst for deepening our technological collaboration and contributing to innovation in the space business and the creation of social value,” Matsubara said in a statement.
Mitsubishi Electric has also invested in Tokyo-based Astroscale, which is supplying docking plates so the national security spacecraft Mitsubishi builds for Japan can be compatible with the venture’s planned debris removal servicers.
Pale Blue declined to detail potential areas of collaboration with the Japanese conglomerate.
Beyond Mitsubishi Electric, Asakawa said the company is in talks with launch providers and satellite integrators about potential bundled solutions.
“In addition to the sustainability aspect, ease of integration and removal of launch site operations will help both ends,” he said.
Other Pale Blue Series C investors included aStart, Nissay Capital, Mitsui Sumitomo Insurance Venture Capital, Itochu Technology Ventures and a venture fund from civil engineering firm Tokyu Construction.
“With its abundant, affordable and easily sourced propellant, environmentally friendly propulsion will address the supply chain fragility and cost issues associated with reliance on noble gas,” Asakawa added.