NASA's NASA CubeSat to Demonstrate Water-Fueled Moves in Space says:
A NASA CubeSat will launch into low-Earth orbit to demonstrate a new type of propulsion system. Carrying a pint of liquid water as fuel, the system will split the water into hydrogen and oxygen in space and burn them in a tiny rocket engine for thrust.
PTD-1’s propulsion system will produce gas propellants – a mix of hydrogen and oxygen – from water, only when activated in orbit. The system applies an electric current through water to chemically separate water molecules into hydrogen and oxygen gases, in a process called electrolysis. The CubeSat’s solar arrays harness energy from the Sun to supply the electric power needed to operate the miniature electrolysis system.
These gases are more energetic fuels than water; burning hydrogen and oxygen gas in a rocket nozzle generates more thrust than using "unsplit" liquid water as propellant. This strikes a better balance between performance and safety for spacecraft propulsion, meaning CubeSats will get more bang for the buck.
"What’s new is that this system uses water as the fuel in an energetic way, with an inherently safe system," said Mayer. "This mission will show that we can use water electrolysis in a rocket engine in space – that’s pretty cool."
Wikipedia's Pathfinder Technology Demonstrator mentions a scheduled December 2020 launch and says:
HYDROS is a hybrid chemical/electrical technology to provide propulsion using water. It uses an electrolysis cell to split water propellant into gaseous hydrogen and oxygen that are stored under pressure in separate tanks. The system then burns the hydrogen and oxygen mix in a simple thruster nozzle to provide up to 1 Newton and a specific impulse of 258 seconds. This propulsion system is being developed by Tethers Unlimited, Inc.
Gunter's Space Page PTD 1 (Pathfinder Technology Demonstrator) lists it as `2021-006BX.
However it does not mention an engine that burns hydrogen and oxygen and derives thrust from the exhaust exiting through a nozzle, and instead says it uses electrospray thrusters for propulsion:
The primary goal of the first Pathfinder Technology Demonstrator spacecraft is to flight qualify and characterize a novel micro-electrospray thruster provided by Busek Space Propulsion and Systems.
Each PTD mission consists of a 6-unit (6U) CubeSat weighing approximately 11 kilograms and measuring 30 cm × 25 cm × 10 cm. Each PTD spacecraft will also be equipped with deployable solar arrays that provide an average of 44 watts of power while in orbit.
- Has Demonstrator-1 2021-006BX demonstrated any split-water derived propulsion?
- Has it demonstrated, or at least is the plan to demonstrate propulsion using combustion of hydrogen and oxygen burned in an engine with exhaust exiting through a nozzle i.e. a conventional "rocket engine"?