Water propulsion technologies picking up steam

[Elderberry]

Space News by Debra Werner — August 27, 2019

When the Aerospace Corp. launched the Optical Communications and Sensor Demonstration in 2017, one mission objective was to test water-fueled thrusters. At the time, the idea was fairly novel. Two years later, water-based propulsion is moving rapidly into the mainstream.

Capella Space’s first radar satellite and HawkEye 360’s first cluster of three radio-frequency mapping satellites move in orbit by firing Bradford Space’s water-based Comet electrothermal propulsion system. Momentus Space and Astro Digital are testing a water plasma thruster on their joint El Camino Real mission launched in July. And an updated version of the water-fueled cold gas thrusters the Aerospace Corp. first flew in 2017 launched in early August.

“Water is an ideal propellant,” said Mikhail Kokorich, Momentus founder and president. “It can be used as-is in solar thermal, nuclear or electrothermal engines. In addition, water can easily be broken down into hydrogen and oxygen.”

Tethers Unlimited takes the later approach with Hydros-C, a thruster that relies on electrolysis to split water into its constituent elements before burning it in a bipropellant nozzle.

“The result is good fuel economy and good thrust,” said Robert Hoyt, Tethers Unlimited chief executive.

NASA plans to test a variety of cubesat technologies including Hydros-C on its first Pathfinder Technology Demonstrator. PTD-1 is scheduled to fly to the International Space Station in November before traveling to a higher altitude to deploy from a Cygnus cargo tug. Meanwhile, Millennium Space Systems, a Boeing subsidiary, is integrating Hydros-C in its Altair spacecraft bus.

A CLEAN, ABUNDANT FUEL

Tethers Unlimited began investigating water propulsion years ago because water poses no harm to technicians during satellite integration nor to payloads riding alongside small satellites into orbit, Hoyt said. Water propellant also fits into Tethers Unlimited’s long-term vision of creating a sustainable in-space ecosystem.

More: https://spacenews.com/water-propulsion-technologies-picking-up-steam/

[Joe Wooten]

Old idea. First suggested back in the 60's for nuclear powered space craft. IMHO, it is a better choice for nukes because it is non cryogenic and needs no support systems to keep it liquid, no problems with leakage, AND it makes a dandy radiation shield.