3D printed rocket fuel pump may power journey to Mars

NASA has successfully tested a 3D printed rocket engine fuel pump with liquid methane, an ideal propellant for engines needed to power spacecraft for future journey to Mars.

"This is one of the most complex rocket parts NASA has ever tested with liquid methane, a propellant that would work well for fuelling Mars landers and other spacecraft," said Mary Beth Koelbl, manager of the Propulsions Systems Department at NASA's Marshall Space Flight Centre in US.

"Additive manufacturing, or 3D printing, made it possible to quickly design, build and test two turbopumps with identical designs that worked well with both liquid methane and liquid hydrogen propellant," said Beth Koelbl.

A turbopump is complex because it has turbines that spin fast to drive the pump, which supplies fuel to the engine.

During the full power test, the turbines generated 600 horsepower and the fuel pump, got its "heartbeat" racing at more than 36,000 revolutions per minute delivering 600 gallons of semi-cryogenic liquid methane per minute – enough to fuel an engine producing over 22,500 pounds of thrust.

These tests along with manufacturing and testing of injectors and other rocket engine parts are paving the way for advancements in 3D printing of complex rocket engines and more efficient production of future spacecraft including methane-powered landers.

Liquid methane is cooled to minus 159 degrees Celsius whereas liquid hydrogen is cooled to minus 240 degrees Celsius.

The higher temperature of liquid methane means it boils off more slowly and thus is easier to store for longer periods, a benefit for Mars missions.

Also, technologies exist today to make it possible to manufacture methane rocket fuel from carbon dioxide, which is plentiful in the red planet's atmosphere.

"By demonstrating the same turbopump can work with different fuels, we've shown that a common design would work for either engines fuelled by methane or hydrogen," said Marty Calvert, the Marshall engineer who designed the turbopump.

"Because liquid methane is much more dense than hydrogen, it requires the turbopump to spin at a different speed to deliver the same amount of mass flow to the engine," said Calvert.

Testing ensures 3D printed parts operate successfully under conditions similar to those in landers, ascent vehicles and other space vehicles.

"Additive manufacturing allowed us to build the turbopump with 45 per cent fewer parts," said Nick Case, the Marshall propulsion engineer who led the testing.

"Our next step will be to test the liquid methane turbopump with other 3D printed engine components in a similar configuration to the liquid hydrogen tests completed last year," said Case.