US engineer builds novel thruster to help send humans to Mars

Washington: Scientists have developed a prototype of a tabletop-sized thruster for a spacecraft propulsion system that may help take humans to Mars. NASA selected the thruster, developed by Alec Gallimore, from University of Michigan in US as part of its Next Space Technologies for Exploration Partnerships, or NextSTEP programme.

These are milestones towards sending humans into orbit between the Earth and the Moon in the 2020s and to Mars the following decade. The thruster 'X3' is central to the propulsion system, dubbed the XR-100. The XR-100 is up against two competing designs.

All three of them rely on ejecting plasma – an energetic state of matter in which electrons and charged atoms called ions coexist – out the back of the thruster. The X3 is relatively small and light for thrusters of its design power, 200 kilowatts.

Its core technology, the Hall thruster is already in use for manoeuvring satellites in orbit around the Earth.
"For comparison, the most powerful Hall thruster in orbit right now is 4.5 kilowatts," said Gallimore. That is enough to adjust the orbit or orientation of a satellite, but it is too little power to move the massive amounts of cargo needed to support human exploration of deep space, researchers said. A Hall thruster works by accelerating the plasma exhaust to extremely high speeds.