NASA thinks it can get people to Mars a little faster, said Tereza Pultarova at Space. A group of researchers at the University of Michigan, working with NASA, have developed a new ion-based thruster that could propel humans to the Red Planet "at much greater speeds than chemical-propulsion rockets can." The X3 thruster uses electricity, "usually generated by solar panels, to expel plasma — a gas-like cloud of charged particles — out a nozzle" to generate thrust.

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This technique helps rockets go faster: The maximum velocity that can be achieved by a chemical rocket is about 5 kilometers per second, whereas the X3 could get a craft up to 40 kilometers per second — while also using less propellant. "You can think of electric propulsion as having 10 times the miles per gallon compared with chemical propulsion," said Alec Gallimore, leader of the X3 project.