A nuclear power propulsion system could propel a spacecraft to Mars in just over a month, a huge step forward from the current 18 months required. Russia might test a nuclear engine as early as 2018, the head of the Rosatom nuclear corporation revealed. Another advantage of a nuclear engine is that it enables a spacecraft to maneuver throughout the flight, whereas existing technology only makes a defined trajectory flight possible. "A nuclear power unit makes it possible to reach Mars in a matter of one to one and a half months, providing capability for maneuvering and acceleration," the head of Rosatom Sergey Kirienko said. "Today's engines can only reach Mars in a year and a half, without the possibility of return," Kirienko said. The nuclear engine project was launched in 2010 and by 2012 an engineering design had been created. The project's budget is estimated at 20 billion rubles (about $US274 million). It has been reported that a prototype nuclear drive could start testing by