The distances a spacecraft has to travel for deep space exploration are enormous. The engines used to power spacecraft currently simply aren’t up to the task of exploring deep space or even our own solar system in a reasonable timeframe. Another problem with spacecraft currently is that they rely mostly on solar power to operate sensors and scientific equipment. The further spacecraft get from the sun, the less power they’re able to harvest and the less efficient and functional they become. Researchers are currently testing a small prototype engine that could be the future of deep space exploration. The prototype engine is based on a Stirling engine that was invented in the 19th century. Read more: http://www.slashgear.com/nuclear-engine-could-power-future-deep-space-exploration-28258692/