So far NASA is exploring two options for propulsion there? A nuclear thermal rocket and a chemicalengine.
迄今为止NASA研究了两种前往那里的备选推进器：核热火箭和化学发动机。
2
The idea for the chemicalengine is similar to that used on the space shuttle, liquid oxygen and liquid hydrogen.
化学发动机跟航天飞机使用的发动机类似，都是用液氧和液氢作燃料。
3
Without the platinum components in the engine, the hydrogen doesn't undergo the chemical reaction that produces the electricity to power the automobile.