In those four years , Toutatis traveled 8.5 billion kilometers .
举个例子，喷气推进实验室的科学家提前四年预测了图塔蒂斯小行星的运行轨迹，误差在30公里内。
For example , scientists at the Jet Propulsion Laboratory predicted where the asteroid Toutatis was going to be four years in advance to within 30 kilometers .
图塔蒂斯