Finally, in the 1960s, astronomers used radio telescopes to bounce radar pulses off of Venus.

最后，在20世纪60年代，天文学家使用射电望远镜将雷达脉冲从金星上反射回来。

As they towed it, they sent radar pulses on the frequency bands used by the satellites downwards into the snow and measured the amount of backscatter.

当他们拖着雪橇的时候，他们在卫星使用的频段向雪中发射雷达脉冲，并测量反向散射的数量。

Synthetic aperture radar (SAR) satellites, which send out radar pulses rather than relying on ambient light, would pick up the metallic reflections of heightened vehicle activity.

合成孔径雷达（SAR）卫星发出雷达脉冲而不是依赖环境光，它会捕捉到车辆活动增强时产生的金属反射。