How Gravity Slingshots Speed Up Space Probes

引力弹弓如何加速探测器

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A gravity slingshot uses a planet’s motion and gravity to boost a spacecraft’s speed without burning extra fuel.

引力弹弓利用行星的运动和引力，在不消耗额外燃料的情况下提升航天器速度。
As the probe approaches a moving planet, it gains momentum from the planet’s orbital velocity around the Sun.

当探测器接近运动中的行星时，会从行星绕太阳公转的速度中获得动量。
This effect works like bouncing a ball off a moving train — the ball leaves faster than it arrived.

这种效应类似于让球撞向一列行驶中的火车——球反弹后的速度比撞击前更快。
Mission planners carefully calculate the flyby angle, distance, and timing to maximize the energy gain.

任务规划人员精确计算飞越角度、距离和时机，以最大化能量增益。
Voyager 2 used slingshots at Jupiter, Saturn, Uranus, and Neptune to visit all four outer planets.

旅行者2号先后借助木星、土星、天王星和海王星的引力弹弓，成功造访全部四颗外行星。
Without this technique, such long-distance missions would require much larger rockets or decades more travel time.

若无此技术，此类远距离任务将需要更大火箭或延长数十年飞行时间。
The probe’s path bends due to gravity, but its speed relative to the Sun increases significantly after departure.

探测器的轨迹因引力而弯曲，但离开行星后其相对于太阳的速度显著增加。
Importantly, the planet loses a tiny, immeasurable amount of orbital energy in the process — conservation holds.

重要的是，行星在此过程中损失了极其微小、无法测量的轨道能量——能量守恒依然成立。
Engineers simulate thousands of trajectories using physics-based software before selecting the final flight plan.

工程师使用基于物理的软件模拟成千上万条轨道，再从中选定最终飞行方案。
Today, slingshots remain essential for deep-space exploration, enabling missions that would otherwise be impossible.

如今，引力弹弓仍是深空探测的关键技术，使原本不可能的任务成为现实。