THE FASTEST SPACECRAFT

While the idea of a ‘speed record’ is clear enough on Earth, things become more complicated in space. Should a spacecraft’s speed be measured relative to Earth, the Sun or whichever planet it happens to be closest to?

And its speed during an interplanetary mission doesn’t necessarily reflect how powerful its rocket engine is. It can also acquire significant speed boosts from the gravitational slingshot effect as it swings around planets without expending any energy at all. However, in terms of its initial speed as it left Earth – 36,373 miles per hour – New Horizons is the fastest spacecraft ever launched.