How is it that we engineer vehicles in space to travel for millions of miles at absurdly fast speeds? When we can only have vehicles on earth (jets) travel for thousands of miles at lower speeds? Why is the gap SO BIG?

Question

We can send vehicles/rovers to space and have them travel at very high speeds for millions of miles to other planets. But vehicles on earth (jets/planes) have significantly shorter range and speed. Why is this? ELI5

In: Physics

Answer 1

In space nothing is slowing you down.

It’s kinda like the difference between bicycle and walking. With bicycle, using the same amount of energy, you end up going much faster. That’s because air is basically the only thing slowing you down when biking, but when walking you gotta keep moving your legs which adds extra energy requirement constantly slowing you down.

In space, you don’t have air slowing you down. No matter how fast you go, nothing is pushing against you, slowing you down.