What Is Escape Velocity?
Introduction There is a question that seems simple until you actually think about it: why do some things fall back to Earth, and others do not? A ball thrown upward comes back down. A rocket launched into orbit keeps going around. A probe launched toward Mars eventually leaves Earth behind entirely. The physics is the same for all three. Gravity pulls everything downward with the same relentless force. So what is the difference? The answer is a single number. And that number, for Earth, is 11.2 kilometers per second. Below it, gravity wins. At it, or above it, you win. That threshold is called escape velocity, and it is one of the most elegant and far-reaching concepts in all of aerospace physics. It determines whether a spacecraft becomes a satellite, leaves for another planet, or escapes the solar system entirely. And, taken to its logical extreme, it explains why black holes exist. Let us break it down from the beginning. What Escape Velocity Actually Means Escape velocity is...