If you were to take a 22-pound rock and fling it 620 miles straight up … you would have superpowers. And an anger management problem. The gravitational force the rock would experience at that altitude is still about three-quarters of what it would be on the surface. That means our planet is constantly begging every single satellite we’ve put into orbit to come back like some kind of crazed ex. An object like the ISS must maintain an astounding steady speed of 17,000 miles per hour just to stay in its 200-plus mile orbit. Any less and it’ll crash down to Earth. Any more, and it escapes our gravitational pull and rockets away into space. The ISS is, in fact, constantly losing altitude – requiring the craft that dock with it to give it regular boosts … just not too much of a boost.
Isaac Newton likened this phenomenon to a cannon perched atop a very high mountain. If the cannon were capable of firing its ball fast enough, the ball could fall toward the ground, but miss it entirely. Similarly, another great mind once said the knack to flying “lies in learning how to throw yourself at the ground and miss.” That’s what every single craft in orbit must perpetually do: Suck at hitting the ground.