Itâ€™s a surprise to many to learn that Andy Griffith was not only the beloved, homespun sheriff of Mayberry, he was also a science fiction space hero.

In the 1979 made-for-TV movie (and subsequent short-lived series), Salvage 1, Griffith played Harry Broderick, owner of the Jettison Scrap and Salvage Co. His ambition is to recover equipment left on the moon following the Apollo missions. He builds a spaceship he names the Vultureâ€”made entirely of recycled scrap, of course. It is fueled by a unique substance called monohydrazine.

And thatâ€™s where Andyâ€™s secret lay.

Everyone knows that escape velocity is the speed you need to be going in order to break free from earthâ€™s gravity. About 7 miles per second, to be exact. Newton figured this out 400 years ago.

According to NASA, "escape velocity is the speed needed for an object to break away from the gravitational pull of a planet or moon and leave it without further propulsion." A spacecraft needs to be going 7 miles per second, or nearly 25,000 miles per hour, to leave the earth without falling back to the surface or falling into orbit.

Or does it?

A slightly more specific NASA definition says that â€śThe projection speed required to escape directly from the Earth's surface is about 36,700 feet per second. If a vehicle takes up unpowered flight (end of rocket propulsion) at an altitude of, say, 300 miles, it requires the somewhat lesser speed of 35,400 feet per second to escape into interplanetary space. This reduction in required velocity has, of course, been obtained at the expense of the energy expended in lifting the vehicle to an altitude of 300 miles.â€ť