On June 2, 1966, NASA's Surveyor 1 landed on the lunar surface to become the first American spacecraft to land on the moon. Surveyor 1 took more than 11,000 photos of the moon along with other measurements, but, more importantly, proved that NASA's soft-landing technique and spacecraft designs were sound. | Space.com

A critical element of spacecraft design and mission planning is maximizing propulsion system efficiency, particularly for more ambitious missions. To accomplish this, NASA employs gravity assists, also known as a gravitational slingshot or flyby. Every planet in our solar system has a unique orbital speed as it travels around the Sun. When a spacecraft approaches a planet in orbit, it's pulled into the planet's gravitational field, changing trajectory and increasingly gaining speed as it nears t