Reed Richards, working in the field of aerospace engineering, was designing a spacecraft for interstellar travel. Everything was going well until the government stopped the funding of his project. Richards, wanting to see his project through, decided to make an unscheduled test flight. Originally, it was only going to be Reed and his best friend, Ben Grimm, involved, but Susan was instrumental in persuading Reed in letting her brother and herself join them on the dangerous space mission. In space, the quartet was exposed to massive amounts of cosmic radiation. As a result, they had to abort the mission and return to Earth. After the crash landing, they realized that they gained superhuman powers; hers was the ability to become invisible at will. Realizing the potential use of their abilities, the four of them became the Fantastic Four, for the benefit of mankind. Susan adopted the code name Invisible Girl.