He’s Worried About Space Rocks
Meteors and asteroids like the ones that reportedly killed the dinosaurs are the threat on Johnson’s mind. From his perspective, it has happened once before and altered the planet forever. This led to the extinction of the dinosaurs and ultimately the rise of humanity. But while most space rocks are so tiny that they burn up in Earth’s atmosphere, Johnson would like to protect Earth from the likelihood of a bigger object crash landing on the planet.