In the late 1940s, the notion of space travel remained squarely in the realm of science fiction ... of the U.S. Air Force's high-altitude balloon experiments and the researchers, scientists ...

For example, Jupiter is the most massive planet in our solar system. It’s so big, it could swallow 1,000 Earths. So it requires a very high escape speed: 133,100 mph (about 214,000 kilometers per hour ...