The radioactive Van Allen belts posed a serious challenge for space travel. NASA had to figure out a way for astronauts to fly through them without being exposed to deadly doses of radiation.
To learn more about NASA's Van Allen belt calculations, check out these links:
The 12 Greatest Challenges For Space Exploration
“It’s a huge, dangerous, maybe impossible project. But that’s never stopped humans from bloody-mindedly trying anyway.”
Studying the Van Allen Belts 60 Years After America’s First Spacecraft
“Sixty years ago today, the United States launched its first satellite into space. Dubbed Explorer 1, the spacecraft followed just months after the Soviet Union’s Sputnik 1 and 2 spacecraft commenced the Space Age. Data captured by the Geiger counter aboard Explorer 1 heralded the emergence of space physics and ushered in a new era of technology and communications.”
6 Surprising Facts About the First Manned Space Mission
“Reaching unprecedented speeds for manned travel, the spacecraft broke free of the Earth's gravitational pull and entered orbit around the planet, circling once before re-entering the atmosphere and landing back on Soviet soil.”