 In the early 1960s, America was deep into testing nuclear weapons and learning about radiation in anticipation of the Cold War with the Soviet Union turning hot. But some tests had unforeseen consequences, like the starfish prime shot that almost stopped Apollo from going to the moon. Hello everyone, I'm Amy and this is the Vintage Space, my little corner of the internet where we talk about all things mid-century that interest me, and many of those things overlap with spaceflight, including a handful of nuclear tests, because radiation is a big issue with space exploration. Radiation is one of the biggest hurdles facing future deep space human missions, or really any human mission that goes beyond the Van Allen belts. So let's take a look at the radiation environment that ensconces our planet. The environment beyond our atmosphere is incredibly hostile. Not only is there no air to breathe, atmospheric pressure to keep our bodies from expanding fatally or comfortable temperatures, there's a radiation everywhere, owing in large part to the constant stream of charged particles issuing from the sun. And there are other sources, including galactic radiation and radiation from other bodies. No matter how you look at it, it's a bad place for humans. Exposure to radiation breaks down the body and can cause a host of problems, none of which you want to deal with on deep space missions going to another planet. Lucky for us on Earth, we're protected by the Van Allen belts. The Van Allen belts were discovered by James Van Allen, who in the mid-1950s was exploring charged particles outside the Earth's atmosphere using sounding rockets and rock hoons, small rockets launched from balloons at altitude. These early experiments couldn't get high enough to leave the atmosphere, but already Van Allen was finding that the environment beyond our planet was well worth studying. Then the International Geophysical Year gave him an opportunity. Agreed to by international partners in 1955, the IGY was an international collaboration between July of 1957 and December of 1958, wherein scientists from various nations agreed to study Earth science and solar activity. As part of this initiative, both the United States and the Soviet Union announced their intentions to launch small satellites to gather data from beyond our atmosphere. The Soviets got their first with Sputnik on October 4th of 1957. The Americans struggled to join the space age in the months that followed before finally finding success with Explorer 1, which launched on January 31st of 1958. Explorer 1 was a small satellite with an array of onboard instruments, including one of Van Allen's radiation experiments designed to detect cosmic radiation. The data returned from Explorer 1, though didn't line up with his expectations. On board cosmic ray equipment registered nearly no radiation where Van Allen expected to see high levels of radiation. So he tried to work with the data to understand what he was seeing, because his early experiments confirmed there was indeed radiation in the area where the satellite was orbiting. The low cosmic ray count he hypothesized was actually a false reading. He suspected his instruments might be oversaturated with particles trapped in the Earth's magnetic field. Instruments on board the Explorer 3 satellite that launched in March of 1958 confirmed Van Allen's hunch, making the Van Allen belts one of the outstanding discoveries of the IGY. This data revealed that our planet's magnetic field is significant. It comes from flowing liquid metal in the Earth's outer core that generates electric currents, and the planet's rotation around its axis turns those electric currents into spheres surrounding the planet. That magnetic field is what protects us from solar radiation. It doesn't allow the stream of charged particles to hit our atmosphere. But what Van Allen found was that the charged particles that don't reach our atmosphere end up trapped in the magnetic field, and that trapped radiation can't dissipate into space. The trapped particles don't have enough energy to escape the magnetic field. So we have two belts that are really like nested doughnuts circling our planet. The inner belt sits between 63700 miles above the planet, and the outer belt is between 9300 and 12400 miles. And though we talk about them as belts, there is variation in the density of charged particles in both, so they are not completely uniform. When NASA started planning the Apollo lunar missions in the early 1960s, even before the missions were officially on the books. One of the big things planners had to consider was radiation, specifically radiation in the Van Allen belts. Earlier missions wouldn't have to worry about this. Because the lower end of the belts is around 600 miles, Earth orbital missions could stay well below the high radiation environment and still achieve their goals. The Mercury and Gemini missions did just this, with the exception of Gemini 11 in 1966 that reached a peak altitude of 850 miles. So for NASA it was going through the Van Allen belts to get to the moon that posed a real challenge. NASA studied the Van Allen problem and some creative solutions emerged, notably the suggestion from Van Allen himself that NASA could clear the belts by nuking them. His idea was that detonating an atomic bomb in the belts could give the trapped particles more energy, just enough to allow them to escape the magnetic field and dissipate into space. NASA decided against nuking the Van Allen belts. Further research determined that with moderate radiation shielding, crews could path through safely. They'd be going fast enough that their exposure to the two high radiation environments would be extremely minimal. It wasn't dangerous enough to cancel the missions. So the radiation issue wasn't prohibitive, but it did get more challenging after an atomic energy commission test in 1962. Among the technologies that came from the Second World War was nuclear weapons. After America's first successful atomic bomb detonation on July 16th of 1945, the Trinity Test, nuclear weapons were identified as the nation's best chance of ending the war in the Pacific Theater. On August 6th, the untested little boy bomb was dropped 1,900 feet above Hiroshima. A second bomb, the Fat Man, was dropped over Nagasaki three days later. The events had the desired effect of forcing a Japanese surrender, effectively ending the Second World War. Nuclear weapons had thus proven sufficiently useful that there was no question of America abandoning its nuclear program. On August 1st, 1946, the Atomic Energy Commission was established to oversee all continued development into nuclear weapons, and from there, the atomic age developed rapidly. The country had the perfect mix of post-war excitement over a new technology, money to fund it, and a cold war to justify that spending. It was the perfect arrangement that also allowed the space age to develop as quickly as it did in the late 1950s and 1960s. There were multiple programs that came out of the atomic testing era, among them Operation Dominic. Within this program was a group of atmospheric tests called the Fishbowl Events. These were designed to help understand how nuclear weapons debris would interact with the Earth's magnetic field in the event of nuclear war. One Fishbowl event was called Starfish Prime, and it saw a 1.4-megaton bomb detonate an altitude of 250 miles. The effect was additional radiation in the lower Van Allen belt, not a clearing out of the radiation that Van Allen had suspected might happen from nuking it. For a brief moment, it looked like Apollo astronauts would be up against a far more dangerous environment on their lunar journeys than anyone had anticipated. But even after Starfish Prime, additional research into the Van Allen problem determined it still wasn't a deal-breaker for lunar missions. By February of 1964, Apollo's hardware had developed to a point where the agency was confident crews would be passing through the belts fast enough for the spacecraft's own structure to provide enough radiation protection. And by 1969, the high-energy electrons injected into the lower Van Allen belts by the Starfish Prime event had decayed to one-twelfth of their post-test peak intensity. It was almost as safe as it had been when the missions were first under development. NASA did safely send astronauts through the Van Allen belts. At the end of the program, onboard and personal dosimeters registered that lunar astronauts had avoided large radiation doses. Their exposure was less than yearly averages of atomic energy commission workers at the time. I do have a whole video right up here about how the Apollo astronauts fared flying through the belts with all the technical details, if you would like to check it out. Given that the radiation question is often cited as one of the reasons the moon landing couldn't have happened, I hope you guys enjoyed this little, almost literal blast from the past that momentarily made the radiation environment that much worse. That is going to do it for me for today. I want to remind you guys that both my books Fighting for Space and Breaking the Chains of Gravity are available however you like to consume books. I've got links to both in the description below. I also want to say a very special thank you to my Patreon supporters and YouTube members. Please truly make all the difference in the world and allow me to continue making this content. So thank you so much. That is going to do it for me for today, you guys. Thank you so much for spending a little bit of time with me and I'll see you next time.