Why Apollo Astronauts Trained at a Nuclear Test Site

On July 20, fifty years ago, Neil Armstrong and Buzz Lightyear set foot on the Moon for the first time. But before they went there, they came here. This is Sedan Crater and was excavated by a

nuclear

bomb in 1962. It is part of the Nevada Test Site, an area of ​​desert larger than Rhode Island. -- located 70 miles northwest of Las Vegas -- Here, the United States conducted 928

nuclear

explosions. And since 1965 they

trained

Apollo

astronauts

such as Neil Armstrong and Buzz Aldrin before their trips to the Moon. In subsequent years,

astronauts

returned with mock-ups of space suits and television cameras.

They even

test

ed a model of the lunar rover. Over a seven-year period, 11 of the 12 men who would eventually walk on the moon vi

site

d this

site

. So why would you take Apollo astronauts to a nuclear bomb

test

site? That's what we're going to find out. The obvious reason is that the Moon is covered in craters, so astronauts needed experience in cratered terrain, but other locations were available, such as Barringer Crater in Arizona, which was claimed to be the site of a meteorite impact, although its origins were disputed until now. Elsewhere in Arizona, scientists used conventional explosives to recreate the exact pattern of lunar craters around the Apollo 11 landing site.

Now, astronauts

trained

at both sites, but the Apollo 11 test site Nevada provided something additional. -- Put on your glasses -- The Nevada Test Site was commissioned in 1951 as a site to test nuclear explosions. The goal was not only to develop better bombs, but also to understand how houses and household items could be made to withstand a nuclear explosion. -- Five... -- -- Four... -- -- Three... -- --Two... -- -- One... -- -- Zero. -- One hundred tests were conducted on the surface before the Nuclear Test Ban Treaty was signed in 1963. It banned tests in the atmosphere, outer space and underwater, leaving only underground tests.

Like the explosion that formed Sedan Crater: a 3-foot-wide hole was drilled into the ground right here, 635 feet deep, and that's where they located a nuclear bomb. It was a 104 kiloton device. That means the energy released was equivalent to 104,000 tons of TNT, about eight times larger than the bomb dropped on Hiroshima. -- This close-up view was taken from a ground station three miles from ground zero. The dome rose to a height of 290 feet before venting in three seconds. -- Excavated 12 million tons of earth and rock, forming what is the largest man-made crater in North America. In fact, it is the second largest in the world after the Chagan crater in Russia.

It is about 400 meters in diameter and almost 100 meters deep. This was part of an operation called "Plowshare." -- The United States is carrying out, for the benefit of all nations, a program it calls "Plowshare." --With the idea that, if you need to make a big hole somewhere, let's say you're doing a big construction project, maybe a canal, could you use nuclear weapons to excavate that dirt? -- Huge energy, relatively economical, compact and easily transportable. -- Huge energy, relatively economical, compact and easily transportable. This is the new power tool that "Plowshare" would add to Man's useful energy resources, to perform jobs that have never before been practical or possible. -- As you can see, it's a pretty good excavator.

But they later discovered that it is very difficult to reduce contamination, the radioactive contamination that results from a nuclear explosion, so the operation was effectively canceled. But what they had created was as close as you can get to a meteorite impact crater. And that seems a little strange, because when I think about meteorite impacts, I imagine these kinds of compressions of a big rock coming in and pushing the earth out of the way. But that's not really how it works. Meteors usually go incredibly fast, like 10 or 20 kilometers per second, so when one hits the ground, it creates an incredibly hot, dense, high-pressure region at the impact site.

This melts and vaporizes the rock. A shock wave leaving the point of contact transforms the minerals due to the extreme pressure. As the high pressure region decompresses, what is essentially a huge explosion is created, and it is this explosion that creates the crater. Something you might notice if you look at craters is that they are almost always circular. But if you think about it, meteors hit from all kinds of different angles. The reason you're seeing a circle is because a meteorite impact is actually an explosion. That's what makes up the crater. It's not the impact, otherwise you would see all kinds of strange oblong-shaped craters.

Nuclear explosions are so similar to meteorite impacts that the craters at this test site provided definitive evidence confirming that Barringer Crater was actually the result of an impact. The scientists compared samples from both sites and found the same impacted minerals, such as coesite, a form of impacted quartz. This mineral can only form under the intense pressure of a meteorite impact or a nuclear explosion. Other similarities to nuclear test craters allowed scientists to estimate that the impact energy was around 10 megatons. That's the size of a pretty large thermonuclear detonation. Another similarity is the way these craters excavate the rock.

All of this earth was taken out of here (12 million tons) and it was expelled out and over the rim, and what really happens in that process is that the rock layers actually flip over at the rim. It's called inverted stratigraphy. This is a telltale sign of meteorite impacts and nuclear explosions and helped astronauts know, when collecting samples on the moon, what to look for and where. Something I was surprised to learn was that the Apollo astronauts actually spent 25%, or a full quarter, of their last year before blasting off to the moon studying science, visiting places like this where they could learn about geology, about their rocks. and minerals. and the formations they should look for when on the moon.

And I guess that makes sense, because these were scientific missions. But they were not carried out by professional scientists. In general, the Apollo astronauts were expert pilots. When Apollo 11 took off, the astronauts were traveling into the unknown, literally. We knew very little about the moon, how it formed, what it was made of, and whether it was volcanically active or not. (-- All engines running.) (We have a liftoff! --) When the Apollo astronauts were on the Moon, they actually used some of their training from here. The astronauts were very excited when they found the rocks they recognized.

In fact, it was probably because of their training here that they were able to recognize those minerals and those rocks that were so important to bring back. And learn not only about the formation of the moon, but also about our entire solar system and the formation of all the planets. This is actual lunar dust, or lunar regolith, collected by the Apollo 11 astronauts. I'm going to take a look at it under the microscope. Now, since the Moon basically has no atmosphere, all of this material had never been exposed to oxygen. So there was some concern that once the astronauts brought it back to their spacecraft and introduced some oxygen, it would spontaneously catch fire.

Then Buzz tells the story of how they were ready to throw away all the samples if that happened. But of course, fortunately nothing happened when they brought those samples back and re-pressurized the lunar module. Among the dark lunar dust brought back by Apollo 11, scientists identified small specks of a light-colored rock, which they immediately identified as anorthosite. And that was an important discovery, because it supported the theory that in the past the Moon was completely melted and covered by a magma ocean at least a hundred kilometers thick. So the idea is that when anorthosite forms, when the minerals that make it up crystallize, they are less dense than the magma around them, so they float to the surface.

So, the initial surface of the Moon, the primordial surface of the Moon. It would have been made of anorthosite, and then about a billion years later there was more volcanic activity on the Moon, causing lava flows over these darker regions called mare. And you can see that they have fewer craters because, well, they're younger. So how do you get anorthosite here in the Sea of ​​Tranquility? Well, that must have happened through giant highland impacts, which would have spread ejecta all over the Moon. And then it mixed with the dark soil here and the astronauts brought it to my petri dish, where I can see it today.

But the anorthosite was just the tip of the iceberg. Within all of these samples was a subtle clue to how the Moon formed. Looking at the amounts of different isotopes in a rock can tell where that rock came from. And when scientists analyzed lunar rocks, they found the same isotopic abundances as in Earth rocks. That is why today we believe that the Earth and the Moon were formed together, from the same event: a giant impact between planets four and a half billion years ago. Going to the Moon and knowing what to look for taught us not only how the Moon formed, but also how our Earth formed.

And all this from less than 400 kilograms of lunar rock from the visible side of the Moon. There is clearly still a lot to learn there and I personally can't wait until we return. Who knows what unexpected discoveries await us when we return. Hey! This episode of Veritasium was supported by viewers like you on Patreon and Audible. You know, for the past few weeks I've been relistening to Andrew Chaikin's "A Man on the Moon." This book tells the extraordinary story of the entire Apollo missions and in such detail that it is truly difficult to stop listening to it.

I was listening in traffic, on flights, even singing shadow dances. Yes, listening to this book is what got me through it. And there's no better place to listen than Audible. Simply go to Audible.com/Veritasium or text “Veritasium” to 500-500 and explore their unmatched selection of audio content. Audible members can choose three titles each month: one audiobook plus two Audible originals that you can't hear anywhere else. On top of that, members get access to audio-guided meditation and fitness programs. And for a limited time, Amazon Prime members can start an Audible membership and save $30 total for the first three months.

That's like having three months for the price of one. Each month is just $4.95 per month for the first three months, and after that, it's just $14.95 per month. The offer is valid from July 1 to July 31, 2019, so I really want to thank Audible for supporting me and I want to thank you for watching.