Space is often considered the crossroads of science, exploration, and life itself, and it’s chock-full of mystery; there is a reason why we call it “the final frontier,” after all. Not surprisingly, those courageous enough to venture beyond Earth’s atmosphere and into the Great Beyond face almost inconceivable dangers.

This was no more true than in the 1970s. Despite knowing the perils of outer space travel, including the possibility that anything could happen, three Russian cosmonauts still bravely and boldly took aim for the stars—and they paid the ultimate price for it.

When space exploration was in its infancy, the Soviet Union had a simple goal: beat America. Doing so would go a long way in lifting the spirit of the Soviet people and bolster their place as the world’s superpower. In other words, the Space Race was heated.

That’s why the Soviet Union so badly needed their Soyuz 11 mission to be successful. They’d whooped America in 1971 by launching a space station—Salyut 1—into orbit, but after failing to dock it with the Soyuz 10, the USSR had some egg on its face.

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After America landed men on the moon, the Soviet’s previous achievements, like the launch of satellites Sputnik and Sputnik 2—and even putting the first man in space, Yuri Gagarin—didn’t really compare to America’s 1969 moon-walking accomplishment. They needed a win, and fast.

Neil A. Armstrong / NASA

So in 1971, the Soviets desperately wanted to regain the upper hand and prove their fully-operational space station wasn’t just an ornament. For this, the Soyuz 11 mission, which hoped to successfully dock the spaceship with the station, was key. However, it was a disaster from the get-go.

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Four days before the Soyuz 11’s scheduled launch, medics discovered early signs of tuberculosis in one crewman, Valeri Kubasov. Instead of killing the mission, the Soviets scrapped the entire crew and went with a new one, consisting of three men. Sadly, this was one job offer they should have turned down.

Space Safety Magazine

The commander, 43-year-old Georgi Dobrovolsky (pictured), would oversee Vladislav Volkov and Viktor Patsayev in the Soviet’s attempt to regain space dominance. Though they were a back-up crew, each was an experienced cosmonaut in his own right.

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Still, experienced as Dobrovolsky and his crew were, they hadn’t received the same training the original crew had. They’d trained for only four months before launch time, but nevertheless, the Soviets felt they were ready for action.

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Soon enough, the Soyuz 11 took off with no problems and arrived at the Salyut 1 space station with its crew intact. Now came the difficult part: the cosmonauts had to dock the ship and actually set foot on the space station.

Slowly and steadily, Dobrovolsky and the Soyuz 11 crew did what the the Soyuz 10 team couldn’t: they successfully docked their spacecraft in the space station. Then, as soon as they stepped aboard, they encountered a major problem.

Kevin Gustafson / YouTube

The Salyut 1 space station smelled bad—like something was on fire. Right away, the Soviet crew retreated back to the Soyuz 11 for 24 hours and made repairs to the station’s ventilation system. Eventually, the Salyut 1 was made habitable… or so they thought.

Soviet Space Program / YouTube

Now safely on the Salyut 1 (sans the burning smell), the cosmonauts went to work. Their mission was to study the effects zero gravity had on the human body, among other things. Part of their research included running on a treadmill aboard the space station.

Soviet Space Program / YouTube

And what was a little space-age propaganda without regular television broadcasts? Dobrovolsky and his crew starred in televised progress reports that the USSR and countries all over the planet broadcasted to their citizens. Then, 11 days in, the crew encountered another issue.

Again, the Soyuz 11 crew smelled something bad, and this time, smoke accompanied the stench. Luckily, any panic didn’t last long, as the crew was able to quickly locate the source of the smoke—a malfunctioning part—and fix the problem. All good, right? Well…

All in all, the crew spent 23 days aboard the Salyut 1, beating the previous record for time in spacial orbit by five days. With a record in hand and 141 separate experiments completed, it was time for Dobrovolsky, Volkov, and Patsayev to return home.

ThezMagiq / YouTube

The Soviet crew gathered up all of their research—notes, recordings, and more—and loaded it onto the Soyuz 11. All in good health, they boarded their ship, undocked from the station, and readied the ship for re-entry into Earth’s atmosphere. That’s when everything went wrong.

Soviet Space Program / YouTube

Dobrovolsky and his crew orbited Earth three times before initiating their descent. Mission control radioed the team, cheerful to see them soon on “Mother Earth.” The commander’s reply? “Thank you, be seeing you.”

NASA

From there, the Soyuz 11 crew initiated every landing procedure exactly right. The ship’s rockets blasted for the correct length of time, the reentry capsule successfully separated from the hull, and its parachutes deployed. It appeared all was well.

Soviet Space Program / YouTube

Only, try as they might, mission control was no longer able to contact the Soyuz 11 crew. They radioed in several times, but they received no reply. So when the re-entry capsule landed in remote Kazakhstan, recovery units were concerned as they rushed to the scene.

NASA

Mission control had instructed the Soyuz 11 crew not to exit the spacecraft without assistance. There was no telling what 23 days in space would have on their bodies, so the Soviets wanted medics on hand for immediate treatment.

NASA

When the recovery team approached the sealed reentry capsule, it too seemed fine. From the outside, the landing had gone off without a hitch. When the recovery team knocked on the exit hatch, however, no crew member responded. Finally, they opened the hatch themselves.

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“On opening the hatch,” reported Russian official Kerim Kerimov in Space Safety Magazine, “they found all three men in their [seats], motionless, with dark-blue patches on their faces and trails of blood from their noses and ears.”

Rescue units rushed to save the three cosmonauts. They removed the men from the reentry capsule, laid them out on the ground, and administered CPR on the still-warm body of Commander Dobrovolsky. It was no use, though. The three men were dead. How did this happen?

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As the re-entry capsule fell towards the Earth, an equalization valve regulating air pressure malfunctioned (as many things on the station had). It opened too early and caused the pressure in the capsule to match that of space. The pod became a vacuum at 104 miles above the ground.

The cosmonauts died when the vacuum conditions inside their capsule hemorrhaged all the blood vessels in their brains. In seconds, they were knocked out. Minutes later, they were dead. Officially, their deaths occurred in space.

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The Soviet Union posthumously awarded Dobrovolsky, Volkov, and Patsayev with Hero of the Soviet Union gold stars and held a ceremony honoring the cosmonauts. In the end, the USSR, America, and every space-faring country learned a valuable lesson from this tragedy.

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Had the three men been wearing the appropriate gear, they would have survived. With that discovery, America and the USSR changed protocol to state that crewmen must always wear a pressurized suit when depressurization is possible.

NASA

Before those Soviet cosmonauts ever stepped foot in a spacecraft, certain discoveries by previous pioneers made their fateful journey possible. Gordon Cooper, the son of an Army colonel, led the way in the groundbreaking research.

NASA via Collect Space

Before he turned 32, Cooper had served in the Marines, the Air Force, and as a test pilot on Edwards Air Force Base. There he suggested industry-changing improvements to the F-106B Delta Dart jet fighter. Then, he received an unbelievable offer…

It was 1959 when NASA invited Cooper to Washington, D.C. as a potential candidate for the Mercury Project. The project sought to put a man into Earth’s orbit and then return him safely, and Cooper was an ideal candidate.

NASA

After placing him on a shortlist of 109 potential candidates, NASA selected Cooper as one of seven men for the program. In May 1963, he conducted his first mission aboard the Faith 7, a craft so small it could only fit someone under five feet and 11 inches tall.

NASA

The instructions NASA gave the enthusiastic Oklahoman were simple: go into space solo, survive, and study zero gravity’s prolonged effects on the human body. At least, this was the mission as far as the public was concerned…

NASA via Space Flight Insider

The project started out a rousing success. From May 15 to 16, for just about 34 hours, Cooper orbited Earth, becoming the first astronaut to sleep in space. But then, in the midst of this enormous accomplishment, disaster nearly struck…

As Faith 7 returned to Earth, the automatic piloting system malfunctioned. An experienced flier that he was, Cooper didn’t panic. Instead, he grabbed the controls and maneuvered the spacecraft into a perfect landing on a waiting aircraft carrier. His mission was complete… or was it?

NASA via Discovery

Though the public didn’t know it at the time, Cooper’s mission also involved taking pictures. “Man, all I do is take pictures, pictures, pictures,” he said in a message to ground control. “I’m up to 5,245 now.” But he wasn’t just looking for eye-catching images…

L. Gordon Cooper / NASA

Cooper’s camera was actually equipped to detect magnetic aberrations along the Earth’s surface. This allowed him to secretly look for Soviet nuclear bases or submarines off the coast of the United States—and, boy, did he uncover some eye-opening stuff.

RR Auction via Collect Space

In the process of searching for secret nuclear bases, Cooper also detected hundreds of anomalies near the Caribbean, which he carefully charted in his small Faith 7 spacecraft. These aberrations, he noticed, weren’t big enough to be nuclear sites—not by a long shot. So, what were they?

Discovery Channel via Mother Nature Network

Cooper wasn’t sure what he’d spotted from space, but he had a few ideas—and they required further research. For an unknown reason, he never told NASA or the Department of Defense about these strange anomalies. He decided to embark on his own personal mission…

NASA via Discovery

Once safely back on Earth, Cooper started investigating his findings. The anomalies he saw all seemed bunched around old trading routes that had been highly trafficked by Spanish ships. Surely this was more than a coincidence…

Cooper quickly made the connection from the shipping routes to possible shipwrecks, and he researched everything he could regarding centuries-old shipwrecks. Eventually, he felt confident that he had, in fact, charted some of them from space! What did this all mean?

The world would have to wait to find out. He had a long and successful career—including a mission on the Gemini 5, during which he spent 190 hours in space. Still, Cooper never had the time to truly explore his findings. Then, as he grew older, time started running out…

NASA via Honey Suckle Creek

Afflicted with Parkinson’s and nearing the end of his days, Cooper didn’t want his secret discovery to be for naught, so he phoned his friend, Darrell Miklos (right). An explorer who had experience hunting for rocket ship debris, Miklos would be able to investigate on Cooper’s behalf.

Cooper passed away in 2004, but by then his map was safely in his friend’s possession. At long last, it was time for Miklos to investigate what Gordon Cooper had seen from space all of those decades ago. Was there any truth to it?

“I believed Gordon 100 percent,” Miklos told Parade magazine. “I didn’t need proof.” Neither did the Discovery Channel, which, along with Miklos, created Cooper’s Treasure, a 2017 TV show that documented the investigation.

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So, what did they find? On one journey, Miklos and his crew traveled to a spot on Cooper’s map looking for evidence of a shipwreck. With the help of deep-sea diving gear, they surveyed the ocean’s floor, hoping for a sign…

Discovery UK / YouTube

Sure enough, the crew uncovered a massive anchor! They hauled it to their deck, and soon after they realized that it was from the era of Christopher Columbus. This made it an extremely valuable artifact from the past!

Discovery UK / YouTube

By mid-2017, Miklos and his crew had searched five spots on Cooper’s map, and at all five, they found evidence of a shipwreck. With hundreds of points still left to explore, what other treasures might be waiting for Miklos to uncover?

Miklos planned to visit the rest of the locations, but it would take time. Still, as he told Newsweek, “I hear Gordon all the time in the back of my head: ‘You’re on the right trail!'” And it sure looked that way.

Discovery Channel via ABC News

Still, Gordon’s research proved valuable for more than just shipwreck hunting. In fact, years later, thanks to what Gordon found out about gravity’s long-term effects, the Soviet Union and America found themselves in a head-to-head battle.