Apollo 11 is rightly celebrated as an extraordinary success for the United States. After all, NASA shot people for the first time on the moon and brought home alive.
During the historic mission, however, there were some close calls that could have ended in a tragedy.
Minutes before the moon landing, for example, alarms sounded in the lunar spacecraft, indicating that the flight computer was overloaded and might not work. Then, a surprise crater threatened to botch the landing, so Neil Armstrong and Buzz Aldrin (the two moon runners) spent almost all of their fuel on safer moon pastures.
These and other stories – frozen fuel pipes, a stuck hatch, a broken switch required to leave the moon ̵
According to one book, however, the mission's three astronauts were far more dangerous than previously reported.
Nancy Atkinson, a science journalist and author who listed information about the event in her new book, "Eight Years to the Moon: The History of the Earth," found that when the crew landed on Earth, they suffered a serious anomaly headed the Apollo missions. "
" Through my interviews and research for the book, I uncovered a serious anomaly that occurred on the return of Apollo 11 to Earth, "said Atkinson – whose book appeared on July 2 – business insiders in one E-mail: "The event was only discovered after the crew had safely returned to Earth."
The problem occurred shortly before Apollo 11's return to Earth, causing a discarded space module to almost sink into the crew's capsule
In addition, according to Atkinson sources, the same problem also threatened the crews of three other Apollo missions.
"We were lucky"
 The anomaly occurred less than an hour before the Apollo 11 crew landed. As Atkinson reports, most NASA employees have not noticed the danger the astronauts are in until weeks after their return to Earth.
For most of their eight-day mission, the crew of Apollo 11 was in a chewing gum-shaped capsule called Command Module. This capsule was on top of the service module: a large cylinder containing supplies, propellant, and a large rocket motor. NASA called the two-part spacecraft the Command and Service Module or CSM.
The CSM delivered a third part, the so-called lunar module, into the lunar orbit. Then, this lander brought Aldrin and Armstrong to and from the surface, while the astronaut Michael Collins remained in orbit around the moon. The CSM then shot everyone back to Earth on a three-day trip.
About 15 minutes before the astronauts jumped into the Pacific, the CSM completely separated into its two parts. This was necessary because only the command module (where the crew was) had a heat shield. The heat shield protected the astronauts by deflecting and absorbing the searing energies produced by plowing through the Earth's atmosphere at a speed of about 40,000 km / h – more than a dozen times as fast as an accelerating orb.
The service module became unusable and posed a risk of collision after the two parts were separated, skipping the Earth's atmosphere like a stone thrown over a pond.
That did not work.
Read more : An Apollo astronaut explains how he almost killed himself on the moon in 1972
Instead, as Atkinson explains, the service module traced the astronauts as they descended.
"Houston, we drove past the service module, a bit up and a little to the right," said Aldrin, looking out the command module window, Mission Control over the radio. Moments later, he added, "It's coming from right to left now."
When plasma formed in front of the capsule, the radio went off temporarily (as expected), but prevented the astronauts from offering more details. But an aircraft pilot discovered the returning command module and the service module, the latter of which broke apart and shattered into glowing pieces.
Gary Johnson, who worked as an electrical engineer for the Apollo program, told Atkinson that the service module on descent was "absolutely nowhere near the command module".
If the command module had collided with the astronauts, it could have crippled or destroyed the vehicle or left it out of control. Chunks of the decaying service module could have hit the capsule too, which could also have led to catastrophe, Atkinson wrote.
"If things went bad, we could have lost the Apollo 11 crew," Johnson told Atkinson. "We were lucky."
Why the Apollo Jettison Anomaly is Unknown
The astronauts, mission controllers and communications staff first realized that there was a problem after NASA had questioned the three lunar men about their mission weeks later.
NASA launched an investigation based on its reports and found that two previous missions – Apollo 8 and Apollo 10 – had suffered the same error. However, these astronauts did not see the service module in front of their windows and did not report it, Atkinson wrote. (A review of the old radar records showed that the service modules were also flying dangerously close to the command modules on these missions.)
The cause of the problem turned out to be a bad sequence in a controller that helped drop or split. the command and service modules. NASA knew that the same problem had invaded the Apollo 12 spacecraft launched in November 1969, but decided not to fix it due to time constraints, Atkinson said.
According to Johnson, NASA has classified the Apollo 11 astronaut debriefings for some time. An official report on the anomaly appeared in November 1970 – about half a year after the devastating Apollo 13 mission – and somehow managed to stay out of newspapers.
"The event never made it into the mission reports of Apollo 11 and has largely been forgotten – I think, due to the rush of time, to move on to the next flight, etc.," Atkinson said. "The first time that this anomaly was fixed was for Apollo 13. And of course you know what happened to 13, and I think the anomaly was probably largely forgotten because of all the other excitement."
For more details on the anomaly, see Atkinson's book.
This story has been updated.