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Apollo 13 - Houston, We Have a Problem

Everyone remembers Apollo 11. Either as the mission that successfully landed men on the moon, or as the hoax filmed on a sound stage in Hollywood. The mission was a technical marvel, and came out of years of research and experimentation. Men died in the pursuit of the moon.

The 60s were a wild time for Earth. NASA undertook so many missions, that by the time Apollo 11 landed back on terra firma, the world had space-fatigue. Humanity felt the moment of pride, and moved on.

So, in 1970, when a second team was being sent to the moon, the world wasn't paying attention. There were no live TV broadcasts. Apollo 13 was a second attempt at the impossible, and no one cared.

At least, until things went horribly wrong.


Apollo 13 - The Crew



James A. Lovell, Jr. had been to space before. He completed two missions in the Gemini program, and one earlier Apollo mission. The choice to make him the commander of the latest mission to the moon was no mistake.

Before becoming an astronaut, James was a test pilot for the Navy. He had over 7,000 flight hours under his belt by the time he became an astronaut. Gemini XII was the final mission of the Gemini program, and he completed that mission without incident.

John L. “Jack” Swigert, Jr. wasn't NASA's first choice of Command Module pilot for the Apollo 13 mission. He was notified 72 hours before launch that he was being pulled from the reserve crew. It turns out that prime crewman, Thomas K. Mattingly had been exposed to Rubella just before the flight.

Fred Haise spent most of his career as an astronaut sitting on the bench. Apollo 13 was his first off world mission. He was given the critical role of Lunar Module pilot, which means that he would, supposedly, get the chance to step on our strange stellar companion.

Apollo 13 was set to land in the hills of the Fra Mauro region of the moon. This would be a much more technical landing zone than previous missions.


The Incident


Things went wrong almost immediately after launch at 2:13 pm, April 11, 1970. The center engine shut down 2 minutes early, and an investigation after the flight discovered that it was one cycle away from catastrophic failure.

Apollo 13's crew was able to compensate for the lost engine, and made it into orbit. From there, they achieved translunar injection within 2 hours. All seemed well.

The crew were in near constant communication with the ground crew. Everyone felt positive about the flight, with one operator on the ground claiming that he was "Dying of boredom."

That all changed when Apollo 13 was roughly 200,000 miles from Earth. It started with an apparent malfunction in the pressure sensor of one of the oxygen tanks. The ground crew noted the strange readings, and requested a stirring of the oxygen tanks.

This process, which was normally performed once daily, mixes the contents of the tank, in order to get more accurate pressure readings. Swigert complied. The tanks were stirred for a few seconds, and then the fans were deactivated.

Ninety-five seconds later, the astronauts heard a loud bang. This was followed by fluctuating electricity levels, and the misfiring of the altitude control thrusters. They also lost contact with the team in Houston for 1.8 seconds.

Swigert reported back to Houston, with the now famous line:


"Houston, we've had a problem."

Soon, two of the three power cells went offline. The mission rules showed that in order to enter the moon's orbit, all three cells had to be online.

Oxygen Tank 2 showed a reading of empty, and Tank 1's pressure seemed to be falling. Seymour Liebergot, the operator in charge of monitoring the mission's readings at Houston, dismissed the reading from Tank 2. He blamed faulty instruments as the cause for the apparent depressurization.

Luckily, Lovell looked out of the window at this point. He saw a mysterious gas leaking into the void. This observation indicated that there was more than a faulty pressure sensor at work.

After their return, an investigation concluded that there had been exposed wires in one of the oxygen tanks. The wires had sparked, igniting the oxygen, and blowing up the tank. The secondary tank was damaged by the blast, and was slowly leaking the precious gas into space.

The explosion, and subsequent leaking gas, affected the spacecraft's trajectory. Some of the adjustment jets had been damaged by the blast, and as such, the module was unable to adequately course correct.

Power in the Command Module relied on oxygen, so the entire thing was rapidly becoming an icy tomb. Their only hope was to escape to the LM, which was still fully operational.

They booted up the LM, and worked to shut the damaged CM down. Lunar Modules weren't built with heat shields, as the moon has no atmosphere to burn as a craft descends. This meant that the LM could support the astronauts in space, but they couldn't reenter Earth's atmosphere with it.

The mission now had only one goal. Get the astronauts back to Earth.


Moonshot


NASA/Crew of Apollo 13 - Apollo 13 Hasselblad camera image cropped in Adobe Photoshop to show Mare Moscoviense. Resolution reduced by half from original due to blurring of the original. The original image is in the public domain because it is a work of the U.S. Government (NASA). Immediate source: Lunar and Planetary Institute, Apollo Image Atlas 70mm Hasselblad Image Catalog, Apollo 13, AS13-60-8648
Why not snap a pic in the middle of a life/death situation

The Command Module was their ticket home, but its oxygen tanks had been depleted. They isolated the oxygen surge tank, to save what they could for their reentry into Earth's atmosphere.

One of their biggest concerns now, was actually getting back to Earth. They were over 200,000 miles away from home, and headed in the wrong direction. Only the moon could save them now.

Timing of the accident was key. Had it happened on the way back from the moon, the LM would have been jettisoned. As it stood, it had full batteries, and oxygen reserves.

There were two routes home, and a big decision to make. Either the team could turn around for a direct return to Earth, or they could save the fuel reserves to loop around the moon.

Gene Kranz, one of the flight Directors, chose the moon route. He reasoned that the engines of the service module could have been damaged by the explosion. There might not be enough fuel to turn the craft around.



Due to their trajectory, they would not return to Earth purely by swinging around the moon's orbit. They had to use the lander's propulsion to adjust their course for a 'free return'.

After getting back on the right trajectory, they faced the problem of where to land. They would land in the Indian Ocean, on their current flight path, but NASA had very little in the way of recovery teams there.

NASA decided to fire the descent propulsion system again, to change course for a splashdown in the Pacific Ocean. During the maneuver, the Apollo 13 team gained the record for the highest altitude ever reached by humans.

The astronauts used stars to navigate, like sailors of old, as the craft's alignment could not be checked on the CM's computers. Most of the stars were obscured by the cloud of debris surrounding them, so they used everyone's favorite star - the Sun.

Splashdown


The course was set for a landing in the Pacific Ocean. Only one problem faced the team now, how were they going to survive reentry in their heavily damaged spacecraft?

They had sufficient oxygen in the LM, but the carbon dioxide removal system wasn't designed for such heavy use. Three people, breathing in an enclosed space create a lot of carbon dioxide.

The LM's system was designed to support two astronauts for 45 hours on the moon. If they could somehow use the carbon-capture canisters from the Command Module, they would have the resources to keep breathing all the way home. Unfortunately, the canisters on the CM were a different shape to those on the LM. They had to fit the square into the circle.

Technicians on the ground were able to create an adaptor using scrap plastic, the covers of procedural manuals, random parts of the LM, and humanity's greatest invention - duct tape.

Their next issue was water. Running out doesn't quite describe the situation they were in. Water was a critical component of the LM's system. They would have to ration their water intake, down to 0.2 liters per person per day.

The crew of Apollo 13 lost a total of 14 kg from the restrictions. Weight loss being sped up by the near frigid temperatures onboard the LM. Shivering burns calories, if you were wondering.

Haise and Lovell put on their moon boots, while Swigert put on an extra overall. Swigert hadn't been scheduled for a moonwalk, so he had no boots to wear. His discomfort was maximized by the fact that he got his feet wet while retrieving water for the crew.

The time was rapidly approaching for Apollo 13 to try to power up the CM again. Entering the atmosphere in their current state would end in a fiery death.

Cold temperatures can adversely affect a human's cognitive and physical performance. The ground team gave the order to fully power up the LM, roughly 133 hours into the flight, in order to heat up the interior.

Reheating the astronauts did the trick, and they were able to implement the reactivation of the CM, which had never been done, and required even more ingenuity from the engineers on the ground.

The LM's guidance system came back online, and they noticed that they had drifted off course. Using the LM's thrusters, they corrected. Moments later, the damaged Service Module was jettisoned. This allowed the astronauts to see the extent of the damage.

Right before reentry, the crew scrambled into the Command Module, and detached the LM. This was made possible by a team of engineers from the University of Toronto, who calculated how much air pressure it would take to push the LM far enough away.

Apollo 13 entered the Earth's atmosphere on April 17, 1970. The Lunar Module, which had been their home for the past few days, burned up in the atmosphere as they splashed, safely, down in the Pacific.

The crew was rescued, and returned home to receive the Presidential Medal of Freedom.



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