This article is the 44th in the History of Space series
Author: Wu Jingping
Past issues can be viewed in "My Home - Articles"
The above document mentions that the service module of Apollo 13 suddenly exploded. There are two hydrogen tanks in the service module of the spacecraft, the hydrogen tank is a capsule shape, the oxygen tank is much smaller than the hydrogen tank, it is a spherical shape, but the hydrogen tank only holds 13 kilograms of liquid hydrogen, and the oxygen tank contains 148 kilograms of liquid oxygen, and the density of liquid hydrogen is pitiful.
The explosion caused the oxygen tank's index to drop suddenly, and it is estimated that there is not much left. It also caused the fuel cell to be blown up. Fuel cells don't just provide 14 kilowatts of electricity, they also provide clean water. Water is not only for astronauts to drink, but also to cool down the instruments. At this moment, the three people fell into a desperate situation.
The blue one is the hydrogen tank, the red one is the oxygen tank, and the green one is the fuel cell
Fortunately, the previous lunar spacecraft was designed with lifeboats in mind. If not prepared in advance. The three of them certainly couldn't come back. Under the dispatch of ground engineers, the three people squeezed into the Aquarius lunar module. The place for two people was stuffed with three people and it was definitely very crowded.
The oxygen of the lunar module is actually not much at all, because the lunar module should take into account the movement of people in and out, and can complete the process of decompression and recompression multiple times. But water has become a big problem. Because in order to save weight in the lunar module, the water it carries is all buttible. There are no fuel cells to produce water, so water is a big problem. The amount of water consumed by the three people was reduced to 20% of the original, and one by one they were dry-mouthed, but there was no way but to endure it. Not drinking water will cause the human body to reduce urination, and it will not be able to take away the waste products that accumulate in the body, which will hurt the kidneys. At that time, astronaut Hayes had a burning sensation every time he urinated, and he actually had nephritis. But there is no way in space, just stay up.
Lovell tried to rest for a while in the icy lunar module, which he was not wearing thickly
The temperature in the lunar module is also very low, only 3.3 degrees Celsius, which is limited than the temperature of the ice. They can't use electricity for heating, the lunar module uses a battery, not a fuel cell, the total energy is a fixed number, and it is a little less to use. What can be saved is saved, and what can be turned off is turned off. The food is frozen hard, and it can't be unfreezed if you want to thaw, so you can only eat cold like this. Fortunately, astronauts' health is generally good, and this difficulty can be overcome. But there are some things that they can't resist by their physical strength. For example, the concentration of carbon dioxide is constantly rising, and if this problem is not solved, they will soon be delirious. After a day and a half in the lunar module, carbon dioxide levels were unbearablely high.
Lithium hydroxide is used on the spacecraft to adsorb carbon dioxide gas, and lithium hydroxide and carbon dioxide undergo chemical reactions to form lithium carbonate and water. 1 gram of anhydrous lithium hydroxide can absorb 450 cubic centimeters of carbon dioxide, which is quite powerful. Everyone who has taken chemistry classes in middle school probably knows that carbon dioxide can react with lime water to form calcium carbonate. It can also react with caustic soda to form sodium carbonate. But both chemicals are too heavy. The spacecraft focuses on the struggle to reduce 1 gram. The specific gravity of sodium hydroxide is 2.13, and the specific gravity of lithium hydroxide is 1.46, which is a lot worse. Therefore, the first choice for spacecraft is lithium hydroxide.
Stills from the movie "Apollo 13" show square and circular filters, which are not common to each other
It is reasonable to say that the command module should also have a lithium hydroxide absorber, and it will be finished when you take it. However, the interface of the absorber used by the command module Odyssey and the one in the lunar module are inconsistent and cannot be connected. The lunar module is lithium hydroxide filter is round, the instruction module lithium hydroxide filter is square, take it over is useless, can not be stuffed into ah!
If not, bureaucracy kills people. Both the command module and the service cabin behind the butt were both produced by North American companies. However, the lunar module was produced by Grumman, which was not a family at all, and NASA, which coordinated in the center, did not think of this stubble. As a result, the chain began to drop at a critical moment.
Engineers are discussing how to solve the problem of filter mismatches
What to do? The engineers on the ground don't eat dry food either. They found what they could have on the ship and immediately began assembling to see if they could come up with a transition interface on their own. All they had in their hands were plastic bags, flight manuals, tape, and other miscellaneous things. You don't have to say, tape is basically a must for everyone, young and old. Not only can it be used to seal express boxes, but special cloth tape can also be used to glue aircraft skin. Even at home, it can be used everywhere, and with this thing, I basically don't have to worry. In addition, the spacesuit used for the moon landing can not be used, and the plastic pipes can be removed and used.
This homemade "plug-in" can work
The filter tank used in the command chamber is square. One end is the air intake, and this one doesn't have to worry about it. The other end is the air outlet. First tear off the cover of the flight manual, it's a crusty one. Use this cardboard to build an arched shed over the air outlet. Then pull a tube from the spacesuit and insert it into the side of this vaulted roof. Slip into a plastic bag, keep the outlet side so that there is no air leakage, and wrap the tape up and down and left and right a few times. Connect the tube to the circular filter tank, put a plastic bag on the interface, and wrap it in several layers of adhesive tape to keep it from leaking. This makes an externally attached filter.
Ground personnel use radio to direct the astronauts in space to grasp the medicine according to the prescription, according to this method to make a plug-in filter, then try it, the effect is not bad, the concentration of carbon dioxide dropped to normal levels. This level is over.
The next level is the problem of navigating the computer. The computer in the lunar module is completely different from the command module, and they pass the data over, although the power of the command module is very valuable, and this is still something to be done. Now 3 people have moved to the lunar module, the center of gravity has changed, and some of the data has to be recalculated. This step cannot be completed in space, and can only be calculated by the people on the ground, and then told the astronauts, who manually entered it into the computer of the lunar module.
This time, you'll need to use the moon's gravity to make a 180-degree turn and embark on a journey home. This process requires turning on the engine to adjust the state of the spacecraft. The engine should start at just the right time, not early or late, not long or short, if it is almost, throwing the wrong angle, not aimed at the earth, it will be troublesome, do not know where it will be thrown. Fortunately, they had passed this level without any danger.
While circling behind the moon, Lovell looked at the moon below, having been here last time. This time, it should have gone down and set foot on the lunar surface in a lunar module. Unfortunately, the service cabin exploded, and I could only use the moon capsule as a lifeboat. The two newcomers were also very hungry, but unfortunately, they all came, but they couldn't go down. The moon is very beautiful, take more photos, so keep it as a souvenir. It is far more important to go home now than to land on the moon, after all, the earth is truly irreplaceable home.
Photos of the moon taken by Apollo 13 astronauts
After bypassing the moon, the ship began to fly in the direction of the Earth. Navigation is all manually controlled by the astronauts themselves. Fortunately, the astronauts had all been trained before, and the ground commanded three people to use the sun as a reference object for calculations. The navigation telescope is broken and cannot be used. The position of the Earth can only be observed with the naked eye. Let the window point in the direction of the earth, and the earth appears exactly in the prescribed position of the window, which is roughly aligned.
Just stayed in space for 6 days. It's a really hard time, it's not something that ordinary people can bear, they're cold and hungry, and they can only drink a little bit of water. There are so many things to deal with, and it is often life-threatening, and the mental pressure is also very high. Hayes was more unlucky than the other two, he had nephritis, he was running a fever, he was suffering a lot. By April 17, they were close to Earth and were about to return to earth's atmosphere. Only the command module Odyssey can withstand the high temperature of returning to the atmosphere, and the lunar module Aquarius does not have this ability. So, they could only return to the command module from the lunar module, and first turn on all the instruments.
The command module has its own spare oxygen tank. This bit of oxygen does not last much time, and it is still enough for returning to Earth. The power of the lunar module should also be mobilized to the command module as much as possible. To put it bluntly, it is to use the lunar module as a charging treasure. The lunar module was not originally used as a charging treasure, it can only be recycled 20 to 30%, and it is a little bit to collect it. Eventually, the lunar module is to be abandoned. But this time it was a special situation, and the ground controller asked them to throw away the service cabin behind their butts and try to see what was going on in the service cabin.
The bulkhead of the service cabin was blown up horribly
When the service cabin was thrown away, the service cabin floated in front of the window of the command module, everyone quickly took pictures of the service cabin, at this time they saw what happened to the service cabin for the first time, they were surprised to find that the entire panel on the fuel cell and oxygen tank was blown up, the high-gain antenna was also damaged, they have been relying on the backup antenna and the ground contact for several days, the damage is very serious. They had to leave the footage and go back to do the accident analysis.
Finally, it was the turn to abandon the lunar module, they took something from the lunar module as a souvenir, and the three of them returned to the command module. Now throw away the lunar module. The three of them were still a little in love, after all, this lunar module saved the lives of the three of them. The ground controller was also a little nostalgic, and he said affectionately to the lunar module: "Goodbye, Aquarius, thank you." There was no way, no matter how reluctant it was, we had to abandon the Aquarius lunar module, and finally the Aquarius entered the Earth's atmosphere and burned up. This is one of the few lunar modules that burned down in the Earth's atmosphere.
Abandoned "Aquarius lifeboats"
Then came the Odyssey re-entry. When returning, the spacecraft rubs against the atmosphere, and the ablative material will constantly take away the heat, and this process will create a black barrier. That is, the plasma completely ate the radio waves, and the communication between the spacecraft and the ground was interrupted. The black barrier to Apollo 13's return to the atmosphere was particularly long, because the spacecraft was relatively light, and they were supposed to bring back some rocks from the moon, but this time they did not land, so they did not bring it. After such a long time, will the insulation layer be burned out? NASA engineers have no bottom in their hearts, and everyone's heart has mentioned the throat eye. They called the Odyssey over and over again, but the Odyssey had no echo, only the rustling of the current noise.
Everyone's patience is disappearing little by little, and the sense of fear is accumulating little by little. Until finally, the voices of three astronauts from the Odyssey came. Everyone's suppressed feelings suddenly erupted, and there was a round of applause in the control hall. They have finally made the impossible possible. Apollo 13 spent 144 hours in space and is now finally home.
The spacecraft landed exactly in the intended South Pacific, and the amphibious assault ship Iwo Jima was waiting nearby. Immediately send a helicopter to salvage. All three people were fished out, and the combined weight of the three people was reduced by 14.3 kilograms. These days they can't drink a few sips of water, and they can't eat well. It's strange that you don't lose weight. Hayes also had nephritis and had to be treated immediately. The Apollo 11 and 12 astronauts also had to go through strict quarantine procedures, and Apollo 13 was not used, and they did not come into contact with anything on the moon.
They slept on the ship overnight, arrived in Samoa the next day, and then went to Hawaii, where President Nixon was waiting for them in Honolulu to give them the medal. Their families and children also came. They failed to land on the moon, a mission failure to be precise, but it was the most successful failure in NASA history, and they came back alive. Even Soviet cosmonauts sent telegrams to congratulate them. The competition between the United States and the Soviet Union is competition, and this aspect is still bright and straightforward.
It's not over yet. NASA also needs to figure out what went wrong and why it exploded. Chasing after it, they found the ins and outs of it. North American companies are manufacturers of service modules. They ordered a batch of liquid oxygen canisters. The 2 liquid oxygen tank that was installed on Apollo 13 was actually installed on Apollo 10. The jar was dismantled and repaired by accident, falling from a height of 6 centimeters and falling. You may think that 6 centimeters is a fart. NASA engineers don't dare take it lightly. I changed a jar to give Apollo 10, took the bumped jar to test, and found no damage, so I continued to use it on Apollo 13. But no one knew at the time that the line in the jar was broken, and the plastic skin of one wire broke a hole.
Apollo 13's oxygen tank structure
In fact, before loading on Apollo 13, testing was done, and the jar was found to be unable to completely empty the liquid oxygen. It is reasonable to say that by pouring gaseous oxygen into it, liquid oxygen can be squeezed out, and it can be squeezed clean. But this jar doesn't work. The test team decided to use heating to empty the oxygen tank. The jar is heated. The temperature of liquid oxygen is -183 degrees, and if you want to heat it, it is enough to add it to zero. There is a temperature switch to automatically control the heating temperature, and if the temperature is too high, the power will be cut off. The test team added a voltage of 28V and found that the liquid oxygen in the tank could not be completely drained. Increased the voltage, increased to 65V, this time it was smoothly drained of liquid oxygen in the jar. But what they did not expect was that the temperature control switch was burned out by the large current, and it stopped in the open state forever and could no longer be closed.
As a result, the jar followed Apollo 13 into space, and the upper limit of the temperature gauge on the tube was 26.6 degrees Celsius. Americans like to use Fahrenheit, which is 80 degrees Fahrenheit. Even if it's a blow, you can't see it. The current is always on, and the temperature of the liquid oxygen is heated to 500 degrees, and it can't stop at all.
After going to space, the liquid oxygen in the jar is in a state of weightlessness, condensing into a lump floating in the jar. This uneven state is difficult to measure, the ground to accurately measure the situation inside the oxygen tank, it is best to stir the liquid oxygen in the tank evenly, spread out. So there is a small fan in the jar, Swegert according to the instructions of the ground to open this small fan stirring, the wire out of a very small spark, in general, this spark is not nothing, the wire plastic skin is made of Teflon, that is, PTFE plastic, known as the plastic king, that is really forbidden to pull and drag, acid and alkali resistance, not afraid of cold and not afraid of heat, otherwise how can you use this thing to make a non-stick pan. But in a pure oxygen environment, the temperature is high, the jar is heated to 500 degrees, is liquid oxygen such an honest thing? The wire skin burned immediately. As a result, the jar exploded with a bang. The main cause of the Apollo 13 accident was this bombing.
However, what you can't imagine is that the explosion is still a blessing in disguise. Because there is another hidden danger, if this hidden danger is attacked at the time of the moon landing, then the three of them will account. Fortunately, there is no process and steps to go to the moon, what is going on? We'll talk about it next time.
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