Hayadan > Skylab 4 - the last manned mission to the space laboratory

Skylab 4 - the last manned mission to the space laboratory

Back during the flight of Skylab 3, a proposal was made to advance the launch of Skylab 4 by two weeks, since every day that the laboratory is under supervision costs 1 million dollars. The concern was that the batteries would not be able to maintain a reduced charge of electrical power. Furthermore, the situation could get worse, but the opportunity the astronomers had to study Comet Kohotek removed this plan from the episode.

Astronaut Geraldo Carr, member of the Skylab 4 crew on the Space Station Skylab. Photo: Nas A

The Space Lab Skylab entered renewed service with the launch of the last crew to it, thus closing the circle of the fourth manned space program of the USA. According to the original plan, the third team was supposed to stay in the laboratory for 56 days. The flight was extended by three days for the same reasons as those that extended the Skylab 3 flight to 59 days. Astronomical calculations have shown that Comet Kohotek will be visible to the naked eye at the end of November, during December and the first half of January 1974. At its minimum distance from Earth, 120 million km, the comet will shine with greater intensity than Halley's Comet in 1910. The astronomers decided to take advantage of this opportunity. The proposal made to get the most out of the Skylab 4 crew was to extend the flight to 85 days. This is provided that during the first 59 days the astronauts will be in good health and the laboratory systems will function properly. In addition to this, changes were made to the astronauts' work plan to cover the comet in the study as well.

Power supply
The loss of the solar shelf raised concerns already during the flight of the first team since the electrical power of the laboratory would not be enough for the last team. A proposal was made to equip the last team with new sun racks. The price of such a battery was 2.5 - 3 million dollars (at the price of 1973) and it weighed 1.932 tons. The shelf is made of an aluminum cylinder with a diameter of 85 cm and a length of 4.05 meters. The central cylinder contains a docking station, contact strips and a connecting bracket of Apollo spacecraft at both ends. The sun shelf is similar to those on the telescope. There are nine batteries with a power of two kilowatts on the connection dock. The contact strips are of the type that was intended for the American and Russian space flight.

At the time of launch, the entire facility is in the launcher's adapter. The connection to the laboratory is made through its side opening. The device comes from the adapter and is moved to the connection point and the spacecraft disconnects this key and connects in the front opening. The astronauts enter the laboratory and connect the shelf to the general power system. The disadvantage of this system lies in the fact that it covers most of the measuring instruments aimed at the Earth. The decision whether to use this shelf was left to the last minute, and before the launch they gave up on this plan.
In preparation for the possibility of an 85-day stay in space, the astronauts were equipped with a supply of 84 kg of food and drink. In addition, the astronauts were equipped with additional research instruments and they are:

An ultraviolet camera such as the one that was on Apollo 16 to photograph the hydrogen halo of Comet Kohotek.
Open containers containing liquids containing carbon to see if they boil at zero acceleration.
A foot stop for operating the 193-S device for short waves. The device includes a radiometer, an explosiveness meter and an altimeter. In cases where the device stops working, the stop is made of a small surface with two footholds. One of the astronauts connects the arrester to the devices to stabilize them and repair the broken system. The purpose of the experiment is to check for a short circuit in the potentiometer located between the electronic case and the antenna. The antenna measures irregularities in the earth's ground temperatures and its spherical shape. The short caused deviations in the direction of the antenna, on the astronauts' first tour, and they had to disassemble the antenna cover from its axis and clean the arc of dirt that probably caused the short. If this operation fails, the astronauts insert an adapter at the connection point between the electronic case and the antenna. The system is isolated and the antenna can be moved by tilting or rotating it, if the latter method is activated it means that the fault has occurred in the electronic case. If the antenna is stopped, rotate the entire laboratory to the appropriate angle for the antenna operation. Repairing the fault may take a long time and may take two tours.
Wandering moth - doctors wanted to get a clean and sterile culture of this insect to reduce the national population infected with it.
An experiment to test the motor fitness of the astronauts under conditions of weightlessness. The astronauts must insert an instrument box into a series of 3 mm diameter holes in the appropriate order. The experiment was conducted before launch, during the flight and after landing.
A moving belt for medical experiments developed especially for Skylab 4.

At the end of the first 56 days, a discussion will be held every week whether to extend the flight for another week. The decision is based on the medical condition of the astronauts.

First week, from November 11 to 22
November 16 - launch day. Eight hours later the spacecraft connected with the space laboratory. This launch date is a delayed date. Twice the launch of the spacecraft was delayed due to malfunctions. Skylab 4 was supposed to launch on November 10. On October 20, the first malfunction happened, while the launcher was being fueled. The domes of the two fuel tanks collapsed by several centimeters, while the fuel was being dried to prevent overpressurization. Attempts to renovate the domes under helium pressure have been largely successful. To increase flight safety, the tanks were replaced with new ones.
On November 6, thin cracks were discovered around the 8 stabilization fins of the launcher. The cracks were at the two lower attachment points of each stabilizer fin. Their length was 2.5 cm each. The cracks were probably caused when the launcher tanks were full and significantly increased the load on the fins, and due to the influence of the salt-saturated air they wore out. It should have been taken into account that the launcher was exposed to the weather for a longer time than necessary, therefore the launch was delayed because it had to be used as a rescue vehicle for the Skylab 3 pilots in an emergency. An order was given to postpone the launch until November 15, and by then to replace the stabilization fins. As the pace of work progressed slowly, the launch was delayed another day. Further tests revealed cracks in the connector between the first stage of the launcher and the second stage. It took 24 hours to fix the problem. The risk of this malfunction damaging the launch itself is small. Replacing parts in this part of the launcher would have caused another delay of the flight, a delay that would have increased the risk of finding the space lab in dire straits. The docking was supposed to take place 7 and a half hours after launch. Due to difficulties in attaching the two bodies, they connected only on the fourth attempt half an hour late.
November 17 - After the connection, William Fogg felt ill. He was nauseous and had to take medication. Only after he recovered, a short time later, the three astronauts entered the laboratory and began to operate its systems. As a precaution, they were instructed to report any malfunction. Fogg's bad feeling became known by chance. A conversation between him and Carr about this was recorded during the Israel Broadcasting. Carr informed the control center about this and that Fogg himself had not reported his health. Because of this he was reprimanded by the control center.
November 18 - The astronauts activated the laboratory's cameras and transferred equipment to it.
November 19 - Continue the transfer of the equipment and its arrangement. The astronauts checked the medical equipment, performed some medical experiments and practiced firefighting. Preparations began for the first space tour on November 22. Today, for the first time, the astronauts slept well. The engineers expressed concern for the fate of the flight due to the ongoing leaks since August from the laboratory's cooling system. The cooling system is important for equipment and food. There was concern that if the leak continued the flight would have to be cut short.
November 20 - After working hard for five and a half hours, William Fogg managed to repair the cooling system. The astronauts tested and practiced weightlessness in preparation for their extended stay in space.
November 21 - The astronauts continued to train themselves in weightless conditions. Fogg and Gibson made preparations for their off-road activity the next day.
November 22 - There was concern that the extravehicular activity would be postponed due to malfunctions in the space suit underwear. The underwear is the suit's cooling system. The clothes were found wet and rotten from being used by the Skylab 3 pilots. Fogg and Gibson disinfected the clothes and hung them to dry. And it is true that the clothes were ready for the planned departure and the final approval for the operation arrived. Fogg and Gibson put film in the telescope cameras, installed a cosmic ray detector and repaired the broken antenna. Repairing the antenna is done quite a bit by acrobatic exercises. Gibson anchored himself to a portable footrest and leveled himself towards Fogg, so that the latter was raised as a lever and could very easily carry out the repairs. After working for three hours, the antenna reached 75% of its tuning capacity.
Second week, from November 23 to 29
November 23 - The repair of the fault was completed at 01:34 (Israel time). In total, the astronauts were outside the laboratory for 6 hours and 34 minutes. There were thoughts of finishing the repair later, on another space tour, but Fogg and Gibson were able to accomplish their task on this tour. On their return to the laboratory, the astronauts engaged in routine activities such as cleaning the laboratory. Fogg took three photographs of Comet Kohotek to calculate its exact orbit. Later one of the three gyroscopes that stabilize the lab and are on the telescope overheated and stopped working. Because of this, the situation of the laboratory has changed, necessitating the cancellation of several experiments, such as the photographing of Comet Kohotek by the telescope the next day.
November 24 - The astronauts were busy organizing and arranging the laboratory for their extended stay in space. Also today, three photographs of Kohotek were taken following the photographs from the previous day. The photo was taken from the laboratory. The engineers began working on an emergency plan in case another gyroscope went out of order. They announced that the laboratory can continue its journey around the Earth even with two gyroscopes without any danger to its pilot.
November 25 - The spacecraft's engine was activated for 88 seconds and moved the laboratory to an orbit suitable for terrestrial observations. The team made final preparations for ongoing national and astronomical scientific activity. Gibson measured the comet's glow using a new instrument and searched for the reasons for the formation of the universe.
November 26 – photographing Comet Kohotek. Geological photographs - prospecting for minerals in the USA that were planned for today have been postponed due to bad weather. Heavy clouds covered the country. Instead they engaged in observations towards the sun.
November 27 - photographing the comet Kohotek, searching for minerals in the USA, observations towards the sun and biological experiments. A missile containing barium is launched from Alaska towards the magnetosphere. When the rocket reached the required height, the barium was sprayed. The astronauts photographed the barium during its dispersion in the Earth's magnetic field from the North Pole to the South Pole. The goal was to learn more about the magnetism that sustains life on Earth.
November 28 - Jayla Carr made two photographs of arid areas in Africa for five hours to find water sources. William Fogg continued at the same time to photograph the barium dispersion, the goal this time is to study how cosmic radiation affects the barium dispersion. The continuation of the terrestrial experiments and the photographing of the comet were postponed due to malfunctions. These experiments require complicated maneuvers to change the position of the laboratory. The navigation engines for some reason consumed 6 times more fuel than needed for maneuvers. The engineers of the space laboratory hoped to overcome the problem within a few days. Until then, the astronauts continued observations towards the sun and medical experiments.
The source of the malfunction is the malfunction of the gyroscope on November 23. Two navigation engines were used to stabilize the laboratory, but their actions canceled each other out. Their fuel consumption the previous day was 3 times greater than needed and today it increased 6 times again. To the surprise of the engineers, it turned out that the electricity production of the solar racks exceeded expectations.
November 29 - Engineers and technicians inspected the laboratory from the ground and it became clear that the malfunction that occurred on the 28th was not as serious as they thought. The high fuel consumption was fundamentally more a result of coincidence than the fault itself. The team can continue with its plan as planned, although in all the terrestrial observations and of Comet Kohotek they will be more careful when performing maneuvers. On this day the USA, Mexico, Guatemala and the Comet were photographed.

Third week, from November 30 to December 6
November 30 - Photographs were taken from South America to the Southeast of the USA without changing the state of the laboratory. Later, a series of photographs was taken from North America to Brazil and the necessary maneuvers were carried out. Observations were made towards the Earth and observations of Comet Kohotek.
December 1 - Four hours after the spacecraft was maneuvered to take the photographs the previous day, vibrations were felt in the Apollo spacecraft. Nationwide footage has been shot from the Rockies in Colorado to Sao Paulo Brazil. The observations are agricultural, meteorological and more. This time a solution was found for the high use of fuel. Medical experiments and observations towards the sun and comet Kohotek.
December 2 - A new navigation method for the spacecraft was tested. From the east coast of the USA - the Goddard Space Center, a laser beam was broadcast that the astronauts were able to distinguish with the naked eye. Observations towards the sun and medical experiments were conducted. Photography of the western USA, Mexico and five countries in South America.
December 3 - In the national observations conducted today, the laboratory once again consumed a larger amount of fuel than needed for maneuvers. The engineers and scientists announced that if the high fuel consumption continues it will be necessary to curtail some of the national experiments. On the other hand, Kohotek observations will not hurt her. These experiments are a higher priority than the terrestrial observations. The waiver of terrestrial observations is in favor of the comet.
The option before the scientists was to give up 50 terrestrial observations. The laboratory has a stock of 12 tons of fuel, of which 2.3 tons must be kept for emergencies. Today's fuel consumption was over half a ton, 3 times what was needed, and in contrast, the fuel consumption the day before was less.
December 4 - A new maneuvering method for national observations was developed, although the need to reduce their scope was still in effect. As part of the observations towards the Earth, three surveys of global energy sources were conducted.
December 5 - the fuel consumption was apparently finally resolved. In order to reduce fuel consumption, the orbit of the laboratory was lowered and it is true that during the observations towards Earth the fuel consumption was lower than in previous observations.
December 6 – Observations towards Kohotek.
Fourth week, from December 7 to 13
December 7 - Observations were made towards Kohotek. In order to make ultraviolet observations of the comet, several maneuvers were conducted. Observations made in the Caribbean revealed a current of cold water in addition to the warm Gulf Stream. This discovery is of great significance to meteorologists because it probably affects the weather. This discovery is of additional importance to the theory of energy exchange between the Pacific Ocean and the atmosphere. At the request of the meteorologists the Caribbean islands were photographed once more.
December 8 - Gyroscopes made headlines again. One of them began to cause concern, although his chances of getting out of action were small. In the event that he remains silent, the astronauts must return to Israel within two weeks. Views towards Kohotek. The astronauts said that they noticed the long and shiny tail. Carr reported that the comet had a double tail. They noticed the comet when it was 181 million km from Earth. As for the Earth itself, Thailand, Java and Australia were photographed.
December 9 – The laboratory orbit was raised to make observations at Kohotek. After that the track was lowered and further observations were made in Thailand, Java and Australia. Observations towards the Sun were made for an hour and a half, after which the telescopes were re-aligned to photograph Kohoutek on February 14. The reference point of the telescopes was the planet Mercury.
December 10 - The observations towards the Earth were interrupted due to a mistake by one of the astronauts. He did not attach their filters to the six cameras aimed at the Earth and the lenses were exposed to light. There was concern that the film had spoiled so the astronauts were asked to take these photographs once more on another occasion. After they finished their earthly observations, their day of rest began.
December 11 - rest day. The astronauts' doctor said that at the end of the first month of their stay in space their condition is good.
December 13 - technological experiments, astronomical observations and scientific experiments were conducted. The observations towards the sun lasted seven hours. Observations were then made towards Kohotek. The astronauts reported that the comet became brighter as it approached the Sun.
On this day, the US Air Force was about to launch a Minuteman land-based missile. The missile had to pass through the upper atmosphere at an altitude of 250 km. The astronauts must photograph it with an ultraviolet camera. The purpose of the photographs is to discover new details about the ionosphere while it is disturbed by the passage of the missile. Technical reasons led to the postponement of the launch and the cancellation of the experiment. A launch of this kind is within the framework of weapon tests that were done on a regular basis.
A camera identical to this camera was in the possession of the Apollo 16 pilots. Photographing the Earth with this camera showed that the equator is surrounded by a magnetic field above the upper atmosphere with two bands of oxygen atoms. Today, more photographs were taken of these strips to measure their width and to learn what it is about the dynamics of the atmosphere in the region where the sun's energy directly affects the earth and the weather.
Three star systems hundreds of millions of light years away from Earth were photographed with the same camera. The purpose of the photographs is to discover hydrogen floating between these huge clusters of stars. A nebula that was a bright star until it exploded 900 years ago was also photographed with this camera. Ultraviolet radiation was captured in the photographs and they hoped to learn what it is about the nebula's composition.
December 13 - Observations were made towards Kohotek. Today they saw him for the first time with the naked eye.
Thursday week, from December 14 to 20
December 14 - The astronauts received permission from their doctors to stay in the laboratory for 85 days according to the proposal made on the eve of the flight. They filmed Kohotek at three different times. Terrestrial photographs of Borneo and Australia and observations towards the sun.
December 15th - Kohotek was photographed at three different times. Observations towards the sun and a photograph of Paraguay. To perform astronomical observations, the laboratory performed several maneuvers. One of the two remaining gyroscopes was malfunctioning. Because of this, several laboratory maneuvers essential to the filming of Kohotek were eliminated. The flight speed was slowed down and stabilization systems developed in recent weeks were put into use. According to observations made the day before, it turned out that the comet's tail is over 60 million km long.
December 16 - the malfunction in the gyroscope worsened and the laboratory's engineers began work to find a solution to the malfunction. There was no danger to the astronauts' lives. Observations were made towards Kohotek.
December 17 - rest day. No problems arose with the gyroscopes.
December 18 - Observations were made towards Kohotek, towards the Sun and towards the Earth - Europe. Today they got up two hours early to make more earthly observations. Today they were looking for energy sources. The cameras were focused on hot areas in the western US and Mexico. They broadcast congratulations to the pilots of Soyuz 13 which was launched today.
The medical tests showed that in the first month of their stay in space they lost weight and grew 2, 3, cm. The doctors said that the astronauts will return to their natural height after returning to Israel. The doctors believed that the temporary increase in their height was probably caused by the movement of fluids in their bodies. Without the effect of gravity, the discs in the spine absorb more water, expand and the muscles work against gravity, again not compressing the discs as they do on Earth. It was the increase in height that caused a decrease in the circumference of the chest and abdomen.
December 19 - began a thorough study of Kohotek for three weeks. The intensive research has now begun since this is the time when the comet approached its short distance from the Sun, passing behind it and returning as it moved away from it.
December 20 - Observations towards the Sun and towards Kohotek. Kohotek observations were made with the help of the telescopes and the ultraviolet camera. Astronomical observations were also made towards the Earth. The astronauts photographed the galaxy where the sun is located and measured the temperature of the stars relative to the sun.
Friday week, from December 21 to 27
December 21 - medical experiments were done and observations were made towards Kohotek. The comet was examined with telescopes and the ultraviolet camera. Experiments were conducted in a manually powered space suit. The astronauts reported that there were no problems with the gyroscopes.
December 22 - for five and a half hours, medical experiments were carried out. In these experiments, Fogg tested his adaptation to zero acceleration. Observations were made towards Kohotek.
December 23 - Observations were made towards Kohotek. Gibson announced that the length of the comet's tail is twice as long as it was seen a few days ago.
December 24 - Observations were made towards Kohotek and blood tests of the astronauts.
December 25 - The astronauts celebrated Christmas in a special television broadcast that was broadcast all over the planet. Greetings were broadcast to them from the control center and back from them. Each astronaut broadcast his own greeting. A surprise awaited the astronauts when the control center informed them that a "fir tree" made of paper and gifts had been placed in the Apollo spacecraft and that they must find them according to appropriate instructions.
Later, Fogg and Carr left the lab to photograph the comet and make minor repairs. Departure was 93 minutes late due to a computer malfunction. The computer should have sided the laboratory by 20 degrees and in fact the sided was 40 degrees. After the repair, the astronauts left the laboratory. Gibson oversaw the course of the activity. Fogg and Carr took 50 photographs of the comet as it moved from place to place on the wall of the laboratory. This walking was done with the help of special legs attached to the laboratory. They were unable to see the comet with the naked eye due to its close proximity to the sun, but they hoped it was caught on camera. Astronomers wanted to know what the common metallic elements are in a comet and based on that to determine if possible the origin of the solar system. Determining the explosiveness of the elements was done by filtering the light in the cameras. Fogg and Carr said that the length of the tail is 25 million km. The comet was photographed with three special cameras. Two of them were the ultraviolet camera and an X-ray camera. Gibson photographed the comet at the same time from inside the laboratory. Other tasks were photographing the sun, changing films in the cameras and performing minor repairs, such as a filter, on one of the cameras.
December 26 - After working for seven hours (at 2:53 am Israel time) Fogg and Carr returned to the laboratory. It later turned out that Kohotek's photographs were excellent. After the astronauts woke up, they gave a report on the Kohotek photographs to the astronomers and began a rest day.
December 27 - With the end of the day of rest, preparations began for the photographing of the comet on December 28. On this day the comet is at its smallest distance from the sun. The comet passed over the hidden side. Today, solar observations were made towards the sun that lasted seven hours.
Seventh week, from December 28 to January 4
December 28 - Observations were made towards Kohotek and preparations were made for another exit from the laboratory to photograph Kohotek. At the end of the day, a conversation was held between the astronauts and the comet discoverer Lobos Kuhotek. The comet was discovered in early 1973.
December 29 - Carr and Gibson left the laboratory and photographed the comet for four hours. Today the comet came out of the hidden side of the sun. Carr and Gibson reported that they saw the comet with the naked eye. Its colors are orange and yellow as the color of the flame. The eyes of the astronauts were dazzled by its great brightness. Arcs came out of the comet towards the sun and it was possible to see the emission of material from them and the clouds originating from the tail of the comet. The astronauts also reported the emission of particles from the sun. Fogg photographed the comet from inside the laboratory.
December 30 - Observations were made towards Kohotek and other experiments were done. The astronauts reported that as it moves away from the sun, more colors are revealed in it. They complained about being over-tasked, but the scientists said the astronauts were eager to do too many scientific experiments.
December 31 - Observations were made towards Kohotek.
On January 1974, 150, the astronauts reported that the comet's tail was getting more prominent and its colors could be seen - fiery orange and yellow stripes. The length of the tail may be 30 million km, but due to the angle of view from Earth, its length may not exceed XNUMX million km. The comet's head looks brighter and smaller today than at the beginning of its appearance and its color is yellowish white. Geological and agricultural observations were made from Chile to the Middle East.
January 2 - a day of rest and a small number of observations towards the sun and Kohotek. A press conference was then held. Fogg said that he has to work like a machine, which will probably affect his family life. The astronauts said that what they lack is wine for Christmas.
January 3 - national observations were conducted. Agricultural observations were conducted in coordination with the UN experts in Sudan. The observations included the structure of the soil, agricultural crops and diseases they spread in the vegetation and the distribution of rainfall and minerals. Observations identical to these were also made towards Iran. Today difficulties arose with one of the gyroscopes. The engineers hoped it would last until the end of the flight.
Eighth week, from January 4 to 10
January 4 - National observations were conducted from South-East Sudan to North Iran. Later observations towards the USA, Canada and Mexico. Observations towards the Sun, Kuhotek and medical experiments. Skilab's engineers put an emphasis today on the ongoing review of the gyroscopes.
January 5 - Observations were made towards Kohotek. The astronauts reported that the brightness of the comet was decreasing. Practically he was not and will not be the comet of the twentieth century as they thought.
January 6 - Search for minerals in the USA and Mexico.
January 7th - The astronauts reported that Kohotek could hardly be seen and that it had lost much of its brightness. Astronomers explained this by saying that a sticky substance emitted from the sun reduced the brightness of the comet. Mineral exploration in Mexico, Florida, USA and the North Atlantic Ocean.
January 8 - Observations were made towards Kohotek, the Sun and national observations. The last observations were made towards the Pacific Ocean, the American continent and the north coast of the USA. The astronomers suggested that Comet Kohotek was formed from clumps of material ejected from the Sun.
January 9- A mineral search was conducted from Florida to California. Observations were made from coast to coast and the volcanoes in Guatemala. Later the observation path was changed and it was made from the center of the USA to the North Atlantic Ocean. The influence of weather in the Gulf of Mexico was also studied.
January 10 - a day of rest to issue national observations in the USA and beyond Kohotek.
Ninth week, from January 11 to 17
January 11 - Observations were made towards Japan, a search for minerals in the USA and observations towards the sun. The astronauts were given permission to stay another week in the laboratory.
January 12 - Observations were made towards the Sun and towards Kuhotak. The laboratory engineers stated that if no technical problems and serious malfunctions arise, it will be possible to finish the flight according to the plan of three months of work.
January 13 - Observations were made towards Saudi Arabia, the Gulf and the Gulf Stream and the East Coast of the USA. Other national observations were canceled due to bad weather. Observations were made towards Kohotek, medical and other experiments.
January 16 - this is the third day that the temperature in the laboratory rises. The temperature reached 25 degrees today and may reach 30 degrees. The laboratory warmed up due to its exit from the Earth's shadow and its entry into the unshaded corridor between the Earth and the Sun, so it received more heat. Usually the laboratory is in the shadow of the earth, a situation that prevents it from overheating. Due to the warming, several experiments were canceled and in their place observations were made towards the sun and medical experiments were carried out.
January 17 - The temperature in the laboratory continued to rise as expected. They hoped that by January 18, when the laboratory enters the Earth's shadow, the heat inside it will decrease. Medical experiments were conducted in which the adaptation of the human body to zero acceleration was tested. Gibson made observations towards the sun. Gibson and Carr later used the spacesuit engines to move faster inside the lab.
Tenth week, from January 18 to 24
January 18 - The astronauts received permission to stay in the laboratory for another week. Observations towards the sun and terrestrial observations were made. Later a discussion was held with scientists about other experiments conducted. The astronomers said that water molecules were found in the tail of the comet. This discovery was the best proof of the presence of frozen water, hydrogen, methane, ammonia and CO molecules in comets.
January 21 – problems arose again with the second gyroscope. There was concern that he was out of action, but according to the assessment it would be possible to end the flight as planned by activating an emergency system. Today, new geothermal energy sources are being sought on Earth.
January 22 - The second gyroscope continued to cause problems, although it does not pose a danger to the astronauts' lives and will not cause the flight to be shortened because there is enough fuel in the laboratory. In any case, preparations began for the return of the astronauts on January 27. In case of emergency, some of the experiments planned for today and some for the next day are cancelled.
January 24 - The gyroscope was getting weaker, but it still did not endanger the lives of the astronauts. The engineers announced that even if the gyroscope stops working, the flight will not be shortened. At most experiments will be canceled. Terrestrial and astronomical observations of the sun were conducted today. Carr experimented with a powered space suit.
Eleventh week, from January 25 to 31
January 26 - Observations were made towards the USA and Mexico and a Minuteman missile launched from the USA into the Pacific Ocean was photographed.
January 27 - Search for geothermal energy sources in the western US, search for water sources in Algiers and Mali and search for minerals in Brazil. Views towards the sun and towards Kohotek.
January 28 - second and last attempt to search for geothermal energy sources in the western US.
January 29 - Terrestrial and solar observations were made and a mysterious red spot in space was photographed.
January 31 - A final press conference was held from space, Carr said that all three are feeling great.
Week twelfth, from the 7st to the XNUMXth of February
February 1 - preparations for the last tour outside the laboratory on February 3 and final national observations. Today they photographed the USA and Latin America.
February 3 - Carr and Gibson went on a final tour outside the lab for a period of four and a half hours, but the work was extended by an hour. During their work, they returned photographic films from the laboratory's cameras, returned results of experiments from devices attached to the outer wall of the laboratory and samples of solar dust.
February 5-4- Preparations for the return to Israel.
February 6 - The astronauts completed the last attempts and transferred the equipment and the photographic films to the Apollo spacecraft. It was decided to leave equipment including food and air tanks in the laboratory for any other team that will visit the laboratory. It was reported that the lifespan of a laboratory is between 5 and 8 years.
February 7 - The astronauts completed the transfer of all equipment to the Apollo spacecraft. In total, a load of 1 ton including 280,000 photographs was transferred to the spaceship. Various samples were left in the laboratory and outside. There were plans to collect these samples after the joint space flight between the Apollo spacecraft and a Russian Soyuz spacecraft, but it was decided to postpone this to a later date to further expose them to space conditions and solar radiation.
February 8 – landing day
The astronauts got up earlier than usual today to complete the final arrangements. Disconnecting systems, locking the doors of the laboratory cells, lowering the pressure and more. After completing all the necessary tasks, they entered the spaceship and disconnected themselves from the laboratory. A small problem arose - a leak from one of the navigation engines, but the astronauts overcame it. They performed a test flight around the laboratory and after a few hours landed. The landing was 280 km southwest of San Diego in California. The spacecraft was picked up by the aircraft carrier New Orleans.
In the last 15 minutes of the flight, it became clear that the navigation engines were not directing the spacecraft to the correct course. The spacecraft would not have entered the atmosphere at the right angle. The heat shield is unable at this angle to protect the spaceship from the heat of friction and it would have burned up. The astronauts did not lose their temper and started the navigation engines manually. A delay of a few seconds in activation would have caused disaster. The source of the malfunction may have been due to a faulty instruction from Houston or the astronauts fed the computer with erroneous data before entering the atmosphere.
Even before the landing, the doctors reported that the medical condition of the astronauts is so good that it can be assumed that the person is able to live and work in the conditions of space for a year or more, the period of time needed to fly to Mars.
It turned out that in the first days of the flight, some problems arose that raised concerns among the space doctors. The astronauts slept more than the first crews that manned the lab. They complained about the workload and had a difficult exchange with the control center. Due to lack of sufficient attention they made some mistakes like in the matter of the camera. They lost some of their self-confidence and it was reflected in not reporting Fogg's weakness. A short time later they took a break from work to make arrangements that took longer than planned and showed little enthusiasm or a complete unwillingness to carry out instructions, but luckily for everyone their relationship with the control center was improving day by day.

The health status of the astronauts after landing
From the first tests after the landing, it became clear that the health of the astronauts is much better than that of their colleagues on the previous flights. They did not suffer from muscle fatigue like their predecessors. Carr put on some weight, and in less than two days they were back to their natural height. The astronauts attributed their good health to a daily regimen of exercise they did every day. The only surprise was in the circulation. The loss of blood cells and plasma was lower than in their predecessors. Immediately after landing, the astronauts entered a semi-medical quarantine. Their contact was limited to their wives and a few NASA officials. The quarantine is to prevent the astronauts from contracting diseases that could sabotage the medical tests and results of the flight. For 21 days they had to eat the food they used on the flight.
Summary of findings
1. Medicine - the immediate effect of space conditions began upon entry into Earth's orbit and included a special increase in vestibular sensitivity, a different than normal movement of body fluids during rest. The increased sensitivity of the inner ear caused dizziness with every movement of the head, in each of the astronauts to a different degree. This sensitivity was not pleasant and reduced the ability to concentrate. The high immunity against weakness, in movement under normal conditions seems to be extremely sensitive to vestibular stimuli in zero gravity conditions and vice versa.
The movement of body fluids includes two operations. Immediate movement of the blood stream towards the upper part of the body and 24 hours later a slower movement of tissue fluids to the head and upper parts of the body. The veins in the neck and forehead are especially swollen and the flesh in the face is somewhat swollen, especially around the eyes and compares to the astronauts a typical oriental appearance. With the weightlessness "taking over", the spine tends to straighten. This phenomenon is more pronounced when the body is at rest.
Among the short-term effects, the fluid flow is the longest and causes heaviness in the head and intermittent accumulation of blood in the inner ear until the 12th week before the flight. The long-term effects are gradual and affect several functions of the body: the explosiveness of body fluids. The mineral balance processes in the body, the cardiovascular system and the skeletal and muscular system.
Prolonged exposure of the body to weightlessness reduces the mechanical transmissibility of body fluids. Because astronauts stand upright, the circulation must withstand a higher pressure to return blood to the heart from the lower part of the body. Arterial blood pressure helps but is not enough due to loss of pressure in the capillary network. The body has developed a capacity for excessive flexibility of the muscles in the lower part of the body around the arteries which helps the blood on its way back. The elasticity of the blood vessels is normal and prevents the flow of fluids in the legs. This mechanism continues to operate in weightlessness and in case there is no normal hydrostatic pressure g1 it is responsible for the continued flow of the liquids. In summary, this manifests itself in an excess of fluids and a loss of fluid volume, some of which are caused by the blood and cause a higher than normal concentration of red cells in the remaining blood volume. This reduces the production of red blood cells until they are needed again. The demand did not arise for nine weeks. Only in the last flight did the production of these spheres change each time.
The long-term effects on the cardiovascular system include intolerance of real or artificial g1 conditions, impatience with work, reduction in cardiac activity, reduction of blood volume and anemia after the flight. Musculoskeletal system suffered from the reduction of muscles, loss of minerals and a gradual change in the state of rest. A body at rest gradually changes from a state of initial uprightness to a normal state of forward bending.
2. Food - the food was satisfying. The strict supervision of the diet fails because it causes loss of appetite on long flights. The failure lies in the inability of the supervision to properly regulate the types of food and the amounts eaten. The metabolic demands of the astronauts were below correct and they ate more food than allowed according to the diet.
3. Personal hygiene - personal hygiene was often ridiculous and was a change in the daily routine even on the slowest day. Urination was necessary and bowel movements were considered a waste of time and overall did not cause any problems. Shaving took a lot of time and for some reason the razors were good for single use. Every day after the gymnastics exercises, they washed themselves with water and a towel and once a week they showered.
4. First aid - throughout the flight they were not hurt or seriously injured. The only problems were minor skin scratches, infections and eye irritations. Minor cuts healed quickly. At the beginning of the flight, dryness was detected in the skin and the moist skin of the nose and it disappeared within a week.
Cleanliness - Garbage collection has always been difficult. For the most part it comes from food containers, dirty clothes, towels, papers and small amounts of metal utensils. Particles also accumulated on the pumps of the fans. These were quickly removed with a vacuum cleaner. This cleaning was not problematic and odors were eliminated by charcoal boxes.
The working day - the rest periods were hardly met at the beginning of the flight and the astronauts were always tired. This situation was due to the workload. In the first days, when they were already accustomed to the new environment, the workload came due to the accumulation of work that resulted from postponements due to the malfunctioning of various systems. The astronauts had to cancel their first rest day, the fourth day into the flight. The cancellation of the rest day was done quite a bit out of a desire to do the first off-train activity.
At the end of the second week, the work and rest cycles were reasonable and stable. They devoted an hour and a half every day to training on gymnastic springs, gymnastic tape (tape folded on a reel) and the treadmill. The many exercises performed by the astronauts manifested themselves in a quick adaptation to the conditions of the country after landing, although it did not prevent a reduction in the circumference of the thighs and calf meat. Thanks to the treadmill, the drop was 50% of that of the previous teams. It should be noted that during a full meal or a lot of exercise, there is a temporary reduction in the symptoms of congestion in the head. The absence of a meal caused negative side effects, fatigue and quickly developed flu symptoms.
The astronauts quickly got used to the weightlessness. Initially, they had difficulties in adapting to the working day, planning and managing working hours. For some reason one of the astronauts got tired quickly. It seems that the reason for this was an underestimation of the metabolic demands.
The astronauts were highly motivated throughout the entire flight. There were also psychological phenomena and intense emotions that resulted from disappointment due to equipment not functioning properly, work stress, incomprehensible instructions, poor vaccination and staff errors. The astronauts were not required to restrict their personal habits. What upset the astronauts during the flight was the great freedom in which their conversations with the control center and various recordings of the conversations could be listened to. This had a moderating effect on their expression. One of them even developed a tendency to use everyday expressions or to remain silent.
Rest, recreation and amusement were of great importance as the flight continued. Based on the ideas of the space laboratory's planners and its staff, a 52 kg case was placed in it containing game films, music films chosen by each astronaut personally, various games and a small library chosen on a personal basis. The astronauts watched the movies every day while doing exercises on the ergometer. Each of them managed to read four books in the three months of work. The most enjoyable pastime was watching space from the laboratory windows.

Difficulties in keeping the schedule
The astronauts got up every day at 11 am (Israel time) and went to bed 16 hours later. On average, each astronaut has an internal clock that allows him to stay on schedule. For some reason, the astronauts were not able to subconsciously get used to the Greenwich Clock and could not trust the sense of time and anticipate actions in advance.

Another problem that arose at the beginning is the great difference between the planned tasks and their complex combination with the daily schedule. The astronauts concentrated on completing the tasks perfectly and already at the beginning of the flight they learned how to regulate time and activity.

The habituation of the body and reference control in zero gravity were learned simply and quickly. The only thing that happened after the first few days was the gradual increase in the ability to move between the work areas while creating a three-dimensional reference that would end on the right side in order to reach the goal. What was required were adequate handles and footrests.

The astronauts were aware that a crew member could suddenly levitate in the cabin and remain helpless in the laboratory space, as it happened a shoe could be easily released and slowly moved forward, the levitation into the laboratory was less than a minute.

Concepts of "up" and "down" in space conditions

The astronauts preferred to work standing because leaning tired them. To do work they preferred to stand on high boxes. The vertical orientation of each workspace was defined by the normal posture of an astronaut in some work he was performing. The control panels and adjacent work surfaces can look relatively crooked without it interfering with working on them later. while moving from one work surface to another. The orientation changes immediately. At times the astronauts hovered in the laboratory with accidental attributions. It happened that one of them did not have a good orientation and the whole laboratory looked strange to him. This strange phenomenon occurred throughout the flight.

routine at work
The work in the laboratory was divided into several groups: spacecraft control systems, household management, unplanned work and repairs, spacecraft activity, experimental operations, unexpected experiments and coordinated work with the ground. Carr is responsible for the control room, Gibson is responsible for most of the experiments and Carr for the laboratory systems itself.
Laboratory operations were mainly divided into household management work, some unexpected work and repairs. The planned operations included the integrity of the water system, periodic sampling, cleaning, replacement of films in the sound recorders, replacement of fans and filters, taking precautions, emergency tests in case of an alarm and drills in case of fires.
The three astronauts made observations towards the sun every day. Gibson made the complicated observations. The terrestrial observations were made on a cyclical basis by the three astronauts. Some problems arose. In reference control problems, experience was gained after the first failures of this type that occurred in flight. These problems arose during the attempt to maneuver the laboratory with two gyroscopes instead of three and were quickly fixed.
The sub-experiments were divided between the three astronauts equally and included experiments from astrophysics to testing the propulsion units of the space suits. 80% of this equipment did not work properly at the same time or at different times and it took a lot of time to repair them and re-plan the experiments.

Planning the schedule and coordinating with the ground was done on a regular basis and often involved the approval of the flight director. As the flight lasted longer, more experience was gained in the ability to regulate the schedule and experiments. Towards the end of the flight, they came to the conclusion that it would be wiser to give astronauts on extended flights more autonomy.

the laboratory after her departure
Tests conducted by the astronauts before leaving the laboratory showed that it would be possible to reactivate a large part of its systems even after a long time of being turned off. In January 1975, NASA announced that it was considering sending a team of astronauts to the laboratory in five years to install a self-destruct mechanism. This plan did not come to fruition, in the end it was decided to put the laboratory into the atmosphere so that during this transition, it would disintegrate and fall into the Pacific Ocean. Parts of it were found in Australia.

In the next chapter, a summary chapter for the series about Skylab