How much water the human body loses in outer space and how the spacesuit heating system is arranged: about the nuances of the work of astronauts in orbit.
On the night of August 16, cosmonauts Oleg Artemyev and Sergei Prokopyev completed their spacewalk under the program of the Russian segment of the International Space Station (ISS). The duration of work outside the station was 7 hours 46 minutes. The astronauts, in particular, dismantled panels with microorganisms installed in 2017, which were supposed to survive in outer space. Also Prokopiev and Artemiev installed Ikarus scientific equipment for environmental monitoring and launched the Siriussat microsatellites.
Both Russians worked in the new Orlan-MKS spacesuits. These space suits use a new polyurethane inner shell instead of rubber. Also, the suits are equipped with a new automatic thermal control system. The system works like a good climate control in the car, independently adjusting to the temperature of the spacesuit's internal environment and increasing or, conversely, reducing the degree of cooling.
Spacewalk is not only an exciting event, but also difficult and in many ways inconvenient work. Cosmonaut Hero of Russia Alexei Ovchinin told TASS about some details of the typical exit.
Two liters for each exit
Behind the thin walls (no more than 20 mm) of the ISS is the so-called open space - an empty lifeless space, in which a person does not even have time to suffocate without protection, but will die from a pressure drop within a few tens of seconds. It will cool down much later - in space, due to vacuum, there is very weak heat transfer, and any object cools slowly. Astronauts go into space in special suits - spacesuits, consisting of a large number of shells. They create a personal microcosm for a person with acceptable pressure, temperature and air that can be breathed.
As Ovchinin notes, the spacesuit is poorly mobile, and the more excess pressure in it, the tougher it is (the suit inflates in a vacuum like a ball). Therefore, cosmonauts carry out a lot of training before the flight both in the hydro laboratory and on special simulators, and the spacesuit itself must be properly fitted. Astronauts work only with their hands: sleeves and gloves are the most mobile part of the suit. However, this activity is not easy: for example, it takes significant effort to completely clench a fist in a glove stretched from the inside by half the atmosphere.
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It's no secret that all overboard work is done with hands. Squeezing the glove of the spacesuit completely, of course, is possible, another thing is that to perform work outside the station it is not always necessary, it is enough to make smaller movements with your fingers so that your hands, shoulder girdle, fingers do not get tired and so that you can perform all tasks of extravehicular activity (EVA)
- Alexey Ovchinin. cosmonaut, Hero of Russia
According to him, astronauts train their hands with special exercises that develop the shoulder girdle and fingers. Also, the work of astronauts is facilitated by special tools that do not require full compression of gloves to hold them in their hands.
In addition to the strong tension of the hands, the person warms up and sweats a lot inside the spacesuit, despite the operation of the cooling system. Alexey Ovchinin noted that no one counted the loss of energy of cosmonauts for spacewalk in joules or calories, but people get tired during extravehicular activities quite strongly. “A lot of water is excreted from the body during the exit, it is about two liters. After leaving, we just fill exactly the need for water. At the same time, no vitamins and other food additives are used,”Ovchinin said.
Remember to re-hook the safety hook
Cosmonauts work in different places outside the station, sometimes it is necessary to travel a long way from the exit from the Pirs module to the place of work. Along the way, the astronauts moving on their hands cling themselves to the rigid and flexible handrails with a belay, like climbers. There are two safety halyards - 1.5 and 3 meters.
“No one has ever counted how many times an astronaut hooks up a carbine during EVA, because it depends on the tasks. During some exits, astronauts work near the airlock. And there can be work much further, then when moving along the handrails, the astronaut must re-fix two carbines from two halyards. In this case, the handrails on the surfaces of the modules are located unevenly - somewhere more often, somewhere less often. In some places the handrails are far enough away or there are generally soft handrails - there is a slightly different interlocking system,”Ovchinin said. At the same time, he added that there were no cases of separation - when the cosmonaut, "slipping" from the station, was rescued only by the safety halyards - so far there have not been.
During the time of going overboard, the cosmonauts repeatedly find themselves both in the shadow of the Earth and on the sunny side. In the shade, the systems of the spacesuit are turned on for heating - warm water begins to flow through the tubes of a special mesh suit worn by the astronaut inside the spacesuit. On the sunny side, the water system is switched on for cooling. Moreover, it is much easier to overheat in a spacesuit than to freeze - it works like a thermos, and the inner space of the spacesuit quickly heats up from the heat of a working person.
On the sunny side, astronauts also use a special protective visor made of multilayer golden mirror glass. It protects their face and eyes from the sun's rays so well that they can look directly at our star.
Astronauts are related to mountain climbers not only with safety halyards and carbines, but also with low air pressure: during an exit, the spacesuit maintains a pressure more than half the normal atmospheric pressure on Earth - about 0.37–0.42 atmospheres. This is slightly higher than the summit of Mount Everest.
A person, in principle, feels comfortable enough under such pressure, the time spent in a spacesuit is limited by other life support systems. And so, on average, during EVA, an astronaut is in a spacesuit for seven to eight hours
- Alexey Ovchinin. cosmonaut, Hero of Russia
It should be noted that at the top of Everest, people can die not because of low pressure, but because of the insufficient oxygen content in the rarefied air.
The right to respite
Astronauts while working overboard have the right to rest. So, they can ask the Mission Control Center (MCC) to take a break from work at almost any time. In this case, no special commands or stop words are used, the cosmonaut simply informs the MCC that he is tired and needs a break. Also, pauses in work can be organized at the direction of the Earth.
“According to the cyclogram, rest during EVA is not provided, the state of the cosmonauts looks like - during extravehicular activities, the medical support team monitors us, each astronaut wears a medical belt that resets many parameters. If doctors see that the pulse is increasing or blood pressure is increasing, they give the command to stop work,”Ovchinin said. He also said that the Russian cosmonauts do not eat or even drink during the exit, although water tanks are provided.
After leaving, the astronauts are also not given any special time to rest - for the most part, at this moment they are engaged in maintaining the spacesuit. After leaving, the space suit must first of all be dried from sweat, then prepared for the next exit and put into a special room at the station.
Valeria Reshetnikov