Knowledge of Astronautics

1. Is it difficult for astronauts to fall asleep in weightlessness?

This is a question worth discussing because there are many reasons that affect sleep. First, it is important to distinguish whether astronauts work in space on one or two shifts. On the ISS and most space shuttles, all astronauts sleep at the same time, and they hang their sleeping bags wherever they like to sleep, such as on the wall, in the corner, on the ceiling, and so on. When astronauts work in shifts, as on some shuttles including the Spacelab, astronauts sleep in a small bunk that is closed off to isolate them from the noise coming from the studio. At first, astronauts have a somewhat uneasy feeling that they are lying in a cramped shoebox, and most have the illusion that their backs are comfortable for 10-15 seconds.

However, when you are going to sleep, you need to get used to the fact that you don't feel your back and sides, and that you are in fact floating in a sleeping bag, just hanging upside down from a rope, so that the feeling of gravity that makes you sleepy is not there, and some astronauts are not quite used to this. Some astronauts are not used to it. They have no sleep and are so nervous that they have to take sleeping pills to fall asleep. Others are able to sleep well even in this particular environment.

It should be added that if you sleep with your head in an unventilated area, the carbon dioxide that you exhale collects near your nose, and when the carbon dioxide in your blood reaches a certain level, an alarm system at the back of your brain warns you, waking you up and making you feel short of breath. At that point, you take a few steps or change places and you can drift off to sleep again.

2. Do astronauts feel anything special when they get dressed in space?

Space suits for astronauts are usually no different from what we wear on Earth, except for special requirements for comfort and safety. For example, the suit must be made of fireproof material. When wearing a space suit in weightlessness, astronauts actually float inside the suit and only feel like they are wearing it when it touches their skin.

3. Is it fun to float in space?

Astronauts agree that floating in space is fun once you've adapted to the microgravity environment. By the way, scientists don't like to refer to microgravity as zero gravity, because unless you're standing right in the center of a spacecraft in free-fall around the Earth, you're inevitably affected by tiny accelerations and tides, and even if they're so small as to be a millionth of the Earth's gravitational pull, you can't think of it as no gravity or zero gravity. This is why we call it weightlessness.

Living in microgravity is interesting and feels different to different people. About 30-40% of first-time astronauts experience "space adaptation syndrome" (a form of motion sickness) in the first two to three days in space, while others do not. Blood flows to the upper body, congesting the sinuses and tongue and affecting one's senses, and within a week or so, the astronaut's body responds by adapting to weightlessness.

In weightlessness, the spine lengthens due to the absence of gravity, making the person taller (1-2 inches taller). In weightlessness, when all the muscles are relaxed, there is a gentle lifting of the thighs upward, the arms are stretched out in front, and the body is slightly arched, as if in water. Since there is no sense of "up" or "down", it is necessary to rely on other markers to determine "up" and "down". When designing the Shuttle's interior, the difference between the ceiling and the floor was considered for orientation.

In microgravity, astronauts often get the wrong impression. When astronauts tell their brain which direction is "up", it immediately assumes it is an illusion. Thus, orientation, transfer or movement in space does not feel the same as on the ground. Walking in space is very easy, and astronauts quickly become accustomed to walking around and anchoring themselves to the station with a fixed foot. Walking in space in a space suit becomes much more difficult due to the large size of the overalls, which are like putting on a balloon, with limited visual and tactile senses.

4. How long can you wear a space suit?

Generally you can wear it for 5-7 hours. Of course, it also depends on the expendable materials in the suit, such as oxygen, electricity, cooling water, etc. The space suit is like a small spaceship. Space suits are literally small spaceships, and working in a space suit is hard work. The wearing time is also related to the wearer's requirements for comfort and abrasion resistance.

5. How do I handle a broken bone or serious illness if I am in space?

Fortunately, the 120 NASA astronauts who have gone to space have never encountered this. In the early days, Apollo 13 astronaut Fred had problems with urinary infections and minor flu problems. The spacecraft always had enough medicine on board to deal with these emergencies. In the event of an accident during orbit around the Earth, astronauts are returned to Earth as quickly as possible, whether on the shuttle or on the ISS. NASA has also developed a large seven-passenger return capsule for the ISS that is designed to be used as a "space ambulance" in special circumstances.

In the event of a fracture, the spacecraft is also equipped to immobilize bones. When humans set off into outer space, such as in the expedition to Mars, the spacecraft will carry medical equipment, one or more astronauts are well trained in medical knowledge, they can rescue and treatment. This is because in such cases a return to Earth in the short term is not possible. When possible, the spacecraft will be equipped with experienced doctors.

6. How many people can the space station accommodate?

The ISS can accommodate up to seven astronauts. The number of astronauts was increased from 3 to 6 at the beginning and to 7 by 2003 (but now, due to problems with resources on board the station, there are only 3 astronauts on board - translator). Of course, it is not possible for all crew to return immediately in an accident. That's why NASA is improving the return capsule so that it can hold more people than the Russian Soyuz spacecraft.

7. How do astronauts on the space station spend their spare time in space?

They each have their own favorites based on their different preferences. During the flight, they can each pick their favorite entertainment. Some can use their laptops to read books or send e-mails to their families, some listen to music or play games, and some just talk to their friends and family on the ground or chat with other coworkers. But the vast majority of astronauts, when they first enter the space station, spend most of their spare time standing by the window, looking out at the universe and watching the Earth disappear from under the station.

8. How are astronauts selected for the ISS? What do you think about that?

Any adult man or woman in good physical condition who meets the basic requirements for astronauts can be selected for astronaut training. To become a mission specialist or astronaut on the International Space Station, the minimum requirement is a bachelor's degree in engineering, natural sciences, or mathematics from at least one nationally recognized institution, with at least three years of relevant work experience in the field; a higher degree would be more appropriate. Space shuttle pilots must have at least 1,000 hours of flight experience in a jet airplane and have better eyesight than experts. Competition is quite fierce, with an average of 4,000 applicants competing for 20 spots every two years. Astronauts are recruited regularly.

9. How do you map space? How do you know which way to go?

Let me be brief, it is not an easy task to fully understand this complex issue as you do need to go to a university for systematic study.

The bottom line is that you need to know that the universe is made up of three spaces, so you should determine your exact position in the system of coordinates formed by these three axes. In astronomy, astronauts map space using azimuth, elevation, declination, distance, and time.

While flying in space, our three coordinates are set as X, Y, and Z. Then all of us have a consistent reference system, the position and orientation of the coordinate system, by which to measure and orient ourselves. Generally this system has the center of the earth as its origin. with the Z-axis up, the X- and Y-axes are in the same plane. Sometimes it is assumed to rotate with the Earth, sometimes it is fixed in space. This "reference system" can also be loaded on your portable computer.

Spaceships (and all large airplanes nowadays) are equipped with a navigation system that knows the motion of flying objects in the vicinity of its three coordinates, and constantly calculates the change of the spacecraft with respect to the reference system. And, of course, by looking at the assigned target, you can predict the direction it's headed. And very quickly, you know what bearing you are in and where you are headed, and can consider adjusting accordingly if you are off the set course.

10. What kind of utensils do astronauts use to eat in space? Are they different?

Ordinary cutlery, like knives, forks and spoons, are used in space, the same as on Earth. Most of the food and drinks that astronauts eat can be put in containers. The difference is that when it comes time to eat these foods, they float out. Some foods, like peas, beans, etc. are prepared with salsa so they stick to the utensils. Foods are served hot, cold or frozen. Drinks are in some squeezable bottles, like sports drink bottles. But there are some things astronauts have a hard time adapting to, and they often complain about not being able to get fresh vegetables and fresh-tasting coffee on long missions.

By the way, on Russia's Mir space station, fresh fruits and vegetables like tomatoes are available once the transporting shuttle arrives. U.S. astronaut Shannon Lucid says they often link up with Russian astronauts. Perhaps in a few years, fresh vegetables will be available on the International Space Station and Mars expeditions. There is no guarantee of fresh-tasting coffee and sodas, but at least one soft drink company has begun to develop a container for use in weightlessness. In addition, in spaceflight astronauts often pick heavily flavored foods due to the transfer of bodily fluids that alter their senses of taste and smell, and in orbit astronauts often pick heavily flavored foods.

11. How long do astronauts stay on the ISS?

Most astronauts stay on the ISS for 90 consecutive days - the average "rotation" time for the current astronaut program. Some come back early for a variety of reasons, and others may stay for a longer period of time, especially if they are to provide the basis for human exploration of Mars, and if they are to fly for long periods of time in order to conduct medical research into the lives and work of astronauts. It is worth noting that the longest stay in space was by a Russian internist, Dr. Valery Polyakov, who set the record in 1994, staying on the space station for 438 days (14 1/2 months), preceded by a flight record of 241 days set in 1988. The longest time an American has lived in space is 188 days, also a world record for a female astronaut, which was set by Dr. Shannon Lucid.

12. Why does Earth have gravity but not in space?

There is gravity in space, but I know that's not what you mean. It can be explained this way: the generation of gravity is related to mass. Mass is affecting space in a very specific way (Einstein would say that mass bends space.) This effect was discovered by Isaac? Newton's discovery of the force we call gravity to transmit it. Based on our observations the doctrine of gravity is correct. If it were not, the Apollo moon landing program would not have been possible. Similarly, the decrease in the gravitational pull of an object is proportional to the square root of the distance between the objects.

On Earth, the force of gravity produced by the mass of an object behaves like a "pressure" on an object in contact with the ground, which we call "weight". When there is no such contact, for example, in Earth orbit, the vehicle is not in direct contact with the Earth, and there is no gravity. But the spacecraft still has mass, which creates its own gravity field (of course, for the smaller space shuttles there is no gravity).

That means that all stars in space with significant centers of mass, like the Sun, the Earth, and other planets, have gravity. Newton also discovered that objects in a vacuum can never stop moving in a straight line without the effect of acceleration. However, an object, such as a space station, cannot be considered to be in a state of "weightlessness" when it is pulled by the Earth so that it orbits the Earth; thus, the "weightlessness" of the orbiting space station is not the absence of gravity, but the effect of gravity on it. In this way, the "weightlessness" of a space station in orbit is not the absence of gravity, but the disappearance of gravity's effect on it. Once there is resistance, atmospheric drag, engine power, centrifugal acceleration from rotation, etc., weightlessness is gone.

13. What does it feel like when the space shuttle launches?

On the launch pad, because of the orientation and position of the cockpit, the astronauts are on their backs with their feet up (the space doctors dictate the amount of time they are in this position before launch). After the hatch has been closed and all final checks have been completed, the astronauts mentally anticipate the launch, recalling in their minds once again the operating procedures they have been trained in over the past few years. For example, are all the cabinets above them locked? What are the cue cards in front of you reminding you of what to do in an emergency? The final countdown reaches six seconds and the three liquid rocket boosters ignite. You can clearly feel the shuttle rocking back and forth 5 feet when the orbiter strongly swings and vibrates up. But the astronauts can't hear the thunderous roar from any of the engines.

Then the count goes to zero and the command comes over the helmet-mounted wireless device, "Ignition, liftoff." The two solid-fuel rocket boosters ignite and the shuttle begins to rush off into space. At this point you don't feel a very noticeable acceleration, much the same as when an airplane takes off. The fuel in the rocket boosters is not burning evenly, and the propulsion process is very bumpy. The whole cockpit is like a car going over cobblestones at maximum speed.

Once the thrusters are lit, they don't stop until the fuel burns out. Two minutes after takeoff, the shuttle's emptied containers begin to fall off, the noise is gone, and each astronaut's discomfort is greatly diminished. The fuel in the engines of the three liquid thrusters continued to burn and hum, and when the fuel burned out, the shuttle became lighter and continued to maintain its acceleration. (Because, according to Newtonian doctrine, acceleration equals mass squared.)

At 7.5 minutes into liftoff, 90% of the fuel in the huge container on the outside has been burned off, and the Shuttle, which weighed 2,000 tons at takeoff, now weighs less than 200 tons, and the pressure is already 3g's - three times the Earth's gravity. The engines decelerate to 3g's. At this acceleration, the astronauts in their heavy spacesuits, whose breathing becomes very difficult, subconsciously breathe and puff out their chests.

Finally, the main engines shut down. Within seconds, the engine propulsion drops to zero. The astronaut will suddenly feel the pressure in his chest disappear and a sense of weightlessness, at which point the astronaut is already in space.

14. Why do we need a space station? What purpose does it serve?

There are many reasons why our country proposes to build a permanent platform in Earth's orbit, and we can benefit greatly through international cooperation with other countries.

The space station offers a whole new way of improving human life. Everyone should know by now that in Earth orbit, space offers many very useful environments that cannot be found on Earth, such as weightlessness, high vacuum, high temperatures, extreme cold, extreme heat, unfiltered sunlight and the ability to see the full extent of the Earth and its environment, as well as the ability to view the universe with astronomical telescopes unobstructed by an atmosphere full of air, clouds and pollutants.

These special environments allow for major scientific and technological innovations in the scientific study of people, animals, plants, and so on, to be carried out there. They also bring new medical breakthroughs, technological advances, new industrial products, new medicines, and many other new opportunities and challenges that will help our country stay ahead of the curve. And, of course, they give our economy, industry, trade and business a competitive edge, and create new jobs, knowledge and wealth.

Because the space station can stay in space for a very long time, it allows us to utilize so many of the resources of space for a long time, whereas the space shuttle can only stay in space for up to 14 days. The space station can also provide more power, more area, more tools and other equipment, and is almost like a large research base, product development center and technology demonstration center on the ground. During long-duration flights, the station could also become a launching pad, a springboard and a launching platform moving at 23,000 feet per second for better human exploration of outer space.

15 What are the physical requirements to become an astronaut?

There are no special requirements other than good health. Both men and women can apply to be candidates for astronaut training as long as they meet these requirements and the basic qualifications I gave in question 8.

16. What are the unusual features of a spacesuit?

Space suits are literally small spaceships that are needed to keep astronauts healthy and working continuously while they are outside the capsule. Since there is no air pressure and no oxygen to sustain life in space, humans must have an environment suitable for their survival. Like the air in the shuttle's working capsule, the air in a space suit can be controlled and regulated.

In this way, the primary function of a space suit must be to provide oxygen for breathing, while maintaining a stable air pressure around the body and keeping the blood in the body in a liquid state. In a vacuum or at very low air pressure, the blood in the body boils like hot water on top of a mountain.

The space shuttle is equipped with a space suit that can withstand a pressure of 4.3 pounds per foot, which is only one-third of normal atmospheric pressure (each atmosphere equals 14.7 psi). Because the gas inside the space suit is 100 percent oxygen, unlike our atmosphere here on Earth which contains only 20 percent oxygen, astronauts in space suits breathe more oxygen than those at 10,000 feet above sea level or at sea level who are not wearing a space suit. Before leaving the spacecraft to work in space, astronauts breathe pure oxygen for several hours. This is a necessary procedure to remove nitrogen dissolved in the blood and to prevent the release of gas bubbles when the air pressure drops, a condition often called diving decompression sickness.

On the other hand, if pure oxygen is breathed at normal atmospheric pressure for too long, it becomes a harmful gas. This oxygen and nitrogen evacuation is an excessive, unproductive and tiresome wait for the astronauts, a real nuisance, and we designed the internal air pressure of the space suit to be 8.3 psi, which shortens the time of oxygen and nitrogen evacuation.

The suit must have the ability to protect the astronauts from fatal injuries. In addition to protecting against micrometeoroid impacts, the suit must also protect the astronauts from the temperature limits of space. Without the Earth's atmosphere to filter the sun's radiation, the temperature on the sun-facing side can be as high as 250 degrees, and on the sun-backed side, it's 250 degrees below zero.

The main features of the spacesuit are: in addition to the boots and gloves, which have a multilayered structure, there is a life support system on the back, a display and control module on the chest, and then there is the equipment designed for spacewalkers and for dealing with emergencies, in particular the back-up oxygen supply system. These combine to form an assemblage known as the EMU (Extravehicular Maneuvering Unit), which allows for free transitions between the different subsystems that can be easily and securely connected, either under normal conditions or in emergencies.

There are also a number of special devices: the urine reservoir, which transports urine to the waste disposal system after returning to the shuttle or station; the liquid cooling and ventilation suit, which has a mesh-like elastane made of zippers at the entrance to the front of the suit, and which weighs 6.5 pounds; and the undergarment, which has cooling tubes in which the water is constantly flowing to make the astronauts feel comfortable while wearing it. The reason for installing the cooling tubes is because inside the suit is a pure oxygen layer, which cannot possibly provide as much cold air as it would in ordinary air. Then there are the underwear drinking pouches that hold 21 ounces, the "probe cap" or communications carrier combination unit, the headset and microphone for two-way communication and warning and alarm devices, and the biomedical detection subsystem.

During spacewalks, astronauts strap on a 310-pound Man-Mobile Unit (MMU) on the ground, a single nitrogen-propellant backpack that is secured to a suit-carrying life support system. Using adjustable hand controls for rotation and translation, astronauts can fly accurately into or around spacecraft cargo docking piers, or freely enter payloads or buildings near the shuttle or station, as well as reach many other seemingly out-of-reach external areas. Astronauts wear MMU's, known as "space bikes," and play a large role in launching, servicing, maintaining and retrieving satellites.

17. What materials are space suits made of? How are they made?

Our generic space suits/EMUs have 12 layers of interlayers, each with a specific purpose. Starting with the lining, the innermost 2 layers are a close-fitting undergarment made up of frozen liquid, made of spandex with tubular plastic sewn inside, and the next layer is a nylon-coated ball-bearing layer wrapped in a layer of dacron fabric. The next seven layers are protective layers against heat and small meteorites, made of aluminized Myra and laminated Dacron cotton and linen weave. The outside of these seven layers is a layer of chemicalized fabric.

18. Who was the first American astronaut to go into space twice?

The first American to orbit the Earth twice was Gordon? Cooper Platinum. First flight: May 15-16, 1963, in the Mercury 9 spacecraft, lasting 1 day, 10 hours and 20 minutes. Second flight: June 3-7, 1965 with Pete Conrad in Gemini 5, lasting 1 day, 10 hours and 20 minutes. Conrad in Gemini 5 for 7 days, 10 hours and 2 minutes.

In fact Gus? Gleason was the first American astronaut to rocket into space twice. But on July 21, 1961, his first flight in the "Liberty Bell" was only a suborbital spacecraft that took him along a parabola for 15 minutes at an altitude of 190 kilometers, and five minutes in weightlessness. He then made his second flight, this time into Earth orbit, on March 23, 1965, in the Gemini 3 with John Young. Young to orbit the Earth three times in Gemini 3. Incidentally, this flight brought the first computer into space: it was a small computer that could run 7,000 calculations per second. Gleason used it to calculate changes in the Earth's orbit. From then on, astronauts could actually fly through space instead of just following a fixed orbit around the Earth.

19. Could the Hubble Space Telescope replace the International Space Station?

The Hubble Space Telescope is still a long way from the ISS, firstly because its orbit is inclined at 28.47 degrees (the ISS is 51.6 degrees), and secondly because its average altitude is 590 kilometers.

20. How much does a spacesuit weigh?

The suit weighs almost 280 pounds net (on the ground), including the backpack. Of course, in space it weighs nothing (even if nothing changes).

21. Why do astronauts have to wear such heavy gear?

Once astronauts are in the pressurized living module, they wear what people on the ground wear on warm spring days, usually shorts, short-sleeved shirts, and socks (because their feet need some crash protection and protection from the cold, but they don't walk, so they don't need shoes.) They only need special clothing for launch and return and when they get out of the pneumatic capsule for extra-spacecraft or extra-cabin activities. The launch/landing suits are fireproof and serve to keep the pressure around the body constant if the shuttle's pressurization system goes out of control.

The suits worn by astronauts for extravehicular activities have to provide oxygen and pressure to sustain survival. They have to keep astronauts safe from fast-flying space debris, so their suits have to be pressurized. The suits must keep them warm when they turn their backs to the sun and get cold away from sunlight. The suits provide wireless equipment to communicate with astronauts on the ground, on the space shuttle, and in other extravehicular activities. It provides the light needed for short walks in space and work in the dark, avoids the astronauts' eyes from direct sunlight, facilitates the carrying of tools for work outside, and meets the astronauts' physiological needs for food. The space suit should be guaranteed to be trouble-free for six hours and can be adapted to the requirements of different astronauts. You can think of it as a small spacecraft. On Earth it weighs 280 pounds, but in space it weighs nothing.

22. How long does it take to get into space?

The space shuttle takes about 8.5 minutes from launch, through detaching the external tanks and solid rockets, to reaching Earth's orbit at what is called orbital velocity, so it's going to be spinning around the Earth constantly. (Nasa.com Contributing Editor/Tang Chengge Shen Xianyun)