Astronautics

Lunar Module of the Mission Apollo 11, in its path to alunizaje (1969)

Astronautics is the theory and practice of navigation beyond the Earth's atmosphere, that is, in outer space, by artificial objects, whether manned or not. It is based on the study of trajectories, navigation, exploration and human survival in outer space. It covers the design and construction of space vehicles and the launchers that will put them into orbit, or take them to other planets, natural satellites, asteroids, comets or other places in the cosmos.

This is a broad and highly complex branch, due to the difficult conditions under which the devices that are designed must function. Various scientific and technological specialties collaborate in astronautics, such as astronomy, mathematics, physics, rocketry, robotics, electronics, computing, bioengineering, medicine or materials science. Astronautics, in combination with astronomy and astrophysics, has originated and promoted new scientific disciplines such as astrodynamics, astrogeophysics or astrochemistry.

History

Robert Goddard with one of his rockets (1926).

The first mention of astronautical flight is recorded in the Greek myth of Icarus, whose father Daedalus fashioned him wings of feathers held together by wax to escape from Crete. Icarus had the temerity to fly in the direction of the Sun, paying with his life for his extreme curiosity, by melting the wax that bound his wings. Cyrano de Bergerac in his Comic Story of a Voyage to the Moon (1650) described for the first time the use of a system composed of gunpowder rockets capable of lifting a ship in the direction of the Moon. Astronautics received a new impulse with Jules Verne's work From the Earth to the Moon (1866) in which the author described, with little scientific rigor, a trip to the Moon using a ballistic system. Verne's work stimulated interest in astronautics and gave rise to the prolific literary genre of science fiction, which has an inexhaustible source of inspiration in astronautical travel.

The satellite Sputnik 1in 1957.

At the end of the XIX century, a number of engineers and scientists in different parts of the world focused their efforts on designing devices propulsive, establishing the theoretical and practical bases of current astronautics. Among them are the Peruvian engineer Pedro Paulet (1874-1945), the Russian scientist Konstantín Tsiolkovski (1857-1935), the American engineer Robert Goddard (1882-1945) and the Romanian physicist Hermann Oberth (1894-1989).

In 1927, the Astronautical Society was founded in the Polish city of Wrocław, which was frequented by Hermann Oberth and Werner von Braun, among others. A significant leap in the development of Astronautics was the manufacture and use for military purposes, by the Nazis, of the V2 rockets, which would be the technological model that the Russians and the Americans would use for their own space devices in the following decade., after World War II. During the 1950s, the United States and the Soviet Union competed to put the first artificial satellite into orbit. On October 4, 1957, the Soviets launched Sputnik 1, a milestone that marks the beginning of practical astronautics. The space race unleashed between the two superpowers advocated other relevant milestones such as the arrival of the human being in space, achieved by the cosmonaut Soviet Yuri Gagarin in 1961, or the arrival of the human being on the Moon, achieved by the American astronauts of the Apollo 11 mission Neil Armstrong and Buzz Aldrin, in 1969.

Timeline

First releases, by country

Country	Date	Hito
Germany	20 June 1944	Cohete V2, making the first suborbital flight of history.
Soviet Union	4 October 1957	Cohete R-7, with the launch of Sputnik 1.
United States	31 January 1958	Cohete Jupiter C, with the launch of Explorer 1.
France	26 November 1965	Cohete Diamant, with the launch of Asterix A1.
Spain	19 July 1969	Cohete INTA-255, on a suborbital flight.
Japan	11 February 1970	Cohete L-4S, with the launch of the Ohsumi.
China	24 April 1970	Long March 1, with the launch of DFH 1.
United Kingdom	28 October 1971	Cohete Black Arrow, with the launch of Prospero X-3.
India	18 July 1980	Cohete SLV, with the launch of Rohini RS-1.
Brazil	02 April 1993	Cohete VS-40, on a suborbital flight.
Ukraine	21 April 1999	Cohete Dnepr-1, with the launch of UoSAT-12.
Argentina	6 June 2007	Cohete Tronador I, on a suborbital demo flight.

Space Vehicle Design

Every design of a space device must take into account the medium in which it moves, be it the atmosphere or the vacuum of outer space; the purpose for which it is designed, be it transport of cargo or human beings, scientific research, communications, military; the propulsion system devised together with the propellants used; and the gravitational forces that govern orbital trajectories.

Classification of Space Vehicles

Regarding the second aspect (utility), spacecraft are usually classified as artificial satellites, when they orbit the Earth based on some specific utility, such as the Russian satellite Sputnik I, the first orbital object placed by man in the space, in spaceships, when they are crewed by at least one person and have their own propellant that allows them to maneuver in space and/or in the atmosphere, such as shuttles, or as were the modules of the North American Apollo program, space probes, when the ships are destined for research in the direction of deep space, whether in demand of the celestial bodies of the Solar System or outside it, such as the probes of the Viking program, from NASA, destined to explore Mars, and the space stations, orbital complexes around the Earth that can house a greater number of occupants and with means of survival that allow them to stay for long periods of time, such as for example the Soviet station Salyut 1.

Manufacturing materials

Thermal shield of the Mars Science Laboratory (2011)

The design must contemplate a structure capable of resisting accelerations, the impact of micrometeorites and the action of solar winds, forces capable of destabilizing any of the ship systems, even causing their partial uselessness or total destruction. This structure is made up of certain materials endowed with properties that allow it to face the rigors of takeoff, navigation and re-entry. Using advanced computer programs, designers usually simulate the conditions and stresses that the materials and elements that will make up the various space devices must withstand.

The materials comply with high standards of resistance to the impact of micrometeorites, with a great capacity to refract heat, capable of withstanding the enormous pressures and vibrations that take-off, acceleration or braking mean, absorbing as much as possible of deadly radiation spatial, but at the same time capable of capturing light energy through its application in solar panels. However, the materials must comply with the limitation imposed by the use of traditional chemical fuels, which require ships with the lowest possible mass: the lower the mass of the ship, the lower the cost of fuel and the greater possibilities of making long trips with return included. (the case of spaceships); the greater the mass, the higher the expenses and the lower the possibilities of doing the above. For example, the sheer mass of NASA's shuttles prevents them from extraorbital flights (eg lunar exploration) since their fuel reserves are limited. Therefore, the ideal is for the materials used to seek maximum resistance, structural solidity and functionality, but with savings as much as possible in mass. The design of the ships that must work in very hostile environments, with extreme conditions of heat, cold or pressure, must have a technology that makes them withstand them. For example, the Soviet space probes named Venera, which explored Venus starting in 1961, included in their design materials capable of withstanding temperatures that melted lead, being able to operate for a few hours on the Venusian surface.

Spaceship Morphology

Spaceships pass through the atmosphere both during launch and re-entry, provided the star in question is endowed with an atmosphere. To achieve this, they have to adopt a favorable shape to the aerodynamics of both events. The stabilizers, control surfaces, heat shields and parachute braking systems are used for orientation in a gaseous medium and to preserve the integrity of the ship at high speeds.

If the ships have to move only in outer space, their shape does not have the obligation to adopt aerodynamic elements, since in the absence of air these elements are useless. To reorient and redirect the devices, reaction control systems, vacuum-optimized rocket motors and gravity assist maneuvers are used, using the stars themselves. Space stations are a good example of the variety of forms in space devices, since they totally dispense with aerodynamic elements, since their function is not to navigate in the atmosphere, but exclusively in space.

On the other hand, the utility assigned to a spacecraft will determine its morphology, its mass and its size. For example, the variation in the shapes, masses, and sizes of satellites is enormous, ranging from absolutely spherical (such as the North American Explorer IX satellite, launched in February 1961 and weighing only 6 kg) to cylindrical, conical, stellate, etc. The morphology of the various types of probes, spaceships and space stations may be more conditioned, in which certain characteristic structures dominate: solar panels, antennas, rockets, fuel tanks, cargo holds and wings (as is the case with shuttles)., service modules (as is the case with lunar exploration spacecraft), modular construction sections (as is the case with current space stations), etc.

Regarding the propulsion systems and the gravity to be overcome, the ship intended to operate from a direct takeoff from the earth's surface must be designed to withstand the strong stresses that the operation of the rockets means for a given period of time. space of time. Likewise, it must have a sufficient volume of fuel storage, depending on the mission it undertakes. A manned ship destined for the exploration of a celestial body generally has larger storage structures than an unmanned one, since it has contemplated the return to Earth in the shortest period of time, while the unmanned ones have longer time frames, they tend to take advantage of gravitational impulses efficiently and are mostly expendable. The design must take into account the type of fuel or propellant; Until today the used fuels are of the chemical type, and occupy a certain volume.

The quantity and quality of the initial fuel, as well as the propulsion system, will be a function of the total mass of the ship. The greater the mass to be raised, the greater the cost of fuel to be used, so the design of the ship must consider the volume measurements and the appropriate manufacturing materials, to support a structure capable of withstanding the necessary force that will take it to the ground. space, or make her navigate it.

Operating systems

Every spacecraft, regardless of its utility, is structured on the basis of the following basic operating systems: propulsion, navigation, power supply (storage, accumulation and distribution of electrical energy) and communication. Propulsion is usually achieved through the use of rocket systems; navigation through the use of sophisticated computer, gyroscopic and directional and alarm systems; the administration of electricity through batteries, solar panels, transformers, etc; communication, through a radio system and specially oriented antennas.

Special care has to be taken in the design of manned ships; Apart from all the aforementioned systems, manned ships, and in particular those destined for re-entry, have another series of additional systems: internal temperature and humidity control system, pressure and supply of air, food and liquids, an interior volume minimum that allows the astronauts to work and rest, one for access to and exit from the ship by its occupants, a coupling system that allows astronauts to access another vehicle in space, in short, all the necessary systems for human survival. In addition, they have an efficient landing system, consisting of a parachute, or wings and landing gear of an aeronautical nature, or specially designed for landing on other celestial bodies.

Communications

Space communication has as its objective the transmission of information from and to Earth or between ships that are operating in a certain sector of space. The need for communication has given rise to space telemetry, the purpose of which is to track the movement of ships, as well as predict their positions in space and transmit data. A fundamental role in space communication, both between ships and Earth, and between the ships themselves, is undoubtedly played by the use of radio waves, in their various ranges and frequencies, and to a lesser extent, the use of optical and light media. Radio communication must take into account, first of all, the distance between the emitting and receiving sources, which will determine the time elapsed between the emission and reception of the messages: little in the vicinity of the Earth, and much, in relative terms., for ships in deep space that make contact with our planet. This last aspect has stimulated, in the development of exploration missions to distant worlds, the use of computer and robotic systems with increasing degrees of autonomy; in this way, the slowness of communications is partially compensated.

Space propulsion

SpaceX SuperDraco rocket engine in a test bench (2014)

The essential means of propulsion that spacecraft have, especially in their takeoff stage, is the use of the rocket system fed by special propellants; they are also used for their orbital evolution or for deep navigation. Once in orbit, the ships can take advantage of the inertial impulse -in the manner of a projectile launched by a slingshot- that gives them their own motion around the Earth, to propel themselves towards deep space, either towards the Moon, the other planets or outside the Solar System.

In their basic form, rockets intended for astronautics respond to the following design: a more or less cylindrical shape that has inside, as a general rule, two containers in which the propellants to react are found: the fuel (eg: liquid hydrogen) and the oxidizer (eg: liquid oxygen). Both are brought into contact at the moment of ignition in a lower ignition chamber; the gases produced in the combustion are ejected to the outside through a nozzle. Thanks to the principle of action and reaction, the ejection of gas in one direction causes the ship to move in the opposite direction. The speed of the ship, if only the thrust provided by the rockets is taken into account, will depend on the speed of ejection of the gases, and this will increase as they heat up and decrease in density.

The most commonly used fuels are hydrazine, kerosene, liquid hydrogen and liquid ammonia. The most commonly used oxidants are liquid oxygen, nitrogen peroxide, and hydrogen peroxide.

Given the almost impossibility of obtaining thrust from a single rocket system, launch techniques suppose the application of a composite system, that is, a vehicle in several stages or sections equipped with its own fuel, which is They are detached to the extent that they are exhausting it. Known vehicles move at a more or less constant speed. The rocket does so by strongly accelerating at the start of its march at the same time as its mass decreases remarkably. This great acceleration contributes to significantly reduce the loss due to gravitation. This design went to the extreme with the gigantic and powerful Saturn V rockets (three-stage) capable of lifting 130 tons into low orbit and launching 45 tons in the direction of the Moon; A new advance was constituted by the compound system of the space shuttles, structured on the basis of two lateral rockets and a large central container that feeds the shuttle engine.

The type of propellant currently used by spaceships, both to take off and to navigate in space, is made up of chemical fuels, whether in liquid or solid state, although they have the drawback that they are only used for short acceleration periods, as they run out quickly once ignition occurs. A promising future holds the application of ion propulsion, which allows long periods of acceleration over longer distances, at relatively low cost and with the theoretical possibility of reaching high speeds.

Other proposed propulsion systems are in the theoretical investigation stage. Examples are: light propulsion (acceleration would be obtained by projecting light rays); propulsion by means of solar sails (acceleration would be obtained by capturing the solar wind); nuclear propulsion (acceleration would be obtained through a series of controlled nuclear explosions). The latter has been prohibited by international treaties, putting an end to old projects, such as the Orion, consisting of an interstellar ship capable of reaching, theoretically, practically light speeds. All these projects have as a practical difficulty that the accelerations obtained are very progressive, which implies difficulty in their application in near-Earth spaces, being rather designed for deep space flights.

As long as some propulsion principle totally foreign to current science and technology is not discovered, conventional rocket propulsion, from the ignition of chemical fuels, will continue to be the main means of obtaining rapid acceleration of spacecraft.

Velocity and trajectories

This topic is related to the escape velocities that spacecraft must reach when taking off from Earth or another celestial body, the minimum velocities that they must acquire to maintain a safe orbit around the Earth and the others bodies, the minimum speed they must acquire to reach them or leave the Solar System. The subject includes the calculation, execution and monitoring of the orbital movements of the ships around the celestial bodies, the different heights to reach in the completion of the orbits, the determination of the most efficient trajectories in terms of fuel consumption and time of those ships that intend to reach the worlds of the Solar System, both interior and exterior; Likewise, the calculation of the reentry trajectories of the ships to the Earth's atmosphere is addressed.

Cosmic Speeds

Regarding the speeds that the ships must reach, there is a first call of satelliteization (7.9 km/s), which is the minimum speed that allows them to maintain a circular orbit without falling to Earth. With increasing speed, the orbits will become more and more elliptical. Upon reaching 11.2 km/sec (parabolic speed) the spacecraft frees itself from the Earth's gravitational attraction and enters that of the Sun in the manner of a small asteroid. Upon reaching 42 km/s (hyperbolic velocity) the spacecraft is able to free itself from the Sun's attraction, and escape from the solar system.

The closer a spacecraft is orbiting Earth, the faster it must move to sustain its orbit; otherwise, it will fall into the upper layers of the atmosphere. Therefore, the orbital lifetime of any spacecraft will depend on how high they have reached (e.g. the Explorer I satellite had a speed of 28,000 km/h to reach an apogee of 2,475 km from the surface). The duration of a ship's orbit will depend on the distance in height it has reached.

Satellite orbits can be described in any sense in relation to the terrestrial equator, although predetermined trajectories are preferred to allow safe tracking by ground stations.

As for the trajectories and speeds required for exploration of the Moon, the spacecraft must reach the point of equilibrium between the lunar and terrestrial attraction. The established speed to reach this point is 10.9 km/s, which allows the artifacts to orbit the Moon without the danger of crashing on its surface or passing by. Because the Moon has a lower gravitational force than Earth, its escape velocity is 2.3 km/s.

Elliptical speeds and trajectories, which lead ships to explore the rest of the celestial bodies in the Solar System, pose more difficult conditions for calculating trajectories and speeds, since a series of factors must be taken into account: movement of the Earth, gravitational attraction of the Sun and the planets, proximity or distance of the body to be explored, speed of said bodies, fuel capacity and thrust developed by the ship. Generally speaking, it is easier for scientists and controllers to explore the inner worlds of the Solar System than the outer worlds; In the first case, the ships take advantage of the gravitational force of the Sun, while in the second they must overcome said force, and that of the other bodies through a greater use of fuel, and carrying out complex calculations of trajectories that make them reach their objective. In the latter case, the paths chosen are usually the longest, but the most economical in terms of fuel consumption. Basically, the ships destined for the outer worlds, launched in the direction of the East, must take advantage of the inertial force provided by the movement of the Earth's rotation (about 1,670 km/h), to which they add their own impulse provided by the rockets..

Prior to carrying out the trip along the chosen trajectory, the ships must be placed in an Earth orbit called parking.

The best time to start the journey to the inner planets (as is the case with Venus) is when they are in conjunction, that is, between the Earth and the Sun. On the other hand, to start the journey to the planets exteriors (as is the case of Mars) you must wait for the moment when they are in opposition, that is, from the opposite side of the Sun with respect to the Earth.

Navigation

During space navigation, spacecraft must permanently control their route through the guidance of powerful computers, both on board and located on Earth. The extraordinary achievements achieved in terms of calculation and control in the days prior to the invention of microprocessors, with limited processing and memory speeds by computers, are surprising. In orbit around the Earth, the horizon of the planet is a valid reference for the orientation of the ships. During deep navigation, the ship's internal computer often guides it using a series of star references. The Canopus star is the most used as a guide.

In all navigation, and even in takeoff and landing, the alarm system plays an important role. The purpose of this system is to notify the crew and/or the on-board computers, thanks to orders from the ground, that position, trajectory, momentum, movement, or other situations must be corrected, or mission protocols activated, or system failures detected, or, in the worst case, warn of a real danger. Both the control alarm system on Earth and that of the ship itself are interconnected, although as they move away from it towards the stars, the internal system of the ship begins to play a more autonomous role.

Throwing Techniques

Launch techniques include careful internal checks of the ship's systems, governed by a countdown, and careful monitoring of weather conditions. Once the count is over, the ignition of the initial phase of the rocket system begins. This moment is especially dramatic, especially for the crews that may be on board. The ship accelerates with constant impulses to reach the required speed. The strong tensions, the noise and the movements generated by the push put the resistance of the materials and the training of the astronauts to the test. Once the upper layers of the atmosphere are reached, the friction of the ship decreases, as well as noise and movement. The various sections of the ship detach one by one and the ship enters its assigned orbit.

Other launch techniques are in the theoretical proposal phase: electromagnetic catapults would provide the acceleration of the ships through long launch ramps, applying the principle of electromagnetism, as a "space cannon". The construction of a space elevator has also been considered, using an anchoring system placed in orbit. The most feasible proposal is the construction of a shuttle that takes off like a conventional airplane, or that is launched into low orbit by high-altitude air transport.

Reentry

The descent phase to Earth generates another series of inconveniences that must be resolved. First, determine and hit the correct angle of reentry into the atmosphere, a true entry "corridor." The angle cannot be too oblique or too vertical. A very vertical angle would cause the ship to practically crash into the air layer, strongly increasing friction and heat, which would cause its destruction. On the contrary, an angle that is too oblique and at high speed will cause the ship to bounce in the upper layers, describing a parabola and passing by; at a lower speed the spacecraft will bounce, but it will enter the atmosphere beyond the point set as optimum. At the correct angle and at the correct speed, the spacecraft will progressively cut through the upper atmospheric layers, slow down, and reduce drag levels and heat. Prior to re-entry, the ship fires its braking rockets, drastically slowing down and losing altitude; During the process, the ship must be turned in such a way that it offers its most resistant flank to the friction zone. Fortunately, ships have an efficient heat shield that dissipates heat.

Until now, two landing methods have been used on ships, particularly manned ones: the use of parachutes, starting at an altitude of about 15 km, followed by ditching (a technique used by the US), or by a direct descent on the ground (a technique used by the former Soviet Union), or by the use of the aeronautical method of gliding (US shuttles) followed by landing on a conventional runway.

A moment of great uncertainty during the re-entry is the passage of the ships through the so-called strip of silence, which lasts about five minutes, occurring in a certain region of the atmosphere, and which supposes the complete interruption of the radio communications with ground control.

Manned exploration

The essential objective of any manned mission is to safely take humans into space, allow them to navigate and work, and bring them back to Earth alive and in the best possible health conditions. Human survival in space depends on the creation of a safe environment, be it inside the ships, outside, at the time of takeoff, in navigation, in the direct exploration of celestial bodies (eg: in the moon landing), in the exterior work, and in the re-entry and landing of the ships. The design of this environment must recreate as much as possible the conditions that the human organism finds on the earth's surface, that is, pressure, temperature, humidity, respiration, food processes, cleanliness, organic waste, exercise, rest and sleep. To achieve this, bioengineering must take into account the hostile factors that space presents to the human body and that are not usually found on Earth: space vacuum and the absolute lack of air, violent thermal oscillations, the action of the solar wind and cosmic rays, the presence of micrometeorites, the absence of gravity, the breaking of day and night patterns, etc; Added to this is the reduced space in which astronauts must work inside their ships and the forced coexistence between them. A key factor in human survival is the interior and exterior design of spacecraft and space stations, as well as the design of space suits.

To face the difficult conditions of takeoff, space and re-entry, astronauts undergo rigorous training programs that try to simulate the various situations: response to extreme acceleration, weightlessness, navigation, to confinement, to coexistence, to work, to maintenance, to face unforeseen situations, to re-entry into the atmosphere. Only the most psychologically and physically fit subjects will be selected for the missions.

Takeoff

The first problem posed by space travel is takeoff itself. Until something completely different is discovered or invented, brute force will remain the most efficient way to lift a spacecraft into space, so astronauts will still have to endure the high stresses that violent acceleration generates. In this phase, the use of specially conditioned suits and seats is essential to lessen its effects.

Spatial environment

Effects of weightlessness

Landing of the Soyuz ship with Expedition 61 aboard (2020).

Second is the problem of weightlessness. Weightlessness forces the human body to re-condition all its systems, especially the cardiovascular, bone and muscle systems. Weightlessness causes, during long journeys, the loss of bone and muscle tissue, which even affects the heart. These negative effects are combated through rigorous exercise routines, which partially offset the loss of tissue.

Weightlessness makes the most basic functions, such as eating and drinking, complex experiences; particles and liquids tend to float freely inside the ship, which can cause damage; food and liquids are brought specially prepared (compact, hermetically sealed). Another problem is the evacuation of organic waste from the body, which is usually processed, stored and sealed for further analysis.

Weightlessness presents special problems for astronauts' extravehicular work, which is very complex in zero gravity, since there is the possibility of accidentally moving away into space, the body tends to rotate when making movements when working with wrenches, the means of locomotion are limited, etc; and to all this is added the rigidity of the spacesuit.

But astronauts must not only survive the mission itself, but also their readaptation to conditions on Earth. For this they have to follow rigorous medical support programs so that the bodies recover their full capacities in the process of atrophy during the mission.

Harmful radiation

Another concern is the action of solar and cosmic radiation, which is harmful to health. Even with the best absorbent coatings, both inside and outside ships, and in space suits, the human body is subjected to higher levels of radiation than on the Earth's surface, with unpredictable long-term consequences..

Micrometeorites and Space Junk

Another cause for concern is the impact of micrometeorites, which can puncture the hull of ships or damage instrumentation. Faced with this, the walls of the ships offer some protection, although certainly not against larger objects, which could impact at tens of thousands of km/h. Fortunately, the probability of being hit by a larger meteorite is very small, given the extent of space. More dangerous are space debris, that is, the myriad objects that orbit the Earth and that constitute the remains of previous missions: "space junk", which is made up of objects that can be of tiny dimensions (for example: a accidentally dislodged nut) or the size of a bus (eg old disused satellites). Although no serious accidents have been reported, these cannot be ruled out. Although the major agencies keep careful track of the largest unused objects, there are thousands that go undetected, and although most of them end up falling into the atmosphere sooner or later, there are just as many that will remain in orbit for thousands of years. Space debris, in progressive increase, constitutes, if radical containment measures are not taken, a serious threat to future orbital navigation.

Life support systems

Air and water

Given the total absence of atmosphere in space, all breathable air, as well as liquids, must be brought entirely from Earth. The essential task of the sensors on board is the constant monitoring of oxygen and carbon dioxide levels, as well as pressure. Excess carbon dioxide is absorbed by suitable materials. On the other hand, oxygen generation techniques from a natural cycle, with the presence of algae resistant to cosmic rays, have been tested since the 1960s. In this sense, the chlorella algae is very easy to cultivate, it reproduces fast and can even be eaten. For its part, the recycling of used water is within the functions of the missions.

Ambient temperature

It is necessary to maintain the ambient temperature around 20 °C. The electrical system plays a major role in heating or in the extraction of internal heat. The violent external thermal oscillations force the use of external coating materials (refractory to heat during exposure to the Sun) and internal (which prevents the dissipation of internal heat). It is convenient that the ships rotate slowly on themselves to avoid overheating; the vehicle can also be covered, between the exterior and interior walls, with a layer of fluids intended to absorb heat. In addition, the ships have mechanisms for absorbing solar energy and transmitting it to the interior for its use at times when they orbit the dark side of the Earth.

Even inside unmanned spacecraft, an adequate temperature and air atmosphere must be maintained to prevent instrument malfunction.

Space Suits

As previously stated, the space suit is of paramount importance to human survival. Basically, the suit is made up of four essential units: the helmet, the body of the suit, the gloves and the survival system (air reserves, battery, communication system, etc.), attached for the most part to the back of the suit. astronaut as a backpack. The suit is made with a series of materials, arranged in successive layers of lesser or greater density, which allows it to maintain air pressure, internal temperature, control humidity, absorb harmful radiation to a certain extent, defend the astronaut from impact. of certain micrometeorites, and even, on occasions, collect organic debris. However, the suit only allows a rather reduced mobility, given its rigidity. The use of the suit makes it possible to better withstand the stresses of takeoff and landing, of work in extravehicular space (maintenance, experimentation, equipment deployment) or in exploration of the lunar soil. In addition, it is the best guarantee of survival in the event of an extreme situation.

Mental stability

Astronauts must adapt to working in rather small spaces. At the beginning of space exploration, mobility was very limited. With the Apollo program the available space increased somewhat; but it was thanks to the development of space stations and shuttles that astronauts found greater availability of space, which has allowed them to work more comfortably, have some privacy, and carry out exercises. Even so, living spaces remain small.

The presence of companions helps the astronaut to dispel the strong feeling of loneliness and remoteness that is experienced in space, but at the same time forces them to live together and endure characters that may appear dissimilar. Only the selection of well-established work teams, with a very professional mentality, helps to face possible coexistence problems, especially if the missions are long-term. The psychological stability of astronauts is one of the essential objectives of the space survival program, allowing them to cultivate their recreational spaces, leisure and communication with their families on Earth.

Human survival requires a good dose of initiative and teamwork in the event of unforeseen situations or, even worse, extreme danger, such as the eventful journey of Apollo XIII, a spacecraft that on a mission to the Moon suffered serious damage, forcing his crew to deploy all their intelligence to return safely to Earth. The astronauts are fully aware that they are alone, and that practical solutions to contingencies depend only on them. It is also difficult for astronauts to adapt to their new patterns of waking and sleeping, since the natural cycle of day and night is broken. As far as possible, it is a question of maintaining the 24-hour cycles, establishing hours of rest, work and recreation.

Space exploration and colonization

The colonization of space is considered in the long term as a remedy to avoid the stagnation and decline of civilization, as well as its fortuitous extinction or self-destruction. Physicist Stephen Hawking has reaffirmed this thesis, warning of the urgent need to colonize space as a means of avoiding extinction.^{[citation needed]} In the short term, the Space colonization has brought technological dividends, in research, development of new space technology and derived products that are used on a massive scale.^{[citation needed]} A limitation that weighs on the public opinion is its high economic cost, despite the fact that in practice and in the longer term, astronautical activity becomes profitable.^{[citation required]}

Actions aimed at the exploration and progressive occupation of near space have been dictated by multiple interests: political prestige, military purposes, technological demands of industrial sectors, communications, geographic or climate observation, or scientific knowledge itself.^{[citation required]} Such interests have materialized in the following general exploration and colonization actions:

1. A real "spattern" between the U.S. and the U.R.S.S. during the 1960s to be awarded the achievements of being the first in the successive milestones: the first object in orbit, the first man in space, the first space walk, the first object to be thrown into another celestial body, etc. Notable were the ships of the Soviet programs Vostok Vosjod and Soyuz and the Americans Mercury Gemini and Apollo.
2. The creation of a dense network of satellites that orbit the globe for multiple purposes: military (Samos, Vela, etc.), telecommunications (e.g., Telstar Eco), aerial navigation (e.g., Transit), geodetic, geographic and climatic observation (e.g., Nimbus Tiros), biological experimentation (e.g., Bios, Cosmos), astronomical Explorer, etc.
3. The effective exploration of the Moon by a manned program (Apollo) and the exploration of the other bodies of the Solar System by unmanned missions, as were, for example, the Lunar Orbiter probes (USA), Moon (URSS), Mariner (USA), Mars (URSS), Pioneer (USA); the Voyager 1 and Voyager 2 (USA), the most artificial objects of the Earth
4. The orbit of space observatories for astronomical and astrophysical research (e.g. the Hubble Space Telescope).
5. Experimentation with new substances and materials, and with living beings, with or without industrial application.
6. The realization of multiple scientific experiments in different fields and that can only be done in microgravity or zero gravity.
7. Research on human behavior in space for long periods of time.
8. Research and launch of a series of starships that have allowed more space access: space shuttles
9. The diffusion of the knowledge obtained by the agencies, and the application by the industry of the technological byproducts that has generated astronautic activity, which are of mass use today. The diffusion of knowledge has made several countries and agencies engage in collaborative activities, saving economic costs.
10. Preparation of plans for re-exploitation of the Moon with manned flights, installation of a permanent base in it, direct exploration of Mars by a manned mission, etc., together with the corresponding investigation of the economic possibilities offered by the exploration and colonization of space.
11. Creation of space stations, which are a key step in colonization, as they mean the permanent presence of the human being in space. Since the 1970s, a progressive effort has been made to create and maintain a series of space stations orbiting the Earth, as well as an intense research programme on human survival for long periods of time in the space environment. At the end of the 1960s, the Soviets began the first tanteos in the direction of building true space stations, successfully linking their Cosmos satellites. But it was at the beginning of the '70s when they managed to complete a true station: Salyut 1. They followed several more until they completed seven. Subsequently, the Russians designed the MIR station an advanced ship that provided fruitful services. For their part, the Americans responded with the Skylab station, although they then dedicated themselves to the design of the ferry program. Since 1998, the major space agencies decided to join their efforts in the implementation of the current International Space Station.

The stations have made it possible to create larger and more welcoming environments for astronauts, the possibility of carrying out scientific experiments without the limited time limits available to spaceships; the stations are points of direct observation of the climatic and other conditions that occur on Earth, the stay in the stations has allowed us to study in detail the psychological and physiological behavior of humans, either alone or in company. In the making is the possibility of using the stations as shipping ports to other worlds in the Solar System.

The human presence in space, this time permanently, raises new challenges and questions about the costs and benefits of colonization, about the behavior of human physiology and its possibilities of adaptation to the space environment and other worlds, of the effective possibilities of occupying the nearby worlds, that is, the Moon and Mars, and of the future possibilities of self-sustainability of the colonization.

Space research in the world

Fire a Ariane rocket.

In addition to the well-established space programs of the United States, the USSR, Japan and Europe (through the European Space Agency), there has been a flourishing since the 1980s of space programs in developing countries, either in nations with a certain tradition such as China (the third space agency to have carried out manned missions, after the United States and Russia) or India (which has its own satellite launchers) as well as in others that have recently started. The space programs of Brazil, Mexico, Chile and Argentina are noteworthy.

For some developing countries, artificial satellites have been the easiest way to improve their internal telecommunications networks, especially in those whose terrain or other causes make traditional means of communication difficult. Such is the case of the domestic satellites used by Indonesia, or the series of satellites shared by Arab nations (Arabsat).

Countries with Hispanic Culture

Mexico

There is a history of advances in this area in the second half of the XX century when President Adolfo López Mateos issued a decree in the Official Gazette of the Federation of August 31, 1962 that created the National Commission for Outer Space (CONEE), attached to the Ministry of Communications and Transportation in order to promote research, exploitation and peaceful use of outer space; Commission that continued with the work of rocketry, telecommunications and atmospheric studies in the country.

Mexico currently has eight satellites and the express company Satmex. The Mexican Space Agency (AEM) is an agency created on July 31, 2010 in charge of space affairs. This project aims to group and coordinate the work of Mexico in space activities.

Spain

Argentina

Uruguay

Space Agencies