Great sailors admitted that they were not only fascinated by sea, but by ships too. Space, like oceans, is not only a place for exploration, but a place for construction. Imagination wants to travel. But it first wants to create...

THE LAST SWISS KNIFE

In the imaginary, spaceship, as an object, has a particular statute. It is, in a certain way, an "extrapolation" of the multi-function pocket Swiss knife, providing more than three, four or five functions, but all the functions necessary for life, in the hostile environment of space. In the void, spaceships are definitively isolated from their mother planet, except by radio communications spending minutes, then hours, to reach destination. They must provide all the needs for their passengers, including recreating atmosphere or – in the best case - artificial gravitation ...

Later, Voltaire too will fly through the solar system in Micromegas. By the way, on a more scientific level, he is the first French editor to spread in France Newton’s work on the universal gravitation, by publishing a translation of the Principia Mathematica.

Jules Verne and H.G. Wells are generally seen as inventors of a new literary genre, science fiction, whose favorite theme is space travel. Spaceships, in SF, always reflect an economic, social or political context.

The "pioneer spaceship", for example, is a product of XIX-century, a product of the industrial era. The machine is sometimes laboriously designed from the technological knowledge of the time, using airships, catapults or cannons. Its credibility depends on the literary talents of the author : Jules Verne tries to demonstrate, in From the Earth to the Moon, that acceleration inside the Columbiad will be supported by passengers thanks to a hypothetical system of hydraulic dampers; Edgar Poe, in The Unparalleled Adventures of Hans Pfaal, supposes that atmosphere does not disappear completely in space, and thanks to a "compressor", reach the Moon in balloon; H.G. Wells, in The First Men on the Moon, creates, to rise in the airs, an new material impermeable to gravitation...

In the years 1920 - 1930, a new "futuristic" image of the space conquest appears, especially in American comics. The poetic force of this popular image will be so strong enough to set visual codes which remain today in the imaginary, like assimilating, for example, spaceship to rockets or flying saucers. It will give rise to Space Opera, equivalent in space of the Western invented a few years later by Hollywood.

At the very beginning of cinema, Mélies himself staged, in an operetta, the Voyage in the moon, which was in the early XX-century the first science fiction movie. In 1929, Fritz Lang tries the voyage in The Woman in the Moon, with a real search for technological credibility, assisted by a scientific consultant, the pioneer of astronautics Hermann Oberth.

THE SPACE OF SYMBOLS

The spaceship is first of all an object with a very strong symbolism : a complex thus mysterious machine, reflecting the labyrinth of human organizations. The possible failures of this machine are always attributed to the complexity of human organizations, which inevitably evokes the myth of Babel, and the claim of builders working on projects seeming to defy the nature.

MOBILIS IN MOBILE

Like Nautilus, any spaceship is "mobile in a mobile element". Even an orbital "station", despite its name, is moving in a space where the concept of immobility does not have, in fact, any sense.

The physical reality of interplanetary space is far from common experience, keeping the sky in the world of symbols. The simple concept of weightlessness, for example, is often misunderstood, and violated even in the greatest science fiction movies. It is still believed that it appears "in the void", or "in space", while, in fact, the Earth’s gravity field spreads in the whole universe. In another way, anybody may experience weightlessness, for a few seconds, while jumping from a diving board...

Where Newton’s physics sees forces of attraction, contemporary physics refers to the geometry of a space locally distorted. This idea leads to a traditional image : the solar system can be seen as an immense flexible membrane on which each planet is a massive ball. Each ball distorts the membrane, creating "gravity wells".

A journey from Earth to Mars will only need energy to leave from Earth’s gravity well, then to slow down in order to fall in the gravity well of Mars. The space flight, between these two points, will just be a billiards play requiring no energy – except to reduce the duration of the flight.

And with "hyperinstruments", there is no material contact anymore between modular components : "hypetelescopes", for example, will be based on a constellation of satellites dispersed all over the solar system, but perfectly synchronized, providing to astronomers images of an extreme precision.

Quite naturally, function makes form. The Space Shuttle pointed out the limits of hybrid vehicles, designed for both passengers and freight. Is it really interesting to support the strict reliability constraints of manned flights for the launch of simple goods? The principle of space rendez-vous being perfectly mastered today, it is much safer and economical to separately launch small shuttles of passengers under excellent conditions of comfort and security, then automatic heavy cargos for the freight.

The space traveler then uses a connection between different vehicles fitting to each environment : an "atmospheric" shuttle for the communication with the Earth, then spacecrafts for the interplanetary flight, and finally modules such as Apollo’s LEM, to join the surface of a planet. In the same time, automatic "tugs" transfer freight from an orbit to another. The connection will be done on space stations, kind of switching yards near the Earth or "anchored" on Lagrange points.

Forms of spaceships depend on their propulsion system. New technologies are still to developed, but all of them will be based on few fundamental principles : to use resources of the environment, to fly like a bullet from a initial impulsion, or to use the action and reaction principle (let us wait for a few years before using Star Trek’s teleportation ...).

Using resources of the environment is the simplest solution: It is already used today to maintain permanently in space nearly one million people... Actually, it is just during flights never exceeding a few hours, in air lines only a few kilometers above sea-level…But in the near future, the plane could become the best way to reach low orbits. This first step in space is also the most energy consuming, as it is a jump from the deep gravity well of Earth.

And in the absence of any tangible material support, why not build rails in space? The idea is not as absurd as it seems, and could be used to connect with long cables two asteroids distant of a few hundreds - or a few thousands – of kilometers. Such an assembly, put in a very slow rotation, would produce an artificial gravitation - by the effects of the centrifugal force - on the surface of these small rock blocks whose own gravity is negligible: inhabited bases built on the surface of these "atolls" would not have to worry any more about the biological constraints related to a long stay in weightlessness, while profiting from a natural material base as large as a city or a county.

The " space rails " - composed of chains formed by links of tens meters in diameters, or simple cables - must be built with new particularly resistant materials, whose technology known as "nanotubes", appeared in the 90ies, gives us a first idea.

In a more distant future, an original and efficient solution to cross the gravity well of Earth could be the space elevator : this idea would consist in hanging, at the level of the terrestrial equator, a very long cable of 100.000 kilometers – the quarter of the Earth-Moon distance - rising to the sky men and goods with simple lift cars... The length of the cable is important, as it is necessary and sufficient to stay in the sky without any use of supernatural forces, and according with the laws of mechanics.

Any machine pursuing its flight by inertia, without any engine, can skillfully benefit from many curiosities of the space "cartography". The most surprising one is certainly the “gravitational rebound”, consisting in flying near a planet to “rebound" on its gravity field in order to increase speed and reach deeper orbits. The technique was already used during the remarkable flight of Voyager 2, launched from Earth in 1977, rebounding on Jupiter in 1979 to reach Saturn in 1981, rebounding there again towards Uranus - joined in 1986 - then flying over Neptune in 1989, and continuing its eternal voyage beyond the solar system. Each one of these "rebounds" needed, for the space probe, just a tiny contribution of energy useful for some trajectory corrections. The fact, however, that speed increased at each step, had nothing to do with magic: the planets transferred a little of their own kinetic energy to the probe, therefore slowed down their rotations around the Sun, but in a completely negligible proportion considering their sizes. It is thus possible to cross the solar system with a minimal energy, if the right trajectory is chosen. The space flight, before being a question of energy, is first a question of strategy.

The chemical engines, for instance, use an explosive couple such as oxygen and liquid hydrogen, especially efficient, whose combustion produces only water, without any danger for the environment. Out of the atmosphere, another kind of reaction engine can be used : ejecting very small quantities of matter, but at considerable speeds – like with the ionic reactor - it will produce a modest push during a very long time, consuming only one small quantity of propergol for an energy delivered comparable to the chemical engine.

A technological panoply is at the disposal of spaceships builders. On the map of the sky, navigators trace new roads, further that ocean...

SPACE EXPLORATION IS LITERATURE ...

It is first to be noticed that spaceships, before traveling in space, begin their voyages in stories, novels, and myths. When - during the XVI and XVII-centuries - the sky gained a scientific consistency, many novelists traveled in this new world, generally as a pretext for a critical - or a satirical - description of the human societies living in the planet Earth.

Cyrano de Bergerac traveled in space in the Comic History of the States and Empires of the Moon and of the Sun. Between two fancy modes of propulsion invented to reach the Moon, he had the remarkable intuition of a system using "quantity of flying rockets", configured so that "as soon as the flame had devoured a row of rockets /…/ another stage was ignited, then another". In three centuries, a similar multi-stage rocket will bring Apollo to the Moon...

In a certain way, spaceship is an utopian object, like islands - from Plato’s Atlantis to Thomas More’s Utopia, form Campanella’s City of the Sun to Captain Nemo’s island. In the imaginary, space replace ocean, as another great “utopian substance”.

The symbol has a form too. Rocket, or egg protecting from a hostile environment, it obviously has to do with psychoanalysis. In one of his last writings, A Modern Myth, the psychoanalyst C.G. Jung studies this symbolism, through the UFO phenomenon emerging - it is not a coincidence - after the Second World War and in the first years of space age. Jung will not be interested by the question of the authenticity of "flying saucers", but in the factual reality of their success in the media. There is a great aspiration for man to dream about these mysterious objects, which, in this context, crystallizes on spaceships - supposed extraterrestrial – paradoxically associating science and irrationality, as a transposition of myths to contemporary images more easily "acceptable". The shapes of these objects, in cigar or saucer, popularized by science fiction, are based on universal symbols, such as the phallic shape of the Fleur de Lys, or the rings of the mandala, found even in the oldest cultures.

New forms have to be invented : in space it is possible to build structures inconceivable on Earth, freed from the terrestrial constraints, spreading indifferently in the three dimensions. And in vacuum, there is no need for aerodynamic fuselages, only necessary for shuttles coming from atmospheric planets.

Some privileged forms remain : first, the circle, real or virtual layout of a rotating habitat creating onboard an artificial gravitation thanks to the centrifugal force, circularity being here like horizon line on Earth. Or the triangle, geometrical figure obtained with the smallest number of vertex, creating isostatic structures useful to design rigid frames.

The space plane will be probably a double machine, composed of a flying wing able to reach the upper atmosphere, using new generation reactors - such as statoreactors - burning residual atmospheric oxygen. From this carrying wing, a small shuttle will take off to join a low orbit, thanks to the final impulse provided by its own engines.

Space itself is not completely void. One can imagine, in the future, propulsion systems using the few particles which remain in this environment. But first of all, space is bathed by sunlight. The small photons of sunlight exert a tiny - but not insignificant – pressure, strong enough to push the long tails of comets in the opposite side of sunlight. Near the Earth, the order of magnitude of this photonic pressure is comparable to the weight of a coin on a surface equivalent to a football field. It is thus possible to conceive extraordinary vessels whose principle of propulsion is close to oceanic sail navigation : the solar sails.