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 l'ascenceur spatial japonais

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patchfree




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Date d'inscription : 19/04/2007

MessageSujet: l'ascenceur spatial japonais   Lun 13 Oct 2008 - 21:12

Oui je sais ce post pourrait être n'importe où ailleurs. Mais comme il est largement fait référence aux idées russes puis soviétiques en la matière...

Japanese to Build Space Elevator Invented in Russia

Japanese engineers intend to build an elevator to deliver cargo into
space. Japanese authorities are prepared to allocate $10 billion for
the project.

The space elevator is expected to cut the cost of delivering cargo
into space and is considered one of the most ambitious projects of the
21st century. The Japanese plan to unveil a schedule for the elevator`s
assembly and commissioning this November.

The idea of a space elevator is over 100 years old. Russia`s
Konstantin Tsiolkovsky, the founder of theoretical astronautics,
suggested building a tower thousands of kilometers high attached to
some firmament in orbit. Steel, the most durable material of
Tsiolkovsky`s time, however, was not capable of bearing even a small
part of the expected physical stress.

In 1960, before the first manned flight was performed by Yury
Gagarin, Yury Artsutanov, a post-gradate student at the Leningrad
Technology Institute, using Tsiolkovsky`s ideas, suggested creating a
cable-guide connecting a spot on the equator and a space platform in a
geostationary orbit at 35,786 km, whose orbit would remain synchronous
to that of the location on Earth. Gravity and centripetal force would
keep the cable, connecting the platform to Earth, constantly taut,
making transportation possible. The time required for cargo from Earth
to reach the platform was estimated at one week.

Later, science fiction writer Arthur Clark wrote of a space elevator
in his novel, The Fountains of Paradise, attracting attention to the
concept. In 1999, NASA and its Scientific Research Institute included
it in the list of probable tasks for early third millennium.

A major problem in the construction of a space elevator is to create
the cable, which must be extremely durable and light-weight. The
durability of carbon nanotubes, invented in 1991, exceeds the
requirements for the space elevator, with a far higher tensile yield
strength and density six times less than that of steel. A one
millimeter diameter strand made up of nanotubes is capable of
supporting up to 60 metric tons. Still, the technology for industrial
production of nanotubes and the weaving of strands into a thread is in
its early development.

Some scientists say the inevitable crystal-lattice defects could
decrease the durability of the nanotubes. Even if flawless threads
could be produced, the micrometeorites, cosmic rays, and atmospheric
oxygen could still damage the cable.

Space junk and the natural vibrations of the giant "rope" could also cause the cable to fail.

Another problem is energy supply. Existing battery technology could
not provide the necessary energy for the whole distance. This means
that an external energy supply will be needed, possibly a laser or
microwave source, which will require corresponding receivers to be
installed on the elevator itself. Another option would be to use the
elevator`s braking energy on its way down.

Let us assume that all the problems with materials and energy are
solved. The cable weighing thousands of tons has been manufactured, and
needs to be placed into space. There are no carrier rockets capable of
doing this, which means the cable would have to be launched into space
in pieces, which need to be joined somehow afterwards. Or one could
drop down a thin strand from the orbiting platform and splice it into
the full diameter of the cable. Neither placement concept seems any
easier to implement than creating a suitable material for the cable.

So far scientists have been experimenting in space with cable
systems of up to several hundred meters long, made of materials which
are far less difficult to produce than nanotubes.

In 1965, Russia`s Rocket and Space Corporation Energia, then called
the Central Design Bureau for Engineering, led by Academician Sergei
Korolev, was preparing the first ever space experiment with a cable
system. The project involved creating artificial gravity on the Soyuz
spacecraft, which would be connected with the carrier rocket`s final
stage via a steel cable, both rotating.

After Korolev died, however, the project was cancelled. Development of cable systems was resumed at Energia 20 years later.

A series of experiments with cable systems were performed within
U.S., U.S.-Italian and U.S.-Japanese programs. Although some of them
failed, part of the planned research was done.

In recent years, scientists at the Space Research Institute of the
Russian Academy of Sciences have been researching the possibility of
setting up a group of orbital cable systems to ensure cyclic delivery
of cargo from Earth to Moon. Each system will consist of two space
vehicles interconnected with a cable and rotating like a slingshot,
with its centre of mass moving along a predetermined orbit. If one of
the two space vehicles is "unclogged," the rotational energy released
will cause its translational movement, like a jet engine.

Theoretical and experimental research has shown that, to keep a
transport corridor between Earth and Moon functioning, the design
should include three cable systems, two in low earth orbits, low
circular and elliptic, and one in a lunar orbit. Cargo would have to be
transported between the three systems, eventually making their way to
the final destination.

Calculations have revealed that this kind of transport system would
weigh 28 times less than the cargo it would be capable of delivering
from Earth to Moon, while traditional delivery by a rocket requires an
amount of fuel that weighs 16 times more than the cargo itself. This
concept would be much simpler and cheaper to implement than a space
elevator.

http://en.rian.ru/analysis/20081006/117469160.html
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Stan




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Date d'inscription : 11/02/2008

MessageSujet: Re: l'ascenceur spatial japonais   Lun 13 Oct 2008 - 22:47

Un article en français sur cet ascenseur spatial, avec des vidéos.

http://www.imaginascience.com/actualites/accueil_actualites.php?action=fullnews&showcomments=1&prevnext=0&id=397#haut

Rmq: si ils mettent vraiment 8 milliards d'euros dans ce projet, ca va commencer a devenir très sérieux cette histoire !
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CosmoS




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Date d'inscription : 13/11/2005

MessageSujet: Re: l'ascenceur spatial japonais   Lun 13 Oct 2008 - 23:50

patchfree a écrit:
Oui je sais ce post pourrait être n'importe où ailleurs. Mais comme il est largement fait référence aux idées russes puis soviétiques en la matière...
Japanese to Build Space Elevator Invented in Russia
Japanese engineers intend to build an elevator to deliver cargo into
space. Japanese authorities are prepared to allocate $10 billion for
the project.
Merci pour l'info, mais je crois qu'on a encore affaire à un cas d'info déformée (comme souvent dans ce type de breves reprises de site en site). En cherchant un peu, on voit qu'à l'origine de cette info se trouve l'organisation d'un prochain symposium sur le sujet, organisé par une association: http://jsea.jp/en
Donc, en fait de "Japanese authorities", on a la "Japanese Space Elevator Association", et en fait de décision de financement 10 Md$ (remarque: à peine 1,5 % du plan Paulson blbl ), on devrait avoir une jolie roadmap, mais pas grand chose de plus. Sleep
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