Probes Voyager

Voyager 1 and voyager 2

In 1977, the space probes Voyager 1 and Voyager 2 were sent in the solar system bound for distant planets (Jupiter, Saturn, Uranus and Neptune). The images that come to us again in 2011, often reflected in our past but also show us our future.
"If there was a Nobel Prize for space probes, it would undoubtedly at Voyager 1 and Voyager 2 that have revolutionized our understanding of planets and continue to make discoveries almost thirty-five years after their launch." Rosine Lallement, an astronomer at the Paris Observatory. At year end 2011, Voyager 1 is 17.9 billion miles and Voyager 2 to 14.5 billion km.
They have long since passed the gas giants.
Voyager 1, the fastest, travels at a speed of 17 km/s (about 60 000 km/h), it is about to leave the solar system crossing the boundary, the heliopause. The heliopause is the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium. Once freed from the gravitational forces of the solar system, the probes will start in the infinite space of the Galaxy, new random stellar influences.

The distance of the probes does not allow astronomers to get information in real time, because the distance makes the operation more complicated and asynchronous. A radio signal takes almost 17 hours, at the speed of light to reach Voyager 1. NASA estimates that the energy supplied by three radioisotope thermoelectric generators should operate until 2020. In 2020 its distance has grown from 4.8 billion km, it will be about 22 billion km.

Image: This image of 2011 positioning, Voyager 1, launched in 1977, it is 17.9 billion km. Its signal is 17 hours to go 117 times the Earth-Sun distance. Pioneer 10 was 15.4 billion km from the Sun, Voyager 2 to 14.5 billion km Pioneer 11 and 12.4 billion km, well beyond the orbit of Pluto. Below the Pluto probe New Horizons is 3 billion km. All these spacecraft sent by man, used the effects of gravitational slingshot for speed. Voyager 1 is the fastest with a speed of 17 km/s.

Voyager 1, leaving us without turning

Voyager 1 is the first space probe that sent us detailed images of the moons of Jupiter and Saturn.
In 2011, 34 years after its launch, it continues to send scientific data.
These 825 kg of metal, full of 20th century technology, takes forever, deep in the Galaxy, its scientific instruments (camera, sensor, particle detector).
These instruments, for the study of our solar system will travel forever, to other stars without warning.
If Voyager 1 and Voyager 2 is heading to Proxima Centauri, the nearest star, they would reach the next star system, in about 75 000 years.
These traces of humanity waiting to testify to the existence of extraterrestrial life, that of a beautiful blue point, become very small in deep space between the stars.
On February 14, 1990, NASA control probe Voyager 1, turn around and photograph the planets it had exceeded (pictured against).
Of the 60 images of this unique event, one of the images that Voyager was sent to the Earth 6.4 billion kilometers, 42 times the Earth-Sun distance.
And yes it is us, the little pale blue dot, lost in the immensity of the Universe, which receives the dim light of the sun yet visible.

Image: The "Pale Blue Dot" is a photograph of Earth taken on February 14, 1990 by Voyager 1 from NASA at a distance of 3.7 billion miles (6 billion kilometers) from the Sun. The almost invisible Earth is the pale blue dot in the first third of the pale vertical trail. The image inspired the title of scientist Carl Sagan's book, "Pale Blue Dot: A Vision of the Human Future in Space," in which he writes: "Look at that dot again. It's here. It's home . It's us.".

Image: The Voyager 1, launched in 1977 is 17.9 billion kilometers, in late 2011.
Its signal takes about 17 hours to reach us at the speed of light. This cookie technology on the planet Earth, a little stardust, which slides into an orbit ideal, just waiting to be captured by the formidable forces of the infinite universe.

Boundaries of the solar system

The solar wind travel at maximum speed to about 95 AU, three times the distance from the last planet (Neptune) in the solar system.
The heliopause is the last frontier of the solar system is the limit where the solar wind fades and where interstellar space begins. At this point the solar wind collides with the opposing winds from the interstellar medium, its thrust is no longer sufficient to push the gas of the Galaxy, the rarefied hydrogen and helium.
The termination shock is a boundary through separated from the heliosheath by the heliopause, the turbulence where the solar wind is slowed and compressed by the interstellar pressure.
When particles from the sun collide with interstellar particles, they slow down, heat up and emit energy. These particles accumulate at the heliopause, highly energized, creating a shock wave. This shock wave is the trace left by the Sun during its journey through the Milky Way.
The distance to the heliopause is not precisely known because it probably varies depending on the solar wind speed and the temporal density of the interstellar medium. In this region called the "magnetic highway", the instruments have recorded the highest rate of cosmic rays from outer space and a sharp decrease of particles from the Sun.

"We saw a very strong and sudden disappearance of particles from the sun whose intensity has decreased by more than a thousand times at the entrance of the magnetic highway," says Stamatios Krimigis, an astrophysicist from the Laboratory of Applied Physics Johns Hopkins University (Maryland's).

NB: The three units of measurement useful in astronomy to express the distances:
- light year (a.l.) A light year is a unit of distance used in astronomy. A light-year is equal to the distance that light travels in a vacuum in the space of one year (31,557,600 seconds), about 10,000 billion kilometers. is the 63242.17881 au, is exactly equal to 9 460 895 288 762 850 m.
- parsec (pc The parsec is the distance at which one astronomical unit subtends an angle of one arcsecond.) is equal to 206 AU or 270.6904 3.2616 years-light or 30 857 656 073 828 900 m.
- astronomical unit (au (symbol: ua ou au) Créée en 1958, c’est l'unité de distance utilisée pour mesurer les distances des objets du système solaire, cette distance est égale à la distance de la Terre au Soleil. La valeur de l'unité astronomique représente exactement 149 597 870 700 m, lors de son assemblée générale tenue à Pékin, du 20 au 31 août 2012, l'Union astronomique internationale (UAI) a adopté une nouvelle définition de l'unité astronomique, unité de longueur utilisée par les astronomes du monde entier pour exprimer les dimensions du Système solaire et de l’Univers. On retiendra environ 150 millions de kilomètres. Une année-lumière vaut approximativement 63 242 ua. Mercure: 0,38 ua, Vénus: 0,72 ua, Terre: 1,00 ua, Mars: 1,52 ua, Ceinture d’astéroïdes: 2 à 3,5 ua, Jupiter: 5,21 ua, Saturne: 9,54 ua, Uranus: 19,18 ua, Neptune: 30,11 ua, Ceinture de Kuiper: 30 à 55 ua, Nuage d’Oort: 50 000 ua.) is from August 30, 2012, exactly 149 597 870 700 meters.

Table of equivalences on units of distances.

Image: The heliosphere protects the solar system from cosmic rays, but Voyager 1 is about to exceed the boundary conditions and exposure to cold and dark interstellar medium unknown to us.