Venus
Venus is the second planet as seen from the sun, and it is "sister planet" Earth. Scientists assumed that the climate on
Venus would be very fruitful through their telescopes they just saw a huge thick cloud, so there would be water. Moreover
Venus closer to the sun and is therefore comfortably warm, argued astronomers.
Upon the arrival of the first spacecraft to the planet would appear that these assumptions were all wrong.
Orbit and rotation
Venus rotates westward around its axis, unlike the other planets, running eastward. The sun is therefore important in the
west! Moreover, Venus rotates very slowly, but they will do 243 Earth days to rotate once approximately itis axis. Because
the planet orbits the sun at the same time, it takes a "day" (the time between two sunrises) yet only 117 Earth days.
Atmosphere and Climate
Venus was the first planet was visited by interplanetary spacecraft: the Russian Venerasondes. Who discovered that Venus
did not appear on the earth. The planet has no water, the atmosphere is CO2, it rains sulfuric acid, the air pressure is
100 times higher than the earth, and the average temperature is 350 ° C. That extreme conditions are not only due to the
fact Venus is closer to the sun, the planet is the victim of a particularly strong greenhouse result , causing the
temperature three times higher than normal.
The greenhouse effect on Venus is caused by the large amount of carbon dioxide (CO2) in the atmosphere 96% of the
atmosphere consists of carbon dioxide. Carbon dioxide that forms dense clouds that hold the heat means heat rising from
the surface of the planet in the form of infrared radiation is reflected back through these clouds to the surface.
The clouds of Venus rotate much faster than the planet itself: in 243 days while Venus rotates on its axis, the thick
layer of clouds rotating in four days around the planet. This difference causes a huge wind speed up to 100 m / s.
Surface
The very dense clouds of Venus has long prevented scientists to see something of the surface of the planet. Since the 60s
were attempts with radars from Earth by watching the clouds.
However, this yielded little results. The Russian Venera's 15 and 16, that same tried in orbit around Venus, all gave
better resolution, but it was the US Magellan probe, which ran between 1992 and 1994 around the planet, which gave us a
very detailed image of the surface.
The Russian Veneralanders sent by pictures of on the surface of Venus. Which showed that the surface consists of flat,
basaltic rock similar to basalt sometimes produce Earth's volcanoes.
Old radar had shown a large number of craters, so they went out that the surface of Venus was pretty older . so, the
Magellan images showed that the mostly volcanic craters dominate the surface. Impact craters of meteors were hardly found.
This means that the surface of Venus is just very young: up to 500 million years. Magellan even found some places where
the surface changed over the 2 year period in which the probe took pictures. Venus is still geologically active!
Origins and evolution
Since the surface of Venus is so young, we know nothing about the origin and early history of the planet. maybe that
compare with the early history of the other terrestrial planets: in the vicinity of the sun arise rocky planetesimals,
which clump together to proto planets and planets. The opposite rotation of Venus suggests that the planet was ever handle
a very heavy impact, as with Mercury and the Earth happened more than once. However, any geological evidence thereof is
obliterated by volcanism.
Composition
Just as the earth Venus has an iron core around there a liquid stone mantle. The magma in the mantle, some places may
break the crust and cause different types of volcanic activity.
Venus shows no signs of plate tectonics. Venus has no magnetic field, and by the high temperatures is any indication of
any previous magnetic field disappeared. Therefore, many scientists believe that the core of Venus is not liquid. Others,
however, think that the core is still liquid, such as on the earth, but is slow to solidify. It is indeed difficult to
explain why the core of Venus it would be solidified, and not of the earth.
Exploration
Like Mars Venus has long been regarded as a sister planet earth. In the beginning of the space age were also numerous
missions to the veiled planet, hoping to discover more of its enigmatic surface.
The first probe who managed to reach the planet was the American Mariner 2, 1962. The earlier probe Mariner 1was lost
shortly after launch. Mariner 2 discovered the retrograde movement of Venus, studied the atmosphere and climate and found
no magnetic field.
Five years later the probe Mariner 5 was sent to Venus. Mariner 5 was a backup probe Mariner 4, which was sent to Mars.
The Mariner 5 investigated especially the effect of the absence of a magnetic field around Venus. A third Mariner who
visited the planet Venus, Mariner 10 was on his way to Mercury. This probe, however, yielded little new information about
Venus.
Meanwhile, since 1961 the USSR had tried to reach Venus. Only in 1967 the Venera 4 managed to reach the planet. Venera 4
dived into the atmosphere and took direct measurements of temperature, pressure and wind speeds. Successive Veneras 5 and
6 went down into the Venus atmosphere. The logical next step was the Venera 7 who first performed a successful landing on
Venus. For 23 minutes, sent the landing capsule measurements from the planet's surface by. Venera 8 held the 50 minutes,
and in 1975 became the first probe Venera 9, which provided us pictures of the Venus surface. Venera 10 did exactly the
same. The USSR launched until 1983 probes to Venus. The Venera 13 sent color images of the surface. Venera 15 and 16 were
equipped strong radars which brought the surface of the planet roughly in card.
The sequel to the Venera probes were the Vega 1 and 2 which in 1985 flew past Venus on its way to the comet called Halley.
During their passage past Venus they left two probes descent down which did extensive measurements of the atmosphere and
after their landing investigated a soil sample.
Meanwhile, NASA had launched a new Venus mission in 1978, the Pioneer Venus. This probe consisted of an orbiter, which the
atmosphere, magneto atmosphere and examined the surface of the planet, and four descent modules did detailed measurements
of the Venus Clouds while flying on a parachute through the atmosphere.
The Pioneer Venus orbiter was reactivated in 1991 to explore the south pole of the planet and the probe in 1992, burned up
in the atmosphere of Venus.
In 1990, the Galileo Jupiter probe flew past Venus. The probe took some photos but was not equipped for scientific
observations of Venus.
The latest Venus Mission was Magellan, who also arrived in 1990 and aimed the surface of the planet had to make very
detailed map. Before the probe had a very strong radar on board, who could see through the clouds. In 1994, it lost
contact with Magellan, but in the meantime had the probe us know a whole new dynamic planet with active volcanism and a
very young surface.
Venus Express:
Venus Express is an unmanned spacecraft sent by the European Space Agency to the planet Venus.
The launch took place at the Baikonur cosmodrome in Kazakhstan on November 9, 2005 4:33 pm with a Russian Soyuz rocket
equipped with a Fregat "upper stage. After peeling the third state brought a first ignition of the Frigate spacecraft in a
circular 'parking orbit' around the Earth. 82 minutes later made a second ignition sure the spacecraft began its
interplanetary journey. 1 hour and 36 minutes after launch, the spacecraft Frigate was disconnected. Interplanetary voyage
lasted 153 days. The operational orbit of Venus Express is a 24-hour, highly elliptical polar orbit. The lowest and
highest point of the at resp. 250 and 66 000 km from the surface of the planet.
The surface of Venus is invisible because it always hides under a thick cloud, but Venus Express will also explore the
planet's surface. This is done by observing in the infrared: the cloud appears to let certain wavelengths in the infrared
range.
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