Wednesday 12 November 2014

Rosetta

Europe's comet chaser

Rosetta orbiting Comet 67P/Churyumov-Gerasimenko



In November 1993, the International Rosetta Mission was approved as a Cornerstone Mission in ESA's Horizons 2000 Science Programme.
Since then, scientists and engineers from all over Europe and the United States have been combining their talents to build an orbiter and a lander for this unique expedition to unravel the secrets of a mysterious 'mini' ice world – a comet.
Initially scheduled for January 2003, the launch of Rosetta had been postponed due to a failure of an Ariane rocket in December 2002. The adventure began March 2004, when a European Ariane 5 rocket lifted off from Kourou in French Guiana.
During a circuitous ten-year trek across the Solar System, Rosetta will cross the asteroid belt and travel into deep space, more than five times Earth’s distance from the Sun. Its destination will be a periodic comet known as Comet 67P/Churyumov-Gerasimenko.
The Rosetta orbiter will rendezvous with Comet 67P/Churyumov-Gerasimenko and remain in close proximity to the icy nucleus as it plunges towards the warmer inner reaches of the Sun’s domain. At the same time, a small lander will be released onto the surface of this mysterious cosmic iceberg.
More than a year will pass before the remarkable mission draws to a close in December 2015. By then, both the spacecraft and the comet will have circled the Sun and be on their way out of the inner Solar System.

Historic mission

The Rosetta mission will achieve many historic firsts.
  • Rosetta will be the first spacecraft to orbit a comet’s nucleus.
  • It will be the first spacecraft to fly alongside a comet as it heads towards the inner Solar System.
  • Rosetta will be the first spacecraft to examine from close proximity how a frozen comet is transformed by the warmth of the Sun.
  • Shortly after its arrival at Comet 67P/Churyumov-Gerasimenko, the Rosetta orbiter will despatch a robotic lander for the first controlled touchdown on a comet nucleus.
  • The Rosetta lander’s instruments will obtain the first images from a comet’s surface and make the first in situ analysis to find out what it is made of.
  • On its way to Comet 67P/Churyumov-Gerasimenko, Rosetta will pass through the main asteroid belt, with the option to be the first European close encounter with one or more of these primitive objects.
  • Rosetta will be the first spacecraft ever to fly close to Jupiter’s orbit using solar cells as its main power source.
Scientists will be eagerly waiting to compare Rosetta’s results with previous studies by ESA’s Giotto spacecraft and by ground-based observatories. These have shown that comets contain complex organic molecules - compounds that are rich in carbon, hydrogen, oxygen and nitrogen.
Intriguingly, these are the elements which make up nucleic acids and amino acids, the essential ingredients for life as we know it. Did life on Earth begin with the help of comet seeding? Rosetta may help us to find the answer to this fundamental question.
Why rosetta?
The Rosetta Stone, discovered in 1799
The European Space Agency's unprecedented mission of cometary exploration is named after the famous 'Rosetta Stone'. This slab of volcanic basalt - now in the British Museum in London – was the key to unravelling the civilisation of ancient Egypt.
French soldiers discovered the unique Stone in 1799, as they prepared to demolish a wall near the village of Rashid (Rosetta) in Egypt's Nile delta. The carved inscriptions on the Stone included hieroglyphics – the written language of ancient Egypt – and Greek, which was readily understood. After the French surrender in 1801, the 762-kilogram stone was handed over to the British.
By comparing the inscriptions on the stone, historians were able to begin deciphering the mysterious carved figures. Most of the pioneering work was carried out by the English physician and physicist Thomas Young, and the French scholar Jean François Champollion. As a result of their breakthroughs, scholars were at last able to piece together the history of a long-lost culture.
Just as the Rosetta Stone provided the key to an ancient civilisation, so ESA's Rosetta spacecraft will unlock the mysteries of the oldest building blocks of our Solar System – the comets. As the worthy successor of Champollion and Young, Rosetta will allow scientists to look back 4600 million years to an epoch when no planets existed and only a vast swarm of asteroids and comets surrounded the Sun.

History of cometary missions
International cometary explorer ( ICE )
                                                      International Cometary Explorer (ICE)
Launched on 12 August 1978, ICE achieved the first-ever comet encounter. This NASA spacecraft was originally known as ISEE-3 (International Sun-Earth Explorer). Having completed its original mission, it was reactivated and diverted to pass through the tail of Comet Giacobini-Zinner on 11 September 1985, coming within approximately 7860 kilometres of the comet at closest approach. It also flew through the tail of Comet Halley on 28 March 1986, at a distance of 31 million kilometres from the comet's nucleus.
Although NASA officially ceased contact with ICE in 1997, on 29 May 2014 a group named the ISEE-3 Reboot Project reestablished two-way communication with the spacecraft, finding it to still be in good working order.
Vega 1 and Vega 2
Launched on 15 and 21 December 1984, these two Russian probes each left a lander on the surface of Venus as they flew past it in June 1985 on the way to investigate and photograph Comet Halley.
Vega-1 made its closest approach to the comet on 6 March 1986 at a distance of 8890 kilometres. Vega-2 flew in closer to the comet nucleus at a distance of 8030 kilometres on 9 March 1986.
Sakigake and suisei
Launched on 7 January 1985 and 18 August 1985, these twin spacecraft were Japan’s first deep-space missions and aimed to explore comet Halley on its journey into the inner Solar System in 1986.
Suisei approached to within 151 000 kilometres of Comet Halley on 8 March 1986 to observe its interactions with the solar wind. Sakigake approached to within seven million kilometres of the comet on 11 March 1986.
Giotto
Launched 2 July 1985, ESA’s Giotto was the first European deep space mission. This spacecraft obtained the closest pictures ever taken of a comet.
Giotto flew past the nucleus of Comet Halley at a distance of less than 600 kilometres on 13 March 1986.
Images showed a black, potato-shaped object with active regions which were firing jets of gas and dust into space. Giotto then became the first spacecraft to visit two comets when it passed within 200 kilometres of Comet Grigg-Skjellerup on 10 July 1992.
Giotto was placed in hibernation on 23 July 1992, and the spacecraft has since been inactive. Giotto returned to the vicinity of the Earth on 1 July 1999. The distance of its closest approach was very uncertain, the estimate being about 220 000 kilometres, just over half the Earth-to-Moon distance. No communication with the spacecraft took place at this time.
Giotto will continue to orbit the Sun for the foreseeable future, completing six revolutions roughly every seven years.
Deep space 1
This was the first spacecraft in NASA’s New Millennium programme. Launched on 24 October 1998, its primary mission was to test 12 new advanced technologies. It approached within 26 kilometres of Asteroid 9969 Braille on 29 July 1999.
The few pictures returned showed that Braille's longest side is about 2.2 kilometres across and its shortest side appears to be about one kilometre. In an extended mission, Deep Space 1 encountered Comet Borrelly on 22 September 2001 and returned images and other science data. The spacecraft was retired on 18 December 2001.
Stardust

Launched 7 February 1999, this NASA mission travelled into the cloud of ice and dust that surround the nucleus of Comet Wild 2, coming to within 240 kilometres (150 miles) of the nucleus itself on 2 January 2004. There, it gathered comet dust particles and delivered them back to Earth in 2006.
In an extended mission phase known as Stardust-NExT (New Exploration of Tempel 1), the spacecraft visited Comet Tempel 1 in 2011, the comet that was the target of the Deep Impact mission (see below).
Contour ( comet nucleus tour)
Launched on 3 July 2002, Contour was a NASA mission to improve our understanding of comet nuclei. Encounters were planned with two comets.
The spacecraft remained in orbit around the Earth until 15 August 2002, when it began manoeuvres to move onto a heliocentric, comet-chasing orbit. NASA controllers were not able to re-establish contact with the spacecraft following this and concluded that Contour was lost.
Deep impact
NASA's Deep Impact mission launched on 12 January 2005. It consisted of two craft. The main spacecraft performed a flyby of Comet Tempel 1 and recorded images and data. The second craft was the ‘impactor’, which was propelled into a target site on the comet in July 2005. The impact excavated debris from the comet, allowing the main spacecraft to analyse the composition of surface and interior materials of a comet.
In an extended mission phase, Deep Impact was reassigned as EPOXI, a combination of two missions: DIXI, Deep Impact Extended Investigation Mission, and EPOCh, Extrasolar Planet Observation and Characterisation. The EPOCh phase was carried out en route to Comet Hartley 2, which it flew past on 4 November 2010.
EPOXI went on to observe Comet Garradd from afar in February and April of 2012, studying its orbit and surface activity. In February 2013 the spacecraft also observed Comet ISON.
NASA lost contact with the probe in August 2013, and ceased attempts to re-establish communications the following month.
Rosetta
ESA's Rosetta mission was launched on 2 March 2004. It has spent ten years in space, passed by two asteroids (2867 Steins in 2008 and 21 Lutetia in 2010) and will reach Comet 67P/Churyumov-Gerasimenko in 2014. Rosetta will follow the comet as it orbits around the Sun, and will be the first mission to attempt a landing onto a comet nucleus.
Why

Tuesday 11 November 2014

Porsche

Welcome to porsche
history of porsche


                                               



                                     





                                   









                                




                                 

thank you for watching

























Sunday 9 November 2014

Felix Sturm

Felix Sturm (born 31 January 1979) is a German boxer of Bosnian descent. Sturm competes in the middleweight division, where he is the former IBF champion, former WBO champion, and a two time former WBA champion.


Amateur career
Highlights included:
  • 1997 2nd place at Light Middleweight in German National Championships, losing to Jürgen Brähmer on points
  • 1998 German National Light Middleweight champion, defeating Jorg Rosomkiewicz
  • 1999 competed at the World Championships in Houston, United States; as a Light Middleweight. Results were:
    • Defeated Andrei Tsurkan (Ukraine) points
    • Lost to Yermakhan Ibraimov (Kazakhstan) points
  • 1999 German National Light Middleweight champion, defeating Jorg Rosomkiewicz
  • 2000 1st place at Light Middleweight at European Championships in Tampere, Finland. Results were:
    • Defeated Karoly Balzsay (Hungary) points
    • Defeated Miroslaw Nowosada (Poland) points
    • Defeated Dmitri Usagin (Bulgaria) points
    • Defeated Andrei Mishin (Russia) 3-1
  • Represented Germany at the 2000 Olympic Games in Sydney, Australia. Results were:
    • Defeated Dilshod Yarbekov (Uzbekistan) points
    • Defeated Richard Rowles (Australia) TKO 3
    • Lost to Jermain Taylor (United States) points

Professional career
On 27 January 2001, Sturm made his debut as a professional boxer facing Antonio Ribeiro from Angola. Six months earlier he had qualified for the Olympic Games in Sydney, but lost his fight to future middleweight champ Jermain Taylor.
After 16 successful matches, Sturm won the WBO Inter-Continental middleweight title on 10 May 2003. On 13 September 2003, he replaced the injured Bert Schenk in a WBO title bout against Argentinian Hectór Javier Velazco and won the match. Sturm defended the title against Rubén Varón Fernández from Spain.
On 5 June 2004 in Las Vegas, Sturm faced Oscar De La Hoya in a defense of his WBO middleweight championship. All three judges scored the fight 115-113 for De La Hoya, while Harold Lederman scored the fight 115-113 for Sturm. Compubox counted Sturm as landing 234 of 541 punches, while counting De La Hoya as landing 188 of 792. Sturm protested the decision with the Nevada Athletic Commission to no avail.
On 11 March 2006, Sturm defeated Maselino Masoe for the WBA middleweight title by a unanimous decision. Sturm then lost his title against former champion Javier Castillejovia TKO on 15 July 2006 but won it back from Castillejo in a rematch on 28 April 2007 by a twelve round unanimous decision in Oberhausen, which he earned after defeating Gavin Topp by TKO in the sixth round.
Sturm became a three-time world champion after defeating Castillejo in the rematch.
He also fought Randy Griffin twice, drawing with him in their first fight and winning their second fight by unanimous decision.
On November 2, 2008, Sturm retained his WBA middleweight title via unanimous decision (118-110, 118-110 and 119-109) over Sebastian Sylvester. He improved to 31-2, with one draw, while Sylvester fell to 31-3.
On July 11, 2009 he defended his title against Khoren Gevor in NuerburgGermany in 12 rounds.
After over a year of inactivity Sturm came back to defend his WBA title against Giovanni Lorenzo, with the winner becoming the WBA "Super" champion. Sturm defeated Lorenzo by a twelve round unanimous decision with the judges giving a comfortable 117-111 twice and 118-111 on the scorecards.

Sturm vs. Macklin

On the 25th of June 2011 he defended his title in the Lanxness Arena against Matthew Macklin of Ireland. Sturm got off to a slow start and absorbed many heavy blows in the first few rounds. Sturm came back strongly however and kept the fight competitive in the middle rounds. Macklin however closed strongly and the fight went to the cards. Sturm would win by a close split decision, something that was heavily criticized by the boxing media, who felt that Macklin had done enough to win the title.

Sturm vs. Murray

Sturm would finish 2011 by challenging British contender Martin Murray. This bout proved competitive with both men having their share of high moments. Sturm would go on to retain his title via a draw, a result that appeared fair to most.
In his latest fight on April 13, 2012, Sturm beat Sebastian Zbik via brutal TKO in the 9th round something WBC Champion Julio César Chávez, Jr. was not able to achieve.

Sturm vs. Geale

Sturm took on IBF Champion Daniel Geale in a fight that was arguably his toughest challenge since Oscar De La Hoya in 2004, on September 1, 2012, in Oberhausen, Germany. Geale's unorthodox swarming, inside and outside tactics frequently befuddled Sturm. Geale would defeat Sturm with a well deserved split-decision win.

Sturm vs. Soliman

Five months later, he returned in an IBF Eliminator to face longtime contender Sam Soliman, after a strong start & scoring a knockdown in round two, Sturm faded down the stretch, allowing Soliman to take advantage and win a close unanimous decision victory. However, Soliman failed a post fight drug test and the result was vacated.
Sturm set his sights on Montenegrin boxer Predrag Radošević in a non-title 12 round bout in his home nation of Germany. Sturm won by a fourth round TKO.

Sturm vs. Barker

On December 7, 2013, in Stuttgart, Sturm faced reigning IBF champion Darren Barker in a title fight. In the second round Sturm knocked down the champion with a shot that caused him to suffer a severe hip injury and after a second knockdown in the round Barker's corner threw in the towel to stop the contest, making Sturm a four-time world champion.

Sturm vs. Soliman II

Sturm' reign however would prove short-lived. Sturm's next fight was a rematch against former opponent Sam Soliman. Sturm was dominated in their match, throwing nearly three times fewer punches than Soliman, and losing a wide unanimous decision.

Fall of the Berlin Wall ( Fall der Berliner Mauer)

How I missed the fall of the Wall

The NVA military service ID of the author. 
It is November 9, 1989. The day the Berlin Wall falls. And I get nothing with it. For while in Berlin events on beat, I am a soldier of the NVA and squat clueless in my barracks. Also, I can not remember how I got the message from the fall of the wall myself. But not only is it my way.

In November 1989, I am 20 years old and for a year at the National People's Army (NVA). I am completing my 18-month basic military service in the air defense in Schwerin. Half a year I have ahead of me. That it ferments for weeks and months in the GDR, demonstrations, occupations and mass escapes message, which I get in the barracks with only little. It's hard to get a picture of the situation in the country, which is independent of the opinion of the state media and political officers.

Shift the army action against its own people?

An impression of this situation I get when I go in early October for a two night getaway home. In the train I'm going for my uniform (soldiers had to travel in uniform) insulted as Stasi pig and threatened.

After October 7, the 40th and last anniversary of the GDR, but can then also in the department no longer conceal what is out there in the cities and on the roads of the country going on. Only the effects on us are absolutely terrifying. It is total output and furloughs. The guards are strengthened, the armories controlled even more than it already is usual anyway. Would use the command to support the police in protests in Schwerin, the neighboring Motorized Rifle Regiment would be disengaged and we have taken over their rearguard. This much we know.

The decisive statement falls - and no one gets it

That Erich Honecker had issued the secret order no. 8/89 on September 26, were, according to the DDR-hostile riots "to prevent from the outset," we do not know about it. The mood is tense. The anxiety to get the command to fire on its own people, is great. However, all units remain in the barracks.

On October 18, we received the order, the DDR main news program "Current Camera" to see. This Egon Krenz announced the resignation of Honecker and takes over his post. The historic press conference with Schabowski on November 9, sees no one. Because nobody looks at these types of voluntary programs. And so no one hears about 18.53 clock the crucial sentence: "private trips abroad can without proof of eligibility (...) can be applied (...) Permanent departures can be made through all border crossing points of the GDR to the FRG.."

A memory lapse and many small changes

They will most likely have informed us about the statement and its dramatic consequences on the following day at morning roll call. But as already written. I can not remember. Surprisingly, it goes all the comrades with whom I served at that time and I asked this on the occasion of this story, as well. For us, the NVA soldiers and sworn in on the GDR, will not be affected by the wall opening. That may have been the setting based on our experience and have caused the memory gap.

But then many things will be different for us. Albeit in small steps. Change almost daily our service provisions and expand to small freedoms. The policy lesson is abolished. Instead of "Comrade" we are addressed as "sir". We are allowed to wear civilian clothes in output and received in the West Barracks media. Overall, the service is a little looser. And then we get back our identity cards, which had to give up any NVA soldier before the convocation. With the pass we are allowed to travel to West Germany in the output or even leave now.

Return to another country

When I after my 1990 New Year's holidays arrive early January again in the barracks, makes the first morning roll call, the message of the shortening of the period of military service from 18 to twelve months for huge cheers. For my born January 26, 1990 is the day of discharge. So I go back 15 months in a country that is a completely different, and in which nothing will be as it once was. A country that prevail in the euphoria and optimism. I have all of what led to so little noticed is the worst memory gap in my life for me. But the decisive factor is that it has happened.

Fall der Berliner Mauer ( Fall of the Berlin Wall )

Wie ich den Fall der Mauer verpasste



Der NVA-Wehrdienstausweis des Autors. (Quelle: privat)

Es ist der 9. November 1989. Der Tag an dem die Berliner Mauer fällt. Und ich bekomme nichts davon mit. Denn während sich in Berlin die Ereignisse überschlagen, bin ich Soldat der NVA und hocke ahnungslos in meiner Kaserne. Auch kann ich mich nicht erinnern, wie mich die Nachricht vom Mauerfall erreicht. Doch nicht nur mir geht es so.

Im November 1989 bin ich 20 Jahre alt und seit einem Jahr bei der Nationalen Volksarmee (NVA). Ich absolviere meinen 18-monatigen Grundwehrdienst bei der Luftabwehr in Schwerin. Ein halbes Jahr habe ich noch vor mir. Dass es seit Wochen und Monaten in der DDR gärt, von Demonstrationen, Botschaftsbesetzungen und Massenfluchten, davon bekomme ich in der Kaserne nur wenig mit. Es ist schwer, sich ein Bild von der Lage im Land zu machen, das unabhängig von der Meinung der Staatsmedien und Politoffiziere ist.

Rückt die Armee gegen das eigene Volk vor?

Einen Eindruck von dieser Lage bekomme ich, als ich Anfang Oktober für einen zweitägigen Kurzurlaub nach Hause fahre. Im Zug werde ich wegen meiner Uniform (Soldaten mussten in Uniform reisen) als Stasischwein beschimpft und bedroht.
Nach dem 7. Oktober, dem 40. und zugleich letzten Jahrestag der DDR, lässt sich dann aber auch in der Dienststelle nicht mehr verheimlichen, was da draußen in den Städten und auf den Straßen des Landes los ist. Nur sind die Auswirkungen auf uns absolut erschreckend. Es herrscht absolute Ausgangs- und Urlaubssperre. Die Wachen werden verstärkt, die Waffenkammern noch stärker kontrolliert als es ohnehin schon üblich ist. Käme der Einsatzbefehl, die Polizei beim Vorgehen gegen Demonstranten in Schwerin zu unterstützen, wäre das benachbarte Motorisierte Schützenregiment ausgerückt und wir hätten deren Nachhut übernommen. So viel wissen wir.

Der entscheidende Satz fällt - und niemand bekommt es mit

Dass Erich Honecker am 26. September den Geheimbefehl Nr. 8/89 erlassen hatte, laut dem DDR-feindliche Krawalle "von vornherein zu unterbinden" seien, wissen wir dagegen nicht. Die Stimmung ist angespannt. Die Angst, den Befehl zu erhalten, auf das eigene Volk zu schießen, ist groß. Doch alle Einheiten bleiben in den Kasernen.
Am 18. Oktober erhalten wir den Befehl, die DDR-Hauptnachrichtensendung "Aktuelle Kamera" anzusehen. Darin verkündet Egon Krenz den Rücktritt Honeckers und übernimmt dessen Posten. Die geschichtsträchtige Pressekonferenz mit Günter Schabowski am 9. November sieht niemand. Denn freiwillig schaut keiner diese Art von Sendungen. Und so hört auch keiner um 18.53 Uhr den entscheidenden Satz: "Privatreisen nach dem Ausland können ohne Vorliegen von Voraussetzungen (…) beantragt werden. (…) Ständige Ausreisen können über alle Grenzübergangsstellen der DDR zur BRD erfolgen."

Eine Erinnerungslücke und viele kleine Änderungen

Vermutlich wird man uns über die Aussage und ihre dramatischen Folgen am darauffolgenden Tag beim Morgenappell informiert haben. Doch wie eingangs schon geschrieben. Erinnern kann ich mich nicht. Überraschenderweise geht es allen Kameraden, mit denen ich damals diente und die ich aus Anlass dieser Geschichte dazu befragte, genauso. Für uns, Soldaten der NVA und vereidigt auf die DDR, wird sich durch die Maueröffnung nichts ändern. Das mag aufgrund unserer Erfahrungen die Einstellung gewesen sein und die Erinnerungslücke verursacht haben.
Doch dann wird auch für uns vieles anders. Wenn auch in kleinen Schritten. Fast täglich ändern sich unsere Dienstvorschriften und erweitern sich um kleinen Freiheiten. Der Politikunterricht wird abgeschafft. Statt mit "Genosse" werden wir mit "Herr" angeredet. Wir dürfen im Ausgang Zivilkleidung tragen und in der Kaserne Westmedien empfangen. Insgesamt wird der Dienst etwas lockerer. Und dann erhalten wir unsere Personalausweise zurück, die jeder NVA-Soldat vor der Einberufung abgeben musste. Mit dem Pass dürfen wir im Ausgang oder Urlaub nun sogar in die BRD reisen.

Rückkehr in ein anderes Land

Als ich Anfang Januar 1990 nach meinem Silvesterurlaub wieder in der Kaserne eintreffe, sorgt beim ersten Morgenappell die Meldung von der Verkürzung der Wehrdienstzeit von 18 auf zwölf Monate für Riesenjubel. Für meinen Jahrgang wird der 26. Januar 1990 zum Entlassungstag. So gehe ich nach 15 Monaten zurück in ein Land, das ein völlig anderes ist, und in dem nichts mehr so sein wird, wie es einmal war. Ein Land, in dem Euphorie und Aufbruchsstimmung herrschen. Dass ich von all dem was dazu führte so wenig mitbekommen habe, ist für mich die schlimmste Erinnerungslücke meines Lebens. Entscheidend aber ist, dass es passiert ist.  


Berlin Wall ( Berliner Mauer )

The Berlin Wall (GermanBerliner Mauer) was a barrier that existed from 1961 through 1989, constructed by the German Democratic Republic (GDR, East Germany) starting on 13 August 1961, that completely cut off (by land) West Berlin from surrounding East Germany and from East Berlin until it was opened in 1989.The barrier included guard towers placed along large concrete walls, which circumscribed a wide area (later known as the "death strip") that contained anti-vehicle trenches, "fakir beds" and other defenses. The Eastern Bloc claimed that the wall was erected to protect its population from fascist elements conspiring to prevent the "will of the people" in building a socialist state in East Germany. In practice, the Wall served to prevent the massiveemigration and defection that marked East Germany and the communist Eastern Bloc during the post-World War II period.
The Berlin Wall was officially referred to as the "Anti-Fascist Protection Rampart" (GermanAntifaschistischer Schutzwall) by GDR authorities, implying that the NATO countries and West Germany in particular were "fascists."The West Berlin city government sometimes referred to it as the "Wall of Shame"—a term coined by mayor Willy Brandt—while condemning the Wall's restriction onfreedom of movement. Along with the separate and much longer Inner German border (IGB), which demarcated the border between East and West Germany, it came to symbolize the "Iron Curtain" that separated Western Europe and the Eastern Bloc during theCold War.
Before the Wall's erection, 3.5 million East Germans circumvented Eastern Bloc emigration restrictions and defected from the GDR, many by crossing over the border from East Berlin into West Berlin, from where they could then travel to West Germany and other Western European countries. Between 1961 and 1989, the wall prevented almost all such emigration.During this period, around 5,000 people attempted to escape over the wall, with an estimated death toll of from 136 to more than 200 in and around Berlin.
In 1989, a series of radical political changes occurred in the Eastern Bloc, associated with the liberalization of the Eastern Bloc's authoritarian systems and the erosion of political power in the pro-Soviet governments in nearby Poland and Hungary. After several weeks of civil unrest, the East German government announced on 9 November 1989 that all GDR citizens could visit West Germany and West Berlin. Crowds of East Germans crossed and climbed onto the wall, joined by West Germans on the other side in a celebratory atmosphere. Over the next few weeks, euphoric public and souvenir hunters chipped away parts of the wall; the governments later used industrial equipment to remove most of what was left. Contrary to popular belief the wall's actual demolition did not begin until Summer 1990 and was not completed until 1992. The fall of the Berlin Wall paved the way for German reunification, which was formally concluded on 3 October 1990.

The Eastern Bloc and the Berlin airlift

Further information: Eastern Bloc and Berlin Blockade
Following World War II, Soviet leader Joseph Stalin headed a union of nations on his Western border, the Eastern Bloc, that then included Poland, Hungary and Czechoslovakia, which he wished to maintain alongside a weakened Soviet-controlled Germany.[10] As early as 1945, Stalin revealed to German communist leaders that he expected to slowly undermine the British position within the British occupation zone, that the United States would withdraw within a year or two, and that nothing would then stand in the way of a united communist Germany within the bloc.
The major task of the ruling communist party in the Soviet zone was to channel Soviet orders down to both the administrative apparatus and the other bloc parties, which in turn would be presented as internal measures. Property and industry was nationalized in the East German zone. If statements or decisions deviated from the described line, reprimands and, for persons outside public attention, punishment would ensue, such as imprisonment, torture and even death.
Indoctrination of Marxism-Leninism became a compulsory part of school curricula, sending professors and students fleeing to the West. The East Germans created an elaborate political police apparatus that kept the population under close surveillance, including SovietSMERSH secret police.
In 1948, following disagreements regarding reconstruction and a new German currency, Stalin instituted the Berlin Blockade, preventing food, materials and supplies from arriving in West Berlin. The United States, Britain, France, Canada, Australia, New Zealand and several other countries began a massive "airlift", supplying West Berlin with food and other supplies.[17] The Soviets mounted a public relations campaign against the western policy change. Communists attempted to disrupt the elections of 1948, preceding large losses therein, while 300,000 Berliners demonstrated for the international airlift to continue. In May 1949, Stalin lifted the blockade, permitting the resumption of Western shipments to Berlin.
The German Democratic Republic (East Germany) was declared on 7 October 1949. By a secret treaty, the Soviet Ministry of Foreign Affairs accorded the East German state administrative authority, but not autonomy. The Soviets penetrated East German administrative, military and secret police structures and had full control.
East Germany differed from West Germany (Federal Republic of Germany), which developed into a Western capitalist country with a social market economy ("Soziale Marktwirtschaft" in German) and a democratic parliamentary government. Continual economic growth starting in the 1950s fuelled a 20-year "economic miracle" ("Wirtschaftswunder"). As West Germany's economy grew, and its standard of living steadily improved, many East Germans wanted to move to West Germany.

Emigration westward in the early 1950s

After the Soviet occupation of Eastern Europe at the end of World War II, the majority of those living in the newly acquired areas of theEastern Bloc aspired to independence and wanted the Soviets to leave.Taking advantage of the zonal border between occupied zones in Germany, the number of GDR citizens moving to West Germany totaled 187,000 in 1950; 165,000 in 1951; 182,000 in 1952; and 331,000 in 1953. One reason for the sharp 1953 increase was fear of potential further Sovietization, given the increasingly paranoid actions of Joseph Stalin in late 1952 and early 1953. 226,000 had fled in just the first six months of 1953.

Erection of the inner German border
By the early 1950s, the Soviet approach to controlling national movement, restricting emigration, was emulated by most of the rest of the Eastern Bloc, including East Germany.The restrictions presented a quandary for some Eastern Bloc states, which had been more economically advanced and open than the Soviet Union, such that crossing borders seemed more natural—especially where no prior border existed between East and West Germany.
Up until 1952, the lines between East Germany and the western occupied zones could be easily crossed in most places. On 1 April 1952, East German leaders met the Soviet leader Joseph Stalin in Moscow; during the discussions Stalin's foreign minister Vyacheslav Molotov proposed that the East Germans should "introduce a system of passes for visits of West Berlin residents to the territory of East Berlin [so as to stop] free movement of Western agents" in the GDR. Stalin agreed, calling the situation "intolerable". He advised the East Germans to build up their border defenses, telling them that "The demarcation line between East and West Germany should be considered a border—and not just any border, but a dangerous one ... The Germans will guard the line of defence with their lives."
Consequently, the inner German border between the two German states was closed, and a barbed-wire fence erected. The border between the Western and Eastern sectors of Berlin, however, remained open, although traffic between the Soviet and the Western sectors was somewhat restricted. This resulted in Berlin becoming a magnet for East Germans desperate to escape life in the GDR, and also a flashpoint for tension between the United States and the Soviet Union.
In 1955, the Soviets gave East Germany authority over civilian movement in Berlin, passing control to a regime not recognized in the West. Initially, East Germany granted "visits" to allow its residents access to West Germany. However, following the defection of large numbers of East Germans under this regime, the new East German state legally restricted virtually all travel to the West in 1956.Soviet East German ambassador Mikhail Pervukhin observed that "the presence in Berlin of an open and essentially uncontrolled border between the socialist and capitalist worlds unwittingly prompts the population to make a comparison between both parts of the city, which unfortunately, does not always turn out in favor of the Democratic [East] Berlin."

The Berlin emigration loophole

With the closing of the inner German border officially in 1952, the border in Berlin remained considerably more accessible then because it was administered by all four occupying powers.Accordingly, Berlin became the main route by which East Germans left for the West.On 11 December 1957, East Germany introduced a new passport law that reduced the overall number of refugees leaving Eastern Germany.
It had the unintended result of drastically increasing the percentage of those leaving through West Berlin from 60% to well over 90% by the end of 1958.Those caught trying to leave East Berlin were subjected to heavy penalties, but with no physical barrier and subway train access still available to West Berlin, such measures were ineffective.The Berlin sector border was essentially a "loophole" through which Eastern Bloc citizens could still escape.The 3.5 million East Germans who had left by 1961 totalled approximately 20% of the entire East German population.
An important reason that the West Berlin border was not closed earlier was that doing so would cut off much of the railway traffic in East Germany. Construction of a new railway bypassing West Berlin, the Berlin outer ring, commenced in 1951. Following the completion of the railway in 1961, closing the barrier became a more practical position.

Construction begin , 1961
On 15 June 1961, First Secretary of the Socialist Unity Party and GDR State Council chairman Walter Ulbricht stated in an international press conference, "Niemand hat die Absicht, eine Mauer zu errichten!" (No one has the intention of erecting a wall!). It was the first time the colloquial term Mauer (wall) had been used in this context.
The transcript of a telephone call between Nikita Khrushchev and Ulbricht on 1 August in the same year, suggests that the initiative for the construction of the wall came from Khrushchev.However, other sources suggest that Khrushchev had initially been wary about building a wall, fearing negative Western reaction. What is beyond dispute, though, is that Ulbricht had pushed for a border closure for quite some time, arguing that East Germany's very existence was at stake.
Khrushchev had been emboldened by US President John F. Kennedy’s tacit indicationthat the US would not actively oppose this action in the Soviet sector of Berlin.On Saturday, 12 August 1961, the leaders of the GDR attended a garden party at a government guesthouse in Döllnsee, in a wooded area to the north of East Berlin. There Ulbricht signed the order to close the border and erect a wall.
At midnight, the police and units of the East German army began to close the border and, by Sunday morning, 13 August, the border with West Berlin was closed. East German troops and workers had begun to tear up streets running alongside the border to make them impassable to most vehicles and to install barbed wire entanglements and fences along the 156 kilometres (97 mi) around the three western sectors, and the 43 kilometres (27 mi) that divided West and East Berlin.
The barrier was built slightly inside East Berlin or East German territory to ensure that it did not encroach on West Berlin at any point. Later, it was built up into the Wall proper, the first concrete elements and large blocks being put in place on 17 August. During the construction of the Wall, National People's Army (NVA) and Combat Groups of the Working Class (KdA) soldiers stood in front of it with orders to shoot anyone who attempted to defect. Additionally, chain fences, walls, minefields and other obstacles were installed along the length of East Germany's western border with West Germany proper. A huge no man's land was cleared to provide a clear line of fire at fleeing refugees.