The Space Shuttle Columbia disaster occurred when broke up when it was reentering the atmosphere on February 1, 2003. The cause of the disaster was that a piece of foam broke from the external fuel tank. This made a hole in the shuttle's wing. During its entry, hot gases entered the wing, causing it to break up. All of the people on board died when it broke up.
Parts of "Columbia" were found across the state of Texas. The cockpit window is now inside the Pavilion at the Kennedy Space Center in Florida.
"Columbia" launched on its final mission on January 16, 2003. It was "Columbia"'s 28th flight and the 113th of any Shuttle.
81 seconds into flight, a briefcase-sized part of the external fuel tank's foam insulation, which stops ice from forming while the very cold liquid fuel is in the tank, broke away and hit "Columbia". Such debris strikes had happened before - in particular on STS-27 in which a piece of a booster's forward heat shield broke and hit "Atlantis"' bottom-side heat shield - and were seen as an acceptable risk. However, this debris strike hit "Columbia"'s left wing head on, punching a hole through the panels on the wing's forward edge.
Once high-quality video of the launch was ready, NASA reviewed it and concluded that everything was fine, and stopped engineers from using Department of Defense images from orbit to get a closer look. NASA management thought that even if something were wrong, it would be better for the crew not to know since rescue or repair would be nearly impossible. One flight director contacted "Columbia" about the concerns, but stressed "we have seen this same phenomenon on other flights and there is absolutely no concern for [re-]entry."
On February 1, "Columbia" prepared to return to Earth on a path that would take it over the USA from west to east. At 8:15 EST, about an hour before "Columbia" was due to land, it lit its engines and changed its course so that it would re-enter the atmosphere. A 13-minute video recorded in the cabin, ending eleven minutes before the loss of signal from "Columbia", shows the astronauts in good spirits and unaware of the danger. As "Columbia" entered the atmosphere, the air heated up around it due to the Shuttle moving at extreme speeds, over twenty times the speed of sound. This air was able to enter the wing through the hole made during launch, melting through it and causing the Shuttle to lose lift on that side. This loss of lift caused the Shuttle to turn away from its re-entry path, tumble, and break up from the drag of the air.
"Columbia" passed over California at 8:53. Video shows flashes happening and an unusual trail left behind "Columbia", which even hobbyist watchers saw as out of the ordinary. At this point, the temperature of the damaged part of the wing was around 3,000°F (1,650°C). By 8:58 "Columbia", still moving at incredible speeds, crossed from New Mexico into Texas, at which point it began shedding debris. By this point several temperature sensors in the damaged left wing had stopped working, and one of the flight controllers reported that the tyre pressure sensors on that side were reporting "off scale low" - meaning the pressure was so low that the sensors could not read it, or in other words the tyres had melted and no longer contained air. The last communication with commander Rick Husband was ""Roger, uh bu-"" at 8:59. 45 seconds later, video from the ground shows "Columbia" breaking apart. Mission Control began its disaster procedures at 9:12.
Fraternities and sororities
Fraternities and sororities are social groups for college students, though sometimes high schools have them too. They exist mostly in the United States and Europe. The words "frater" and "soror" are Latin for "brother" and "sister" and used to show closeness between members. They also denote whether the group is for men or women. Sororities are only for women. Fraternities are only for men.
Fraternities and sororities often have groups at many different schools. Each fraternity or sorority is given two or three Greek letters to call themselves, for example, ΑΦ (Alpha Phi) or ΑΧΩ (Alpha Chi Omega). To tell the difference between groups at different schools, called chapters, each chapter is given another set of Greek letters. For example, a man in the Kappa Sigma fraternity who goes to the University of Louisiana at Lafayette is part of the fraternity's EX (Epsilon Chi) chapter. Chapters sometimes have houses on or near the campus of the college the members attend that members can live in.
Fraternities and sororities often participate in community service.
Fraternities and sororities are often exclusive, meaning people who want to join need to be invited to do so. This is done during a process called "rushing". During a rush, people who want to join a chapter will talk to current members. If the member think the person rushing is a good fit for the group, they will get an invitation, called a "bid", to join the chapter. If the person rushing accepts, they become a "pledge".
The pledging period is a time when the pledge is not yet a full member, and may leave or be refused membership at any time. Sometimes, members of the chapter will put the pledge through trials. Sometimes they are tests on the history of the fraternity they are trying to join, wearing a badge with the fraternity's letters on it at all times, or performing public service. Sometimes the trials are cruel, dangerous or humiliating. If the trials are cruel, it is called "hazing". Hazing is illegal in 44 states.
After the pledging period, the pledge becomes a full member of the chapter and fraternity or sorority.
Bernese mountain dog
The Bernese mountain dog is a breed of dog from Switzerland.
These dogs are "tricolour", which means their coat of fur is made up of three colors: black, white, and tan. They are gentle, loyal, and good with children. Bernese Mountain Dogs are very large dogs, weighing from 70 to 120 pounds (32 to 54 kilograms) as adults. They were first used to pull carts and worked as all-around farm dogs.
Fire ecology
Fire ecology is about the effects of fire on the ecosystems where it occurs. The results of fire are studied, and also what causes the fires.
In many ecosystems, fire helps keep the habitat healthy. Examples of such habitats are the North American prairie and chaparral ecosystems, and the South African savanna. In these ecosystems, fire helps renew the habitat. In theses places, many plants and trees have adapted and need fire to grow well, or for their seeds to germinate and start ecological succession.
If the fires are stopped, dry wood and dead plants accumulate. Bushes and trees that catch fire easily will start growing. When this area finally does catch fire, it will make the wildfire larger and more damaging, and be harder to control.
In the United States, campaigns have made people believe that wildfires are always bad for nature. This comes from the old belief that ecosystems grow towards a stable system, and disturbances like fires stop that, and destroy the harmony of nature. But we have since learned that in some areas, fire is needed to make the system work properly; fire also helps biodiversity of many habitats. The plants and animals in these habitats have adapted to protect themselves from fire, and sometimes must have fire to survive.
Still, fire can kill people or burn down buildings. Now, controlled burns are sometimes done to have fire where it is needed, but don't let it go where it can cause damage to people or their property.
Goldman Sachs
The Goldman Sachs Group, Inc., or just Goldman Sachs is an investment banking and securities firm. They are involved with global investment banking, securities, investment management, and other financial services mainly with institutional clients. They are also known to be a primary dealer in the United States Treasury security market.
2017-Four have Goldman Sachs USD 7.830.000.000 ("deutsch 7,83 Milliarden Dollar").
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