Our World
Sabtu, 25 April 2009
History Of MS-DOS
Jumat, 24 April 2009
NASA gears up for its last mission to Hubble
After a six-month delay, the final preparations are now underway for the last mission to service the Hubble Space Telescope. If all goes well, the space shuttle Atlantis will launch on the mission a day early, on 11 May.
Ground crews finished installing the last equipment, which includes 180 tools needed to manipulate parts of the telescope, into the shuttle's payload bay on Wednesday, according to Tracy Young of NASA's
Now mission managers are looking to see how much time can be shaved off final preparations and are hoping to launch a day before the current launch target of 12 May.
They want to provide as many days as possible to launch the shuttle before 14 May, when there's a black-out window for shuttle launches that will last until 22 May. During that time, an Air Force facility needed to track shuttle launches will be used for military operations instead.
Flying backwards
During a press briefing on Thursday, NASA officials discussed some of the safety concerns for the mission. Despite initial worries, they said the debris from an unprecedented collision between two satellites in February should not pose a significant risk to the shuttle, even though it will fly at a higher orbit – which lies closer to the debris – than typical shuttle missions to the International Space Station.
Initial estimates put the risk of a catastrophic impact with orbital debris at 1 in 185. But further analysis suggests the mean risk is now 1 in 221, deputy space shuttle programme manager LeRoy Cain told reporters. That risk level is lower than a limit of 1 in 200, above which special approval for the mission would be required by top officials.
The shuttle Atlantis will drop down to a lower orbit after the spacewalks, which will reduce the risk of a collision with orbital debris. The shuttle will also spend as much time as possible flying with its tail forward and its payload bay pointed at Earth, an orientation that protects vulnerable parts, like the shuttle's nose cap.
Top of its game
The 11-day shuttle mission will be the last to visit the iconic telescope. Over the course of five consecutive spacewalks, astronauts will install six new gyroscopes that help the telescope stabilise itself, six new batteries, two new science instruments and repair two others.
The mission is expected to extend Hubble's life until 2014 and provide it with its best vision yet (see Pimp my scope: Revamping Hubble). After the mission, "Hubble will be at the apex of its abilities," Hubble senior project scientist David Leckrone of NASA's
The servicing mission was originally set to fly in October 2008, but was delayed weeks before launch after a problem was discovered in a unit that relays commands and images to and from the telescope's instruments. The delay allowed the Hubble team to prepare a spare unit.
MICROSOFT EXCEL
Senin, 20 April 2009
BERMUDA TRIANGLE
The Bermuda Triangle, also known as the Devil's Triangle, is a region of the northwestern Atlantic Ocean in which a number of aircraft and surface vessels are alleged to have disappeared in mysterious circumstances which fall beyond the boundaries of human error, pirates, equipment failure, or natural disaster. Popular culture has attributed some of these disappearances to the paranormal, a suspension of the laws of physics, or activity by extraterrestrial beings.
A substantial body of documentation exists showing numerous incidents to have been inaccurately reported or embellished by later authors, and numerous official agencies have gone on record as stating that the number and nature of disappearances is similar to any other area of ocean, however proponents of paranormal phenomena claim that many incidents remain unexplained despite considerable investigation.
The Triangle area
The boundaries of the Triangle vary with the author; some stating its shape is akin to a trapezoid covering the Straits of Florida, the Bahamas and the entire Caribbean island area and the Atlantic east to the Azores; others add to it the Gulf of Mexico. The more familiar triangular boundary in most written works has as its points somewhere on the Atlantic coast of Florida; San Juan, Puerto Rico; and the mid-Atlantic island of Bermuda, with most of the accidents concentrated along the southern boundary around the Bahamas and the Florida Straits.
The area is one of the most heavily-sailed shipping lanes in the world, with ships crossing through it daily for ports in the Americas, Europe, and the Caribbean Islands. Cruise ships are also plentiful, and pleasure craft regularly go back and forth between Florida and the islands. It is also a heavily flown route for commercial and private aircraft heading towards Florida, the Caribbean, and South America from points north.
History of the Triangle story
Origins
The first article of any kind in which the legend of the Triangle began appeared in newspapers by E.V.W. Jones on September 16, 1950, through the Associated Press. Two years later, Fate magazine published "Sea Mystery At Our Back Door", a short article by George X. Sand covering the loss of several planes and ships, including the loss of Flight 19, a group of five U.S. Navy TBM Avenger bombers on a training mission. Sand's article was the first to lay out the now-familiar triangular area where the losses took place. Flight 19 alone would be covered in the April 1962 issue of American Legion Magazine. It was claimed that the flight leader had been heard saying "We are entering white water, nothing seems right. We don't know where we are, the water is green, no white." It was also claimed that officials at the Navy board of inquiry stated that the planes "flew off to Mars." This was the first article to connect the supernatural to Flight 19, but it would take another author, Vincent Gaddis, writing in the February 1964 Argosy magazine to take Flight 19 together with other mysterious disappearances and place it under the umbrella of a new catchy name: "The Deadly Bermuda Triangle"; he would build on that article with a more detailed book, Invisible Horizons, the next year. Others would follow with their own works: John Wallace Spencer (Limbo of the Lost, 1969, repr. 1973); Charles Berlitz (The Bermuda Triangle, 1974);[11] Richard Winer (The Devil's Triangle, 1974),[12] and many others, all keeping to some of the same supernatural elements outlined by Eckert.[13]
Kusche's research
Lawrence David Kusche, a research librarian from Arizona State University and author of The Bermuda Triangle Mystery: Solved (1975) has challenged this trend. Kusche's research revealed a number of inaccuracies and inconsistencies between Berlitz's accounts and statements from eyewitnesses, participants, and others involved in the initial incidents. He noted cases where pertinent information went unreported, such as the disappearance of round-the-world yachtsman Donald Crowhurst, which Berlitz had presented as a mystery, despite clear evidence to the contrary. Another example was the ore-carrier Berlitz recounted as lost without trace three days out of an Atlantic port when it had been lost three days out of a port with the same name in the Pacific Ocean. Kusche also argued that a large percentage of the incidents which have sparked the Triangle's mysterious influence actually occurred well outside it. Often his research was surprisingly simple: he would go over period newspapers and see items like weather reports that were never mentioned in the stories.
Kusche came to a conclusion:
- The number of ships and aircraft reported missing in the area was not significantly greater, proportionally speaking, than in any other part of the ocean.
- In an area frequented by tropical storms, the number of disappearances that did occur were, for the most part, neither disproportionate, unlikely, nor mysterious; furthermore, Berlitz and other writers would often fail to mention such storms.
- The numbers themselves had been exaggerated by sloppy research. A boat listed as missing would be reported, but its eventual (if belated) return to port may not have been reported.
- Some disappearances had in fact, never happened. One plane crash was said to have taken place in 1937 off Daytona Beach, Florida, in front of hundreds of witnesses; a check of the local papers revealed nothing.
Kusche concluded that:
- The Legend of the Bermuda Triangle is a manufactured mystery… perpetuated by writers who either purposely or unknowingly made use of misconceptions, faulty reasoning, and sensationalism.
Further responses
When the UK Channel 4 television program "The Bermuda Triangle" (c. 1992) was being produced by John Simmons of Geofilms for the Equinox Programme, the marine insurer Lloyd's of London was asked if an unusually large number of ships had sunk in the Bermuda Triangle area. Lloyd's of London determined that large numbers of ships had not sunk there.
United States Coast Guard records confirm their conclusion. In fact, the number of supposed disappearances is relatively insignificant considering the number of ships and aircraft which pass through on a regular basis.
The Coast Guard is also officially skeptical of the Triangle, noting that they collect and publish, through their inquiries, much documentation contradicting many of the incidents written about by the Triangle authors. In one such incident involving the 1972 explosion and sinking of the tanker V.A. Fogg in the Gulf of Mexico, the Coast Guard photographed the wreck and recovered several bodies, in contrast with one Triangle author's claim that all the bodies had vanished, with the exception of the captain, who was found sitting in his cabin at his desk, clutching a coffee cup.
The NOVA / Horizon episode The Case of the Bermuda Triangle (1976-06-27) was highly critical, stating that "When we've gone back to the original sources or the people involved, the mystery evaporates. Science does not have to answer questions about the Triangle because those questions are not valid in the first place. ... Ships and planes behave in the Triangle the same way they behave everywhere else in the world."
Skeptical researchers, such as Ernest Taves and Barry Singer, have noted how mysteries and the paranormal are very popular and profitable. This has led to the production of vast amounts of material on topics such as the Bermuda Triangle. They were able to show that some of the pro-paranormal material is often misleading or inaccurate, but its producers continue to market it. Accordingly, they have claimed that the market is biased in favour of books, TV specials, etc. which support the Triangle mystery, and against well-researched material if it espouses a skeptical viewpoint.
Finally, if the Triangle is assumed to cross land, such as parts of Puerto Rico, the Bahamas, or Bermuda itself, there is no evidence for the disappearance of any land-based vehicles or persons. The city of Freeport, located inside the Triangle, operates a major shipyard and an airport which annually handles 50,000 flights, and is visited by over a million tourists a year.
Supernatural explanations
Triangle writers have used a number of supernatural concepts to explain the events. One explanation pins the blame on leftover technology from the mythical lost continent of Atlantis. Sometimes connected to the Atlantis story is the submerged rock formation known as the Bimini Road off the island of Bimini in the Bahamas, which is in the Triangle by some definitions. Followers of the purported psychic Edgar Cayce take his prediction that evidence of Atlantis would be found in 1968 as referring to the discovery of the Bimini Road. Believers describe the formation as a road, wall, or other structure, though geologists consider it to be of natural origin.
Other writers attribute the events to UFOs. This idea was used by Steven Spielberg for his science fiction film Close Encounters of the Third Kind, which features the lost Flight 19 as alien abductees.
Charles Berlitz, grandson of a distinguished linguist and author of various additional books on anomalous phenomena, has kept in line with this extraordinary explanation, and attributed the losses in the Triangle to anomalous or unexplained forces.
It has also been thought that the Bermuda Triangle is a wormhole, (a gap in space and time).
Natural explanations
Compass variations
Compass problems are one of the cited phrases in many Triangle incidents. While some have theorized that unusual local magnetic anomalies may exist in the area, such anomalies have not been shown to exist. It should also be remembered that compasses have natural magnetic variations in relation to the Magnetic poles. For example, in the United States the only places where magnetic (compass) north and geographic (true) north are exactly the same are on a line running from Wisconsin to the Gulf of Mexico. Navigators have known this for centuries. But the public may not be as informed, and think there is something mysterious about a compass "changing" across an area as large as the Triangle, which it naturally will.
Deliberate acts of destruction
Deliberate acts of destruction can fall into two categories: acts of war, and acts of piracy. Records in enemy files have been checked for numerous losses; while many sinkings have been attributed to surface raiders or submarines during the World Wars and documented in the various command log books, many others which have been suspected as falling in that category have not been proven. It is suspected that the loss of USS Cyclops in 1918, as well as her sister ships Proteus and Nereus in World War II, were attributed to submarines, but no such link has been found in the German records.
Piracy, as defined by the taking of a ship or small boat on the high seas, is an act which continues to this day. While piracy for cargo theft is more common in the western Pacific and Indian oceans, drug smugglers do steal pleasure boats for smuggling operations, and may have been involved in crew and yacht disappearances in the Caribbean. Piracy in the Caribbean was common from about 1560 to the 1760s, and famous pirates included Edward Teach (Blackbeard) and Jean Lafitte. Lafitte is sometimes said to be a Triangle victim himself.
Gulf Stream
The Gulf Stream is an ocean current that originates in the Gulf of Mexico, and then through the Straits of Florida, into the North Atlantic. In essence, it is a river within an ocean, and like a river, it can and does carry floating objects. It has a surface velocity of up to about 2.5 metres per second (5.6 mph). A small plane making a water landing or a boat having engine trouble will be carried away from its reported position by the current, as happened to the cabin cruiser Witchcraft on December 22, 1967, when it reported engine trouble near the Miami buoy marker one mile (1.6 km) from shore, but was not there when a Coast Guard cutter arrived.
Human error
One of the most cited explanations in official inquiries as to the loss of any aircraft or vessel is human error. Whether deliberate or accidental, humans have been known to make mistakes resulting in catastrophe, and losses within the Bermuda Triangle are no exception. For example, the Coast Guard cited a lack of proper training for the cleaning of volatile benzene residue as a reason for the loss of the tanker V.A. Fogg in 1972. Human stubbornness may have caused businessman Harvey Conover to lose his sailing yacht, the Revonoc, as he sailed into the teeth of a storm south of Florida on January 1, 1958. Many losses remain inconclusive due to the lack of wreckage which could be studied, a fact cited on many official reports.
Hurricanes
Hurricanes are powerful storms which are spawned in tropical waters, and have historically been responsible for thousands of lives lost and billions of dollars in damage. The sinking of Francisco de Bobadilla's Spanish fleet in 1502 was the first recorded instance of a destructive hurricane. These storms have in the past caused a number of incidents related to the Triangle.
Methane hydrates
An explanation for some of the disappearances has focused on the presence of vast fields of methane hydrates on the continental shelves. Laboratory experiments carried out in Australia have proven that bubbles can, indeed, sink a scale model ship by decreasing the density of the water; any wreckage consequently rising to the surface would be rapidly dispersed by the Gulf Stream. It has been hypothesized that periodic methane eruptions (sometimes called "mud volcanoes") may produce regions of frothy water that are no longer capable of providing adequate buoyancy for ships. If this were the case, such an area forming around a ship could cause it to sink very rapidly and without warning.
A white paper was published in 1981 by the United States Geological Survey about the appearance of hydrates in the Blake Ridge area, off the southeastern United States coast. However, according to a USGS web page, no large releases of gas hydrates are believed to have occurred in the Bermuda Triangle for the past 15,000 years.
Rogue waves
In various oceans around the world, rogue waves have caused ships to sink and oil platforms to topple. These waves are considered to be a mystery and until recently were believed to be a myth. However, rogue waves don't account for the missing aircraft.