Related topics: space · launch · satellite

How to test the twin paradox without using a spaceship

Forget about anti-ageing creams and hair treatments. If you want to stay young, get a fast spaceship. That is what Einstein's Theory of Relativity predicted a century ago, and it is commonly known as "twin paradox".

Land bulge clue to aviation threat from volcanoes

Bulging in land that occurs before a volcano erupts points to how much ash will be spewed into the sky, providing a useful early warning for aviation, geologists in Iceland said on Sunday.

Giant 'balloon of magma' inflates under Santorini

A new survey suggests that the chamber of molten rock beneath Santorini's volcano expanded 10-20 million cubic metres – up to 15 times the size of London's Olympic Stadium – between January 2011 and April 2012.

GPS data reveals more on mega-thrust earthquakes

(PhysOrg.com) -- New GPS data of the 2010 earthquake that devastated parts of Chile and killed over 500 people is revealing new clues about large earthquakes such as the quake in Chile and the magnitude 9.0 earthquake that ...

New theory of why midcontinent faults produce earthquakes

A new theory developed at Purdue University may solve the mystery of why the New Madrid fault, which lies in the middle of the continent and not along a tectonic plate boundary, produces large earthquakes such as the ones ...

Glitch shows how much US military relies on GPS

A problem that rendered as many as 10,000 U.S. military GPS receivers useless for days is a warning to safeguard a system that enemies would love to disrupt, a defense expert says.

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Global Positioning System

The Global Positioning System (GPS) is a global navigation satellite system (GNSS) developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing. It is the only fully functional GNSS in the world, can be used freely by anyone, anywhere, and is often used by civilians for navigation purposes. It uses a constellation of between 24 and 32 medium Earth orbit satellites that transmit precise radiowave signals, which allow GPS receivers to determine their current location, the time, and their velocity. Its official name is NAVSTAR GPS. Although NAVSTAR is not an acronym, a few backronyms have been created for it.

Since it became fully operational on April 27, 1995, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, tracking and surveillance, and hobbies such as geocaching. Also, the precise time reference is used in many applications including the scientific study of earthquakes and as a required time synchronization method for cellular network protocols such as the IS-95 standard for CDMA.

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