One of the most powerful telescopes in existence is being built on a high-altitude plateau in Chile. The Atacama Large Millimeter/submillimeter Array (ALMA) will combine dozens of individual radio telescope dishes into a single observing instrument. The resolution of the ALMA radio telescope will be 10 times finer than the Very Large Array (VLA) and five times finer than the Hubble Space Telescope.
The water vapor in the Earth’s atmosphere absorbs radio waves, making radio astronomy difficult from sea level. The plateau’s elevation (16,000 feet, or about 5,000 meters) places it above 40 percent of the Earth’s atmosphere. [Amazing Photos from Giant Radio Telescope]
The universe emits light in many wavelengths that are invisible to human eyes. The Earth’s atmosphere blocks much of this invisible light. Satellites orbit above the atmosphere for a clear view. The ALMA radio telescope receives wavelengths of around 1 millimeter, between the infrared and radio parts of the electromagnetic spectrum.
Building ALMA: Earth's Largest Radio Telescope (Video)
The ALMA array is an interferometer: many small radio telescopes working together as a single large telescope. [8 Cool Facts About the ALMA Telescope]
Each individual dish is up to 40 feet in diameter (12 meters) and weighs 115 tons. Dishes are being provided by European, Asian and American partners.
ALMA employs two transporter vehicles for moving the individual telescope dishes. Each has 28 wheels and weighs 130 tons. Two engines generate 1,400 horsepower. The vehicle can travel 7.5 mph (12 km/hr) when carrying a telescope.
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