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Saturday, November 2, 2013

Arecibo Birthday


Thanks to Bob Crane for this birthday alert:

The Arecibo Observatory opened on this date in 1963. At a diameter of a thousand feet, it's the largest single-aperture telescope ever built. It's also got the largest focusing dish in the world, which gathers electromagnetic waves from space. Located near the city of Arecibo in Puerto Rico, it's close to the equator, which enables it to "see" (via radio waves) all the planets in the solar system; within six months of its opening, it enabled scientists to study the rotation rate of Mercury and determine that it rotated every 59 days, rather than 88 as was previously thought. It's also been used for military purposes like locating Soviet radar installations by tracking their signals as they were reflected off the moon. It's provided the first full imaging of an asteroid and also led to the first discovery of planets outside our solar system.

In 1999, it began collecting data for the SETI Institute; SETI stands for "search for extraterrestrial intelligence," and the organization looks for deliberate radio or optical signals from other planets. The Arecibo Observatory also sends data over broadband to the home and office computers of 250,000 volunteers, who, through the Einstein@Home program, donate their computers to be used for data analysis during periods when they would otherwise be idle. A year ago, three such volunteers in Iowa and Germany discovered a previously unknown pulsar, 17,000 light years from Earth.

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1 comment:

  1. Don't forget, Arecibo was blown up in the 1995 James Bond film, Goldeneye. In a nod to "You Only Live Twice", the reflector is hidden underwater until it's needed.

    But seriously, Arecibo also caused Sam Harris to give up a lot of ham radio, he moving down there to do technical stuff (it's a reflection of the times that it wasn't until decades later that I realized he was fairly important at Arecibo, not just "some technician").

    Either he was too busy or the location not right, but after being a key player in moonbounce and VHF, he kind of disappeared.

    Though before that, he got permission to use the dish I think two times for amateur radio. The thing was so large that Wayne Green (who went down for one of the times) said it was like a pileup on 20metres. Endless hams with relatively low power and simple antennas could be heard, because the dish gave so much gain that they didn't need much of a station. They made contacts, but also used a video recorder to record a band of signals, later tuning through it all to get the individual stations and callsigns.

    That sort of thing became possible decades later, when some hams had enough antenna to compensate for low power or small antennas at the other end, but at the time of the Arecibo tests, it was a pretty wild thing.

    I have no idea why they never got permission again later, maybe simply that in 1964 or 65 demand for the dish hadn't grown so large, or maybe the ham stuff was treated like general testing of the equipment, which wasn't needed later.

    Apparently Sam got much busier as time progressed, and then died, sometime in the late seventies if I remember properly.

    Michael VE2BVW

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