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ARECIBO OBSERVATORY APPRECIATION THREAD LET'S GO 1/
The Arecibo telescope is the world’s third-largest radio telescope, at 307 m (1,007 ft) wide. Unlike the fully-steerable GBT, its dish is dug into the mountains of Arecibo, Puerto Rico, and relies on the rotation of the Earth to point it at different places in the sky.
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(The Five-hundred-meter Aperture Spherical Telescope, or FAST, in Pingtang County, China, is #2, and RATAN-600, in Zelenchukskaya, Russia, is #1)
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Arecibo doesn't just collect signals, though-- It can send them, too!
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In 1974, Arecibo transmitted this signal towards the globular star cluster M13. It includes the numbers 1-10, the molecular structure of DNA, a figure of a human, a map of the solar system, and the Arecibo telescope itself.
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Arecibo's transmitters also can be used to map Near-Earth Objects (NEOs) like the NEOWISE comet, as well as objects in our solar system, using bi-static radar (bi-static = two non-moving, or "static" antennas).
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Here's how it works!
1. Arecibo sends a radar signal towards a NEO.
2. Some of that signal bounces off the NEO, and heads back towards the Earth
3. A second telescope, like the GBT, picks up that signal, and measures how long it took to bounce back
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1. Arecibo sends a radar signal towards a NEO.
2. Some of that signal bounces off the NEO, and heads back towards the Earth
3. A second telescope, like the GBT, picks up that signal, and measures how long it took to bounce back
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Using this technique, the Green Bank Observatory and Arecibo have worked together to create lots of images! For example...
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In 2001, we mapped the surface of Venus
https://public.nrao.edu/gallery/venus-as-seen-in-radar-with-the-gbt/
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https://public.nrao.edu/gallery/venus-as-seen-in-radar-with-the-gbt/
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In 2005, we got a great map of the Moon's south pole
https://news.cornell.edu/stories/2006/10/leave-skates-earth-no-evidence-ice-moon
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https://news.cornell.edu/stories/2006/10/leave-skates-earth-no-evidence-ice-moon
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We thought the Moon was so nice, we imaged it twice!
https://greenbankobservatory.org/lunar_radar/
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https://greenbankobservatory.org/lunar_radar/
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In 2018, we caught a binary asteroid!
https://greenbankobservatory.org/observatories-team-up-to-reveal-rare-double-asteroid/
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https://greenbankobservatory.org/observatories-team-up-to-reveal-rare-double-asteroid/
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And, the next year, we worked together to get these images of another NEO
https://greenbankobservatory.org/holiday-asteroid-imaged-with-nasa-radar/
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https://greenbankobservatory.org/holiday-asteroid-imaged-with-nasa-radar/
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In conclusion, Arecibo is an incredible observatory we work with to produce amazing science, and we wish them the best in their repairs.
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