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What was unique about it compared to this one for example? https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope https://en.wikipedia.o

What was unique about it compared to this one for example? https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...

superkuh 2y ago
Arecibo did high power transmit for radar imaging of asteroids/comets/the sun/etc and ionosphere studies, among other things. FAST is not capable of transmit (it was not designed for it and the suspended receiver mass is much lower). Also, FAST has a RF-noise emitting theme park built just outside of it's grounds. The uniqueness of Arecibo was this transmit coupled with such a large aperture (so small pattern on sky).
- SirMaster 2y ago
  Thanks! To a layman it seemed like they were really similar devices.
- dylan604 2y ago
  > Arecibo did high power transmit for radar imaging of the Sun? that's something I never thought about, and now that I'm thinking about it, still seems very interesting. It seems like there would be so much noise radiating from the burning ball of fusion that radar signals would just get absorbed/lost. And now I've sat here for 5 minutes doing nothing but imagining this.
  - superkuh 2y ago
    The sun is bright, but it's not bright all over in the lower VHF/UHF ranges. The quiet sun has a mimimum radio emission at about 50 MHz and then linearly (mostly) increases up to 10 GHz (and more). So at the lower frequencies radar echos can be detected as long as there are no active flares/etc going on. http://a.superkuh.com/radio-sources.jpg http://a.superkuh.com/radio-sources.jpg Although it's emission (due to the transparence of it) is not just a disk but sometimes increases on the limb depending on frequency, http://a.superkuh.com/solar-disk_relative-brightness_vs_solar-radii.png http://a.superkuh.com/solar-disk_relative-brightness_vs_sola... Here's a diagram of how the ray paths from an Earth based radar reflect from the soft target that is the sun, http://a.superkuh.com/what-solar-radio-looks-like.jpg http://a.superkuh.com/what-solar-radio-looks-like.jpg

superkuh 2y ago

Arecibo did high power transmit for radar imaging of asteroids/comets/the sun/etc and ionosphere studies, among other things. FAST is not capable of transmit (it was not designed for it and the suspended receiver mass is much lower). Also, FAST has a RF-noise emitting theme park built just outside of it's grounds. The uniqueness of Arecibo was this transmit coupled with such a large aperture (so small pattern on sky).

SirMaster 2y ago
Thanks! To a layman it seemed like they were really similar devices.
dylan604 2y ago
> Arecibo did high power transmit for radar imaging of the Sun? that's something I never thought about, and now that I'm thinking about it, still seems very interesting. It seems like there would be so much noise radiating from the burning ball of fusion that radar signals would just get absorbed/lost. And now I've sat here for 5 minutes doing nothing but imagining this.
- superkuh 2y ago
  The sun is bright, but it's not bright all over in the lower VHF/UHF ranges. The quiet sun has a mimimum radio emission at about 50 MHz and then linearly (mostly) increases up to 10 GHz (and more). So at the lower frequencies radar echos can be detected as long as there are no active flares/etc going on. http://a.superkuh.com/radio-sources.jpg http://a.superkuh.com/radio-sources.jpg Although it's emission (due to the transparence of it) is not just a disk but sometimes increases on the limb depending on frequency, http://a.superkuh.com/solar-disk_relative-brightness_vs_solar-radii.png http://a.superkuh.com/solar-disk_relative-brightness_vs_sola... Here's a diagram of how the ray paths from an Earth based radar reflect from the soft target that is the sun, http://a.superkuh.com/what-solar-radio-looks-like.jpg http://a.superkuh.com/what-solar-radio-looks-like.jpg