General > General Technical Chat
The end of the line for the Arecibo radio telescope
BravoV:
--- Quote from: David Hess on December 04, 2020, 12:02:43 pm ---Maintenance is a rubber band which can be indefinitely stretched a small bit at a time by management and politics.
--- End quote ---
Problem is, thing like these (and as many others) need much-much more longer time (decades ?) for the commitment and support, far more than just 4 or 8 years of elected governmental administration, which we all see & experience, that sometimes can turn up side down 180 degrees in just 4 years.
MadTux:
--- Quote from: BravoV on December 04, 2020, 11:35:14 am ---Yep, just for the look, ... or .. maybe hiding the rust. :palm:
--- End quote ---
Painting cables is a dumb idea, whether it's rust or fretting. With paint, lube can't go in there and the cables can't move along each other. So they will rub against each other which causes fretting. Fretted surface likely starts corrosion and cracks so wire snaps. If the wire strands are locked in place, they also can't move along each other to share load, so some wires get higher stresses than others, until they yield and eventually break. With nough broken single wires, the whole cable snaps.
Marco:
Couldn't you build a radio telescope in the same way as a heliostat concentrating solar power plant? An a simple planar array of reflectors, but all concentrating on a single receiver.
BravoV:
--- Quote from: MadTux on December 04, 2020, 01:30:49 pm ---
--- Quote from: BravoV on December 04, 2020, 11:35:14 am ---Yep, just for the look, ... or .. maybe hiding the rust. :palm:
--- End quote ---
Painting cables is a dumb idea, whether it's rust or fretting. With paint, lube can't go in there and the cables can't move along each other. So they will rub against each other which causes fretting. Fretted surface likely starts corrosion and cracks so wire snaps. If the wire strands are locked in place, they also can't move along each other to share load, so some wires get higher stresses than others, until they yield and eventually break. With nough broken single wires, the whole cable snaps.
--- End quote ---
+1
fourfathom:
--- Quote from: Marco on December 04, 2020, 03:21:25 pm ---Couldn't you build a radio telescope in the same way as a heliostat concentrating solar power plant? An a simple planar array of reflectors, but all concentrating on a single receiver.
--- End quote ---
All the reflections need to arrive at the detector in phase, which would not be the case with a planar array. If each reflector has it's own detector (as is the case with multi-dish arrays), then phases of the individual detected signals can be adjusted electronically to focus and steer the antenna beam pattern.
Heliostat's don't much care about phase-coherence.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version