A new era for Arecibo: legendary observatory begins next phase

Re:A new era for Arecibo: legendary observatory begins next ... by world2vec on Friday September 29, 2023 @11:30AM (#37705694)

Very sad that its next phase is not as a bigger, better observatory. RIP.

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Re:A new era for Arecibo: legendary observatory begins next ... by oh_sigh on Friday September 29, 2023 @11:52AM (#37706028)

Do these massive telescopes have a future, when we could just build smaller ones and use aperture synthesis to pretend like we have a really really big telescope?

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Re:A new era for Arecibo: legendary observatory begins next ... by mandevil on Friday September 29, 2023 @12:42PM (#37706753)

For receive only, yes, aperture synthesis (like the VLA and the GVLBI) is capable of resolving more precisely than even Arecibo could. But Arecibo also did a bunch of active radar mapping of things within the solar system, which aperture synthesis cannot replace. You can't solve the coherent beam problem without actually having an antenna that really is that big.

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Re:A new era for Arecibo: legendary observatory begins next ... by markhahn on Friday September 29, 2023 @01:03PM (#37707072)

huh? wouldn't all the planes with AESA radar dispute this characterization?

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Re:A new era for Arecibo: legendary observatory begins next ... by mcpackieh on Friday September 29, 2023 @02:04PM (#37707971)

https://en.wikipedia.org/wiki/Thinned-array_curse

> The thinned-array curse (sometimes, sparse-array curse) is a theorem in electromagnetic theory of antennas. It states that a transmitting antenna which is synthesized from a coherent phased array of smaller antenna apertures that are spaced apart will have a smaller minimum beam spot size, but the amount of power that is beamed into this main lobe is reduced by an exactly proportional amount, so that the total power density in the beam is constant

So you can transmit with a sparse array, but the power you can deliver with it (for a set synthetic aperture size) decreases with the degree of sparseness. No free lunch.

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Re:A new era for Arecibo: legendary observatory begins next ... by echelon on Friday September 29, 2023 @12:45PM (#37706789)

> You can't solve the coherent beam problem without actually having an antenna that really is that big.

What's the tl;dr on the math here?

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Re:A new era for Arecibo: legendary observatory begins next ... by adgjlsfhk1 on Friday September 29, 2023 @02:43PM (#37708500)

massive telescopes still win in terms of light sensitivity per dollar. apature synthesis/VLBI are the clear way to go for angular resolution but for bigger fainter objects, you care more about area where a big dish does better.

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Re:A new era for Arecibo: legendary observatory begins next ... by SoftTalker on Saturday September 30, 2023 @12:24AM (#37712759)

Looking at the photos, the dish itself looks relatively thin. With modern composite materials, I bet it could be rebuilt much lighter than before and not need such substantial support. Still, it would need to be paid for so....

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