Most radio astronomy these days is done via interferometry, which can get much higher resolution than any single dish, even one which fills an entire valley.
As far as single dishes go, the Green Bank Telescope isn’t as big, but it’s also fully steerable.
I merged the 2 threads on the Arecibo Radio Telescope, both where active.
Actually it’s easy. Any structurally damaged facility is dangerous to either dismantle or repair because further collapse could happen at any time; there’s no way for the engineers to really understand the load paths of the damaged structure.
The point is that gravity is working hard every second of every day on an un-designed structure in an un-designed = unpredictable way.
That’s why multi-story buildings are “imploded”. It’s a way to eliminate the vast majority of that gravitational potential energy (“PE”) from the structure and turn it into a simple rubble pile. And do so quickly from a distance.
As applied to Arecibo:
First mount charges where the surviving receiver assembly support cables attach to the 3 support towers. Blow them simultaneously to part the cables and the very heavy receiver assembly crashes through the flimsy reflector bowl and is safely on the ground.
Next mount charges around the periphery of the reflector dish. Blow them and the reflector falls into the pit too. Bring on the chopper-upper-crawlers to dice the wreckage into truckable chunks. Or, if the bowl topography is too deep / steep to work in, just leave / bury the mess in the handy pre-made landfill.
Seems pretty safe; none of the work need be done where / while there’s still high PE stuff overhead or uphill from the workers.
I got the impression they’re going to try to avoid damaging the environment below the bowl. At least as much as possible. There’s a whole ecosystem living below it. Your method basically trashes it. Also, there’re some buildings nearby that they do not want to damage.
looks like James Bond did more damage than we thought.
NYC does not allow buildings to be imploded , at least in Manhattan Too much risk of other buildings being damaged along with all the pipes, cables, etc. underground
Anyone else hear that the whole upper assembly collapsed earlier today? As in no more cables from those three towers? AP Story: https://apnews.com/article/puerto-rico-0da6abb251f455977bf0c752348e712e
The picture in the blurb doesn’t show it. There’s a tweet I saw of the three towers, daylight photo, with no cables on any of them. EDIT: Tweet in question. https://mobile.twitter.com/DeborahTiempo/status/1333741751069192195/photo/1
local reporter in PR on twitter said it totally collapsed
“The Arecibo Observatory is gone. Its 900-ton instrument platform, suspended above a dish in the karst hills of Puerto Rico, collapsed this morning, at about 8 a.m. local time, says Ramon Lugo, director of the Florida Space Institute at the University of Central Florida, which manages the 57-year-old radio telescope for the National Science Foundation (NSF).”
today’s pictures from above
That looks like something you would see in a post-apocalyptic movie when the human race is mostly wiped out.
I guess they were right in not trying to fix it once one of the main cables snapped. Imagine this happening while folks were in the upper structure.
Brian
first big radio telescope in WV collapsed after 30 years of use. The current one was built in 2000, It’s no longer funded 100% by the feds , it’s independent and gets cash from various sources including some fed money.
more video here
For the non TwitFace users in our crowd, such as me, here’s a good article with some good vids:
Wow, you can see the individual strands in the cable break.
Brian
I was thinking Jurassic Park
They certainly got lucky that the top chunk of the tower near the visitor center fell in the opposite direction (down into a small valley). Otherwise it would have smashed up the building pretty well. It probably still took some damage, but it wasn’t crushed by a few hundred tons of concrete.
Nice. But I’m surprised that the asteroid appears lit from photo top. Radar imaging is based on radio “illumination” coming from the observer, not from someplace else roughly perpendicular to the line of sight. What is that about?
Good question. Not my area of expertise, but radar essentially produces a depth image (with velocity in there). They may have artificially illuminated the point cloud based on the estimated surface vector, and arbitrarily chose the light to come from above.