Thought 2020 couldn’t get much worse?
I’m sure most of you will already have come across the sad news about the cable failures at Arecibo from various sources:
This is a sad end for an iconic instrument, with ties to amateur radio through operators there and even use with EME.
Can some of its work be done by Qianan or interferometers? What will track asteroids, now? At least we can see it intact, again, in Golden Eye with James Bond… Shaken and also stirred.
Elliott, K6EL
Well, there are “square-kilometre” arrays being built in Western Australia and South Africa - whether they are intended for the purpose of tracking asteroids and the like, I don’t know, but these, when finished, will be some of the most powerful radio telescopes on earth.
73 Ed.
To some extent. Otherwise one might ask how it was they had such a hard time finding funding over recent years.
FAST is in many ways a much more sophisticated instrument. It has not just greater collecting area but also a fancy system to reshape the dish. At both sites lots of work has been done on receivers, developing multi-beam or phased-array systems. But, what FAST doesn’t have is transmit capability. That leaves more work for Goldstone but of course that does not have the range of Arecibo.
Interferometers are great, but they don’t have the sensitivity on the angular scales that a single dish has. A big instrument like Arecibo (or other big, but not that big, dishes like the Lovell Telescope, Effelsberg or Green Bank Telescope) has lots of sensitivity on broad angular scales – angular frequencies down to dc – meaning they can make absolute power measurements, which interferometers can’t. Sometimes that’s what you need.
SKA will be hugely important (and SKA pathfinder instruments already are) but it certainly won’t do TX.
You may be interested in the following article: " Starlink already threatens optical astronomy. Now, radio astronomers are worried", By Daniel CleryOct. 9, 2020 , 2:25 PM
Link: “The American Association for the Advancement of Science (AAAS)”
I can not attest as to the total veracity of the article, but it definitely gets one thinking.
Yes John, it is indeed of concern, as is OneWeb.
I was saddened by this news Simon.
I really don’t believe that there isn’t a solution other than blowing the structure up. Surely there is a method to safely repair the damage. I guess ultimately it all boils down to cost and balancing that cost against the perceived benefits that the dish brings.
One of my most memorable ham experiences was listening to KP4AO on 70cm CW from my back garden with my FT817 and SOTAbeams SB270 6 element UHF beam pointed at the moon! Joe Taylor (yes, that Joe Taylor!) and his colleagues were using the Arecibo dish to do EME. I believe the power from the rig was 50w.
Receiving signals from Puerto Rico on UHF via the moon - just magical!
73, Colin
Post script edit- I told a fib - the Arecibo TX power was 35w!
https://physics.princeton.edu/pulsar/k1jt/Moonbounce_at_Arecibo.pdf
“with ties to amateur radio through operators there and even use with EME.”
Arecibo was unique in the world for its planetary radar capability. UHF signals were bounced off all the planets out to, and including, Saturn. I was involved with a team of researchers at Cornell U. studying the Jovian magnetosphere way back when. They were among the first to make use of this capability of Arecibo to do pioneering research.
73 Barry N1EU
Still time to fly a radio carrying drone into the focus and do some last EME. The link budget should stack up.
The feed will be hanging into one focal point, but there should still be plenty of sky around that point - after all we manage to get by with the optic disc blind spot.
I think one of the researchers using Arecibo was K1JT, Joe Taylor. To some extent those digital modes may owe their existence to this dish. What a loss… not only to amateur radio’s occasional uses, but to science in general.
To be realistic, the telescope is situated on the boundary between the North American and Caribbean plates and is subject to severe earthquakes, historically up to magnitude 7.5, it could only ever have had a limited life expectancy.
The only things that brought a slight smile to my face about this loss of a wonderful piece of engineering was The Register’s comment that Arecibo observatory has relieved engineers of the problem and dilemma over how to safely and successfully dismantle the platform by dismantling itself into a pile of wreckage.
Drone video of collapse… two parts:
Elliott, K6EL
Engineering analysis of cable failure starts at 5:30 minutes
EL
