GordonH wrote:Wasn’t this used in the movie Goldeneye
Yes it was and also the movie "Contact" (The story was written by Carl Sagan and his wife).
Here's a bit of coverage from UniverseToday. The video I posted above from CTV is a somewhat shortened version of 2 videos (one taken from the control room, the other taken by a drone). UniverseToday links both slightly longer versions.
One thing that always fascinated me with Arecibo was it's use not only as a sensitive radio receiver, but also as a transmitter and as such a Radar station. It was used to radar image the surfaces of Mercury, Venus and Mars at lower resolution than the visible images we've received from space probes. Never the less, important discoveries were made from those images. It's ability to radar image Earth passing asteroids was uncanny; revealing their shape and rotation rates where optical telescopes couldn't do the same.
And then there's that "Hello from Earth" message that was sent in the direction of Globular star cluster M13; 25,000 light years distant back in 1974. It could be considered a publicity stunt because if any planets with life exist in M13's thousands of stars, they wouldn't receive the message for about 25,000 years; and any response (by radio) would take another 25,000 years to be received here on Earth. Of course, any star systems in the path of the signal between us and M13 might receive it sooner; but it's still a bit of dream.
Fascinating to think that that transmission is still propagating through space having traversed a tiny fraction of it's intended distance; while the equipment used to send it has been destroyed.
There's probably not much Arecibo could do that can't be done by more recently developed radio and sub-millimeter telescopes. But all the same; RIP Arecibo, a definite window on the universe for it's time.
Re: Watch Arecibo radio telescope collapse
Posted: Dec 5th, 2020, 2:04 am
by Sonny Taylor
OK... for a little fun (hope This isn't getting boring); more details on the message sent to space by Arecibo.
The message was very short and overly well thought out.
The entire message consisted of 1,679 binary digits, approximately 210 bytes, transmitted at a frequency of 2,380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 450 kW. The "ones" and "zeros" were transmitted by frequency shifting at the rate of 10 bits per second. The total broadcast was less than three minutes.
The number 1,679 was chosen because it is a semiprime (the product of two prime numbers), to be arranged rectangularly as 73 rows by 23 columns.[7] The alternative arrangement, 23 rows by 73 columns, produces an unintelligible set of characters (as do all other X/Y formats).
How they decided to encode the message contents within those constraints is even more ridiculous if you read the link.
I wondered why the 2,380 MHz frequency was chosen and what might be special about it, while knowing of things like the Hydrogen line at 1,420 MHz. A little research turned up that 2,380 MHz is the same frequency that Arecibo used for radar transmissions.
So, Boom! a radio message was sent by a giant antenna at 2.380 GHz over a 3 minute interval with 1/2 megawatt of power. Can't help but harmlessly notice that 2.450 GHz is the frequency for microwave ovens.
That signal has by now traversed about 46 light years of space. There are more than 50 stars within that distance from us, but most would probably not be aligned with the directional signal.
Still somehow, it's fun to think about.
Re: Watch Arecibo radio telescope collapse
Posted: Dec 6th, 2020, 7:31 pm
by Jlabute
This is the big baby in China with a 500M diameter. Not that BIG is the answer to everything. Some arrays under construction will be larger, such as the SQ Km array in Australia.
