ASAP Talk-Dale Ferguson: A Preliminary Plan to Quickly Restore Utility to the Arecibo 305m Telescope
Channel: Michael Nolan
Date: 2022-07-15

Lecture/Discussion: Thurs., 7th July, 12 noon ET
Title: A Preliminary Plan to Quickly Restore Utility to the Arecibo 305m Telescope
Dr. Dale Ferguson — USAF Spaceforce
Host:  Dr. Eliana Nossa, George Mason University.

Since the collapse of the Arecibo 305m telescope platform on Dec. 1, 2020, there has been much discussion of building a new Arecibo telescope or rebuilding the facility that was destroyed. In the collapse, the tops of the three platform support towers were sheared off, and the feed arm fell free from the swinging platform and destroyed 25% of the dish. Fortunately, the Control Building, with the computers, spectrometers, masers, atomic clocks, 430 MHz Klystrons, etc., was spared. By replacing the main dish support cables and resurfacing with coarse mesh, the main dish can be repaired as a reflector for less than HF operation.  By replacing the 
damaged aluminum panels to make the dish whole again, RF operations at up to  500 MHz can be resumed. In this presentation, we outline the steps that can be  taken to restore HF (High Frequency, 3-30 MHz) ionospheric heating, 430 MHz ionospheric incoherent scattering radar, passive radio observations of satellite arcing and pulsars, and to extend the field of view to 47 degrees from the zenith. This would restore and improve much of the utility of the Arecibo dish. Part of this 
plan involves supporting, positioning and pointing novel point feeds from lightweight football-camera-like cables, strung from the rebuilt tower tops. It is believed that the dish may thus become broadly useful long before replacement facilities can be engineered and constructed.

Lightly edited chat log:
00:11:16 Eliana: https://areciboscience.org
00:20:27 Eliana: secretary@areciboscience.org
00:39:21 Felix Fernandez: Small correction, Figure 8 is to scale .
00:40:45 Jim "Rompe Todo" Breakall: Thanks Felix. Correct.
00:43:32 Felix Fernandez: Another small correction, Figure 10 is the beam pattern of the fedhorn only, not the complete system. Figure 11a is the complete system pattern.
01:10:22 Dana   K8YUM: What about cryogenics for the LNAs for passive radio astronomy?  Also, is there a diagram showing raytraces for the various "optical" configurations, both at center of field and at extreme edges?
01:10:49 Luca Olmi: would this be a temporary or permanent installation? would future solutions require to dismantle it?.....
01:12:34 Tiger Du: I have the same question as Luca related to how this proposed repair might affect a more long-term repair.
01:15:09 Robert Kerr: are there funds identified for a "long term repair" ? Cross that bridge if you come to it.
01:24:58 Jim "Rompe Todo" Breakall: Don't forget that there are still world class optical facilities intact there and on Culebra as well as the HF and the 12m dish.