Arecibo Observatory

My memorable 1990 visit; memorable to me, not necessarily to anyone else!

This post was prompted by two factors: the catastrophic collapse of the 900 ton, suspended platform, on Dec 3, 2020; and finding the photos from my visit.

In August, 1990 I visited Andrea at the Arecibo Observatory in Puerto Rico where she had a summer fellowship. She was working on pulsars and this was the premier instrument in the world for finding and studying them.

This enormous instrument was completed in 1963, about the time I began graduate school in Rochester, New York. It was very relevant to my field of astrophysics. I heard about Arecibo this and Arecibo that throughout my 5 years in graduate school.

Two of the more notable speakers I remember at the Friday afternoon University of Rochester Physics Department Colloquia were Frank Drake, Director of the observatory, and Carl Sagan, well known popularizer of science. They were both professors at Cornell at the time, about 90 miles away from Rochester in Ithaca.

The telescope itself

I won’t be saying much about the telescope — there’s a lot out there available.

A radio telescope detects radio waves, not light rays as a “normal” telescope does. Radio waves are millions of times less energetic, and their wavelengths are millions of times longer. Many astronomical bodies emit radio waves.

It was big, very big: 1000 foot diameter reflector dish in a natural sinkhole. The world’s largest single-aperture telescope for 53 years (1963-2016), it comprised 39,000 perforated 3′ x 6′ panels — an area of about 20 acres (about 15 American football fields). It was a fixed, spherical (not parabolic) reflector. In collecting data from the source of interest, the receiver was moved, not the dish.

The current mechanical troubles began in August, 2020; an important cable broke in November; catastrophic cable failure in December. Consult internet for videos and other information. Sad.

All the electronics and steel structures suspended over the dish were to get the detection point to the right place. I’m sure it was made as small and inconspicuous as possible because you really don’t want to block any more of the incoming radio waves than you have to. But you also want it to be rigid and stable and to ever so smoothly compensate for the rotating Earth as you collect data. The final design, all 900 tons of it, was approximately equivalent in weight to two, fully loaded, 747s. It was roughly the same size, too, depending on how you stack them.

The azimuth arm, the banana-shaped appendage hanging from the bottom of the triangular platform, was suspended on a circular track 450 feet above the dish and was 328 feet long. Various receivers (the Gregorian dome and that long pointy thing, e.g.) move along the track of the azimuth arm.

Thus, to point the telescope at your star or galaxy or pulsar you would rotate the azimuth arm around on its circular track and move the receiver along the azimuth arm until you were pointed correctly.

In the 1995 James Bond movie GoldenEye, Pierce Brosnan was shot at when he was running up the catwalk on his way to save the world. Also, before he could complete his mission the entire dish was blown up. It has since been fully repaired.

More details on the platform, the reflective dish, 747s, my favorite peanut butter cake recipe, pulsars, and the Gregorian dome available on request.

Photos, impressions, comments

Andrea mentioned the Gregorian dome during my visit, and said it generated a lot of anticipation among scientists. It became reality 6 years later.

All photos in this post, except the first two, are from my 35mm film camera. (I wouldn’t own a digital camera for 12 more years.) Andrea and Owen (former boyfriend) took a couple of the shots.

The three of us were allowed to go out on the platform one day during during a maintenance period. Our little trip up the catwalk was peaceful, unlike James Bond’s.

I remember Owen asking me how could you let her do that? He meant the waving both arms while sitting on the railing stunt. (As if I had any control!)

Fourteen and a half years after my Arecibo visit, in early 2005, I was visiting Andrea again, this time in Lancaster, Pennsylvania, when her twin girls were only a few months old. She’d been allocated some observation time on the Arecibo telescope that fell during my visit. She didn’t need to go to Puerto Rico — with appropriate passwords and software she could do it remotely from home.

I have photo in my deep archives of her, in her own house, controlling the movement of the 328 foot-long azimuth arm and data collection point along it, from her 5 or 10 pound laptop 1600 miles away, all while nursing one of the girls.

You should not be surprised to hear the photo will not be available on request.

=====End of post