If you visit Arecibo Observatory, you’ll probably see the suspended platform from the visitor center.

It’s a great view.  Better is the view from the cable car, or the platform itself.  Best is from inside the receiver dome housing.

Weighing around 90,000 pounds, the platform is very stable for being suspended 500 feet in the air.  We took the cable car to tour the structure.

After alighting from the cable car, you walk down a staircase to the “rotary joint”, the hub around which the platform rotates.  Photons/waves come out of the grey box in the upper left.

Climbing through the rotary joint is a bit awkward, but the rest of the trip involves stairs and ladders.

Hello, line feed!

Another few more staircases we were in the dome proper where both transmitters and receivers dwell.

After some dire warnings, we went into the transmitter room where several klystrons stood.  These beasts are what produce our megawatt radar wave, similar to the klystrons at SLAC (though theirs can produce 50 megawatts at about the same frequency).  Signals from the klystrons are focused by the telescope and sent to bounce off asteroids, whether near-Earth or out in the main asteroid belt.

Down another staircase, now to the receivers’ instrument room.

And down another level to the receivers themselves: “business end” of the telescope.  These strange plates receive the tiny radio signals from galaxies, pulsars, and yes, asteroids.  The largest is about three feet across.  When you’re getting just a few parts in a billion back of your signal, you need all the sensitivity you can get.

At this point you couldn’t go any lower without falling out of the dome, or into the tertiary mirror, below.

Looming over us as we emerged from the receiver and transmitter rooms was the 8 o’clock tower.

The 16-meter dish toward the Atlantic.

We just missed the 10 o’clock cable car down to the control room, but we opted to take the catwalk to the visitor center.

It’s an IEEE Milestone in Electrical Engineering & Computing, as well as an ASME Mechanical Engineering Landmark!

Looks much smaller from down here!