Jet Engine for blowing snow off the (former) 300 foot telescope at the NRAO Green Bank. Photo courtesy NRAO.
I found this photo, which shows an unnamed technician, Clifford Barkely, and Paul Devlin inspecting a jet engine, in NRAO’s facebook photo album. Back in the olden days (okay, before the 1988 collapse of the 300-Foot Telescope), engineers used to set up a jet engine next to the dish to blow it clean it of accumulated snow. I can only imagine the noise—I used to complain about the wind machines in the orchard next to my house when they ran during cold spring nights, and those were powered by car, not jet, engines (you can listen to one here, or you can just imagine a Chevy V-8 parked outside your bedroom window).
Since the 300-Foot Telescope is no more, the snow now accumulates in the dish of its replacement, the Green Bank Telescope (GBT). I’ve never seen it in action, but apparently controllers just tilt the dish past the angle of repose so the snow slides out. Maybe not as awesome as a jet engine blowing snow off the instrument, but I bet it’s still plenty interesting to watch an avalanche clearing a 100-meter dish.
