The Green Bank Telescope’s 2.3-acre dish is supported by 7,652 pieces of steel welded and joined together in a complex framework known as a backup structure, or BUS. It weighs around 2.3 million pounds. Keeping it strong and sound requires constant vigilance.
On the BUS
Telescope technicians carefully balance on the maintenance trusses to work on the Green Bank Telescope’s backup structure (BUS). The GBT’s 2.3-acre dish is supported by 7,652 pieces of steel welded and joined together in the complex framework. The BUS weighs around 2.3 million pounds. Keeping it strong and sound requires constant vigilance.
Empty Nest
The prime focus of the Green Bank Telescope is equipped with a cage to hold a special receiver. In this photograph, that cage, about the size of a small refrigerator, is empty. The GBT will then observe with its standard receivers out on the turret platform behind the photographer.
Patting the Subreflector Actuator
Green Bank Engineer Dennis Egan is nearly 400 feet above the ground at the end of the feed arm of the Green Bank Telescope. He is working on the motors that gently adjust the position of the telescope’s secondary reflector, a small dish that aims the GBT’s collected radio waves down into its receivers.
Removing the Focal Plane Array
At the Prime Focus of the Green Bank Telescope (GBT), technicians carefully separate the Focal Plane Array receiver from the cage. Its conical feed horn will then be detached, and the receiver will be carefully lowered to the ground via wires.
Lowering a Receiver
When a large receiver is removed from the Green Bank Telescope’s prime focus, it takes an unusual route back to the electronics lab: via wires. In this photo, the new Ka-band Focal Plane Array is too big to ride the elevators down the GBT, so instead, it is lowered carefully to engineers on the ground who have a truck waiting to bring it back to the lab.