Mouse Hunt
Last semester, while I was away on sabbatical leave, the large telescope at CFO became inoperative. Closer examination showed that
a mouse had invaded the telescope cable conduit, built a nest, and chewed on the cables.
This is undoubtedly the primary cause of the malfunction, however there may be secondary effects due to shorts produced by the exposed wiring.
On these pages, I will document the investigation, cleanup, and repair of the telescope control system.
Day 1: Feb. 14, 2005 - Not the best way to spend Valentine's day.
I will have to take everything apart and try to trace down the cause of the telescope's malfunction. Because mouse droppings are
involved, I'll also have to wear gloves, and sanitize all surfaces and cables as we go. I started by clearing and sanitizing the darkroom,
then moved into the warm room, cleaning the back counter and floor. Then the data computer was disconnected, sanitized, and moved
onto the back counter. All loose wiring was disconnected, sanitized, and removed. The monitor and keyboard for the telescope control
computer were similarly cleaned and removed. Finally I could get at the main control computer.
- Uh oh. What is that by the control computer?
- Is that what I think it is?
- Oh no! Not inside the computer!
- It's everywhere!!!
- Check the cable conduit - Oh no, the control cables are chewed!
- Here's a closeup
- More chewing - that mouse must have been hungry
- Finally, the nest is discovered. The wires you see run from the computer through the opened conduit and the hole in the wall
to the dome room and telescope. They carry signals which control the telescope motors and monitor its position.
- Close up of the nest:
- Home Sweet Home.
- A view of the debris field from opening the conduit. Looks like the mouse enjoyed a midnight snack or two.
- Yet another closeup.
- After clearing away the nest, I'll be able to check out the pipe feeding through the wall into the dome room:
- Even worse news: major chewing.
- Close up: The mouse has chewed all the way through both layers of insulation, exposing the bare wires.
This could lead to shorting that would damage the drive electronics. I'll have to track down which wire this is.
Conclusions so far:
The mouse entered the observatory in the crawl space under the (unheated) main dome. Once there, it followed the control cables and climbed them, passing through the wall feedthrough into the conduit in the warm room, where it built its nest.
It then followed the cables down the conduit, across the wall, and down into the control computer with occasional stops for rest
and snacking on wire insulation.
Other than the mess made by the mouse, the only actual damage discovered so far consists of the two chewed wires shown above.
Tomorrow, I'll check the control electronics and computer.
