Challenging environment on orbit aboard ISS: broken lamp?

Today, in the course of attempting to collect more data for our experiment, we ran into a significant problem. Normally, the lamp intensity should be constant; however, when we started running experiments today, we observed significant fluctuations, without changing anything in the experimental setup itself.

We are not entirely sure what is happening. The intensity reading on the lamp, taken a from a photodiode on the microscope, reads that the intensity is constant—so something clearly is not right. Indications are that it might be the plasma lamp, or the fiber bundle that transports light in the microscope.

Of course, in any laboratory, things do break. What makes it much more challenging on orbit is that there are a limited set of parts onboard, and precious crew time must be allocated to troubleshoot the instrument, and replace any parts. The schedule is always tight, and we were fortunate that this problem arose toward the end of this experimental run, so we may lose just a couple of days, but not much else. We have scheduled the crew to look into this next week, and hopefully can resolve the issue then.