A photo of the Parker Solar Probe was captioned as follows:

In the Astrotech processing facility in Titusville, Florida, near NASA's Kennedy Space Center, on Tuesday, June 5, 2018, technicians and engineers perform light bar testing on NASA's Parker Solar Probe.

I wasn't able to find any references to this sort of process in NASA literature - even Armadillo's Ben Brockert was perplexed.

Is this something specific to the Parker probe, or a standard NDT process?


1 Answer 1


This test was performed to ensure that the 44 series of solar cells (or "strings") were still connected. After the acoustic and vibration testing, there was a chance that some of the electrical connections could have been broken, so the test used a bar of purple lasers (a "light bar") to verify that the strings were still functioning properly. A laser bar was used because it could test a single string at a time. Purple lasers happened to be on hand, and the solar cells function efficiently at that wavelength. Infrared lasers were also used.

This test is usually referred to as an illumination test, which is why it was not readily identifiable.


  • 2
    $\begingroup$ Nice! I've never even heard of a purple laser. $\endgroup$ Commented Jan 30, 2019 at 22:27
  • 3
    $\begingroup$ I would have used a bunch of purple lensed LEDs taped to a stick and just held it a few cm away, but then again I don't work for NASA. Sharks with lasers! $\endgroup$
    – uhoh
    Commented Jan 31, 2019 at 0:57

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