Project Highwater
The ionosphere is a cool subject. As an undergrad, I worked on a sounding rocket payload under a man named Mike Kelley[1] (rest in peace) who did a lot of work in this area. Our mission was to launch a sounding rocket from PFRR during an aurora to catch and return particles in situ a la Stardust. Our payload never flew, but I learned a lot.<p>I was invited to help collect data on noctilucent clouds[2] (NLC) at PFRR with one of his collaborators. NLCs are due to the presence of upper atmospheric water vapor. The transport of water vapor into this region is usually by some interesting process (e.g. volcanic explosions, rocket launches, Project Highwater). The sun is still shining through that very high, thin atmosphere when nighttime has already taken hold on Earth&#x27;s surface, so the clouds formed from (very rare) water vapor at this altitude appear to glow at night. It&#x27;s easiest to observe in the extreme latitudes (where we were in Alaska for instance), because the late twilight period is extended. In addition, closer the Earth&#x27;s poles, NLC are more common for some reason I don&#x27;t remember. To measure NLC density, we aimed a laser into the ionosphere and imaged the same region via telescope, counting the photons returned as a measure of NLC density.<p>Dr. Kelley postulated that the Tunguska Event[3] was actually an icy comet (rather than a rocky meteor) based on NLC sightings published in newspapers around the same time, thinking the injected water vapor induced the NLC.<p>[1]: <a href="https:&#x2F;&#x2F;cpb-us-e1.wpmucdn.com&#x2F;blogs.cornell.edu&#x2F;dist&#x2F;3&#x2F;6798&#x2F;files&#x2F;2018&#x2F;10&#x2F;KELLY-1z7978m.pdf" rel="nofollow">https:&#x2F;&#x2F;cpb-us-e1.wpmucdn.com&#x2F;blogs.cornell.edu&#x2F;dist&#x2F;3&#x2F;6798&#x2F;...</a><p>[2]: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Noctilucent_cloud" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Noctilucent_cloud</a><p>[3]: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Tunguska_event" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Tunguska_event</a>