I wonder about these mesospheric contrails left after Space Shuttle launches. (The one on the left; the one on the right is a "regular" tropospheric contrail.) Turco et al. modeled them in 1982 () which was a long time ago and our understanding of the mesosphere and relevent processes was pretty meager then. Indeed, mesospheric temperatures and composition are significantly different since 1982 as earth's climate has changed. Maybe it is time for a second look?