The science is pretty clear on this, though I have not seen a paper on this particular cloud. The mesopause is so cold and the Shuttle emits so much water vapor that contrails form at about 85 km altitude. At least occasionally. This sort of very high altitude cloud is usually only found near the polar summer mesopause. Is it important that rockets can cause these mesospheric clouds to form at midlatitudes? Do mesospheric rocket contrails say anything about climate?