Water vapor from Shuttle exhaust may cause high unusual polar clouds

Solid Rocket Booster exhaust left behind during a Space Shuttle launch
From Aerospaceweb

Shuttle exhaust ends up at Arctic?

It is likely water vapor from the Space Shuttle launch causes rare clouds in upper atmosphere -

MAHRSI allowed scientists to follow the plume’s rapid pole-ward transport and then to observe a discrete region of ice clouds as it appeared in the Arctic near the end of the mission. Stevens and colleagues find that the water contained in these clouds is consistent with the amount injected into the thermosphere by the shuttle on its ascent off the east coast of the United States.

“This study is important because it shows that there is a new source of water ice for the polar upper atmosphere,” said Stevens, lead scientist for MAHRSI. “Our results indicate that the water vapor released by launch vehicles can end up in the Arctic mesosphere.”

About half of the water vapor exhaust from the shuttle’s main fuel tank is injected into the thermosphere, typically at altitudes of 64 to 71 miles (103 to 114 km). Stevens and colleagues found that this water vapor can then be transported all the way to the Arctic in a little over a day, much faster than predicted by models of atmospheric winds. There is currently no explanation for why the water moves so quickly.

Stevens and colleagues also include observations from a ground-based experiment in Norway measuring water vapor moving toward the Arctic Circle. These observations reveal the passage of a large plume of water vapor overhead a little over a day after the same (STS-85) shuttle launch, confirming the plume trajectory inferred from the MAHRSI measurements.

As the water vapor moves to the Arctic it falls from the warmer thermosphere down to colder areas in the mesosphere. Over the North Pole in the summer mesospheric temperatures can plummet below minus 220 Fahrenheit (minus 140 Celsius), the lowest found in the Earth’s atmosphere. At these temperatures, water vapor condenses into ice particles and clouds form.

“The amount of water found here is tiny compared to the amount in the lower atmosphere,” Stevens said. “But the long term effects in the upper atmosphere have yet to be studied.”

from NASA

This is mentioned here -

Space shuttle exhaust hints comet caused Tunguska blast

Was the Tunguska explosion of 1908 caused by a comet hitting Earth? That's the claim of a new study based on the behaviour of water vapour from the space shuttle's exhaust. But other scientists dispute the claim, and say the evidence still points to a stony meteoroid as the culprit.

The explosion was somewhere in the megaton range, and destroyed a great swathe of forest in eastern Siberia. The most likely cause is the impact of an object from space, exploding as an air-burst several kilometres up. What type of object is unclear, however, because no large solid remnants have been found.

A more nebulous kind of clue comes in the form of strange glowing clouds that lit up the night sky of Europe only a day after the Tunguska event. These were probably noctilucent clouds: rare clouds of ice crystals that appear about 85 kilometres above the ground. They are high enough to reflect sunlight even after the sun has set.

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