The ATREX cloud trail marks its trajectory - the exhaust trail is smeared by high velocity winds in the upper stratosphere.

The ATREX cloud trail marks its trajectory - the exhaust trail is smeared by high velocity winds in the themrosphere.

by Melanippe of Themiscyra

An eye-catching experiment, the Anomalous Transport Rocket Experiment, or ATREX, finally launched from NASA’s Wallops facility in Virginia on Tuesday morning, March 27th, after several weather delays.  The small rockets, nothing in size like NASA’s more familiar Saturn vehicles, took off in the pre-dawn darkness spaced 80 seconds apart.

Once aloft, each suborbital rocket headed for an altitude between 50 and 90 miles (80 and 145 kilometers).  This zone, the lower reaches of the thermosphere, is where the aurora borealis and aurora australis form; the International Space Station’s orbit, also in the thermosphere, is about 200 kilometers higher than where the experiment took place.

ATREX was designed to assist in better understanding of the process responsible for the high-altitude jet stream located 60 to 65 miles above the surface of the Earth.  Not the jet stream featured in weather forecasts (which is the northern polar jet stream), this high-speed atmospheric transport shares an altitude with strong electrical turbulence, the kind which can disrupt satellite and radio communications.  The sounding rockets used for the mission were two Terrier-Improved Malemutes , two Terrier-Improved Orions and one Terrier-Oriole; two of them carried instrument packages to measure pressure and temperature of the targeted jetstream.

At the zenith of their flights, the rockets injected their trimethyl aluminium payloads into the 200-mile-per-hour winds.  This chemical reacts with water and oxygen to create milky-opaque clouds of aluminum oxide, carbon dioxide, and water vapor, reflecting the sunlight accessed at that high altitude but which had not yet angled around the curvature of the earth to dawn over the launch site.  The high-contrast ‘glow’ provided easy visual tracking of how and how fast the high-level winds moved the clouds.

As proof of how easily the reflective chemical could be tracked visually, clouds were reported to be seen from as far south as Wilmington, N.C.; west to Charlestown, W. Va.; and north to Buffalo, N.Y.


Launch footage (3:13, edited down by NASA from 16+-minute raw footage)