When the night began, Nation, Hartviksen, and their clients were treated to a display of auroras, ignited by a stream of solar wind buffeting Earth's magnetic field. "As the auroras started to ebb away, our friends at Andøya launched their rockets into the fading lights," says Nation. "The show began anew as the rockets released their payload into the upper atmosphere."
An automated webcam operated by Chad Blakely of Lights over Lapland in Abisko, Sweden, caught the first puffs of powder emerging from the rockets. "It looked like an invasion of UFOs," says Blakley.
The name of the sounding rocket mission is AZURE--short for Auroral Zone Upwelling Rocket Experiment. Its goal is to measure winds and currents in the ionosphere, a electrically-charged layer of the Earth's atmosphere where auroras appear. Specifically, the researchers are interested in discovering how auroral energy might percolate down toward Earth to influence the lower atmosphere.
The twin rockets deployed two chemical tracers: trimethyl aluminum (TMA) and a barium/strontium mixture. These mixtures create colorful clouds that allow researchers to visually track the flow of neutral and charged particles, respectively. According to NASA, which funded the mission, the chemicals pose no hazard to residents in the region.
Update--a movie! "Here is my realtime video of the surprise rocket launch last night from NASA/ASC," reports Ole Salomonsen of Tromsø, Norway. "I was shocked when I saw this in the night sky facing north, I was not aware of the launch.