A group of scientists from the University of New Hampshire, led by Dr. Marc Lessard, along with researchers from Dartmouth College, participated in a launch Saturday night of scientific experiments into the ionosphere outside Fairbanks, Alaska.
The 40-foot-long Terrier-Black Brant rocket launched to an altitude of 200 miles above the Earth, before finally coming to rest 200 miles downrange.
During its flight, the experiment radioed back real-time measurements of the ionosphere, including taking samples of the charged particles (ions) that make up that layer of our atmosphere.
One of the experiments on-board was the Electron Retarded Potential Analyzer (ERPA), developed in New Hampshire by Lessard's team, including Ian Cohen, the manager of the astronomical observatory at UNH. ERPA measured the temperature (energy) of the ionosphere as the rocket passed through the layer.
Cohen says that he hopes that the launch will help people “learn more about the environment in which the aurora occurs.”
The ionosphere extends from about 85 to 600 km (50 to 375 miles) above the Earth. It is where ultraviolet light coming from the Sun is powerful enough to add enough energy to atoms to knock electrons free from their host atoms, giving them a positive charge, “ionizing” the gas. When these ionized atoms drift downward where the UV light is less prevalent, they can regain electrons, thereby releasing energy in the form of photons, creating the Northern Lights.
Some of these charged particles are stirred by a form of electromagnetic radiation known as Alfvén waves. These may be the main cause behind discrete aurora, which stretch from horizon to horizon. This wave is like a tall, thin ribbon which is “plucked” like a guitar string by passing particles from the Sun, causing it to resonate like a musical instrument being played.
The Black Brant rocket was first developed in 1961, and UNH has been doing launches and taking part in high-altitude experiments since the early 1960s. Participating with the UNH researchers were team members from Cornell University, the Southwest Research Institute, the University of Alaska Fairbanks, and the University of Oslo.
Cohen stated that the team is just beginning to analyze their data, “...to get processed, 'readable' data on the electric and magnetic fields, electron and ion energies and temperatures, and the other in situ measurements that were taken. The launch was really just the beginning of the exploration.”
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