Finishing Up the Rocket Season
ATMOSPHERIC WIND---Miguel Larsen's photo shows how
brilliant chemical trails can trace winds in the upper atmosphere.
The center oval was created when trimethyl aluminum was released
during the upward flight of a rocket launched from Poker Flat this
winter; the smaller oval was discharged during the rocket's descent.
The luminous trails have helped scientists identify a narrow band of
wind blowing about 65 miles above Earth.
Four rockets were launched from Poker Flat Research Range this winter. All of them carried experiments designed to help scientists improve satellite communication and understand more about the aurora. The next launch from the range is scheduled for January 1997.
Oedipus-C, a rocket named after a Greek myth about a wayward son and his mother, was the first to launch this winter season. Three smaller rockets, two of which released brilliant chemical tracers, concluded the rocket season in late November.
The four-stage rocket Oedipus-C shot more than 560 pounds of instruments about 500 miles high through the auroral zone in the upper atmosphere on November 6.
During the flight, the rocket payload separated into two units, which were tethered together about a half mile apart aligned along Earth's magnetic field.
One part of the payload held a transmitter; the other held a receiver. The transmitter sent out radio waves at different frequencies, ranging from 25 khz to 8 mhz. The transmissions were sent two ways--over the tether and using a series of antennas on the payload.
Space-borne communication between the split payload, which continued for about 13 minutes, was tracked by two large antennas on the ground at Poker Flat and recorded for later study. The payload later landed about 642 miles downrange in the Arctic Ocean, where it was not recovered.
Experiments aboard Oedipus-C were designed to help scientists figure out how an active aurora affects satellite transmissions, according to Gordon James from the Communications Research Center in Ottawa, Canada.
"By studying charged particles associated with the aurora, the experiments may help scientists understand and prevent undesirable noise from spreading around a satellite and from interfering with its operation," said James, the principal investigator for the launch.
The rocket motor used to propel Oedipus-C into the upper atmosphere was a NASA-provided Black Brant-12. The primary contractor for the payload, which was developed by the Canadian Space Agency, was Bristol Aerospace Limited, from Winnipeg, Canada. The experiment was the second in a series of launches. The first Oedipus rocket was launched from Norway seven years ago.
Brilliant blue-green chemical trails that traced wind in the upper atmosphere were released during another series of launches from Poker Flat this winter.
The luminous trails, released by rockets launched from the range on November 24 and 26, each curled into coil-like designs after being buffeted by winds at various altitudes above Earth.
The trails, which each persisted for about 10 minutes, were photographed at ground stations in Coldfoot, Fort Yukon, and Poker Flat.
Photographs of the trails will help scientists determine the speed and direction of wind in the upper atmosphere. High-altitude wind can affect the orbits of satellites and interfere with long-range radio transmissions.
"Data from the experiment may help scientists design, track and operate satellites and other manmade space systems more effectively," said Clemson University Professor Miguel Larsen, the principal investigator for the mission.
Colorful trails from previous launches helped researchers identify a narrow band of wind about 65 miles above Earth that scientists believe is associated with the aurora.
The final rocket of the winter season was launched after Larsen's rocket released chemical tracers on November 26.
Andrew Christensen, the director of the Space and Environment Technology Center at the Aerospace Corporation in California, was the principal investigator for the final rocket launch, which shot about 700 pounds of instruments nearly 200 miles high to measure light in the aurora and small-scale weather in the upper atmosphere.
After it descended under parachute to a remote location in the Brooks Range, the instrumented payload was recovered by helicopter.
Taken together, Larsen and Christensen's rocket launches marked the last stage of a four-part series of experiments funded by NASA. They launched similar rocket combinations from Poker Flat seasonally from 1992 through 1995.