Dual rocket mission successfully launched from Poker Flat

Release Date: 
Tuesday, March 25, 2003


Two rockets were successfully launched from Poker Flat Research Range at 12:50 and 1:09 a.m. Tuesday as part of a UAF Geophysical Institute-lead experiment to study winds in the upper atmosphere related to the aurora.

The mission, known as the Horizontal E-region Experiment or HEX project, differed from other launches at Poker Flat since one of the rockets was designed to tip on its side in mid-flight. NASA scientists were interested in the project because the tilting of the rocket’s trajectory was unprecedented.

“The whole idea of tipping a rocket on its side was brand new,” said Geophysical Institute Assistant Professor and HEX Principal Investigator Mark Conde. “It was a resounding success.

The trajectory was perfect for our science, we hit exactly the auroral arc that we wanted, and we hit it spot on.”

Once HEX’s three-stage, Black Brant X rocket was free of the drag imposed by lower atmosphere gases, it tipped on its side enabling the rocket to pierce a curtain of aurora horizontally. The rocket flew precisely as planned.

Nineteen minutes after the horizontal rocket was launched, a second rocket was launched. That Terrier-Orion rocket traveled a more conventional, vertical trajectory for comparative observation and study.

Each rocket released long trails of the chemical trimethyl aluminum, which is harmless to the atmosphere. Downrange camera sites at Toolik Lake, Arctic Village and Old Crow successfully recorded the luminous trails and their movement in the upper atmospheric winds for further study. The 55-foot tilting HEX rocket contained instrument payloads designed by Geophysical Institute Professor of Physics John Craven and University of Alaska students supervised by Professor of Electrical Engineering Joe Hawkins.

“We are extremely happy with the trajectory, with the chemical trail imaging, and with the instrument data,” said Conde.

Conde admits that he did not dream up the idea of tilting a rocket’s trajectory sideways to perform his research. He attributes the idea to fellow Geophysical Institute scientists. 

Professor of Physics Hans Nielsen once suggested releasing a horizontal chemical trail from an orbiting payload launched from Kodiak Island.

Craven recommended using a sub-orbital sounding rocket to release the horizontal trail. Conde was skeptical because he knew sub-orbital sounding rockets cannot fly truly horizontal.

“But eventually I realized that we would be able to make the sub-orbital trajectory flat enough to do the science I wanted,” Conde said.

With that insight, Conde designed a suitable sounding rocket mission, then pursued and received funds from NASA.

To ensure the rocket did not fly off course while horizontal, a NASA flight safety officer was present during the launch. The safety officer used telemetry and radar data to monitor flight performance. Should the rocket performance have departed from acceptable limits, the safety officer would have sent a thrust termination command to prevent the vehicle from leaving the authorized safe flight path.

The data gathered by Conde’s mission will help scientists learn more about the role the aurora plays in the mixing of ionospheric gases. It will also cause space physicists to view the sounding rocket as a more versatile research tool.


A full-color image of the HEX rocket’s chemical trail passing through the aurora and caption information explaining the image is available electronically by visiting
ftp://ftp.gi.alaska.edu/pub/media. In using this photo, please cite the UAF Geophysical Institute as the source and Dirk Lummerzheim as the photographer.

HEX mission Web site: http://www.uaf.edu/asgp/hex

Mark Conde, UAF Geophysical Institute Assistant Professor and HEX Mission Principal Investigator
Office: (907) 474-7347

Poker Flat: (907) 455-2110
Vicki Daniels, UAF Geophysical Institute Public Relations Specialist (907) 474-5823 or info@gi.alaska.edu