PUMA Mission Update:
Cora Randall-Linnea Avallone’s research group recently participated in a project to study the dispersion of rocket exhaust in the atmosphere. In conjunction with the WB-57 Ascent Video Experiment (WAVE), which was charged with imaging the Space Shuttle during liftoff, we carried out measurements in support of a National Science Foundation-funded exploratory project called Plume Ultrafast Measurements Acquisition (PUMA) of which Linnea is co-PI (http://paos.colorado.edu/~toohey/PUMA.html). Collaborators include Darin Toohey of PAOS, Robert Herman of JPL, and Greg Kok and Darrel Baumgardner of Droplet Measurement Technologies.

The NASA WB-57 aircraft served as an airborne platform from which high-resolution digital imagery of the 26 July 2005 launch of STS-114 was captured (see some of this video at http://www.nasa.gov/returntoflight/crew/index.html—look for the link labeled “WB57 Chase Plane video”). Following the video part of the experiment, the pilot turned the plane back toward Cape Canaveral and sampled the remains of the shuttle plume eight times. Instruments on the WB-57 measured particles, water vapor, condensed (particulate) water, ozone, and carbon dioxide.

The first photo above shows the shuttle launch from Patrick Air Force Base beach— about 25 miles south of KSC. The second photo shows a bit of the shuttle plume and the WB-57 contrail as it samples the plume.

The overall goals of PUMA are primarily focused on understanding dispersion processes in the upper troposphere and lower stratosphere, as well as extending our knowledge of the microphysical processes involved in cloud formation. Earlier studies of rocket exhaust showed that the classical descriptions of dispersive processes in the atmosphere were inadequate to represent the expansion and dilution of these plumes (Gates et al., 2002). As the name of the project indicates, PUMA measurements are fast—at least 1 Hz—to better define the edges of the plume and filaments that result from mixing of the plume into the background atmosphere. Our group was responsible for the measurements of condensed (particulate) water (a 2 Hz measurement using tunable diode laser spectroscopy) and of ozone (a 10 Hz measurement using ultraviolet absorption). Data analysis is on-going, with presentations at the Fall American Geophysical Union meeting anticipated. Additional sampling will take place during the launch of STS-121, now planned for March 2006. Stay tuned!