The ESA/NASA Multi-Aircraft ATV-1 Re-Entry Campaign: Analysis of Airborne Intensified Video Observations from the NASA/JSC Experiment
- Paper number
IAC-09.A6.1.1
- Author
Mr. Paul Maley, United States
- Coauthor
Dr. Ed Barker, NASA Johnson Space Center (NASA-JSC), United States
- Coauthor
Mr. Mark Mulrooney, United States
- Year
2009
- Abstract
In September 2008, a joint ESA/NASA multi-instrument airborne observing campaign was conducted over the Southern Pacific ocean. The objective was the acquisition of data to support detailed atmospheric re-entry analysis for the first flight of the European Automated Transfer Vehicle (ATV)-1. Skilled observers were deployed aboard two aircraft which were flown at 12.8 km altitude within visible range of the ATV-1 re-entry zone. The observers operated a suite of instruments with low-light-level detection sensitivity including still cameras, high speed and 30 fps video cameras, and spectrographs. The collected data has provided valuable information regarding the dynamic time evolution of the ATV-1 re-entry fragmentation. Specifically, the data has satisfied the primary mission objective of recording the explosion of ATV-1’s primary fuel tank and thereby validating predictions regarding the tanks demise and the altitude of its occurrence. Furthermore, the data contains the brightness and trajectories of several hundred ATV-1 fragments. It is the analysis of these properties, as recorded by the particular instrument set sponsored by NASA/ Johnson Space Center, that we present here. NASA placed a pair of USA-designed co-aligned wide and narrow field, micro-channel-plate (MCP) intensified video imaging systems in the window of the Gulfstream V campaign aircraft, The ATV-1 target and debris trail was tracked along its re-entry path by manually slewing the instrument. Data from the narrow field instrument has been used exclusively for the analysis herein since its greater spatial resolution enabled better differentiation of individual debris fragments. Via photometric and trajectory analysis, involving measurement of dozens of fragments in each of 5000 frames of video data, we have demonstrated a loose correlation between fragment brightness and drift rate within the debris trail. As indicated by their tendency to decouple more rapidly (both laterally and longitudinally) from the global motion of the debris stream, fainter objects appear to exhibit higher drag coefficients than bright objects. It is hypothesized that this behavior is indicative of a relationship between fragment density and luminosity. Lower density objects, tending toward higher area to mass (A/m) ratios and lower heat capacity, may encounter a lower total frictional heating load and cool more rapidly and thereby be typically less luminous as blackbody radiators. Additionally our analysis indicates that there is little or no correlation between object brightness and variability within our ability to measure (the analog video data is of limited dynamic range). We also observed several cascading events wherein some larger objects fragment into a cluster of smaller objects. We have developed new processes and procedures to acquire and analyze the ATV-1 re-entry data. Future aircraft-based re-entry intercepts such as that of the upcoming Japanese HTV-1 may benefit from the ATV-1 experience.
- Abstract document
- Manuscript document
(absent)