Detectability of Cold Rocket Plumes.
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
Pagination or Media Count:
The problem of detecting high altitude rocket plumes with satellite-borne submillimeter-wave radiometers is examined from both theoretical and experimental points of view. To estimate the sizes of plume signatures contrasted against a 250-K earth background or in self-emission against the cold sky, a computer program has been developed to predict plume brightness temperatures and optical depths of rotational lines of plume molecular constituents e.g., H2O as a function of distance from the nozzle. The methods employed in the computations are described in general terms, and examples are presented to indicate that detectable H2O signatures extending to several thousand nozzle diameters should exist at plume altitudes above 250 km. Details of a laboratory water vapor jet operating in a high vacuum environment designed to simulate a rocket plume at high altitude are outlined. Sensitivity considerations relevant to the plume detection problem are discussed for Fourier transform spectrometers and heterodyne receivers designed to study spectral lines in the submillimeter-wave region. Finally, a technique for converting the heterodyne radiometer into a spectrometer is described as a means of obtaining line shape details of the 752-GHz H2O line. Author
- Combustion and Ignition