Accession Number : ADA266197


Title :   Optical Properties of Water Released in Low Earth Orbit


Corporate Author : PHOTOMETRICS INC WOBURN MA


Personal Author(s) : Gardner, James A , II ; Rall, David L ; Trowbridge, Christian A ; Kofsky, Irving L ; Viereck, Rodney A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a266197.pdf


Report Date : 21 Jun 1993


Pagination or Media Count : 13


Abstract : Analysis of intensified video photographs of a twilight venting of excess water from space shuttle showed that the approx. 1 mm diameter stream cavitationally fragments within about 1 m, forming two discrete-particle components and vapor. The images from nearby cameras are dominated by irregular, polydisperse water/ice droplets with sizes comparable with the venting orifice and outward velocity indistinguishable from that of the initially coherent liquid. In contrast the 2 1/2 km-long quasiconical trail imaged from a distant ground station consists of accompanying submicron ice spherules that were produced by partial recondensation of the overexpanded vacuum-evaporated water gas, which are sublimating at rates that we calculated from the measured falloff of axial sunlight-scatter radiance and the energy balance of progressively roughening ice at 329 km altitude; at low latitudes they cool to 180K in 1 s, and their radii transition to the Rayleigh-scattering range in approx. 1 min. The very much larger fragmentation particles come to a slightly higher equilibrium temperature within approx. 2 min, and persist for a few earth orbits. These three components of the vented water (and other high vapor pressure liquids) radiate and scatter earthshine and solar photons, and the orbital-velocity molecules are also excited by collisions with the residual atmospheric gas, overlaying wide-angle contaminating foregrounds on remote optical sensing from onboard.


Descriptors :   *OPTICAL PROPERTIES , *EARTH ORBITS , *LIQUIDS , *WATER , *VAPOR PRESSURE , VELOCITY , STATIONS , ANGLES , DENSITY , DIAMETERS , PARTICLE SIZE , TEMPERATURE , VOLUME , CONTRAST , FRAGMENTATION , MOLECULES , EXCITATION , ENERGY , VACUUM , RATES , CAVITIES , SPHERES , GASES , ICE , RESIDUALS , SOLAR ENERGY , RAYLEIGH SCATTERING , RADIANCE , IMAGES , SPACE SHUTTLES , CAMERAS , PRESSURE , BALANCE , PHOTONS , TRANSITIONS , ALTITUDE , ONBOARD , REMOTE DETECTION , WIDE ANGLES , GROUND STATIONS , COLLISIONS , STREAMS , PHOTOGRAPHS , ORIFICES , LATITUDE , TWILIGHT , SUNLIGHT , VENTING , ATMOSPHERICS


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Optics
      Spacecraft Trajectories and Reentry


Distribution Statement : APPROVED FOR PUBLIC RELEASE