Liquid dispersal study - A proposed Space Shuttle liquid release experiment

<title>Optical properties of water released in low earth orbit</title>

“…These comments are of necessity qualitative, and in view of the incomplete information about the response of nonreactive liquids to the near-vacuum and radiation field of low earth orbit we have suggested further space and laboratory experiments 7 . The liquid-solid-vapor phenomenology for a given initial temperature, diameter, and flow rate in general depends nonlinearly on the macroscopic parameters vapor pressure, specific heats and heats of fusion and evaporation, thermal couductivity, expansion coefficient, surface tension, and viscosity, as well as on the molecular weight and elastic collision cross-sections of the vaporized material.…”

“…Larger-diameter, higher-temperature, lower-velocity, more contaminated and gas-laden water coiumns burst nearer the venting nozzle 6 , 9 , and impurities and lower initial temperatures lead to smaller fragmentation-cone angles (human waste water dumped from shuttle has been observed to form a narrower particle trail than supply water, b, a camera held outboard on the spacecraft's Remote Manipulator Arm). Alteration of the equation of state and surface tension of the injected substance by dissolved materials can be expected to lead to quantitative differences in the number and initial size of the two droplet components, and high concentrations of *dye* dopants could increase the absorptivities/emissivities and so change the sublimation rates 7 (although the large water-ice drops are already optically thick across virtually all of the infrared). We note also that low vapor pressure liquids that contain little dissolved gas may not explosively rupture due to boiling, but remain subject to breakup into droplets initiated by fluid stream instabilities 6 .…”

“…(These cameras detected no slower-moving discrete particles, such as have been proposed as originating from fracturiig of frost formed on the spacecraft wall near th-venting nozzle.) Detailed orbital trajectory calculations ' 7 have shown that 1-mm ice particles would not collide with Shuttle Orbiter on its subsequent passes, at all angles relative to its flight path that the liquid stream may be injected. Since the much shorter-lived recondensation droplets have the same outward velocity, they also do not return to physically contaminate the spacecraft.…”

“…Despite the approximations in the existing theory for cylindrical 6 or spherical liquid geometry, and the uncertainty in the (assumed uniform) water temperature upon injection and breakup distance, the predicted gas-evolution rate summed along X is satisfactorily close to the aforementioned thermodynamic value of one-sixth. We are currently developing a Navier-Stokes equations-based numerical model 7 of the coupling between the two phases that will provide an improved spatial distribution of the vapor escape rates.…”

“…The brightness profile shapes are broadly similar for emission features other than these summed rotational lines and the two overlying principal short wavelength infrared bands, which with the cross-sections applied have about equal excitation probabilities [5][6][7][8][9][10][11][12][13][14][15][16][17][18] . A further caveat 4) is that the brigbtnesses near 6.3 Am looking out into the hemisphere into which the water is vented are about twice those predicted from collisional impact at 329 km altitude due to emission within about -30 m from their evolution point by H20 molecules that evaporate from the stream or droplets in the 010 state.…”