Thruster-plume-induced contamination measurements from the PIC and SPIFEX flight experiments

Abstract

This paper documents thruster plume induced contamination measurements from the PIC (Plume Impingement Contamination) and SPIFEX (Shuttle Plume Impingement Flight Experiment) flight experiments.The SPIFEX flight experiment was flown on Space Shuttle mission STS-64 in 1994. Contamination measurements of molecular deposition were made by XPS (X-ray Photo Spectroscopy). Droplet impact features were also recorded with SEM (Scanning Electron Microscope) scans on Kapton and aluminum foil substrates.The PIC flight experiment was conducted during STS-74 in 1996. Quartz Crystal Microbalances (QCMs) measured contaminant deposition from U.S. and Russian thruster firings. Droplet impact observations were made with SEM scans of the Shuttle RMS (Remote Manipulator System) camera lens.These flight experiments were successful in providing measurements of plume induced contamination as well as droplet impact damage. These measurements were the basis of the plume contamination models developed for the International Space Station (ISS).

Analysis of Space Shuttle Primary Reaction-Control Engine-Exhaust Transients

“…Next, we relate these angular distributions to previous centerline deposition rates and suggest values for the deposition rate as a function of distance and angle. Previous experiments have quantified deposition rates on the thrust centerline [1,2]. In the work by Soares et al [2], a deposition rate of 1:282 10 5 g cm 2 s 1 was derived from the study of 20 80 ms PRCS engine firings at a distance of 10.58 m. The deposition rate was derived assuming a total engine firing duration of 1.6 s. From the Brook equation for the engine-exhaust number densities and the parameters in Table 3, we can determine an estimate for the total centerline exhaust particle flux F at a distance of 10.58 m from…”

“…A series of experiments have investigated contamination caused by space shuttle reaction-control-system engine exhaust [1,2]. The experiments measured deposition rates and clearly identified significant surface erosion, as evidenced by microcrater formation attributed to hypervelocity impacts by condensates in the exhaust.…”

Degradation of solar cell optical performance due to plume particle pitting

“…The damage is dependent upon the material properties of the surface that is impacted. 3,12,13 The SPIFEX experiment had both aluminum and Kapton witness coupons. Figure 3 shows an image of the aluminum witness sample; the impact craters are visible in the image.…”

GIADA performance during Rosetta mission scientific operations at comet 67P

“…The QCMs determine the cumulative mass of sub-micron and micron-sized particles collected on a sensor quartz crystal by measuring the resonance frequency variation with respect to a reference quartz crystal (McKeown, 1998;Sauerbrey, 1959). These sensors were used as dust collectors on Mars Pathfinder Mission (Landis et al, 1996) and as molecular contamination monitoring systems on MSX (Wood et al, 2000) and SDS-4 (Nakamura et al, 2013) satellites, on the Space Shuttle (Soares et al, 2002), and on the International Space Station (Tighe et al, 2009).…”

“…During the mission, we monitored the functional parameters of the sensors, evaluating their health status and checking their performance over time and in different environmental conditions. The laser emission intensity (Pankove, 1968;Xiang et al, 2009) and the QCM crystals resonance frequency (Palomba et al, 2002;Soares et al, 2002;Tighe et al, 2009) are sensitive to the operative environmental conditions, e.g. the temperature.…”