Ronald J. Sicker

Orders-of-magnitude performance increases in GPU-accelerated correlation of images from the International Space Station

We implement image correlation, a fundamental component of many real-time imaging and tracking systems, on a graphics processing unit (GPU) using NVIDIA’s CUDA platform. We use our code to analyze images of liquid-gas phase separation in a model colloid-polymer system, photographed in the absence of gravity aboard the International Space Station (ISS). Our GPU code is 4,000 times faster than simple MATLAB code performing the same calculation on a central processing unit (CPU), 130 times faster than simple C code, and 30 times faster than optimized C++ code using single-instruction, multiple-data (SIMD) extensions. The speed increases from these parallel algorithms enable us to analyze images downlinked from the ISS in a rapid fashion and send feedback to astronauts on orbit while the experiments are still being run.

Constrained Vapor Bubble Heat Pipe Experiment Aboard the International Space Station

A constrained vapor bubble heat pipe experiment was run in the microgravity environment of the International Space Station. Here we present the initial results that demonstrate significant differences in the operation of the constrained vapor bubble heat pipe in the microgravity environment as compared to the Earth’s gravity. The temperature profile data along the heat pipe indicate that the heat pipe behavior is affected favorably by increased capillary flow and adversely by the absence of outside convective heat transfer as a heat loss mechanism. The reflectivity pattern viewed through the transparent quartz wall documented complex microflow patterns. Image data of the liquid profile in the grooves of the heat pipe indicate that the curvature gradient giving capillary flow is considerably different from that on Earth. Using experimental data for the temperature and meniscus profiles, a one-dimensional model gives the inside heat transfer coefficient, which was significantly higher in microgravity. An in...

Constrained Vapor Bubble Experiment for International Space Station: Earth's Gravity Results

The constrained vapor bubble experiment scheduled to fly aboard the International Space Station in the near future promises to give us new insight into the fundamental science of interfacial thermophysics. The evaporating meniscus formed at the corner of the vapor bubble is expected to behave in a significantly different manner in the microgravity environment as compared with the Earths gravity environment. Since the constrained vapor bubble can also behave as a micro heat pipe, it will additionally help in gaining a technical understanding of the performance of a micro heat pipe in a space environment. Earth-based experiments have been conducted for the past two decades to gain a better knowledge of the rich phenomenon observed in the relatively simple constrained vapor bubble setup. Here, some recent Earths-gravity-environment-based data obtained on a 30-mm-long constrained vapor bubble have been presented. The data were fitted to a model, and a self-consistent value of the inside heat transfer coefficient was obtained. The external convective and radiative heat transfer coefficients were also determined. These ground-based experiments form a calibration against which the future data from space-based experiments will be compared.

The Constrained Vapor Bubble (CVB) Experiment in the Microgravity Environment of the International Space Station

The Constrained Vapor Bubble (CVB) experiment was run in the microgravity environment of the International Space Station as part of the Increment 23-24 which ended in September 2010. Here we present preliminary results which indicate significant differences in the operation of the CVB heat pipe in the micro-gravity environment as compared to the Earths gravity. The temperature profile data along the heat pipe indicate that the heat pipe behavior is affected favorably by increased capillary flow and adversely by the absence of convective heat transfer as a heat loss mechanism. Image data of the liquid profile in the grooves of the heat pipe indicate that the curvature gradient is considerably different from that on Earth. An initial discussion of the data collected is presented.

Microgravity Phase Separation Near the Critical Point in Attractive Colloids

We investigate the phase behavior of mixtures of colloids and polymers near their critical point in a microgravity environment. Astronauts onboard the International Space Station (ISS) are using photography to record the rate of phase separation of six samples near the liquid-gas critical point. These photographs are taken both by an automated photography system (based on EarthKAM hardware and software) and manually by the astronauts who have setup the experiment. We have obtained high-quality photographs of processes that are not observable on Earth, since both sedimentation and convection are negligible onboard the International Space Station. Interestingly, we observe that gravity does not affect the onset of phase separation in colloid-polymer mixtures near the liquid-gas critical point: samples which phase separate on earth also do so onboard the ISS. However, the rates at which this phase separation occurs is affected by several orders of magnitude by gravity, suggesting future avenues for exploration. The understanding of this system is important for both practical earth-bound applications, as well as the development of products and materials that are stable and functional over long periods of time in a lowgravity environment. Thus, our results may assist the long-term spaceflight required for proposed exploration missions to the moon and to Mars.

The Constrained Vapor Bubble Experiment: Results From the International Space Station

The constrained vapor bubble (CVB) experiment is an experiment in thermal fluid science currently operating on the International Space Station. Flown as the first experiment on the Fluids Integrated Rack on the Destiny module of the US part of the space station, the experiment promises to provide new and exciting insights into the working of a wickless micro heat pipe in the micro-gravity environment. The CVB consists of a relatively simple setup — a quartz cuvette with sharp corners partially filled with pentane as the working fluid. Along with temperature and pressure measurements, the curvature of the pentane menisci formed at the corners of the cuvette can be determined using optical measurements. This is the first time the data collected in space environment is being presented to the public. The data shows that, while the performance of the CVB heat pipe is enhanced due to increased fluid flow, the loss of convection as a heat loss mechanism in the space environment, leads to some interesting consequences. We present some significant differences in the operating characteristics of the heat pipe between the space and Earth’s gravity environments and show that this has important ramifications in designing effective radiators for the space environment.© 2011 ASME

Long-Time Observation of Near-Critical Spinodal Decomposition of Colloid-Polymer Mixtures in Microgravity

We investigate liquid-gas phase separation near the critical point of colloid-polymer mixtures aboard the International Space Station, as part of the BCAT3 and BCAT4 experiments. In this microgravity environment, the higher-density liquid phase does not sink beneath the lower-density gas phase, as it does on the surface of the earth. Instead, we can observe the patterns formed during spinodal decomposition, using time-lapse photography for days to weeks, while previous experiments have been limited to observations of minutes to hours. We give a primer on phase separation and detail our sample preparation procedures. We also describe the speciflc innovations in our photography procedures made by a number of astronauts on orbit, demonstrating the importance of a manned microgravity laboratory to our investigation.