Advanced Colloids Experiment-1 (ACE-1) is the first in a series of microscopic imaging investigations of materials which contain small colloidal particles, which have the specific characteristic of remaining evenly dispersed and distributed within the material. This investigation takes advantage of the unique environment onboard the International Space Station (ISS) in order to separate the effects induced by Earth?s gravity in order to examine flow characteristics and the evolution and ordering effects within these colloidal materials. Engineering, manipulation and the fundamental understanding of materials of this nature potentially enhances our ability to produce, store, and manipulate materials which rely on similar physical properties.Principal Investigator(s)
ZIN Technologies Incorporated, Cleveland, OH, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration:
May 2012 - March 2014Expeditions Assigned
31/32,33/34,37/38Previous ISS Missions
The Preliminary Advanced Colloids Experiment (PACE) is an engineering evaluation of the capabilities and limitations of the ACE hardware. With PACE special attention is paid to vibration effects on image resolution when using ACE hardware during times of astronaut activity and sleep.
The Advanced Colloids Experiment-1 (ACE-1) incorporates hundreds of individual samples, and these samples all differ in type or concentration. There is a broad array of fundamental questions being studied by the ACE-1 scientists; for example, how does one understand the basic physics that describes the time-dependent evolution in the microstructure in concentrated dispersions? This is a complex problem because of the interplay of inter-particle, Brownian (i.e., random particle collision) and hydrodynamic (i.e., particle drag) forces and thermodynamics. Procter and Gamble (P&G), for example, hopes to measure the rate of coarsening (i.e., the process of whereby particles shrink or grow as a result of diffusion of a solute) of weak depletion gels (i.e., weak stress bearing gels) to compare to delayed sedimentation in earth-based samples. These microgravity experiments allow a significant simplification of the problem (e.g. by eliminating sedimentation from gravitational stress).
This work also provides some very unique opportunities to study the shelf-life problem. Fundamental microgravity research at Harvard University by Weitz and Lu and at (P&G) by Lynch and Kodger on the underlying fluid physics may provide the understanding needed to enable the development of better, less expensive, longer shelf-life household products, foods, and medicines. Stabilizers, which are presently used in these products, are expensive, take up volume, and are needed to extend the life of products. Even a 1% savings for a $100 billion dollar industry would prove significant. To present, the P&G microgravity experimental designs have been relatively simple, whereby samples are stirred and changes are measured at low magnification with a camera. To connect the physics to the observations, it becomes necessary to evoke phase separation theories. The advent of a space-based confocal microscope, in the future, allows one to remove the need to macroscopically model images of the underlying physics. Scientists at P&G feel that measuring the movement of individual particles directly enhances their ability to move the science forward. Specific objectives being addressed by this research and by different investigators are as follows:
ACE-1addresses basic physics questions with regards to colloids, but some of the results may eventually have applications for space exploration. Supercritical fluids, which represent one of the applications of the critical point (i.e., phase boundary) experiment, are a potential application in propulsion systems for future spacecraft design. Additionally, associated shelf-life studies impact not only products on store shelves, but those being stored for later use in space.Earth Applications
The ACE-1 samples provide important data that is not available on Earth; data which can guide our understanding of crystallization, production quality control and phase separation (e.g., shelf-life and product collapse). Additionally, since product shelf-life may be dependent upon binodal decomposition and possibly upon Oswald ripening in the emulsion samples, a better understanding of these processes could have an enormous commercial impact in terms of quality, production, and longevity.
These colloidal materials have applications ranging from the very mundane to the very esoteric. Particle additives, for example, offer practical control of fluid rheologies, improving the performances of conventional materials such as paints, motor oils, food, and cosmetics, while further offering insights into microfluidics and cell biology processes. Control of particles on micro and nano-scales also hold potential regarding high-tech problems such as photonics, lithography, biochemical sensors and processors, as well as in the design of advanced composites. In a different vein, studies of complex fluids are increasingly stimulated by analogies from cell biology, and in some cases provide critical insights about mechanisms that arise in the crowded, aqueous, and near-room-temperature cellular environments. The development of micro- and nano-particle fluid suspensions and colloids plays a major role in many industries. One example is drug-delivery within the biomedical market, where these systems and their development result in billions of dollars in sales for the pharmaceutical industry.
Generally, colloidal nucleation experiments seek an understanding of the most fundamental liquid/solid transitions. Particle shape impacts the rise of order out of disorder. Particles can be fabricated which enable self-assembly and the self-replication of structures. Though direct applications of that understanding do not yet drive the research, the growth of ordered colloidal phases has attracted interest in a number of areas, e.g., ceramics, composites, optical filters and photonic band-gap materials. For example, the use of asymmetric particles may produce directionally dependent crystal properties, and the use of particles whose size depends upon temperature may afford temperature tunable crystals.
The ACE-1 investigation consists of twenty sample disks that each contains up to ten wells of colloidal particles (each sample well typically contain 2.1 microliters). One set of ten disks launches around June of 2012 and an additional set of ten disks launch 12 to 16 months later, and perhaps incrementally. The experiment requires crewmember time to set-up in the Light Microscopy Module (LMM) facility on the ISS. The samples in each sample disk are mixed and then observed, one disk at a time. The microscope is controlled from the ground and the pictures are down-linked to investigators for analysis and planning.Operational Protocols
ACE-1 Operations: Crewmember required to install ACE-1 hardware, Power to rack is OFF