MSFC-PLAN-2969 REV A CHG NOTICE 1

Abstract

The official title of this project is "Observable Protein Crystal Growth Apparatus" (OPCGA). The University of California, Irvine (UCI), is performing this development and flight investigation for the National Aeronautics and Space Administration (NASA) Microgravity Science and Applications Department (MSAD) under NASA contract, NAS8-00017. The initial OPCGA definition activity was selected by the NASA Office of Life and Microgravity Science and Applications (OLMSA), Microgravity Research Division (MRD) as a project within the Microgravity Research Program as identified in the Microgravity Research Program Plan. This Organization is now referred to as the Office of Biological and Physical Research (OBPR), Physical Sciences Research Division (PSR), from a proposal submitted by Dr. Alexander McPherson, UCI, in response to NASA Research Announcement NRA-91-OSSA-18. The selection notification was made by letter from NASA Headquarters, dated September 22, 1992. The definition phase contract, NAS8-39763, was issued on October 30, 1992 to conduct definition work as outlined in the proposal. The Science Requirements Document (SRD), UCI-OPI-SRD1-001, was approved January 28, 1998. <br>Purpose <br>The purpose of the OPCGA flight investigation is to conduct LLD biological crystallization in space, to determine what differences exist that discriminates the process in microgravity from that on Earth, and to optimize the LLD method of biological crystallization for crystals grown in microgravity. The immediate objective is to test the theory of the depletion zone. The OPCGA flight experiment seeks to observe the formation of stable depletion zones around growing macromolecular crystals in microgravity. The experiment apparatus will perform non-intrusive in-situ observations of the fundamental fluid phenomena about growing macromolecular crystals in microgravity and terrestrial laboratories. The observation capability will define the size and location of crystals, growth rates, and macromolecule concentration in the fluid about growing crystals. This data will initially be collected from a set of well-characterized macromolecules covering a range of molecular sizes at a variety of growth conditions. The instrument will provide two dimensional maps of the refractive index utilizing a phase shift Mach Zehnder interferometer. It will record images from the interferometer for measurement of crystal size and gross growth rates, and record video images from a video microscopy system to collect crystal size and gross growth rates from a view orthogonal to the interferometer. From these, and ground based data correlating the refractive index to concentration, two dimensional concentration maps about growing crystals can be developed. These flight measurements will be compared to those predicted by computer simulated models of the depletion zone developed in collaboration with the University of Alabama in Huntsville. <br>The planned experiments will also provide observations to test secondary hypotheses that crystals nucleate at, or assume positions within the fluid, that allow optimized growth, as well as the hypothesis that electrostatic effects produce a crystal distribution more closely approximating a colloidal dispersion. If this is seen to be so, then additional experiments can be conducted to alter the electrolyte properties of the mother liquor and correlate these changes with distribution patterns.