Naresh K. Rohatgi

Certification of vapor phase hydrogen peroxide sterilization process for spacecraft application

This paper describes the selection process and research activities JPL is planning to conduct for certification of hydrogen peroxide as a NASA approved technique for sterilization of various spacecraft parts/components and entire modern spacecraft.

Evaluation of sample preservation methods for space missions

This paper will present the research data using samples collected from the Mars 2001 orbiter, Odyssey, and all environmental samples collected from the cleanroom, during final assembly.

Cross Contamination of Martian Rock Samples

This paper presents the results of theoretical analyses conducted to investigate potential of various particle removal techniques.

Thermal, Mass, and Power Interactions for Lunar Base Life Support and Power Systems

A model has been developed for quantitative examination of the integrated operation of the lunar base power system, employing regenerative fuel cell technology, which would lead to incorporation into a lunar base life support system. The model employs methods developed for technology and system trade studies of the Life Support System configuration for the National Aeronautics and Space Administration (NASA). This paper describes the power system and its influence on life support while comparing various technologies, including pressurized gas storage and cryogenic storage, and different operation conditions. Based on preliminary assumptions, the mass, power, and thermal requirement estimates are made at the level of major components. The relative mass contribution and energy requirements of the components in various configurations are presented. The described intractions between power and life support include direct influence, such as water and oxygen storage, and indirect influence, through reliability and maintenance considerations.

Conversion of bioprocess ethanol to industrial chemical products: applications of process models for energy-economic assessments

Ethanol is commercially produced by bioconversion and by hydration of ethylene. Bioconversion has the significant advantage that utilization of nonrenewable petroleum resources is minimized. Advanced bioprocesses for aqueous ethanol can also be integrated with downstream systems for energy-efficient conversion to added-value chemicals, such as esters or other ethylene or ethanol derivatives. Since the energy-intensive step involving azeotrope dehydration is eliminated, net process energy requirements can be less than for production of anhydrous ethanol. Energy-economic assessments of a potential esterification process are described, where ethanol vapor in the presence of water from a bioreactor is catalytically converted to ethyl acetate. A commercial ASPEN process simulation program was used, and results were compared with an assessment based on a JPL computer model. Detailed evaluations of the sensitivity of cost of production to factors, such as material costs and annual production rates, were also completed.

Sensor Systems for Regenerative Life Support Systems

Successful operation of life support systems for space exploration missions of the future will require unique sophisticated sensor systems for highly dependable operation, i.e., autonomous and fault tolerant. These sensor systems will require the use of multifunctional in situ sensors that are strategically located throughout the life support systems. These sensors will communicate through control loops that are hierarchically interconnected at several levels of the life support system. Development of the sensor system must be done synergistically with the integration and testing of the subsystems, and their process units, as they are assembled and tested. The plan for proceeding with the sensor systems development and the integration with the test bed assembly and operation is described in this paper.

Hardware Scaleup Procedures for P/C Life Support Systems

This paper compares scaleup correlations developed at the Jet Propulsion Laboratory and at the Langley Research Center for various life-support hardware to estimate mass, volume, and power-consumption values as a function of feed or product-mass flow rates. The scaleup correlations are provided for a few selected advanced life-support technologies developed for the Space Station Freedom. In addition, correlation-validity limits and sources of data on various life-support hardware are also discussed.

Development of Vapor Phase Hydrogen Peroxide Sterilization Process for Spacecraft Applications

This paper will present test data and discussion on the work we are conducting at JPL to address the following issues: 1) efficacy of sterilization process; 2) diffusion of hydrogen peroxide under sterilization process conditions into hard to reach places; 3) materials and components compatibility with the sterilization process and 4) development of methodology to protect sensitive components from hydrogen peroxide vapor.

Human Life Support During Interplanetary Travel and Domicile Part V: Mars Expedition Technology Trade Study for Solid Waste Management

A model has been developed for NASA to quantitatively compare and select life support systems and technology options. The model consists of a modular, top-down hierarchical breakdown of the life support system into subsystems, and further breakdown of subsystems into functional elements representing individual processing technologies. This paper includes the technology trades for a Mars mission, using solid waste treatment technologies to recover water from selected liquid and solid waste streams. Technologies include freeze drying, thermal drying, wet oxidation, combustion, and supercritical-water oxidation. The use of these technologies does not have any significant advantages with respect to weight; however, significant power penalties are incurred. A benefit is the ability to convert hazardous waste into a useful resource, namely water.

Human Life Support During Interplanetary Travel and Domicile - Part II: Generic Modular Flow Schematic Modeling

This paper describes the Generic Modular Flow Schematic (GMFS) architecture capable of encompassing all functional elements of a physical/chemical life support system (LSS). The GMFS can be implemented to synthesize, model, analyze, and quantitatively compare many configurations of LSSs, from a simple, completely open-loop to a very complex closed-loop. The GMFS model is coded in ASPEN, a state-of-the-art chemical process simulation program, to accurately compute the material, heat, and power flow quantities for every stream in each of the subsystem functional elements (SFEs) in the chosen configuration of a life support system. The GMFS approach integrates the various SFEs and subsystems in a hierarchical and modular fashion facilitating rapid substitutions and reconfiguration of a life support system. The comprehensive ASPEN material and energy balance output is transferred to a systems and technology assessment spreadsheet for rigorous system analysis and trade studies.