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Ramohalli, Kumar

Publications and source records attributed to Ramohalli, Kumar.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Oxygen plant breadboard design, and techniques for improving mission figure-of-merit

A breadboard oxygen plant to process anaerobic carbon dioxide is designed and constructed; the objective is not only to produce a key propellant component extraterrestrially, but also to develop the important technologies that are necessary for a successful operation of in-situ materials utilization hardware. The solid electrolytic cells are supplied to specifications by an established vendor. The cell thermal control, electrical control, and flow control are installed after detailed designs. Extensive data are obtained that characterize the operation of the plant as the input parameters are varied. The initial mass, energy, and volume-needs provide the input to a figure-of-merit software program to calculate the impact of various candidate technologies upon the overall mission. The desirability of studies on storage and high-density propellants is shown. This task dovetails into other tasks that are evaluating alternative cell materials, catalysis for compactness, and smart sensors for effective control.

Ramohalli, Kumar↗
NASA NTRS1991

Development of a figure-of-merit for space missions

The concept of a quantitative figure-of-merit (FOM) to evaluate different and competing options for space missions is further developed. Over six hundred individual factors are considered. These range from mission orbital mechanics to in-situ resource utilization (ISRU/ISMU) plants. The program utilizes a commercial software package for synthesis and visual display; the details are completely developed in-house. Historical FOM's are derived for successful space missions such as the Surveyor, Voyager, Apollo, etc. A cost FOM is also mentioned. The bulk of this work is devoted to one specific example of Mars Sample Return (MSR). The program is flexible enough to accommodate a variety of evolving technologies. Initial results show that the FOM for sample return is a function of the mass returned to LEO, and that missions utilizing ISRU/ISMU are far more cost effective than those that rely on all earth-transported resources.

Preiss, Bruce↗
NASA NTRS1991

Mining the air - Resources of other worlds may reduce mission costs

It is proposed that the mining of resources on another planet to support operations there and also to provide a means for the return trip to earth provides a less expensive way to send humans beyond low earth orbit to live on the moon and to explore Mars. Since a large fraction of any chemical propellant combination is the oxidizer that burns with the fuel to generate the rocket jet, and for life support, the generation of oxygen from any of its atmospheric or mineral compounds is a valuable capability. Such materials include the lunar minerals ilmenite and anorthite, Martian permafrost, water ice at the Martian poles, and atmospheric carbon dioxide on Mars. The possibilities of developing such technologies are discussed and the prospects of developing building materials for such facilities from local resources are considered. The role of the Space Engineering Research Center at the University of Arizona in exploring the use of local planetary resources is noted.

Ramohalli, Kumar↗
NASA NTRS1991

Options for Martian propellant production

A quantitative evaluation methodology for utilizing in-situ resources on Mars for the production of useful substances. The emphasis is on the chemical processes. Various options considering different feedstock (mostly, carbon dioxide, water, and iron oxides) are carefully examined for the product mix and the energy needs. Oxygen, carbon monoxide, alcohols, and other chemicals are the end products. The chemical processes involve electrolysis, methanation, and variations. It is shown that maximizing the product utility is more important than the production of oxygen, methane, or alcohols. An important factor is the storage of the chemicals produced. The product utility is dependent, to some extent, upon the mission. A combination of the stability, the enthalpy of formation, and the mass fraction of the products is seen to yield a fairly good quantitative feel for the overall utility and maximum mission impact.

Dowler, Warren↗
NASA NTRS1991

Oxygen production on Mars: A figure-of-merit approach

A new approach is described toward evaluating the overall system performance in space missions; the objective is to demonstrate a new quantitative tool that can effectively synthesize and display the big picture. It considers a large number of individual components and factors that influence the big picture. The approach was found to be valuable in evaluating various options that must be considered in choosing one or more final ones. The application is especially suited to evaluate missions that consider ISRU. The Figure-of-Merit (FoM) can be different for different missions. In fact, it should be different for different priorities. Simple mass at launch, mass at the moment of departure from LEO, the payback time, the mass returned to LEO, the overall life-cycle costs, etc. are possible indicators of the FoM. After mentioning all of these possible definitions, the FoM for various historical missions will be presented. The FoM of a simple Mars Sample Return (MSR) mission is next presented. It is shown that the FoM is not only higher for missions employing ISRU, but that even among ISRU missions, several mundane propellant combinations are more desirable than the highest-performance propellants.

Preiss, Bruce↗
NASA NTRS1991

Experimental data from an oxygen plant for Mars

Experimental data are presented on various aspects of the plant operation intended to produce oxygen from the atmospheric carbon dioxide at any Martian site. A solid electrolytic cell is used in the tubular geometry. Anaerobic carbon dioxide is procured from a gas vendor and is used at a pressure of 1 bar (entrance to the plant). The variables include the voltage applied to the cell, the temperature of the cell, the current density, the flow rate and the duty-cycle. The oxygen production rates have been consistent with the specifications of the cell manufacturer. It is projected that a plant weighing between 145 and 197 kg can be built to produce 10 kg of oxygen per day. Various operational characteristics such as cell poisoning, carbon formation, nitrogen embrittlement, local current densities exceeding the breakdown potential for the cell material, reliability, risk, are all being quantitatively assessed.

Schallhorn, P. A.↗
NASA NTRS1991

Autonomous space processor for orbital debris

The development of an Autonomous Space Processor for Orbital Debris (ASPOD) was the goal. The nature of this craft, which will process, in situ, orbital debris using resources available in low Earth orbit (LEO) is explained. The serious problem of orbital debris is briefly described and the nature of the large debris population is outlined. The focus was on the development of a versatile robotic manipulator to augment an existing robotic arm, the incorporation of remote operation of the robotic arms, and the formulation of optimal (time and energy) trajectory planning algorithms for coordinated robotic arms. The mechanical design of the new arm is described in detail. The work envelope is explained showing the flexibility of the new design. Several telemetry communication systems are described which will enable the remote operation of the robotic arms. The trajectory planning algorithms are fully developed for both the time optimal and energy optimal problems. The time optimal problem is solved using phase plane techniques while the energy optimal problem is solved using dynamic programming.

Ramohalli, Kumar↗
NASA NTRS1991

NASA Space Engineering Research Center for utilization of local planetary resources

Because of a change in the NASA funding cycle, the present reporting period covers only the six months from March to September 1991. Nevertheless, remarkable progress was made in a number of areas, some of the most noteworthy of which are: (1) Engineering operation of a breadboard CO2 yields O2 demonstration plant that produced over 10 grams of oxygen per day during several runs of over 100 hours each with a single electrolytic cell. Complete automation of controls, monitoring of various inputs/outputs and critical internal variables, diagnostics, and emergency shutdown in an orderly manner were also included. Moreover, 4-cell and 16-cell units, capable of much higher rates of production, were assembled and tested. (2) Demonstration of a 200 percent increase in the carbothermal reduction of ilmenite through vapor deposition of carbon layers on particles of that material. (3) Demonstration of the deposition of strong iron films from carbonyl chemical vapor deposition, establishing the crucial role of additive gases in governing the process. (4) Discovery of an apparent 800 percent increase in the conversion rates of a modified ilmenite simulant in a plasma-augmented reactor, including direct enhancement by solar radiation absorption. (5) Proof that test specimens of lunar soil with small amounts of metallic additives, recrystallized at moderate temperatures, exhibit an improvement of several orders of magnitude in ductility/tensile strength. (6) Experiments establishing the feasibility of producing silicon-based polymers from indigenous lunar materials. (7) Application of CCD technology to the production of maps of TiO2 abundance, defining primary ilmenite deposits, on the disk of the full moon. (8) Attainment of a discovery rate of approximately 3 new near-Earth asteroids per month by Spacewatch, more than doubling the previous global rate. (9) Coordination of industry and university magma electrolysis investigations in a workshop designed to define remaining problem areas and propose critical experiments.

Ramohalli, Kumar↗
NASA NTRS1990

Initial steps toward automation of a propellant processor

This paper presents the results from an experimental study aimed at ultimately automating the mixing of propellants in order to minimize unintended variations usually attributed to human error. The water heater and delivery system of a one-pint Baker-Perkins (APV) vertical mixer are automated with computer control. Various innovations are employed to introduce economy and low thermal inertia. Some of these include twin heaters/reservoirs instead of one large reservoir, a compact water mixer for achieving the desired temperature quickly, and thorough insulation of the entire water system. The completed system is tested during two propellant mixes. The temperature uniformly is proven through careful measurements employing several local thermocouples.

Schallhorn, Paul↗
NASA NTRS1990

Theoretical performance of unconventional propellants and fuel/oxidizer combinations

A comparative study is made to identify the most advantageous fuel/oxidizer combinations which could be supplied to spacecraft from in situ resources or from the most economical earth-transported storable fuels. The performance of the unconventional fuel/oxidizer combinations in question are computed for a wide range of pressures, expansion ratios and initial temperatures. The propellants discussed are, (1) for LEO: H2 + O2, NH3 + N2O4; (2) for the moon: CH4 + O2, SiH4 + O2, H2 + Al + O2, butyl rubber + O2, silicone + O2, and polystyrene + O2; and (3) for Mars: CO + O2, CO + H2O2, CO + N2O4, C2H5OH + O2, and CH3OH + O2.

Rascon, Mario↗
NASA NTRS1990

Autonomous space processor for orbital debris

Advanced designs are being continued to develop the ultimate goal of a GETAWAY special to demonstrate economical removal of orbital debris utilizing local resources in orbit. The fundamental technical feasibility was demonstrated in 1988 through theoretical calculations, quantitative computer animation, a solar focal point cutter, a robotic arm design and a subcase model. Last year improvements were made to the solar cutter and the robotic arm. Also performed last year was a mission analysis which showed the feasibility of retrieve at least four large (greater than 1500 kg) pieces of debris. Advances made during this reporting period are the incorporation of digital control with the existing placement arm, the development of a new robotic manipulator arm, and the study of debris spin attenuation. These advances are discussed.

Ramohalli, Kumar↗
NASA NTRS1990

NASA Space Engineering Research Center for utilization of local planetary resources

The University of Arizona and NASA have joined to form the UA/NASA Space Engineering Research Center. The purpose of the Center is to discover, characterize, extract, process, and fabricate useful products from the extraterrestrial resources available in the inner solar system (the moon, Mars, and nearby asteroids). Individual progress reports covering the center's research projects are presented and emphasis is placed on the following topics: propellant production, oxygen production, ilmenite, lunar resources, asteroid resources, Mars resources, space-based materials processing, extraterrestrial construction materials processing, resource discovery and characterization, mission planning, and resource utilization.

Ramohalli, Kumar↗
NASA NTRS1990

Autonomous production of propellants

The autonomous production of propellants is addressed. Since 80 to 90 percent of a spacecraft's mass is typically propellants, it is advantageous to produce propellants in strategic locations en route to, and at, the desired mission destination. This reduces the weight of the spacecraft and the cost of each mission. Since one of the primary goals of the space program is safety, a totally automated propellant production system is desirable. This system would remove, from hostile, high-risk extraterrestrial environments, the constant human intervention currently required in the production of many propellants. This enables the exploration of space to be more than the search for and production of fuel. As a proof-of-concept demonstration, one specific case was chosen for this study. That case was a composite propellant processor (the principle is more important than the application), and the specific processor used saved SERC the considerable cost of acquiring a new liquid propellant processor that would also have required similar automation.

Ramohalli, Kumar↗
NASA NTRS1989

A 'figure-of-merit' approach to extraterrestrial resource utilization

An approach for interrelated optimizations in space missions that utilize extraterrestrial resources is developed, consisting in the concept of an overall mission 'figure-of-merit' leading to more realistic designs than through individual performance maximizations. After a brief discussion of this concept, the synthesis of four major components of any future space mission is considered. The four major components are: orbital mechanics of the transportation; performance of the rocket motors; support systems including power, thermal and process controls, and instruments; and in situ resource utilization plant equipment. The Mars Sample Return mission is the basis of an illustration of the proposed concept. A popular spreadsheet is used to quantitatively demonstrate the interdependent nature of the mission optimization. Future prospects are outlined, that promise great economy through extraterrestrial resource utilization and a quick evaluation technique.

Ramohalli, Kumar↗
NASA NTRS1989

Autonomous space processor for orbital debris

This work continues to develop advanced designs toward the ultimate goal of a GETAWAY SPECIAL to demonstrate economical removal of orbital debris utilizing local resources in orbit. The fundamental technical feasibility was demonstrated last year through theoretical calculations, quantitative computer animation, a solar focal point cutter, a robotic arm design and a subscale model. During this reporting period, several improvements are made in the solar cutter, such as auto track capabilities, better quality reflectors and a more versatile framework. The major advance has been in the design, fabrication and working demonstration of a ROBOTIC ARM that has several degrees of freedom. The functions were specifically tailored for the orbital debris handling. These advances are discussed here. Also a small fraction of the resources were allocated towards research in flame augmentation in SCRAMJETS for the NASP. Here, the fundamental advance was the attainment of Mach numbers up to 0.6 in the flame zone and a vastly improved injection system; the current work is expected to achieve supersonic combustion in the laboratory and an advanced monitoring system.

Ramohalli, Kumar↗
NASA NTRS1989

Aging behavior and life prediction of graphite composites

This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

Ramohalli, Kumar↗
NASA NTRS1989

Composite Solid Propellant Predictability and Quality Assurance

Reports are presented at the meeting at the University of Arizona on the study of predictable and reliable solid rocket motors. The following subject areas were covered: present state and trends in the research of solid propellants; the University of Arizona program in solid propellants, particularly in mixing (experimental and analytical results are presented).

Ramohalli, Kumar↗