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NASA NTRS2006

The Lunar Landing Research Vehicle; Prelude to the Arrival at Tranquility Base

The flight of Apollo 11 was the end of a decade-long race to reach the moon, a race between the US and Soviet Union, but also a race with time, for we as a nation only had the 1960s to reach our objective. Most of us remember that particular day, July 20, 1969, but the further we are from any date the harder it is to recall details. It s easy to forget, for instance, how close together the Apollo flights came to each other as the lunar flight date approached. Apollo 7 circled Earth for almost 11 days testing the systems of the spacecraft in October 1968; Apollo 8 gave us the first glimpse of our entire planet while circling the moon during Christmas of 1968. Apollo 9 lifted off on March 3 of 1969, and Apollo 10 returned to Earth on May 26 of that year. Less than two months later, on 16 July, Apollo 11 lifted off on its mission of landing on the moon. That s five Apollo launches in ten months, three of which went to the moon.

Gelzer, Christian↗

NASA NTRS1994

The NASA Mission Operations and Control Architecture Program

The conflict between increases in space mission complexity and rapidly declining space mission budgets has created strong pressures to radically reduce the costs of designing and operating spacecraft. A key approach to achieving such reductions is through reducing the development and operations costs of the supporting mission operations systems. One of the efforts which the Communications and Data Systems Division at NASA Headquarters is using to meet this challenge is the Mission Operations Control Architecture (MOCA) project. Technical direction of this effort has been delegated to the Mission Operations Division (MOD) of the Goddard Space Flight Center (GSFC). MOCA is to develop a mission control and data acquisition architecture, and supporting standards, to guide the development of future spacecraft and mission control facilities at GSFC. The architecture will reduce the need for around-the-clock operations staffing, obtain a high level of reuse of flight and ground software elements from mission to mission, and increase overall system flexibility by enabling the migration of appropriate functions from the ground to the spacecraft. The end results are to be an established way of designing the spacecraft-ground system interface for GSFC's in-house developed spacecraft, and a specification of the end to end spacecraft control process, including data structures, interfaces, and protocols, suitable for inclusion in solicitation documents for future flight spacecraft. A flight software kernel may be developed and maintained in a condition that it can be offered as Government Furnished Equipment in solicitations. This paper describes the MOCA project, its current status, and the results to date.

Ondrus, Paul J.↗

NASA NTRS2017

Data Production on Past and Future NASA Missions

Data return is a metric that is commonly publicized for all space science missions. In the early days of the Space Program, this figure was small, and could be described in bits or maybe even megabits. But now, missions are capable of returning data volumes two or three orders of magnitude larger. For example, Voyager 1 and 2 combined produced a little over 5 Terabits of data in 39 years of operation. In contrast, the Cassini mission, launched two decades after Voyager, produced about one and a half times those data volumes in half the time. NISAR, an Earth Science Mission currently in implementation, plans to produce over 28 Petabits of raw data in just 3 years. This means that NISAR will produce about as many data in 30 days as the combined data production of nearly all planetary missions to date. These increases in capability are a result of technology enhancements in two main areas: telecommunications architecture (both space and ground segments) and data storage technology. This paper describes the progression of these two technologies over the course of more than three decades of space missions and provides additional insight into the design of the end-to-end NISAR Data System Architecture. Trends in the data are briefly explored and compared to Moore’s Law which provides only a qualitative model for memory growth but not for data production. In summary, early missions are found to be driven by unrefined processes while later missions, having utilized earlier lessons learned, focus more on improvements to flight and ground capabilities. Data return seems to fall into three categories. First, deep space missions are driven by the large distances that limit data return to the Earth. Next, the orbiter infrastructure around Mars helps these missions generate more data than other deep space spacecraft. Finally, near-Earth missions have the greatest capabilities for the studied metrics due to their close proximity to Earth and the ground network availability.

Xaypraseuth, Peter↗

NASA NTRS2017

DEEP SPACE INDUSTRIALIZATION: Key To Sustainable Exploration, Development and Settlement of the Solar System

Recent developments related to deep space exploration and development have raised the question of whether the paradigm shift that many people have been expecting, from space exploration to space development and industrialization, is finally occurring. These recent events include Space Exploration Technologies (SpaceX) announcement that they have been contacted by two wealthy individuals who would like to travel around the Moon within the next two years and a recently reported story of Jeff Bezos’ proposal to the Trump Administration to offer cargo delivery services to the Lunar surface (Blue Moon) by mid 2020 as part of a public/private partnership with NASA. In addition Bob Bigelow, founder of Bigelow Aerospace, has announced the capability and desire to put a crewed space station in orbit around the Moon in this same 2020 time period. Moon Express has also recently announced that they are fully funded for their attempt to land their robotic probe on the lunar surface at the end of this year, not only to win the Google Lunar XPrize but also to jump start their lunar mining efforts. On the international front the Grand Duchy of Luxembourg has established a 200 million euro fund to invest in space mining companies with the aim of making Luxembourg the European leader in deep space commerce. To date they have made investments in two companies; Deep Space Industries and Planetary Resources both of which were established to prospect and mine near Earth asteroids. Other counties such as India, China, Japan and even Israel are eying this high frontier for deep space commerce. This paper will explore how these developments could help enable this deep space industrialization and jumpstart a thriving deep space economy. The role that NASA and the US government can and should play in this effort and the role of public/private partnerships will also be discussed. Finally, what these developments could lead to over the next 10-15 years will be analysed and the potential size of this deep space economy will be estimated.

Pittman, Robert B.↗

NASA NTRS2003

Wilbur and Orville Wright: A Reissue of a Chronology Commemorating the Hundredth Anniversary of the Birth of Orville Wright, August 19, 1871

During the year 2003, hundreds of events will mark the one-hundredth anniversary of the Wright brothers historic first flights at Kitty Hawk, North Carolina. The centennial year will witness exhibitions, lectures, television documentaries, films, air shows, flight recreations of Wright aircraft, the issuing of postage stamps and medals, the publication of dozens of new books and articles, and numerous other commemorative activities. One of these events, although not likely to make the evening news, is among the most important of all in terms of a lasting contribution to the observance of this ultimate aviation milestone: the reprinting of Arthur G. Renstrom WIlbur & Orville Wrght: A Chronology Commemorating the Hundredth Anniversary of the Birth of Orville Wright, August 19, 1871. Since its appearance in 1975, Wilbur end Orville Wright: A Chronology has become indispensable to students and authors concerned with the life and work of the famous brothers. No doubt every book on the subject published in the last quarter century, including three of my own, was written with this treasure close at hand. This volume is far more than a simple compilation of dates and facts. Renstrom was a master reference librarian and bibliographer with a passion for aviation and the Wright brothers. He brought his considerable research skills to bear on the topic, and the result is a richly detailed, ever-informative, often entertaining walk through the lives and achievements of these two extraordinary individuals. Renstrom was not content to offer a date with a one-line tidbit. His entries are brimming with information. This is a highly readable reference work that, believe it or not, can be enjoyably read from cover to cover. The project was clearly a labor of love by a talented professional. During most of the last twenty years, I have been privileged to be the curator of the 1903 Wright Flyer at the Smithsonian Institution s National Air and Space Museum. The position brings a steady stream of inquiries about the Wright airplane and the endlessly fascinating brothers who created it. I do not know how I would have done this job without Renstrom s superb volume on my bookshelf. It is the first place I go to check anything on the Wright brothers, and I typically find what I am looking for in its pages. Arthur Renstrom also published two other classic reference works on the Wright brothers: Wilbur & Orville Wright: A Bibliography Commemorating the Hundredth Anniversary of the Birth of Wilbur Wright, April 16, 1867, in 1968 (an updated revision was published by the National Aeronautics and Space Administration in 2002) and Wilbur & Orville Wright, Pictorial Materials: A Documentary Guide in 1982, completing a series of research tools for which there are few peers on any subject. He was also part of the team that produced the landmark two-volume compilation of the Wrights letters, notebooks, and diaries in 1953, The Papers of Wilbur and Orville Wright, edited by Marvin W. McFarland. Renstrom s contribution to the documentation and preservation of the Wright story is a lasting legacy that will serve researchers, students, and general enthusiasts for generations to come. In this busy, high-profile anniversary year, the reprinting of a nearly thirty-year-old reference book may seem a mundane and quiet contribution to the celebration surrounding the Wright brothers world-changing achievement, but it is perhaps one of the most important. The U.S. Centennial of Flight Commission and NASA are to be commended for their foresight.

Renstrom, Arthur George↗

NASA NTRS2003

VPS GRCop-84 Liner Development Efforts

For the past several years, NASA's Marshall Space Flight Center (MSFC) has been working with Plasma Processes, Inc. (PPI) to fabricate combustion chamber liners using the Vacuum Plasma Spray (VPS) process. Multiple liners of a variety of shapes and sizes have been created. Each liner has been fabricated with GRCop-84 (a copper alloy with chromium and niobium) and a functional gradient coating (FGC) on the hot wall. While the VPS process offers versatility and a reduced fabrication schedule, the material system created with VPS allows the liners to operate at higher temperatures, with maximum blanch resistance and improved cycle life. A subscal unit (5K lbf thrust class) is being cycle tested in a LOX/Hydrogen thrust chamber assembly at MSFC. To date, over 75 hot-fire tests have been accumulated on this article. Tests include conditions normally detrimental to conventional materials, yet the VPS GRCop-84 liner has yet to show any signs of degradation. A larger chamber (15K lbf thrust class) has also been fabricated and is being prepared for hot-fire testing at MSFC near the end of 2003. Linear liners have been successfully created to further demonstrate the versatility of the process. Finally, scale up issues for the VPS process are being tackled with efforts to fabricate a full size, engine class liner. Specifically, a liner for the SSME's Main Combustion Chamber (MCC) has recently been attempted. The SSME size was chosen for convenience, since its design was readily available and its size was sufficient to tackle specific issues. Efforts to fabricate these large liners have already provided valuable lessons for using this process for engine programs. The material quality for these large units is being evaluated with destructive analysis and these results will be available by the end of 2003.

Elam, Sandra K.↗

NASA NTRS2000

Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications

The Terra spacecraft (formerly identified as EOS AM1) is the flagship in a planned series of NASA/GSFC (Goddard Space Flight Center) Earth observing system satellites designed to provide information on the health of the Earth's land, oceans, air, ice, and life as a total ecological global system. It has been successfully performing its mission since a late-December 1999 launch into a 705 km polar orbit. The spacecraft is powered by a single wing, flexible blanket array using single junction (SJ) gallium arsenide/germanium (GaAs/Ge) solar cells sized to provide five year end-of-life (EOL) power of greater than 5000 watts at 127 volts. It is currently the highest voltage and power operational flexible blanket array with GaAs/Ge cells. This paper briefly describes the wing design as a basis for discussing the operation of the electronics and mechanisms used to achieve successful on-orbit deployment. Its orbital electrical performance to date will be presented and compared to analytical predictions based on ground qualification testing. The paper concludes with a brief section on future applications and performance trends using advanced multi-junction cells and weight-efficient mechanical components.

Kurland, Richard↗

NASA NTRS2000

Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications

Kurland, Richard↗

NASA NTRS2015

Sulfur and Metal Fertilization of the Lower Continental Crust

Mantle-derived melts and metasomatic fluids are considered to be important in the transport and distribution of trace elements in the subcontinental lithospheric mantle. However, the mechanisms that facilitate sulfur and metal transfer from the upper mantle into the lower continental crust are poorly constrained. This study addresses this knowledge gap by examining a series of sulfide- and hydrous mineral-rich alkaline mafic-ultramafic pipes that intruded the lower continental crust of the Ivrea-Verbano Zone in the Italian Western Alps. The pipes are relatively small (<300 m diameter) and primarily composed of a matrix of subhedral to anhedral amphibole (pargasite), phlogopite and orthopyroxene that enclose sub-centimeter-sized grains of olivine. The 1 to 5 m wide rim portions of the pipes locally contain significant blebby and disseminated Fe-Ni-Cu-PGE sulfide mineralization.Stratigraphic relationships, mineral chemistry, geochemical modeling and phase equilibria suggest that the pipes represent open-ended conduits within a large magmatic plumbing system. The earliest formed pipe rocks were olivine-rich cumulates that reacted with hydrous melts to produce orthopyroxene, amphibole and phlogopite.Sulfides precipitated as immiscible liquid droplets that were retained within a matrix of silicate crystals and scavenged metals from the percolating hydrous melt. New high-precision chemical abrasion TIMS-UPb dating of zircons from one of the pipes indicates that these pipes were emplaced at 249.1+/-0.2 Ma, following partial melting of lithospheric mantle pods that were metasomatized during the Eo-Variscan oceanic to continental subduction (approx. 420-310 Ma). The thermal energy required to generate partial melting of the metasomatized mantle was most likely derived from crustal extension, lithospheric decompression and subsequent asthenospheric rise during the orogenic collapse of the Variscan belt (<300 Ma). Unlike previous models, outcomes from this study suggest a significant temporal gap between the occurrence of mantle metasomatism, subsequent partial melting and emplacement of the pipes.We argue that this multi-stage process is a very effective mechanism to fertilize the commonly dry and refractory lower continental crust in metals and volatiles. During the four-dimensional evolution of the thermo-tectonic architecture of any given terrain, metals and volatiles stored in the lower continental crust may become available as sources for subsequent ore-forming processes, thus enhancing the prospectivity of continental block margins for a wide range of mineral systems.

Marek Locmelis↗

NASA NTRS1993

The advanced orbiting systems testbed program: Results to date

The Consultative Committee for Space Data Systems Recommendations for Packet Telemetry and Advanced Orbiting Systems (AOS) propose standard solutions to data handling problems common to many types of space missions. The Recommendations address only space/ground and space/space data handling systems. Goddard Space Flight Center's AOS Testbed (AOST) Program was initiated to better understand the Recommendations and their impact on real-world systems, and to examine the extended domain of ground/ground data handling systems. Central to the AOST Program are the development of an end-to-end Testbed and its use in a comprehensive testing program. Other Program activities include flight-qualifiable component development, supporting studies, and knowledge dissemination. The results and products of the Program will reduce the uncertainties associated with the development of operational space and ground systems that implement the Recommendations. The results presented in this paper include architectural issues, a draft proposed standardized test suite and flight-qualifiable components.

Newsome, Penny A.↗

NASA NTRS2015

Survival of Organic Materials in Ancient Cryovolcanically-Produced Halite Crystals

Spectroscopic evidence supports the presence of Mg-Na-K salts derived from cryovolcanism on the surface of Europa. Halite (NaCl) is effective at very long-term preservation of organic phases and structures. Collection of salt crystals from Europan plumes would provide solid inclusions of organics, potentially also biomaterials, all suitable for analysis. Two thermally-metamorphosed ordinary chondrite regolith breccias (Monahans 1998 (H5) and Zag (H3-6)) contain fluid and solid inclusion-bearing halite crystals, dated to approximately 4.5 billion years, and thus the trapped aqueous fluids and solids are at least as old. Heating/freezing studies of the aqueous fluid inclusions in these halites demonstrated that they were trapped near 25 degrees Centigrade, and their continued presence in the halite grains requires that their incorporation into the H chondrite asteroid occurred after that body's metamorphism ended, since heating would have dessicated the halite. O and H isotopes of the trapped fluids are consistent with mixing of asteroidal and cometary water. Cryovolcanic Origin of the Halite: We hypothesize that these meteoritic halites derive from ancient cryovolcanism based on the following points. (1) Salts crystals are observed as products of current cryovolcanism on Enceladus. (2) In-situ spacecraft analysis of some of the icy grains associated with the Enceladus salt found minor organic or siliceous components, including methane, also found in the Monahans halite. (3) Cryovolcanic fluids are observed to be in chemical disequilibrium, reflecting incomplete reactions between interior volatiles and rocky materials. The coexistence of N2 and HCN in Enceladus' cryovolcanic fluids requires that the plume consists of a mixture of materials whose sources experienced different degrees of aqueous processing, including primordial material trapped in ice that has not been in contact with liquid water. The observed mineral assemblage within the Monahans and Zag halites is also far from equilibrium. Cryovolcanoes on Ceres are a potential source of our halite, however the processes that form halite should also be operating within Europa. Dissolution of Monahans halite grains has revealed a remarkable variety of organics, which dominate the population of solid inclusions. Thermal alteration of this macromolecular carbon (measured by Raman spectroscopy) shows remarkable diversity. We have identified highly-condensed aromatics, diamond, carbonates and chloromethane. Light organic compounds like methane tend to be water soluble and require cold formation temperatures at high hydrogen fugacity - i.e. require water ice. Another indication that these halites have not been heated is that light organics readily volatilize or aromaticize into PAHs. We are currently analyzing the organics by Raman and C-XANES, and measuring the content and exploring the potential chirality of amino acids in the halite. Implications for Europa Plumes: Organic materials and structures erupted by a Europa cryovolcano should be similarly preserved within halite, and other salts, which will be a convenient form for capture and analysis, since halite will serve to encapsulate and protect the organics from spacecraft contamination. Also, being transparent at many wavelengths halite will permit analysis by spacecraft-mounted spectroscopic techniques. In addition, halite is readily dissolved, permitting further analysis of entrained organics.

Zolensky, M.↗

NASA NTRS2017

Oxygen Candle Background for Subs and Space

"At any time and without warning, a submarine may have to remain submerged for several days on account of the presence of the enemy, or rough weather, or serious accident to the machinery. Fortunately such occurrences are rare; but every commanding officer must be prepared to meet such an emergency that will afford his men the greatest possible chance of survival." Reference (1) This quotation is taken from a review of submarine air purification technology published by the Bureau of Medicine and Surgery in 1919. At that time, the U.S. Navy had just begun to experiment with possible air purification devices and supplies of oxygen that might permit submarines to remain submerged longer that the untreated closed atmosphere would allow. Submariners were exposed to elevated levels of carbon dioxide and reduced levels of oxygen that would be considered completely unacceptable by current standards. It was a different world, but humans are still humans, and the requirements for safe and effective functioning in a self-contained environment are really unchanged. The maximum submergence time for submarines as published in that work was approximately 48 hours, reference (1) In early submarines, the preferred supply of oxygen was 1800 psig compressed gas bled into the boat as needed, references (1,2). The need for added oxygen was occasionally "measured" by the physiological impact on the crew rather than a reliable instrument, reference (1). The design of submarine oxygen supply was limited to approximately 25 day submerged operation, reference (2). It was not until 1958 that U.S. submarines were able to carry out dives beyond that period and necessitated new sources of oxygen, reference (2). A curious second source of oxygen at the time was compressed air vessels that were bled into the boat while "vitiated" air (air with reduced oxygen and elevated carbon dioxide) from the opposite end of the boat was compressed into waiting empty vessels, reference (1). The periodic use of pressurized air to control oxygen caused swings in ambient pressure that was uncomfortable to the crew, reference (1). As early as 1919, liquid oxygen was a commercially available product and its use on submarines was contemplated, reference (1). It is interesting that even at this date, 1919, the danger of oils or greases when exposed to compressed or liquid oxygen was recognized: "One precaution must be always taken. No oil or grease should be used in the gauge or fittings or a dangerous explosion may result."

Graf, John↗

NASA NTRSDate not supplied

Radar Observations from the Haystack Ultrawideband Satellite Imaging Radar in 2019

The NASA Orbital Debris Program Office (ODPO) conducts radar measurements of the low Earth orbit (LEO) orbital debris environment on a continual basis for monitoring and to enable modeling of the environment over time. Radar observations from the Haystack Ultra-wideband Satellite Imaging Radar (HUSIR) in 2019 are the most recent snapshot of the environment to date that has been both measured and analyzed. HUSIR provides data on orbital debris in LEO down to a NASA size estimation model (SEM) size of approximately 5.5 mm, depending upon altitude and year-to -year variation in the sensitivity of the radar. This is of interest as it is the millimeter-sized orbital debris that drives mission-ending risk to robotic spacecraft in LEO. This paper will explore the results of the 2019 HUSIR radar measurements, including above-average flux measurements at lower LEO altitudes and the evolution of the flux during the time of observations.

James Murray↗

NASA NTRS2006

The In-Space Soldering Investigation: To Date Analysis of Experiments Conducted on the International Space Station

Soldering is a well established joining and repair process that is of particular importance in the electronics industry. Still, internal solder joint defects such as porosity are prevalent and compromise desired properties such as electrical/thermal conductivity and fatigue strength. Soldering equipment resides aboard the International Space Station (ISS) and will likely accompany Exploration Missions during transit to, as well as on, the moon and Mars. Unfortunately, detrimental porosity appears to be enhanced in lower gravity environments. To this end, the In-Space Soldering Investigation (ISSI) is being conducted in the Microgravity Workbench Area (MWA) aboard the ISS as "Saturday Science" with the goal of promoting our understanding of joining techniques, shape equilibrium, wetting phenomena, and microstructural development in a microgravity environment. The work presented here will focus on direct observation of melting dynamics and shape determination in comparison to ground-based samples, with implications made to processing in other low-gravity environments. Unexpected convection effects, masked on Earth, will also be shown as well as the value of the ISS as a research platform in support of Exploration Missions.

Grugel, Richard N.↗

NASA NTRSDate not supplied

NASA’s Geospace Dynamics Constellation—Providing the first Systematic Measurements of Global Magnetospheric Energy Inputs and Ionosphere-Thermosphere Responses

The Geospace Dynamics Constellation (GDC) is NASA's next strategic Living With a Star mission. GDC's goals are: 1) Understand how the high-latitude ionosphere-thermosphere system responds to variable solar wind/magnetosphere forcing; and 2) Understand how internal processes in the global ionosphere-thermosphere system redistribute mass, momentum, and energy. Planned for launch by the end of the decade, GDC will use six identical observatories, each identically instrumented to fully characterize the magnetospheric drivers of the I-T system as well as the global response of the ionized and neutral gases. GDC will do this with a series of orbital configurations that will enable it to study the widest range of spatial and temporal scales to date, ranging from hundreds of kilometers and several seconds to tens of minutes, and extending through the regional to the global scale. This talk presents GDC's current status, measurement capabilities, sampling scheme, and model development efforts and show how GDC will fit into the larger Heliophysics ecosystem, by 1) obtaining critically needed scientific observations; 2) providing a source for real-time space weather and situational awareness, as well as retrospective studies to further the science of space weather; 3) serving as a "strategic hub" for other space-based and ground-based efforts that want to leverage GDC to perform complementary science. To get the most benefit from GDC’s observations, it will be critical to identify partnerships with other research efforts in the ITM and Geospace arenas, including those utilizing space-based, ground-based, or theoretical investigations. We particularly would like to discuss with groups who are planning or considering observational campaigns during the GDC era, to find ways to leverage GDC observations to do synergistic science that could not be done otherwise.

Douglas E Rowland↗

NASA NTRS1992

Effects of the space environment on space-based radar phased-array antenna; status and preliminary observations (LDEF Experiment A0133)

The overall objective of the experiment was to evaluate the effect of the space environment on components considered for a Space-Based Radar (SBR) Phased-Array Antenna. Of primary interest was a study of the degradation of the polyimide film Kapton (DuPont trademark), the material considered for use in the antenna plane. The most striking result of the experiment was the overall good condition of the Kapton antenna planes and Kapton tensile specimens, despite nearly six years of exposure to the space environment. This was largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the Long Duration Exposure Facility (LDEF) in orbit. However, weathering of exposed Kapton surfaces was not insignificant. Results on elongation and mechanical properties of the plain and the fiberglass-reinforced Kapton are presented. Reduction in strain to failure of flight-exposed Kapton is attributed to surface defects of these specimens. Physical property testing of the materials to date reveals no significant difference between flight-exposed and control material. The second objective was to investigate the interaction between high-voltage electrodes and typical spacecraft contaminants in simulation of discharge triggering across differentially charged dielectric surfaces (spacecraft charging conditions). Electronic data acquisition and memory systems appeared to operate correctly, but very few discharges were recorded. Induced radioactivity, contamination, impacts, and orientation features of atomic oxygen erosion were observed.

J B Whiteside↗

NASA NTRS2015

An Overview of WFIRST-AFTA Coronagraph Modelling

The WFIRST/AFTA 2.4 m space telescope currently under study includes a stellar coronagraph for the imaging and spectral characterization of extrasolar planets. Based largely on performance predictions from end-to-end optical propagation modeling, promising coronagraphic methods were selected in late 2013 for further consideration for use on AFTA. Since those downselect analyses further modeling work has been done on evaluating refined coronagraph designs, wavefront sensing and control, detector representation, and time-dependent effects. Thermal, structural, ray trace, and diffraction propagation models are used in these studies. Presented here is the progress to date and plans for future analyses.

Krist, John↗

NASA NTRSDate not supplied

A Model-Based Systems Engineering Journey to Developing a Concept of Operations

Starting in 2017, NASA’s Human Research Program (HRP) Exploration Medical Capability (ExMC) element began a systems engineering transition from traditional, document-centric development to model-centric development when defining its foundation medical systems. These foundation medical systems define a Concept of Operations (ConOps) and identify the generic requirements for a medical system based on assumptions about a generic crew and mission environments and guidance from NASA standards (e.g., Medical “Levels of Care”). By making the transition, ExMC intends to improve communication among stakeholders about foundation medical system requirements and content. In addition, this transition will enable ExMC to lower both development and crew treatment risks for future, mission-specific medical systems. ExMC followed a Model Based Systems Engineering (MBSE) paradigm when developing the foundation medical systems. A model-based approach provides several advantages over a traditional, document-centric approach. First, when Systems Engineers (SE) develop diagrams in a model using a standard modeling language, they produce information dense pictures that facilitate understanding much more efficiently with less room for misinterpretation than text. Second, due to the evolving nature of projects, documentation becomes out of date the minute it is published. This can result in people making decisions based on information that is no longer current, especially if they are referencing a locally-stored copy of a document. A model, on the other hand, is always up to date with the latest approved changes and information. It serves as a single point of truth. Third, a model-centric approach centralizes all important information in one place. Rather than having to flip through separate ConOps documents, design specifications, requirements specifications, and the like to coordinate information, a model captures the content in one, integrated spot. This integration makes tracing information from end-to-end easier with greater reliability. The ExMC Systems Engineering Lifecycle follows a well-defined process. ExMC Systems Engineers perform all major steps of the process, regardless of the development methodology. One of the first steps in the process is developing the ConOps that describes the operation of the system from the point of view of the users. It includes a list of the users and their needs, the goals of the medical system, key assumptions about the system, and definitions of the medical system’s operational environments. For this development effort, ExMC chose to replace the traditional text-based ConOps document with a model. While the decision to change the development workflow was not difficult, implementing the structural and organizational workflows were. It required showing ExMC’s users, most of whom are not Systems Engineers, how the information they require would be presented in the model and to gain their acceptance of this approach. This paper documents key lessons learned during the ConOps transformation by focusing on how the model represents information, the agile workflow used by SEs when developing the model and how it integrates into a project plan, how leadership influenced key users to accept the transformation, and how the users interact with the model information.

Jeffrey Robert Cohen↗