InSight and SEIS on Mars: First results after 200 Sols
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Renee Weber↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Lithium Dinitramide as an Additive in Lithium Power Cells
Lithium dinitramide, LiN(NO2)2 has shown promise as an additive to nonaqueous electrolytes in rechargeable and non-rechargeable lithium-ion-based electrochemical power cells. Such non-aqueous electrolytes consist of lithium salts dissolved in mixtures of organic ethers, esters, carbonates, or acetals. The benefits of adding lithium dinitramide (which is also a lithium salt) include lower irreversible loss of capacity on the first charge/discharge cycle, higher cycle life, lower self-discharge, greater flexibility in selection of electrolyte solvents, and greater charge capacity. The need for a suitable electrolyte additive arises as follows: The metallic lithium in the anode of a lithium-ion-based power cell is so highly reactive that in addition to the desired main electrochemical reaction, it engages in side reactions that cause formation of resistive films and dendrites, which degrade performance as quantified in terms of charge capacity, cycle life, shelf life, first-cycle irreversible capacity loss, specific power, and specific energy. The incidence of side reactions can be reduced through the formation of a solid-electrolyte interface (SEI) a thin film that prevents direct contact between the lithium anode material and the electrolyte. Ideally, an SEI should chemically protect the anode and the electrolyte from each other while exhibiting high conductivity for lithium ions and little or no conductivity for electrons. A suitable additive can act as an SEI promoter. Heretofore, most SEI promotion was thought to derive from organic molecules in electrolyte solutions. In contrast, lithium dinitramide is inorganic. Dinitramide compounds are known as oxidizers in rocket-fuel chemistry and until now, were not known as SEI promoters in battery chemistry. Although the exact reason for the improvement afforded by the addition of lithium dinitramide is not clear, it has been hypothesized that lithium dinitramide competes with other electrolyte constituents to react with lithium on the surface of the anode to form a beneficial SEI. Apparently, nitrides and oxides that result from reduction of lithium dinitramide on the anode produce a thin, robust SEI different from the SEIs formed from organic SEI promoters. The SEI formed from lithium dinitramide is more electronically insulating than is the film formed in the presence of an otherwise identical electrolyte that does not include lithium dinitramide. SEI promotion with lithium dinitramide is useful in batteries with metallic lithium and lithium alloy anodes.
Gorkovenko, Alexander A.↗
Exploration Technology Program plans and directions
A summary of the proposed Space Exploration Initiative (SEI) needs that have been identified is presented along with a detailed review of the status of SEI technology planning. Plans are also being formulated to implement an Exploration Technology Program (ETP) that will develop the major technologies required for SEI. The ETP will provide in the near term clear demonstrations of potential exploration technologies, results of research to support SEI architecture decisions, and a foundation of mature technology that is ready to be applied in the first round of SEI missions. A family of functional building blocks has been defined from which both lunar and Mars SEI mission architectures can be constructed.
Aldrich, Arnold↗
Mars direct - A coherent architecture for the Space Exploration Initiative
The coherency of the conventional earth-orbital assembly/Mars orbital rendezvous is analyzed in terms of the Space Exploration Initiative (SEI) architecture and an alternate approach is given. The coherency - defined as a combination of simplicity, robustness, and cost-effectiveness - of the conventional SEI is found to be inadequate. The Mars Direct plan is described in detail and proposed as an efficient alternative for both Martian and lunar applications. In situ propellant production on the target-planet's surface is described, and candidate vehicle designs are set forth. Objectives and problems associated with a manned mission are outlined, and details regarding surface activities and support are given. Nuclear thermal rocket propulsion is determined to be an efficient way to improve mission capability, and the Mars Direct SEI architecture can integrate such technology. The Mars Direct SEI is concluded to be a more effective plan than the conventional rendezvous mission.
Zubrin, Robert M.↗
On-orbit assembly operations and in-space infrastructure
The paper describes the development of a set of top-level system requirements for an in-space infrastructure which will accommodate the vehicles proposed for the Space Exploration Initiative (SEI). Issues considered include the current SEI mission strategy, the launch capability, the role of Space Station Freedom (SSF), the on-orbit assembly operations, and the manned tended versus robotic capability. Current SEI mission strategy coupled with SSF planning led to the conclusion that an independent assembly servicing facility (ASF) will best meet the requirements of the SEI program, and an analysis was performed to define the functions required at an ASF. It is shown that the ASF functions can be performed by telerobotic operations.
Cockrell, Charles E.↗
4-Vinyl-1,3-Dioxolane-2-One as an Additive for Li-Ion Cells
Electrolyte additive 4-vinyl-1,3-dioxolane-2-one has been found to be promising for rechargeable lithium-ion electrochemical cells. This and other additives, along with advanced electrolytes comprising solutions of LiPF6 in various mixtures of carbonate solvents, have been investigated in a continuing effort to improve the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures. In contrast to work by other researchers who have investigated the use of this additive to improve the high-temperature resilience of Li-ion cells, the current work involves the incorporation of 4-vinyl-1,3-dioxolane-2-one into quaternary carbonate electrolyte mixtures, previously optimized for low-temperature applications, resulting in improved low-temperature performance. The benefit afforded by 4-vinyl-1,3- dioxolane-2-one can be better understood in the light of relevant information from a number of prior NASA Tech Briefs articles about electrolytes and additives for such cells. To recapitulate: The loss of performance with decreasing temperature is attributable largely to a decrease of ionic conductivity and the increase in viscosity of the electrolyte. What is needed to extend the lower limit of operating temperature is a stable electrolyte solution with relatively small lowtemperature viscosity, a large electric permittivity, adequate coordination behavior, and appropriate ranges of solubilities of liquid and salt constituents. Whether the anode is made of graphitic or non-graphitic carbon, a film on the surface of the anode acts as a solid/electrolyte interface (SEI), the nature of which is critical to low-temperature performance. Desirably, the surface film should exert a chemically protective (passivating) effect on both the anode and the electrolyte, yet should remain conductive to lithium ions to facilitate intercalation and de-intercalation of the ions into and out of the carbon during discharging and charging, respectively. The additives investigated previously include alkyl pyrocarbonates. Those additives help to improve low-temperature performances by giving rise to the formation of SEIs having desired properties. The formation of the SEIs is believed to be facilitated by products (e.g., CO2) of the decomposition of these additives. These decomposition products are believed to react to form Li2CO3-based films on the carbon electrodes. The present additive, 4-vinyl-1,3-dioxolane-2-one, also helps to improve lowtemperature performance by contributing to the formation of SEIs having desired properties, but probably in a different manner: It is believed that, as part of the decomposition process, the compound polymerizes on the surfaces of carbon electrodes.
Smart, Marshall↗
Predicting Thermal Response in a Li-ion Cell on a UAV Fight Profile
As the energy storage devices continue to "pack" more energy in a small space, any damage, battery component failure, manufacturing defect, or electrically abusing the battery can lead to catastrophic thermal runaway events. A catastrophic thermal event in a cell leads to high temperature, in some instances spewing of battery materials due to gas development from side reactions initiated due to high internal temperatures. Also, a thermal runaway event can propagate from a single "failed" cell to the pack in a battery pack, leading to a more significant event. Mitigating a thermal runaway event is important in the commercial and automotive sectors. However, preventing such events in an electric aircraft (or air taxis) is paramount due to the lack of alternatives in the event of a failure. Battery prognostics algorithms allow the prediction of state-of-charge (SOC) and end-of-life (EOL) of a Li-ion battery in a UAV (unmanned air vehicle) [1]. For this presentation, we will extend this two-level battery predictive algorithm to predict SOC, EOL, and estimated maximum temperature during a simulated flight. The model is extended by integrating a lumped physics-driven thermal model for high current densities [2]. The parameters used to control SOC and EOL are maximum storable charge, time constant for Li-ion diffusivity in the carbon particles, and internal cell resistance. Cycling leads to an increase in the heat generated by an aged Li-ion cell with a LiyCoO2 (LCO) cathode and a LixC6 (MCMB) anode. The aging of a cell leads to increase in SEI layer thickness, the diffusion time for the lithium ions inside the electrodes, and the local reaction rates, in addition to the thermodynamic abuse caused by fixed cycling voltages controlled by a Battery Management System. As the battery ages, the cell resistance increases, while the onset temperature of the thermal runaway decreases (depends on the cell chemistry and cell abuse history). Any large deviation of the cell temperature from the estimated (expected) value can identify a faulty cell. Since SEI decomposition has the lowest onset temperature in the series of reactions leading to thermal runaway, the model considers the self-heating rate of the SEI decomposition as onset temperature (similar to Ref. [3]). The parameters in the Arrhenius equation for the SEI heating rate depend on the number of cycles, the cell's operating temperature, and the cell's abuse history [4,5]. Coupling the electrochemical, thermal, and aging model allow the prognostic algorithm to estimate a typical cell voltage and temperature as a function of age (cycling and calendar), whose departure from measured values from the BMS is used to identify a safety event. In addition, we will present the results from two simulated flight scenarios for a UAV: typical and extreme, since the power requirements vary significantly during take-off, landing, and changing altitudes, while the power requirements remain low during the cruise. For this presentation, the power requirement for a battery pack in a UAV is scaled to a single cell. This cell is cycled through a simulated profile, and the data is collected and used to predict a safety event.
Li-ion↗
Next generation: In-space transportation system(s)
The development of the next generation In-Space Transportation System presents a unique challenge to the design of a propulsion system for the Space Exploration Initiative (SEI). Never before have the requirements for long-life, multiple mission use, space basing, high reliability, man-rating, and minimum maintenance come together with performance in one system that must protect the lives of space travelers, support the mission logistics needs, and do so at an acceptable cost. The challenge that is presented is to quantify the bounds of these requirements. The issue is one of degree. The length of acceptable life in space, the time it takes for reuse to pay off, and the degree to which space basing is practical (full, partial, or expended) are the issues that determine the reusable bounds of a design and include dependability, contingency capabilities, resilency, and minimum dependence on a maintenance node in preparation for and during a mission. Missions to planet earth, other non-NASA missions, and planetary missions will provide important but less demanding requirements for the transportation systems of the future. The mission proposed for the SEI require a family of transportation vehicles to meet the requirements for establishing a permanent human presence on the Moon and eventually on Mars. Specialized vehicles are needed to accomplish the different phases of each mission. These large scale missions require assembly in space and will provide the greatest usage of the planned integrated transportation system. The current approach to defining the In-Space Transportation System for the SEI Moon missions with later Mars mission applications is presented. Several system development options, propulsion concepts, current/proposed activities are reviewed, and key propulsion design criteria, issues, and technology challenges for the next generation In-Space Transportation System(s) are outlined.
Huffaker, Fredrick↗
Technology needs of the Exploration Initiative
An overview of the U.S. Space Exploration Initiative (SEI) is presented. The two primary objectives of the initiative are a return to the moon to create a permanent lunar base and a human mission to Mars. Even though mission architectural concepts are not yet defined, previous studies indicate that the SEI will require developments in numerous areas, including advanced engines for space transportation, in-space assembly and construction to support permanent basing of exploration systems in space, and advanced surface operations capabilities including satisfactory levels of power and surface roving vehicles, and technologies to safely support human space operations of long duration. The process of mission definition has begun and it is shown that it is possible to identify a family of fundamental functional building blocks from which all SEI mission architectures will be constructed.
Aldrich, Arnold↗
Status and plans for exploration technology
The present status of the Space Exploration Initiative (SEI) is discussed. SEI mission planning is reviewed, including various architectural options, their waypoints, and their strategic features. SEI technology needs and issues are examined in order of priority and technology development plans are described.
Aldrich, Arnold D.↗
Is bigger always better? An economic study of U.S. ETO vehicle architectures
This analysis, performed as part of NASA's Space Transportation Infrastructure Study, compares the cost efficiency of two candidate launch vehicle families, used in conjunction with existing expendable launch vehicles and the Shuttle, to accomplish the nation's future space missions through 2030. Missions analyzed include those identified in NASA's Civil Needs Data Base (CNDB) and Space Exploration Initiative (SEI) Option E program, as well as estimates of commercial and U.S. Department of Defense flights. A family of Shuttle-derived In-line vehicles is compared against a family designed around a vehicle optimized for large (250t) payloads. The analysis is performed within the context of an entire space transportation architecture. The goal is to determine which architecture best captures the required missions most cost-effectively. Results indicate that, for the particular mission model analyzed, neither option is clearly superior across the entire payload range. The Shuttle-derived family displays a better evolutionary path for supporting the total mission model (CNDB plus SEI missions). It also reduces earth-to-orbit (ETO) peak funding by 20 percent. The architecture incorporating the Heavy Lift ETO family minimizes SEI program cost and on-orbit operations but is subject to greater schedule risk because of the need for concurrent ETO core and engine development.
Eimers, Dan R.↗
An assessment of prospects for international cooperation on the Space Exploration Initiative
This paper discusses the unique characteristics of the Space Exploration Initiative (SEI) which will have to be taken into account if the Initiative is to become an international one; the technical capabilities offered by prospective international partners; the political and economic prospects for proceeding with the Initiative both in the United States and elsewhere; and the advantages and disadvantages of various possible approaches to international cooperation on SEI. SEI preparatory activities are likely to extend over a several-year period. Such an extended preparatory period should provide the time needed for coordinating studies, for identifing interests and potential contributions, and for resolving the numerous planning, budgeting, organizational and political issues which will have to be dealt with if such a complex undertaking is to be successfully internationalized.
Cline, Lynn F. H.↗
The Space Exploration Initiative - An information system perspective
The authors look at the Space Exploration Initiative (SEI) from an information system perspective an discuss information system definition effort being conducted in support of NASAs Lunar Mars Exploration Program Office (LMEPO) Johnson Space Center (JSC). The development of an integrated, effective SEI information system (SIS) is recognized as crucial to the success of the SEI missions. Some of the new and unique challenges for the SIS as evidenced in the Lunar and the Mars missions are outlined along with some preliminary conceptual approaches, both architectural and technological, being investigated to address them.
Hartenstein, Ray↗
Needs for supervised space robots in space exploration
The areas of application for space robots in the Space Exploration Initiative (SEI) are examined by reviewing the roles of SEI supervised robots particularly with planet-surface systems (PSSs). Treatment is given to both teleoperated conventional robot systems and autonomous intelligent systems for comparison in terms of safety, reliability, and productivity. Two development stages are proposed including one with a robotic actor, human observer, and a human supervisor and a second in which a closed-loop control and monitoring system is established. The use of remote control is shown to require robustness, self-calibration and -diagnosis, adjustable autonomy, and multitask capability. The requirements of intelligent control are also listed so that the PSSs of the SEI can be used to enable surface exploration, local-resource utilization potential, and reductions of human tasks.
Erickson, Jon D.↗
Space Exploration Initiative - Overview, current status, near term plans
An overview is presented of the Space Exploration Initiative (SEI) describing current activities, accomplishemnts, and directions. The program is considered in terms of activities relevant to the three phases which are: manned robotic/precursor missions, manned lunar missions, and manned Mars missions. SEI is shown to be in the First Lunar Outpost (FLO) mission phase which is based on an early manned lunar return, and development is described of earth-to-orbit (ETO) vehicles, a translunar injection stage, and a lunar surface habitat. Two ETO vehicles are considered, and the translunar injection stage is illustrated. The FLO mission is also considered as an initiation of the design activity for the Mars mission so that the requirements and preliminary designs could be defined. The FLO program demonstrates the feasibility of a manned return to the moon as an initiation of subsequent SEI activities.
Adams, Alan M.↗
Nuclear thermal propulsion transportation systems for lunar/Mars exploration
Nuclear thermal propulsion technology development is underway at NASA and DoE for Space Exploration Initiative (SEI) missions to Mars, with initial near-earth flights to validate flight readiness. Several reactor concepts are being considered for these missions, and important selection criteria will be evaluated before final selection of a system. These criteria include: safety and reliability, technical risk, cost, and performance, in that order. Of the concepts evaluated to date, the Nuclear Engine for Rocket Vehicle Applications (NERVA) derivative (NDR) is the only concept that has demonstrated full power, life, and performance in actual reactor tests. Other concepts will require significant design work and must demonstrate proof-of-concept. Technical risk, and hence, development cost should therefore be lowest for the concept, and the NDR concept is currently being considered for the initial SEI missions. As lighter weight, higher performance systems are developed and validated, including appropriate safety and astronaut-rating requirements, they will be considered to support future SEI application. A space transportation system using a modular nuclear thermal rocket (NTR) system for lunar and Mars missions is expected to result in significant life cycle cost savings. Finally, several key issues remain for NTR's, including public acceptance and operational issues. Nonetheless, NTR's are believed to be the 'next generation' of space propulsion systems - the key to space exploration.
Clark, John S.↗
Telecommunications, navigation and information management concept overview for the Space Exploration Initiative program
An overview is provided of the Space Exploration Initiative (SEI) concepts for telecommunications, information systems, and navigation (TISN), and engineering and architecture issues are discussed. The SEI program data system is reviewed to identify mission TISN interfaces, and reference TISN concepts are described for nominal, degraded, and mission-critical data services. The infrastructures reviewed include telecommunications for robotics support, autonomous navigation without earth-based support, and information networks for tracking and data acquisition. Four options for TISN support architectures are examined which relate to unique SEI exploration strategies. Detailed support estimates are given for: (1) a manned stay on Mars; (2) permanent lunar and Martian settlements; short-duration missions; and (4) systematic exploration of the moon and Mars.
Bell, Jerome A.↗