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NASA NTRSDate not supplied

Interpretable Machine Learning Models for Autonomous Characterization of Analogue Ocean World Seawater Chemistry and Biosignature Potential Using Isotope Ratio Data

Background: Future missions to ocean worlds, such as Enceladus and Europa, will attempt to characterize the subsurface seawater chemistry and assess the potential for life. Such missions will be equipped with capabilities to precisely measure volatile isotopes in plumes, atmospheres, and exospheres. Motivation: While large isotopic fractionations can indicate a biological source, there are signatures resulting from abiotic geochemical processes that mimic isotopic biosignatures. While machine learning (ML) has the potential to disentangle competing effects and biotic mimicry, high-dimensional isotope ratio mass spectrometry (IRMS) data is likely to contain noise/irrelevant features and involve complex statistical interactions that make human inference and interpretation difficult. Further, ML predictions with as far-reaching implications as an extraterrestrial biosignature on an ocean world requires the use of interpretable models (i.e., not “black box” models) with physically and mathematically meaningful feature spaces along with false positive diagnostics. Methods: We use volatile CO2 IRMS data of analogue ocean world seawaters to validate an ML approach to provide biogeochemical context for biosignature detection. We employ a feature selection method called nearest-neighbor projected distance regression (NPDR) that detects statistical interactions and helps elucidate the mechanisms of the Random Forest classification models. Results: We train and validate predictive ML models on volatile CO2 IRMS data of analogue ocean world seawaters to predict major salt components (e.g., MgSO4, NaHCO3), pH, ionic strength, and the presence of biosignatures. Features derived from IRMS measurements are augmented with extracted time-series features. Our results show high test accuracy and interpretability, which is increased by interaction network visualization, sample-wise variable importance scores, and single-sample class probability estimates. We demonstrate an ML mission software solution that triggers autonomous data transmission and biogeochemical sample prediction.

geochemistry↗

DOE OSTI2026

Latest Development to Establish the World Reference with Traceability to SI Units for Measuring the Atmospheric Shortwave and Longwave Irradiance

To date, Interim world reference traceable to blackbody (not sky/atmosphere) is used as a reference noted as a World Infrared Standard Group (WISG). Plan forward: to develop a reference standards traceable to SI InfraRed Integrating Sphere (IRIS) Developed by the World Radiation Center (PMOD) is traceable to blackbody irradiance. Absolute Cavity Pyrgeometer (ACP) developed by NLR is a self-calibrating radiometer using heat substitution to measure the atmospheric longwave irradiance. ACP is a contribution to develop the world reference with traceability to SI, using the outdoor irradiance as the source, instead of blackbody.

14 SOLAR ENERGY↗

NASA NTRS1980

LAMMR world data base documentation support and demonstrations

The primary purpose of the World Surface Map is to provide the LAMMR subsystem with world surface type classifications that are used to set up LAMMR LEVEL II process control. This data base will be accessed solely by the LAMMR subsystem. The SCATT and ALT subsystems will access the data base indirectly through the T sub b (Brightness Temperature) Data Bank, where the surface types were updated from a priori to current classification, and where the surface types were organized on an orbital subtrack basis. The single most important factor in the design of the World Surface Maps is the ease of access to the information while the complexity of generating these maps is of lesser importance because their generation is a one-time, off-line process. The World Surface Map provides storage of information with a resolution of 7 km necessary to set flags concerning the earth's features with a different set of maps for each month of the year.

Chin, R.↗

NASA NTRS1988

Possible world-wide middle miocene iridium anomaly and its relationship to periodicity of impacts and extinctions

In a study of one million years of Middle Miocene sediment deposition in ODP Hole 689B in the Weddell Sea near Antarctica, a single iridium (Ir) anomaly of 44 (+ or - 10) x 10 to the 12th gram Ir per gram rock (ppt) was observed in core 6H, section 3, 50 to 60 cm, after background contributions associated with manganese precipitates and clay are subtracted. The ODP Hole 689B is 10,000 km away from another site, DSDP Hole 588B in the Tasman Sea north of New Zealand, where a single Ir anomaly of 144 + or - 7 ppt over a background of 11 ppt was found in an earlier study of 3 million years of deposition. From chemical measurements the latter deposition was thought to be impact-related. Ir measurements were made, following neutron activation, with the Iridium Coincidence Spectrometer. The age vs depth calibration curves given in the DSDP and ODP preliminary reports indicate the ages of the Iranomalies are identical, 11.7 million years, but the absolute and relative uncertainties in the curves are not known. Based on the newest age data the age estimate is 10 million years. As the Ir was deposited at the two sites at about the same time and they are one quarter of the way around the world from each other it seems likely that the deposition was world-wide. The impact of a large asteroid or comet could produce the wide distribution, and this data is supportive of the impact relationship deduced for Deep Sea Drilling Project (DSDP) 588B from the chemical evidence. If the surface densities of Ir at the two sites are representative of the world-wide average, the diameter of a Cl type asteroid containing the necessary Ir would be 3 + or - 1 km, which is large enough to cause world-wide darkness and hence extinctions although the latter point is disputed.

Asaro, F.↗

NASA NTRS1992

The role of the World Data Centers in handling ocean climate data

The World Data Center System, set up for the International Geophysical Year in 1957, is an international network of data centers that links data contributors to data users in the geosciences. It includes means for the synthesis, analysis, and preparation of data products. It was set up in response to the needs of the international scientific community, and is still overseen by non-governmental scientific organizations. Because it is freely available to researchers in all countries, the World Data Center System has a special role to play in support of ocean climate research and monitoring programs. The World Data Centers face a number of challenges today. Apathy is probably the greatest, since many scientists take the system for granted. There is need to improve access and exploit new technology. The system must establish new links to assure continuity in a world with political changes. The multidisciplinary needs of global change research will demand capabilities for data and information management that go beyond the traditional emphasis on geophysics.

Webster, Ferris↗

NASA NTRS1993

International organizations to enable world-wide mobile satellite services

Numbers of systems exist or have been proposed to provide world-wide mobile satellite services (MSS). Developers of these systems have formulated institutional structures they consider most appropriate for profitable delivery of these services. MSS systems provide niche services and complement traditional telecommunications networks; they are not integrated into world-wide networks. To be successful, MSS system operators must be able to provide an integrated suite of services to support the increasing globalization, interconnectivity, and mobility of business. The critical issue to enabling 'universal roaming' is securing authority to provide MSS in all of the nations of the world. Such authority must be secured in the context of evolving trends in international telecommunications, and must specifically address issues of standardization, regulation and organization. Today, only one existing organization has such world-wide authority. The question is how proponents of new MSS systems and services can gain similar authority. Securing the appropriate authorizations requires that these new organizations reflect the objectives of the nations in which services are to be delivered.

Anglin, Richard L., Jr.↗

NASA NTRS1994

The real-world navigator

The success of every mobile robot application hinges on the ability to navigate robustly in the real world. The problem of robust navigation is separable from the challenges faced by any particular robot application. We offer the Real-World Navigator as a solution architecture that includes a path planner, a map-based localizer, and a motion control loop that combines reactive avoidance modules with deliberate goal-based motion. Our architecture achieves a high degree of reliability by maintaining and reasoning about an explicit description of positional uncertainty. We provide two implementations of real-world robot systems that incorporate the Real-World Navigator. The Vagabond Project culminated in a robot that successfully navigated a portion of the Stanford University campus. The Scimmer project developed successful entries for the AIAA 1993 Robotics Competition, placing first in one of the two contests entered.

Balabanovic, Marko↗

NASA NTRS1996

From the Primitive Atmosphere to the Prebiotic Soup to the Pre-RNA World

Organic compounds would have been produced in an earth's atmosphere that was reducing. The soup would contain amino and hydroxy acids, together with smaller amounts of purines and pyrimidines. The presence' of sugars is less likely, although they can be produced by the formose reaction from formaldehyde. However, the prebiotic synthesis of RNA has not been demonstrated. One problem is that ribose is not produced selectively over other pentoses and hexoses, except under special conditions. The second problem is that ribose is unstable, with a half-life at pH7 and 100 C of 73 minutes (44 years at 0 C). Other sugars are similarly unstable. Another problem is that there is no efficient prebiotic synthesis of polyphosphates, nor the glycosidic bond of nucleosides. This suggests that there may have been an informational macromolecule that preceded RNA. The RNA world refers to the time when RNA carried both the genetic information and the catalytic activity, and was subsequently converted to the DNA/protein world when protein synthesis began. Preceeding the RNA world was the Pre-RNA world, where a backbone different from ribose phosphate was used, and the bases may have been different from adenine, uracil, guanine and cytosine. We have shown recently that cytosine and uracil can be synthesized efficiently under prebiotic conditions using a dried lagoon model instead of the usual dilute ocean hypothesis. In addition, we have shown that uracil adds formaldehyde efficiently to give 5- hydroxymethyl uracil, which in turn adds various nucleophiles to give uracil analogs of most of the amino acids that occur in proteins. For example, the ammonia, guanidine and imidazole adducts from the analogs of lysine, arginine and histidine. This suggests that the catalytic potential of RNA may have been much more extensive than previously assumed. The major problem is finding out what was the precursor to the ribose phosphate backbone. This will be the key to developing prebiotic self-replicating systems.

Miller, Stanley L.↗

NASA NTRS1999

The Question of Future Droughts in a CO2-Warmed World

Increased droughts are to be expected in a warmer world, and so are increased floods. A warmer atmosphere can hold more moisture, and evaporate more water from the surface. Thus, when it is not raining, available soil water should be reduced. When it is raining, it could very well rain harder. Most researchers agree then that a warmer world will have greater hydrologic extremes. In addition, there is a basic imbalance that develops as climate warms, between the loss of moisture from the soil by evaporation and replenishment via precipitation. The land has a smaller heat capacity than the ocean, so it should warm faster. Evaporation from the land proceeds at the rate of its warming, while precipitation derives primarily from evaporation at the ocean surface. As the latter is increasing more slowly, in a warmer world, precipitation will not increase as rapidly as evaporation due to the fact that the oceans warm more slowly than the land surface (evaporation over the ocean is slower than over the land). Hence, more droughts are anticipated in a warmer world, but the specific location of such droughts is somewhat uncertain. To address the question of where droughts are likely to occur, one first needs to have a reasonable sense of what the future magnitude of warming will be, and what the latitudinal distribution of warming will be. For example, the greater the warming at high latitudes relative to low latitudes, the more likely there will be increased drought over the U.S. in summer. In contrast, substantial tropical warming could give us El Nino-like precipitation, with intensified flooding along the southern tier of the U.S. All of these conditions are likely to intensify as the global temperature rises.

Rind, David↗

NASA NTRS2003

The Roads to and from the RNA World

The historical existence of the RNA world, in which early life used RNA for both genetic information and catalytic ability, is widely accepted. However, there has been little discussion of whether protein synthesis arose before DNA or what preceded the RNA world (i.e. the pre-RNA world). We outline arguments of what route life may have taken out of the RNA world: whether DNA or protein followed. The metabolic arguments favor the possibility that RNA genomes preceded the use of DNA as the informational macromolecule. However, the opposite can also be argued based on the enhanced stability, reactivity, and solubility of 2-deoxyribose as compared to ribose. The possibility that DNA may have come before RNA is discussed, although it is a less parsimonious explanation than DNA following RNA.

Dworkin, Jason P.↗

NASA NTRS2004

Water for Two Worlds: Designing Terrestrial Applications for Exploration-class Sanitation Systems

At the United Nations Millennium Summit in September of 2000, the world leaders agreed on an ambitious agenda for reducing poverty and improving lives: the Millennium Development Goals (MDGs), a list of issues they consider highly pernicious, threatening to human welfare and, thereby, to global security and prosperity. Among the eight goals are included fundamental human needs such as the eradication of extreme poverty and hunger, the promotion of gender equality, the reduction of child mortality and improvement of maternal health, and ensuring the sustainability of our shared environment. In order to help focus the efforts to meet these goals, the United Nations (UN) has established a set of eighteen concrete targets, each with an associated schedule. Among these is Target 10: "By 2015, reduce by half the proportion of people without access to safe drinking water." A closely related target of equal dignity was agreed at the World Summit on Sustainable Development (Johannesburg, September 2002): "By 2015, reduce by half the proportion of people without access to basic sanitation." One of the greatest successes in the development of Exploration-class technologies for closed-loop, sustainable support of long-duration human space missions has been the work both ESA and NASA have done in bioregenerative water reclamation (WRS), and secondarily, in solid-waste management. Solid-waste and WRS systems tend to be combined in the commercial world into the field of sanitation, although as we will see, the most essential principles of sustainable terrestrial sanitation actually insist upon the separation of solid and liquid excreta. Seeing the potential synergy between the space program ALS technologies developed for Mars and the urgent needs of hundreds of millions of people for secure access to clean water here on Earth, we set out to organize the adaptation of these technologies to help the United Nations Development Programme (UNDP) meet Target 10. In this paper, we will summarize the issues and results of the first "Water for Two Worlds" summit held in January of this year, describe,the status of the sustainable sanitation systems that are on the table for adaptation to widespread terrestrial use, and present fundamental strategies for forward work.

Adams, Constance↗

NASA NTRS2006

Working Group Reports and Presentations: Virtual Worlds and Virtual Exploration

Scientists and engineers are continually developing innovative methods to capitalize on recent developments in computational power. Virtual worlds and virtual exploration present a new toolset for project design, implementation, and resolution. Replication of the physical world in the virtual domain provides stimulating displays to augment current data analysis techniques and to encourage public participation. In addition, the virtual domain provides stakeholders with a low cost, low risk design and test environment. The following document defines a virtual world and virtual exploration, categorizes the chief motivations for virtual exploration, elaborates upon specific objectives, identifies roadblocks and enablers for realizing the benefits, and highlights the more immediate areas of implementation (i.e. the action items). While the document attempts a comprehensive evaluation of virtual worlds and virtual exploration, the innovative nature of the opportunities presented precludes completeness. The authors strongly encourage readers to derive additional means of utilizing the virtual exploration toolset.

LAmoreaux, Claudia↗

NASA NTRS2008

Polar Gateways Arctic Circle Sunrise 2008 Conference at the Top of the World

The Polar Gateways conference was hosted during January 23-29, 2008, the first week of polar sunrise at Barrow, Alaska, at the new Barrow Arctic Research Center of the Barrow Arctic Science consortium (BASC). The dawn week of polar day, the highly variable low temperatures, and the ice-covered shore tundra and adjacent sea ice conditions provided an appropriate locale for a conference dedicated in the spirit of the International Polar and Heliophysical Years 2007-2009 to the educational exploration of polar and icy world science of Earth and the solar system. The many scientific, educational, and cultural interactions with the local community of four thousand residents, sixty percent native Inupiat Eskimo, further provided an unforgettable experience of what life might be someday be like on other remote polar and icy worlds to be explored and eventually inhabited. Over one hundred active participants, more than half participating remotely, contributed science presentations and educational activities during this unique circumpolar and very "green" conference. Most remote contributions came via videoconference from the Swedish Institute of Space Physics (IRF) at Kisuna, Sweden, the EISCAT Svalbard Radar Facility at Spitzbergen, Norway, the University of Alaska at Fairbanks, NASA Goddard Space Flight Center and the Jet Propulsion Laboratory, the University of California at Berkeley, and the University of Arizona. A few contributors participated via teleconference, including one from the Polar Geophysical Institute at Apatity in Russia. These active contributions spanned up to thirteen time zones (Alaska to Russia) at various tirnes during the conference. Primary videoconferencing support between Barrow and other sites was ably provided by the University of Alaska at Fairbanks, and local operators at each remote site collectively made this conference possible. Science presentations spanned the solar system from the polar Sun and heliospheric environment to Earth, Moon, Mars, Jupiter, Saturn, the Kuiper Belt, and the solar wind termination shock now crossed by both Voyager spacecraft. Barrow participants experienced look and feel of icy worlds like Europa by going "on the ice" during snowmobile expeditions to the near-shore sea ice and Point Barrow. Extensive educational outreach activities were conducted with the local Barrow township and North Slope Borough communities, partly through several interviews with local host Earl Finkler on Barrow's KBRW Radio, and through the NASA Digital Learning Network (DLN) "live from the top of the world" at Barrow. The Goddard robotic rover "Nunuq of the North" became a local celebrity. The complete science program and photo library, eventually also including video recordings of all main presentations, will be available at the new polargateways2008.gsfc.nasa.gov web site (old version: polargateways2008.org) with links to educational materials from the conference already accessible at sunearthday.nasa.gov/polarsunrise.

Cooper, John F.↗

NASA NTRS2012

Sensing and Virtual Worlds - A Survey of Research Opportunities

Virtual Worlds (VWs) have been used effectively in live and constructive military training. An area that remains fertile ground for exploration and a new vision involves integrating various traditional and now non-traditional sensors into virtual worlds. In this paper, we will assert that the benefits of this integration are several. First, we maintain that virtual worlds offer improved sensor deployment planning through improved visualization and stimulation of the model, using geo-specific terrain and structure. Secondly, we assert that VWs enhance the mission rehearsal process, and that using a mix of live avatars, non-player characters, and live sensor feeds (e.g. real time meteorology) can help visualization of the area of operations. Finally, tactical operations are improved via better collaboration and integration of real world sensing capabilities, and in most situations, 30 VWs improve the state of the art over current "dots on a map" 20 geospatial visualization. However, several capability gaps preclude a fuller realization of this vision. In this paper, we identify many of these gaps and suggest research directions

Moore, Dana↗

NASA NTRS2017

Raman Life Detection Instrument Development for Icy Worlds

The objective of this project is to develop a compact, high sensitivity Raman sensor for detection of life signatures in a flow cell configuration to enable bio-exploration and life detection during future mission to our Solar Systems Icy Worlds. The specific project objectives are the following: 1) Develop a Raman spectroscopy liquid analysis sensor for biosignatures; 2) Demonstrate applicability towards a future Enceladus or other Icy Worlds missions; 3) Establish key parameters for integration with the ARC Sample Processor for Life on Icy Worlds (SPLIce); 4) Position ARC for a successful response to upcoming Enceladus or other Icy World mission instrument opportunities.

astrobiolog↗

NASA NTRSDate not supplied

Predicting the Seawater Chemistry of an Ocean World Using Machine Learning on Isotopic Measurements of Volatile CO2

Introduction: Given the long time intervals required for data transmission to and from ocean worlds targets, low bandwidth for data transmission, time required for data processing and analysis, and potentially extreme radiation environments (e.g., Europa), it is clear that ocean worlds missions will need more autonomous flight instruments and software in order to achieve established science goals. Protracted time intervals for data analysis (e.g., Europa Lander) strongly motivates the development of rapid, consistent and streamlined methods for interpreting data from flight mass spectrometers to e.g., determine how mass spectra from a plume or surface liquid/ice relates to the surface/subsurface. Since mass spectrometry also has the potential to correctly identify biosignatures[1], it is imperative that such methods for interpreting data are consistent and accurate. We used 848 isotope ratio mass spectra from laboratory analyses of CO2 that interacted with ocean worlds-relevant seawaters as a ‘training’ dataset for ‘unsupervised’ machine learning. In unsupervised learning, characteristics of the data are not labeled or linked, and any similarities found only result from the neural network. CO2 isotopologues analyzed for this dataset mimic the remote measurements of CO2 by a flight mass spectrometer, and are detailed in Theiling [2]. From this dataset, we used measured features of the spectra, such as retention time, intensity, and (isotopologue) mass ratios as inputs for our autoencoder neural network. Our neural network was trained to find similarities in these and other spectral features for seawaters of a particular composition and amount of initial CO2. Successful training then created an output of these similarities for various seawaters, which included MgSO4, Na2SO4, NaCl, MgCl2, KCl, and NaHCO3, and combinations of these salts. We then applied dimensionality reduction techniques such as Principal Component Analysis (PCA), T-Distributed Stochastic Neighbor Embedding (TSNE), and Uniform Manifold Approximation and Projection (UMAP) to demonstrate latent data features as a two-dimensional projection in a unitless, high-dimensional space. In this projection, a data point represents the combined effect of spectral features such as intensity, retention time, and isotope ratio. Our initial UMAP demonstrates data clustering (organization of the data by the neural network) based on the amount of CO2 that had initially interacted with each seawater. Further training using more ‘supervised’ learning techniques demonstrate strong clustering of preliminary data based on initial CO2 concentration, seawater chemical composition, and ionic strength (salinity). Our preliminary work therefore suggests that machine learning has the potential to identify compositional variants of an ocean world seawater based on mass spectra from volatile CO2 measurements. Acknowledgments: This work was funded through a Strategic Task Group at NASA Goddard Space Flight Center. The training dataset was collected through funding from the Oklahoma Space Grant Consortium. References: [1] Pappalardo, R. et al. (2013) Astrobiology, 13, 740–773. [2] Theiling (2020) Icarus, 114216.

Europa↗

NASA NTRS2021

Thermal Analysis of Landers using Radioisotope Power Systems on Ice Worlds

The surfaces of Ice Worlds record evidence of interior processes, chemical potential, habitability, and potentially life within the interior. Volatile and organic chemistry at the surface is critical in determining habitability and detecting the presence of past or extant life. Radioisotope Power Systems (RPS) could be an enabling technology for in situ missions to ice worlds, providing both power and heat for long durations where solar power would not be feasible. However, it is necessary to understand the potential impact of RPS upon the local environment, to ensure that the rejected heat from RPS does not compromise science measurements or planetary protection requirements. To address these concerns, an RPS Ice World Lander Study was carried out in 2019 to investigate possible requirements on RPS surface mission concepts and approaches to excess heat management. The study focused on two destinations that are representative of the range of potential environments: Europa and Enceladus.Initial analysis showed that, due to the very low pressures on the surfaces of most ice world targets, surface melting does not occur because the water ice does not meet the triple-point. A 4 kW heat source suspended above the surface of Europa or Enceladus would not cause any melting, only sublimation.The study used a surface sublimation limit of 10 cm over a two-year period (the baseline for the recent Europa Lander study). To stay within this limit, Europa, with its relatively warm surface, could tolerate only 10 W/m2 of surface heat flux. Enceladus, with its relatively cold pure ice composition, could tolerate up to 100 W/m2.Various lander and heat shield configurations were analyzed for their heat flux radiated from the RPS to the surface. For a given heat shield configuration, the study team determined the minimum height of the RPS above the surface for which the heat flux would be within the accepted parameters for Europa and for Enceladus. Based on these thermal analyses, such RPS-powered landers could remain compliant with science investigation and planetary protection requirements with only modest mass allocated to spacecraft thermal accommodations.

Perl, Scott↗

NASA NTRSDate not supplied

NASA Science Technology Development Programs for Ocean Worlds Exploration

The exploration of icy satellites such as Europa and Enceladus supports NASA’s goal to search for life and potentially habitable regions elsewhere in the universe, and further promises to help us understand the origins, evolution, and limits of life on Earth. Over the past several years, NASA’s Planetary Science Division has funded several technology development programs to enable future surface and subsurface missions to ocean worlds. These programs include Instrument Concepts for Europa Exploration (ICEE), Concepts for Ocean Worlds Life Detection Technology (COLDTech), Scientific Exploration Subsurface Access Mechanism for Europa (SESAME), Applied Information Systems Research: Autonomous Robotics Research for Ocean Worlds (AISR:ARROW), and Astrodynamics in Support of Icy Worlds Missions. Tasks selected under these programs include the development of scientific instruments including seismometers, imagers, spectrometers, and organic analyzers, and also platform technologies including drills, melt probes, through-ice communications, radiation-hard electronics, and autonomy for surface operations. This paper describes the objectives of each of these programs and provides a summary of the work that has been completed or is underway in each.

science instruments↗