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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Exobiological Exploration of Mars

Of all the other planets in the solar system, Mars remains the most promising for studying concepts about chemical evolution and the origin of life. Strategies were developed to pursue three exobiological objectives for Mars: determine abundance and distribution of biogenic elements and organic compounds, detect evidence of an ancient biota, and determine if organisms exist anywhere on the planet. The three strategies share the same sequence of phases. In the first phase, each requires global reconnaissance and remote sensing by orbiters to select sites of interest for detailed in situ analyses. In the second phase, lander missions are conducted to characterize the chemical and physical properties of the selected sites. The third phase involves conducting "critical" experiments at sites whose properties make them particularly attractive for exobiology. These critical experiments would include, for example, identification of organics, detection of fossils, and detection of extant life. The fourth phase is the detailed analysis of samples returned from these sites in Earth-based laboratories to confirm and extend previous discoveries. Finally, in the fifth phase, human exploration is needed to establish the geological context or to discover and explore sites that are not accessible to robotic spacecraft.

DeVincenzi, Donald L.↗
NASA NTRS1999

Bring'em Back Alive or at Least Carefully

Within the next decade, the world's space agencies plan to launch a variety of robotic spacecraft that will return samples from the surface of Mars, the tail of a comet, the nucleus of a comet, the surface of an asteroid, and the solar wind. Most of these places are not considered likely spots for life, but any mission returning from a location with the potential for harboring life will require special containment and handling because of the possible inclusion of living entities within returned samples. In its 1997 report on sample return from Mars, the Space Studies Board of the National Research Council (NRC) noted that the only risk of significant adverse effects would be from returning a replicating organism. Furthermore, the report noted: 'While the probability of returning a replicating biological entity in a sample from Mars' is judged to be low and the risk of pathogenic or ecological effects is lower still, the risk is not zero. Therefore, it is reasonable that NASA adopt a prudent approach, erring on the side of caution and safety when dealing with returned samples. More recently, a 1998 NRC report on small solar system bodies (asteroids, comets, planetary satellites, and interplanetary dust) recommended a similarly cautious approach for samples returned from anywhere else within the solar system that could have environmental conditions conducive for harboring life. We have not detected life elsewhere in the solar system, at least not yet. Nonetheless, the rationale behind the conservative approach to sample handling is similar to the environmental, health, and safety measures taken on Earth when transporting or handling infectious agents or importing non-native organisms to a new area. Better safe than sorry.

Race, Margaret S.↗
NASA NTRS2003

Planetary Protection Considerations for JIMO

Europa is the only body in the solar system besides Mars that is currently viewed as a body of significant interest relative to the process of chemical evolution and/or the origin of life or for which scientific opinion provides a significant chance of contamination which could jeopardize a future biological experiment. Thus, both NASA and COSPAR policy require that Europa be protected from biological contamination that could result from scientific exploration conducted by robotic spacecraft. In 2000, the Task Group on the Forward Contamination of Europa (Space Studies Board) published its report on Preventing the Forward Contamination of Europa recommending a limit of 10(exp -4) probability of contamination of Europa's ocean per mission (at any time in the future) by a single viable terrestrial microbe. While NASA guidelines do not yet explicitly reflect this new recommendation, it is likely that the SSB recommendation will be adopted by NASA planetary protection in the form of a sterility requirement or at least a stringent total microbial burden requirement. In our presentation, we will present an overview of the anticipated planetary protection requirements for both orbiters and landers destined for Europa and some of the challenges these requirements will present.

Koukol, R. C.↗
NASA NTRS2004

Monitoring the Performance of a Neuro-Adaptive Controller

Traditional control has proven to be ineffective to deal with catastrophic changes or slow degradation of complex, highly nonlinear systems like aircraft or spacecraft, robotics, or flexible manufacturing systems. Control systems which can adapt toward changes in the plant have been proposed as they offer many advantages (e.g., better performance, controllability of aircraft despite of a damaged wing). In the last few years, use of neural networks in adaptive controllers (neuro-adaptive control) has been studied actively. Neural networks of various architectures have been used successfully for online learning adaptive controllers. In such a typical control architecture, the neural network receives as an input the current deviation between desired and actual plant behavior and, by on-line training, tries to minimize this discrepancy (e.g.; by producing a control augmentation signal). Even though neuro-adaptive controllers offer many advantages, they have not been used in mission- or safety-critical applications, because performance and safety guarantees cannot b e provided at development time-a major prerequisite for safety certification (e.g., by the FAA or NASA). Verification and Validation (V&V) of an adaptive controller requires the development of new analysis techniques which can demonstrate that the control system behaves safely under all operating conditions. Because of the requirement to adapt toward unforeseen changes during operation, i.e., in real time, design-time V&V is not sufficient.

Schumann, Johann↗
NASA NTRS2004

Lunar Navigation with Libration Point Orbiters and GPS

NASA is currently studying a Vision for Space Exploration based on spiral development of robotic and piloted missions to the moon and Mars, but research into how to perform such missions has continued ever since the first era of lunar exploration. One area of study that a number of researchers have pursued is libration point navigation and communication relay concepts. These concepts would appear to support many of NASA's current requirements for navigation and communications coverage for human and robotic spacecraft operating in lunar space and beyond. In trading libration point concepts against other options, designers must consider issues such as the number of spacecraft, required to provide coverage, insertion and stationkeeping costs, power and data rate requirements, frequency allocations, and many others. The libration points, along with a typical cis-lunar trajectory, are equilibrium locations for an infinitesimal mass in the rotating coordinate system that follows the motion of two massive bodies in circular orbits with respect to their common barycenter. There are three co-linear points along the line connecting the massive bodies: between the bodies, beyond the secondary body, and beyond the primary body. The relative distances of these points along the line connecting the bodies depend on the mass ratios. There are also two points that form equilateral triangles with the massive bodies. Ideally, motion in the neighborhood of the co-linear points is unstable, while motion near the equilibrium points is stable. However, in the real world, the motions are highly perturbed so that a satellite will require stationkeeping maneuvers.

Carpenter, J. Russell↗
NASA NTRS2005

Bridging a High School Science Fair Experience with First Year Undergraduate Research: Using the E-SPART Analyzer to Determine Electrostatic Charge Properties of Compositionally Varied Rock Dust Particles as Terrestrial Analogues to Mars Materials

NASA missions to Mars confirm presence of surficial particles, as well as dramatic periods of aeolian reworking. Dust deposition on, or infiltration into, exploration equipment such as spacecraft, robotic explorers, solar panel power supplies, and even spacesuits, can pose significant problems such as diminished power collection, short circuits / discharges, and added weight. We report results conducted initially as a science fair project and a study now part of a first year University undergraduate research experience.

Scott, A. G.↗
NASA NTRS2005

Performance Monitoring and Assessment of Neuro-Adaptive Controllers for Aerospace Applications Using a Bayesian Approach

Modem aircraft, UAVs, and robotic spacecraft pose substantial requirements on controllers in the light of ever increasing demands for reusability, affordability, and reliability. The individual systems (which are often nonlinear) must be controlled safely and reliably in environments where it is virtually impossible to analyze-ahead of time- all the important and possible scenarios and environmental factors. For example, system components (e.g., gyros, bearings of reaction wheels, valves) may deteriorate or break during autonomous UAV operation or long-lasting space missions, leading to a sudden, drastic change in vehicle performance. Manual repair or replacement is not an option in such cases. Instead, the system must be able to cope with equipment failure and deterioration. Controllability of the system must be retained as good as possible or re-established as fast as possible with a minimum of deactivation or shutdown of the system being controlled. In such situations the control engineer has to employ adaptive control systems that automatically sense and correct themselves whenever drastic disturbances and/or severe changes in the plant or environment occur.

Gupta, Pramod↗
NASA NTRS2005

A Unifying Multibody Dynamics Algorithm Development Workbench

The development of new and efficient algorithms for multibody dynamics has been an important research area. These algorithms are used for modeling, simulation, and control of systems such as spacecraft, robotic systems, automotive applications, the human body, manufacturing operations, and micro-electromechanical systems (MEMS). At JPL's Dynamics and Real Time Simulation (DARTS) Laboratory we have developed software that serves as a computational workbench for these algorithms. This software utilizes the mathematical perspective of the spatial operator algebra, which allows the development of dynamics algorithms and new insights into multibody dynamics.

Ziegler, John L.↗
NASA NTRS1997

Micro Pump Technology and Applications

The days of large, multi-instrumented, billion-dollar robotic spacecraft are over. The emphasis is now on miniaturizing instruments and spacecraft and reducing the costs of fabrication, test, launch and operations.

Micro Pump↗
NASA NTRS1995

Pluto Express - Out of the Darkness

Pluto, discovered in 1930, is the largest of a class of primordial bodies at the edge of our solar system that have comet-like properties and remain relatively unmodified by warming from the sun. It is the only planet in the solar system not explored via robotic spacecraft. This lecture discusses the status of the Pluto Express preproject (science objectives, etc.), and its telecommunication subsystem.

Pluto Pluto Express Planetary Exploration Spacecra↗
NASA NTRS2005

Dynamic testing and simulation of the Mars Exploration Rover

In January of 2004, NASA landed two mobile robotic spacecraft on the surface of Mars as part of the Mars Exploration Rover (MER) project. The results and lessons learned of the test and dynamic simulation of the MER vehicles is provided in this paper.

rovers↗
NASA NTRS1977

Spinoff 1977

The National Aeronautics & Space Administration has many missions but they can all be reduced to a common denominator: to explore Earth and its surroundings, conduct aeronautical research, and put the results to work for the benefit of mankind. At times the benefit may be dimly perceived. Take, for instance, last year's monumental triumph of exploration, the landing of robot spacecraft on Mars. How, some ask, does probing a neighbor planet improve the lot of Earth's people? In two ways: scientific gain and technological advancement. Though perhaps little understood, they are concrete benefits, assets as tangible as sunshine, more valuable than gold. Technological advancement, on the other hand, offers equally important but more immediate returns. Technology is science applied. It is the ability of a society to make things that improve the quality of human existence. It is compounded of intellect and skill, which draw upon the scientific base to bring forth new ideas, inventions, materials and processes. It is, in a word, knowledge. It builds like an inverted pyramid, each level broader than the one . before as successive generations contribute to the cumulative lore. Knowledge is readily transferable. If you build a better mousetrap, you may acquire experience in the course of the project that can be applied to a need totally unrelated to mouse-traping. This transfer process has been going on since the dawn of technology. In the last two decades it has accelerated enormously, spurred by the immense flow of aerospace-stimulated technology. There have been literally thousands of spinoffs, new products and processes that owe their origins to aerospace research. Collectively, they add up to significant gain in terms of personal convenience, human welfare, industrial efficiency, and economic value.

Haggerty, James J.↗
NASA NTRS2007

Observing Mode Attitude Controller for the Lunar Reconnaissance Orbiter

The Lunar Reconnaissance Orbiter (LRO) mission is the first of a series of lunar robotic spacecraft scheduled for launch in Fall 2008. LRO will spend at least one year in a low altitude polar orbit around the Moon, collecting lunar environment science and mapping data to enable future human exploration. The LRO employs a 3-axis stabilized attitude control system (ACS) whose primary control mode, the "Observing mode", provides Lunar Nadir, off-Nadir, and Inertial fine pointing for the science data collection and instrument calibration. The controller combines the capability of fine pointing with that of on-demand large angle full-sky attitude reorientation into a single ACS mode, providing simplicity of spacecraft operation as well as maximum flexibility for science data collection. A conventional suite of ACS components is employed in this mode to meet the pointing and control objectives. This paper describes the design and analysis of the primary LRO fine pointing and attitude re-orientation controller function, known as the "Observing mode" of the ACS subsystem. The control design utilizes quaternion feedback, augmented with a unique algorithm that ensures accurate Nadir tracking during large angle yaw maneuvers in the presence of high system momentum and/or maneuver rates. Results of system stability analysis and Monte Carlo simulations demonstrate that the observing mode controller can meet fine pointing and maneuver performance requirements.

Calhourn, Philip C.↗
NASA NTRS2007

Observing Mode Attitude Controller for the Lunar Reconnaissance Orbiter

The Lunar Reconnaissance Orbiter (LRO) mission is the first of a series of lunar robotic spacecraft scheduled for launch in Fall 2008. LRO will spend at least one year in a low altitude polar orbit around the Moon, collecting lunar environment science and mapping data to enable future human exploration. The LRO employs a 3-axis stabilized attitude control system (ACS) whose primary control mode, the "Observing mode", provides Lunar Nadir, off-Nadir, and Inertial fine pointing for the science data collection and instrument calibration. The controller combines the capability of fine pointing with that of on-demand large angle full-sky attitude reorientation into a single ACS mode, providing simplicity of spacecraft operation as well as maximum flexibility for science data collection. A conventional suite of ACS components is employed in this mode to meet the pointing and control objectives. This paper describes the design and analysis of the primary LRO fine pointing and attitude re-orientation controller function, known as the "Observing mode" of the ACS subsystem. The control design utilizes quaternion feedback, augmented with a unique algorithm that ensures accurate Nadir tracking during large angle yaw maneuvers in the presence of high system momentum and/or maneuver rates. Results of system stability analysis and Monte Carlo simulations demonstrate that the observing mode controller can meet fine pointing and maneuver performance requirements.

Calhoun, Philip C.↗
NASA NTRS2008

Robotic Exploration of Moon and Mars: Thematic Education Approach

Safe, sustained, affordable human and robotic exploration of the Moon, Mars, and beyond is a major NASA goal. Robotic exploration of the Moon and Mars will help pave the way for an expanded human presence in our solar system. To help share the robotic exploration role in the Vision for Space Exploration with classrooms, informal education groups, and the public, our team researched and consolidated the thematic story components and associated education activities into a useful education materials set for educators. We developed the set of materials for a workshop combining NASA Science Mission Directorate and Exploration Systems Mission Directorate engineering, science, and technology to train informal educators on education activities that support the robotic exploration themes. A major focus is on the use of robotic spacecraft and instruments to explore and prepare for the human exploration of the Moon and Mars.

Allen, J S.↗
NASA NTRS2007

Computational Workbench for Multibody Dynamics

PyCraft is a computer program that provides an interactive, workbenchlike computing environment for developing and testing algorithms for multibody dynamics. Examples of multibody dynamic systems amenable to analysis with the help of PyCraft include land vehicles, spacecraft, robots, and molecular models. PyCraft is based on the Spatial-Operator- Algebra (SOA) formulation for multibody dynamics. The SOA operators enable construction of simple and compact representations of complex multibody dynamical equations. Within the Py-Craft computational workbench, users can, essentially, use the high-level SOA operator notation to represent the variety of dynamical quantities and algorithms and to perform computations interactively. PyCraft provides a Python-language interface to underlying C++ code. Working with SOA concepts, a user can create and manipulate Python-level operator classes in order to implement and evaluate new dynamical quantities and algorithms. During use of PyCraft, virtually all SOA-based algorithms are available for computational experiments.

Edmonds, Karina↗