Pamela Elizabeth Clark

ANTS for Human Exploration and Development of Space

The proposed Autonomous Nano-technology Swarm (ANTS) is an enabling architecture for human/robotic mission envisaged by NASAs mission for the Human Exploration and Development of Space (HEDS). ANTS design principles draw on successes observed in the realm of social insect colonies, which include task specialization and sociality. ANTS spacecraft act as independent, autonomous agents for specific functions, while cooperating to achieve mission goals. For example, the Prospecting ANTS Mission (PAM) is a long-term mission concept for the 2020-2025 time frame involving individual spacecraft agents that are optimized for specific asteroid prospecting functions. The objective of PAM is to characterize at least one thousand asteroids during each year of operations in the main belt. To achieve this objective, PAM spacecraft, individually and as a group, must achieve a high level of autonomy. This high degree of autonomy opens the possibility of a new kind of interaction between humans and these spacecraft, where human explorers and developers could interact with ANTS enabled resources by communicating high-level goals and data products. Thus ANTS enables new kinds of missions in which human and robotic agents work together to achieve mission goals. In this paper we review and discuss the ANTS architecture in the context of the HEDS mission.

Compositional mapping with the NEAR X ray/gamma ray spectrometer

The X ray/gamma ray spectrometer (XGRS) instrument on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft will map asteroid 433 Eros in the 0.7 keV to 10 MeV energy region. Measurements of the discrete line X ray and gamma ray emissions in this energy domain can be used to obtain both qualitative and quantitative elemental compositions with sufficient accuracy to enable comparison to the major meteorite typies. It is believed that Eros is an S-type asteroid, the most common of the near-Earth asteroids. The determination of whether Eros consists of either differentiated or undifferentiated materials is an important objective of this mission. Observations of Eros during the NEAR mission will contribute significantly to our understanding of the structure and composition of this asteroid. The NEAR spacecraft was successfully launched on February 17, 1996. The NEAR XGRS was turned on during the week of April 7, 1996, and all detector systems operated nominally. Background spectra have been obtained.

Tetrahedral Robotics for Space Exploration

A reconfigurable space filling robotic architecture has a wide range of possible applications. One of the more intriguing possibilities is mobility in very irregular and otherwise impassable terrain. NASA Goddard Space Flight Center is developing the third generation of its addressable reconfigurable technology (ART) tetrahedral robotics architecture. An ART-based variable geometry truss consisting of 12 tetrahedral elements made from 26 smart struts on a wireless network has been developed. The primary goal of this development is the demonstration of a new kind of robotic mobility that can provide access and articulation that complement existing capabilities. An initial set of gaits and other behaviors are being tested, and accommodations for payloads such as sensor and telemetry packages are being studied. Herein, we describe our experience with the ART tetrahedral robotics architecture and the improvements implemented in the third generation of this technology. Applications of these robots to space exploration and the tradeoffs involved with this architecture will be discussed.

Neural Basis Function Control of Super Micro Autonomous Reconfigurable Technology (SMART) Nano-Systems

** Nanotechnology, taken to its full three-dimensional potential, will place within the volume of a cube of sugar systems of vast complexity that far exceed the quantitative and qualitative capabilities of today’s largest supercomputers. Currently, the uncertainty and imprecision of the real world is tamed, rigidly fixed, by addressable, digital techniques and the careful orchestration of digital patterns within our machines. How to handle the interaction between our digitally implemented systems and continuous, disorganized nature is a key question. NASA is currently researching ways to move beyond autonomy implemented as bruteforce control over every degree of freedom we can discover in our systems. Our systems operate in natural environments: inhumanly harsh, unfamiliar, unknown, and uncontrolled environments. Nature often surprises us, and so we turn to natural systems for clues about how to make massively complex systems more robust, reliable, and truly autonomous. Turning to Computer Science we draw on what we’ve learned about multi-agent systems running continuously and autonomously to understand information flow at the highest semantic levels. From physics we recall that the behaviors of systems may often be enumerated in a basis of fundamental behaviors. Non-linear physics contains clues about how to connect the physical world with the patterns of electric signals that make up the soft, information component of the systems. Genetics and control theory instruct how to handle long and short-term feedbacks throughout the system. Chemistry and biology provide important guiding principles governing system functions.

Radiation effects in the Si-PIN detector on the Near Earth Asteroid Rendezvous mission

Abstract A Si-PIN photodiode is being used as a solar X-ray monitor on the X-ray/gamma-ray spectrometer experiment which is flying on the Near Earth Asteroid Rendezvous spacecraft. Since its launch in February 1996 this photodiode has experienced several brief failures. These anomalies and other performance characteristics will be described. Efforts to reproduce these failures in ground tests with flight spare equipment will also be discussed.

Data management and analysis techniques used in the near X-ray and gamma-ray spectrometer systems

Abstract The NEAR Earth Asteroid Rendezvous (NEAR) spacecraft will encounter the 433Eros asteroid for a one year orbital mission in December 1998. Its on-board remote sensing instrumentation includes X-ray and gamma-ray (XGRS) spectrometers. NEAR is an orbital mission and long integrations over spatially specific asteroid regions are generally not possible. A methodology for simulating longer integrations has been developed for XGRS and uses unique management, correlative and analytical ground systems to render mapping data products. Evaluation of the spatial environment is accomplished through virtual renderings of the asteroid surface giving incidence, emission and surface roughness factors. Extended computer plate modeling information is employed to optimize ground computer systems processing time. Interactive visualization systems have been developed to manage close to a million spectra that will be collected during the encounter. Feedback systems are employed to inspect, tag and calibrate spectral data products. Mission planning, systems development and managerial responsibilities have been distributed to cooperating science organizations at The Goddard Space Flight Center, The University of Arizona, Cornell University, The Applied Physics Laboratory and The Max Plank Institute.

Electrostatic Dust Control on Planetary Surfaces

Successful operation for exploration of planetary regoliths will depend on the capability to keep surfaces free of dust which could compromise performance and to collect dust for characterization. Such study is essential in order to resolve issues in dealing with regolith fines identified during the Apollo missions where dust behaved like abrasive Velcro before returning to the Moon. During Moon landings, locally‐induced stirring of the regolith caused dust to be suspended long enough to come into contact with conducting surfaces. Lunar fines, because of their electrostatic charging, were difficult to collect and sparsely sampled: bag seals were broken, samples contaminated and lost. Our objectives here are to describe a multi‐faceted electrostatically‐based approach and methodology for addressing this issue, as well as to present our preliminary results which confirm the view that the successful strategy will deal with dust dynamics resulting from interaction between mechanical and electrostatic forces. ...

Future planetary X-ray and gamma-ray remote sensing system and in situ requirements for room temperature solid state detectors

Abstract X-Ray and gamma-ray remote sensing observations find important applications in the study of the development of the planets. Orbital measurements can be carried out on solar-system bodies whose atmospheres and trapped radiation environments do not interfere significantly with the emissions. Elemental compositions can be inferred from observations of these line emissions. Future planetary missions also will involve landing both stationery and roving probes on planetary surfaces. Both X-ray and gamma-ray spectrometers will be used for performing elemental analysis of surface samples. These future planetary missions will impose a number of constraints: the flight instruments must be significantly reduced in weight from those previously flown; for many missions, gravity assist will be required, greatly increasing mission duration, resulting in the passage of several years before the first scientific measurement of a solar system body. The detector systems must operate reliably after years of cosmic-ray irradiation. Both spectroscopy and imaging detection systems are required. Room temperature systems show great promise for application to planetary X-ray and gamma-ray remote systems. A number of laboratory and sub-orbital, orbital, and planetary flight mission investigations have been and will be carried out in order to develop room temperature solid state detector systems for space flight.

Data processing system for the Near-Earth Asteroid Rendezvous (NEAR) x-ray and gamma-ray spectrometer (XGRS) ground system

An x-ray and gamma-ray spectrometer (XGRS) is onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433 Eros. The Eros asteroid is highly non-spherical in physical shape and the development of data management and analysis methodologies are in several areas a divergence from traditional remotely sensed geographical information systems techniques. Field of view and asteroid divergence from traditional remotely sensed geographical information system techniques. Field of view and asteroid surface geometry must be derived virtually and then combined with real measurements of solar, spectral and instrument calibration information to derive meaningful scientific results. Spatial resolution of planned geochemical maps will be improved from the initial conditions of low statistical significance per integration by repeated surface flyovers and regional spectral accumulation. This paper describes the results of a collaborative effort of design and development of the NEAR XGRS instrument ground system undertaken by participants at the Goddard Space Flight Center, University of Arizona, Cornell University, Applied Physics Laboratory, and Max Planck Institute.

A small X-ray/gamma-ray geochemical experiment package for Discovery class missions

Abstract Remote sensing X-ray and gamma-ray spectrometers can be used to infer elemental composition on atmosphereless bodies, such as asteroids, the Moon, and Mercury. For Discovery class missions a combined geochemical experiment package has been proposed that can meet the mission science objectives while still remaining within the mass, power, and cost constraints of the mission. Calculations for two asteroid missions (NEAR and MASTER) indicate that surface mapping at up to tens of kilometer spatial resolution is possible, and that the relation of the asteroid composition to that of meteorite classes should be determined relatively early in the mission. Datasets from each of the two experiments provide independent, yet complimentary measures of elemental abundances. Comparisons between results for the same elements can give information on near-surface regolith statigraphy and/or differences between local and regional rock types.