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At least 271 records · Page 15

Incorporating CCSDS telemetry standards and philosophy on Cassini

The Cassini project at the Jet Propulsion Laboratory (JPL) is implementing a spacecraft telemetry system based on the Consultative Committee for Space Data Systems (CCSDS) packet telemetry standards. Resolving the CCSDS concepts with a Ground Data System designed to handle time-division-multiplexed telemetry and also handling constraints unique to a deep-space planetary spacecraft (such as fixed downlink opportunities, small downlink rates and requirements for on-board data storage) have resulted in spacecraft and ground system design challenges. Solving these design challenges involved adapting and extending the CCSDS telemetry standards as well as changes to the spacecraft and ground system designs. The resulting spacecraft/ground system design is an example of how new ideas and philosophies can be incorporated into existing systems and design approaches without requiring significant rework. In addition, it shows that the CCSDS telemetry standards can be successfully applied to deep-space planetary spacecraft.

Day, John C.↗

Incorporating CCSDS Telemetry Standards and Philosophy on Cassini

The Cassini project at the Jet Propulsion Laboratory (JPL) is implementing a spacecraft telemetry system based on the Consultative Committee for Space Data Systems (CCSDS) packet telemetry standards. Resolving the CCSDS concepts with a Ground Data System designed to handle time-division-multiplexed telemetry and also handling constraints unique to a deep-space planetary spacecraft (such as fixed downlink opportunities, small downlink rates and requirements for on-board data storage) have resulted in spacecraft and ground system design challenges. Solving these design challenges involved adapting and extending the CCSDS telemetry standards as well as changes to the spacecraft and ground system designs. The resulting spacecraft/ground system design is an example of how new ideas and philosophies can be incorporated into existing systems and design approaches without requiring significant rework. In addition, it shows that the CCSDS telemetry standards can be successfully applied to deep-space planetary spacecraft.

CCSDS↗

Orbital evolution of the PSR1257+12 planetary system

The detection of orbital perturbation effects in the PSR1257+12 timing data would provide irrefutable confirmation that planets are indeed orbiting the pulsar. Here we give an overview of how perturbation effects are expected to affect the orbital elements of the two planets over the next few years. In particular, we give a simple calculation of resonant perturbations, including the nonlinear effects which could be important if sin i less than about 0.1. We also present a new analysis of the effects of close encounters between the two planets and we discuss their detectability.

Rasio, Frederic A.↗

Primary Velocity and Orbital Phase Effects on Planetary Detectability from Small Epoch Number Data Sets

Cross-correlation analyses of high-resolution spectroscopic data have recently shown great success in directly detecting planetary signals and enabling the characterization of their atmospheres. One such technique aims to observe a system at multiple epochs and combine the measured planetary radial velocities from each epoch into a measurement of the planetary Keplerian orbital velocity K {sub p}, constituting a direct detection of the planetary signal. Recent work has shown that in few-epoch (∼5) data sets, unintended structure can arise at a high level, obscuring the planetary detection. In this work, we look to simulations to examine whether there are ways to reduce this structured noise in few-epoch data sets by careful planning of observations. The choice of observation date allows observers to select the primary (stellar) velocity through a set systemic velocity and chosen barycentric velocity and the planetary orbital phase so we focus on the effects of these two parameters. We find that epochs taken when the primary velocity is near zero and the stellar lines remain relatively fixed to the telluric rest-frame greatly reduce the level of structured noise and allow for much stronger planetary detections, on average more than twice the significance of detections made with epochs using randomly selected primary velocities. Following these results, we recommend that observers looking to build up high-resolution multi-epoch data sets target nights when their system has a near-zero primary velocity.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Solar-System Ephemeris Toolbox

NASA s Jet Propulsion Laboratory (JPL) generates planetary and lunar ephemeris data and FORTRAN routines that allow users to obtain state data for the Sun, the moon, and the planets. The JPL Solar System Ephemeris Toolbox, developed at Kennedy Space Center, is a set of functions that provides the same functionality in the MATLAB computing environment along with some additional capabilities. The toolbox can be used interactively via a graphical user interface (GUI), or individual functions can be called from the MATLAB command prompt or other MATLAB scripts and functions. The toolbox also includes utility functions to define and perform coordinate transformation (e.g., mean-of-date, true-of-date, J2000) that are common in the use of these ephemerides. An attached README file guides the user through the process of constructing binary ephemeris files, verifying correct installation, and using functions to extract state data. This process also can be performed using the GUI. Help from each toolbox function is available through MATLAB s "help" function. Many of the functions in the toolbox are MATLAB equivalents of the JPL-written FORTRAN programs and subroutines used for the same purposes. A novice can use the GUI to extract state data, while a more experienced user can use the functions directly, as needed, in his/her applications. The toolbox has been tested using MATLAB Releases 13 an

Walker, Charles F.↗

Spitzer Pre Launch Mission Operations System - The Road to Launch

Spitzer Space Telescope was launched on 25 August 2003 into an Earth-trailing solar orbit to acquire infrared observations from space. Development of the Mission Operations System (MOS) portion prior to launch was very different from planetary missions from the stand point that the MOS teams and Ground Data System had to be ready to support all aspects of the mission at launch (i.e., no cruise period for finalizing the implementation). For Spitzer, all mission-critical events post launch happen in hours or days rather than months or years, as is traditional with deep space missions. At the end of 2000 the Project was dealt a major blow when the Mission Operations System (MOS) had an unsuccessful Critical Design Review (CDR). The project made major changes at the beginning of 2001 in an effort to get the MOS (and Project) back on track. The result for the Spitzer Space Telescope was a successful launch of the observatory followed by an extremely successful In Orbit Checkout (IOC) and operations phase. This paper describes how the project was able to recover the MOS to a successful Delta (CDR) by mid 2001, and what changes in philosophies, experiences, and lessons learned followed. It describes how projects must invest early or else invest heavily later in the development phase to achieve a successful operations phase.

observatory↗

NASA activities and plans

An overview is provided of the NASA tracking, data acquisition, communications, and mission control systems and capabilities. These systems include the NASA Spaceflight Tracking and Data Network (STDN) which supports earth-orbital spacecraft, the Deep Space Network (DSN) which supports the planetary exploration and deep space missions, and the Tracking and Data Relay Satellite System (TDRSS) currently under development and scheduled to come into service in 1983. TDRSS will then displace STDN for support of low earth orbital spacecraft. A description is presented of the current status of the considered systems, and plans are discussed for future developments and new capabilities.

Smylie, R. E.↗

Solar system exploration

Two fundamental goals lie at the heart of U.S. solar system exploration efforts: first, to characterize the evolution of the solar system; second, to understand the processes which produced life. Progress in planetary science is traced from Newton's definition of the principles of gravitation through a variety of NASA planetary probes in orbit, on other planets and traveling beyond the solar system. It is noted that most of the planetary data collected by space probes are always eventually applied to improving the understanding of the earth, moon, Venus and Mars, the planets of greatest interest to humans. Significant data gathered by the Mariner, Viking, Apollo, Pioneer, and Voyager spacecraft are summarized, along with the required mission support capabilities and mission profiles. Proposed and planned future missions to Jupiter, Saturn, Titan, the asteroids and for a comet rendzvous are described.

Briggs, Geoffrey A.↗

An ethnographic object-oriented analysis of explorer presence in a volcanic terrain environment: Claims and evidence

An ethnographic field study was conducted to investigate the nature of presence in field geology, and to develop specifications for domain-based planetary exploration systems utilizing virtual presence. Two planetary geologists were accompanied on a multi-day geologic field trip that they had arranged for their own scientific purposes, which centered on an investigation of the extraordinary xenolith/nodule deposits in the Kaupulehu lava flow of Hualalai Volcano, on the island of Hawaii. The geologists were observed during the course of their field investigations and interviewed regarding their activities and ideas. Analysis of the interview resulted in the identification of key domain entities and their attributes, relations among the entities, and explorer interactions with the environment. The results support and extend the author's previously reported continuity theory of presence, indicating that presence in field geology is characterized by persistent engagement with objects associated by metonymic relations. The results also provide design specifications for virtual planetary exploration systems, including an integrating structure for disparate data integration. Finally, the results suggest that unobtrusive participant observation coupled with field interviews is an effective research methodology for engineering ethnography.

Mcgreevy, Michael W.↗

Solar-System Tests of Gravitational Theories

This research is aimed at testing gravitational theory, primarily on an interplanetary scale and using mainly observations of objects in the solar system. Our goal is either to detect departures from the standard model (general relativity) - if any exist within the level of sensitivity of our data - or to support this model by placing tighter bounds on any departure from it. For this project, we have analyzed a combination of observational data with our model of the solar system, including planetary radar ranging, lunar laser ranging, and spacecraft tracking, as well as pulsar timing and pulsar VLBI measurements.

Shapiro, Irwin I.↗

Planetary Exploration Reinvented

During the past 50 years, we have learned to explore and work in space. Much of what we know about the Solar System we owe to observations and sampling made by robotic spacecraft, landers, planetary rovers, and astronauts. As we look to the future, however, there is ample opportunity to reinvent planetary exploration: to develop new techniques and systems that will enhance and enable discovery.In this talk, I will describe how the NASA Ames Intelligent Robotics Group (IRG) is working to reinvent planetary exploration. First, I will present IRG's development of robots for human exploration. These robots are designed to perform work before, in parallel, and after human activity. Next, I will show how IRG is building automated planetary mapping systems to process the enormous amount of data that NASA collects from orbit. Finally, I will discuss how IRG is changing the way ground control software is created, particularly for supporting science operations.

robotics↗

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science

We often look "through a glass, darkly" at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers are radiation crusts on cometary nuclei and iogenic components of sulfate hydrate deposits on the trailing hemisphere of Europa. Weathering processes include plasma ion implantation into surfaces, sputtering by charged particles and solar ultraviolet photons, photolytic chemistry driven by UV irradiation, and radiolytic chemistry evolving from products of charged particle irradiation. Regolith structure from impacts, and underlying deeper structures from internal evolution, affects efficacy of certain surface interactions, e.g. sputtering as affected by porosity and surface irradiation dosage as partly attenuated by local topographic shielding. These processes should be regarded for mission science planning as potentially enabling, e.g. since direct surface sputtering, and resultant surface-bound exospheres, can provide in-situ samples of surface composition to ion and neutral mass spectrometers on orbital spacecraft. Sample return for highest sensitivity compOSitional and structural analyses at Earth will usually be precluded by limited range of surface sampling, long times for return, and high cost. Targeted advancements in instrument technology would be more cost efficient for local remote and in-situ sample analysis. More realistic laboratory simulations, e.g. for bulk samples, are needed to interpret mission science observations of weathered surfaces. Space environment effects on mission spacecraft and science operations must also be specified and mitigated from the hourly to monthly changes in space weather and from longer term (e.g., solar cycle) evolution of space climate. Capable instrumentation on planetary missions can and should be planned to contribute to knowledge of interplanetary space environments. Evolving data system technologies such as virtual observatories should be explored for more interdisciplinary application to the science of planetary surface, atmospheric, magnetospheric, and interplanetary interactions.

Cooper, John F.↗

Research Opportunities Supporting the Vision for Space Exploration from the Transformation of the Former Microgravity Materials Science Program

The Microgravity Materials Science Program established a strong research capability through partnerships between NASA and the scientific research community. With the announcement of the vision for space exploration, additional emphasis in strategic materials science areas was necessary. The President's Commission recognized that achieving its exploration objectives would require significant technical innovation, research, and development in focal areas defined as "enabling technologies." Among the 17 enabling technologies identified for initial focus were: advanced structures, advanced power and propulsion; closed-loop life support and habitability; extravehicular activity systems; autonomous systems and robotics; scientific data collection and analysis, biomedical risk mitigation; and planetary in situ resource utilization. Mission success may depend upon use of local resources to fabricate a replacement part to repair a critical system. Future propulsion systems will require materials with a wide range of mechanical, thermophysical, and thermochemical properties, many of them well beyond capabilities of today's materials systems. Materials challenges have also been identified by experts working to develop advanced life support systems. In responding to the vision for space exploration, the Microgravity Materials Science Program aggressively transformed its research portfolio and focused materials science areas of emphasis to include space radiation shielding; in situ fabrication and repair for life support systems; in situ resource utilization for life support consumables; and advanced materials for exploration, including materials science for space propulsion systems and for life support systems. The purpose of this paper is to inform the scientific community of these new research directions and opportunities to utilize their materials science expertise and capabilities to support the vision for space exploration.

Clinton, R. G., Jr.↗

Solar-System Tests of Gravitational Theories

We are engaged in testing gravitational theory, primarily using observations of objects in the solar system and primarily on that scale. Our goal is either to detect departures from the standard model (general relativity) - if any exist within the level of sensitivity of our data - or to place tighter bounds on such departures. For this project, we have analyzed a combination of observational data with our model of the solar system, including mostly planetary radar ranging, lunar laser ranging, and spacecraft tracking, but also including both pulsar timing and pulsar very long base interferometry (VLBI) measurements. This year, we have extended our model of Earth nutation with adjustable correction terms at the principal frequencies. We also refined our model of tidal drag on the Moon's orbit. We believe these changes will make no substantial changes in the results, but we are now repeating the analysis of the whole set of data to verify that belief. Additional information is contained in the original extended abstract.

Shapiro, Irwin I.↗

A Systems Engineering Approach to the Analysis of a Planetary Mission Ground System in Terms of Science Objectives

The most fundamental objective of all planetary missions is to return data. To accomplish this, a spacecraft is fabricated and built, software is planned and coded, and a ground system is designed and implemented. However, a systems engineering approach to determine how the collection of data drives ground system capabilities has received little attention.This paper defines a technique by which science objectives can be quantitatively evaluated. For illustrative purposes, it will be applied to NASA's Cassini Mission. This mission, to be launched in 1997, is an international endeavor designed to orbit Saturn for four years.The results of this systems engineering approach will show which science objectives drive specific ground system capabilities. In addition, this technique can assist system engineers in the selection of the science payload during pre-project mission planning; ground system designers during ground system development and implementation; and operations personnel during the mission.

systems engineering, ground systems↗