National Aeronautics and Administration

The National Aeronautics and Space Administration (NASA) is investigating alternative technologies to facilitate building communication networks for future Spaceports and Ranges. This reports documents an investigation conducted from October 2002 through September 2003 of an emerging communication technology known as Ultra Wideband (UWB) communication. Contained in this report is an overview of UWB communication technology, a survey of UWB equipment vendors, and complete details of the theoretical and experimental research that was performed during this emerging communication technology investigation. The summary conclusion of this report is that UWB communication holds great promise for augmenting future Spaceport and Range communication networks through enhancing short-range, high speed, wireless communication. This enhancement is accomplished through simultaneously integrating position-aware functions with traditional communication functions. UWB technology achieves this dual-function integration through using short impulses instead of the continuous waveforms common to most wireless systems. Because short impulses are used, UWB communication links are inherently immune to most multi-path interference, and also achieve better instantaneous spectrum re-use among users. UWB modulation also provides a Low-Probability-of-Detection (LPD) waveform with selectable security. UWB systems can therefore provide fade resistant, high speed data links wherever the presence of easily detectable wireless transmissions must be avoided, such as in specialized tactical situations. Despite the many theoretical advantages that exist for UWB modulation, much anxiety commonly arises with UWB emissions because of their ultra wide bandwidths. This characteristic especially causes concern vis- -vis possible deleterious effects to narrowband legacy systems that typically operate at low link margins, such as GPS navigation systems, which often operate with link margins of only 1 or 2 dB. Though this concern has been addressed previously in Federal regulations through the inclusion of spectral emission mask requirements for UWB emissions, not all of the technical concerns have been settled. This report further researches some of these interference concerns by investigating UWB interference to, and UWB susceptibilities from, legacy wireless systems. The summary recommendation of this report is that UWB technology appears to hold many of the key advantages needed to tackle a number of wireless systems requirements needed in the future, provided it can co-exist successfully with both legacy narrowband wireless systems, and with other UWB wireless systems. Based on the demonstrated performance seen during testing, there is ample reason to believe that UWB wireless systems will be able to coexist with most legacy wireless systems. This report is a first step in understanding and assessing UWB's applicability for supporting the communication needs of future Spaceports and Ranges.

This publication contains graphical data necessary for the analysis of planetary exploration missions to Saturn. Positional and geometric information spanning the time period from 1985 through 2020 is presented; the text explains the data and its usage. This volume is one in a planned series covering planetary mission targets. This publication is one in a series of volumes devoted to planetary positional and geometric data. The present Volume V provides information describing the planet Saturn. Other volumes to be published in 1983 are II, III, and IV, describing Venus, Mars, and Jupiter geometric data, respectively. The presentations of planetary positional and geometric data for Mercury (Volume I), Uranus (Volume VI), Neptune (Volume VII), and the Pluto/Charon System (Volume VIII) are included in their respective volumes. The purpose of this series of planetary geometry handbooks is to provide mission and science planners, as well as trajectory designers with graphical information sufficient for preliminary mission design and evaluation. It is intended to be used in conjunction with the appropriate volumes and parts of the Mission Design Handbooks. It extends their coverage by commencing in 1985 and continuing to the year 2020. This time span was chosen to provide sufficient mission duration flexibility for all Earth departures through 2005. The present Volume V is devoted to data on the positions of the planet Saturn. It presents information characterizing the geocentric and heliocentric positional geometry of a space- craft while it is in the vicinity of the subject planetary body. The spacecraft could encompass a lander, an entry probe, or a flyby vehicle at encounter. Such wide usage of the data is possible because planetary positions change but slowly, while the distances to Earth or Sun are always large compared to those between the spacecraft and the target planet during the encounter.

This publication contains graphical data necessary for the analysis of planetary exploration missions to Venus. Positional and geometric information spanning the time period from 1988 through 2020 is presented; the text explains the data and its usage. This volume is one in a planned series covering planetary mission targets. This publication is one in a series of volumes devoted to planetary positional and geometric data. The present Volume II provides information describing tile planet Venus. Other volumes to be published in 1983 are III, IV, and V, describing Mars, Jupiter, and Saturn geometric data, respectively. Other volumes include the presentations of planetary positional and geometric data for Mercury (Volume I), Uranus (Volume VI), Neptune (Volume VII), and the Pluto/Charon System (Volume VIII). The purpose of this series of planetary geometry hand- books is to provide mission and science planners as well as trajectory designers with graphical information sufficient for preliminary mission design and evaluation. It is intended to be used in conjunction with the appropriate volt.n.es and parts of the Mission Design Handbooks. The present Volume II is devoted to data on the positions of the planet Venus. It presents information characterizing the geocentric and he iocentric positional geometry of a spacecraft while it is in the vicinity of the subject planetary body. The spacecraft could encompass a lander, an entry probe, or a flyby vehicle at encounter. Such wide usage of the data is possible because planetary positions change but slowly, while the distances to Earth or Sun are always large compared to those between the spacecraft and the target planet during the encounter.