International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Presently, NASA's Space Network (SN) does not have the ability to receive random messages from satellites using the system. Scheduling of the service must be done by the owner of the spacecraft through Goddard Space Flight Center (GSFC). The goal of NASA is to improve the current system so that random messages, that are generated on board the satellite, can be received by the SN. The messages will be requests for service that the satellites control system deems necessary. These messages will then be sent to the owner of the spacecraft where appropriate action and scheduling can take place. This new service is known as the Demand Assignment Multiple Access system (DAMA).

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / NASA's Space Network (SN) provides both single access (SA) and multiple access (MA) services through a pre-scheduling system. Currently, a user's spacecraft is incapable of receiving service unless prior scheduling occurred with the control center. NASA is interested in efficiently utilizing the time between scheduled services. Thus, a demand assignment multiple access (DAMA) service study was conducted to provide a solution. The DAMA service would allow the user's spacecraft to initiate a service request. The control center could then schedule the next available time slot upon owner approval. In this paper, the basic DAMA service request design and integration is presented.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper details the interaction of a small satellite with a space network and estimates the number of contacts and duration of contacts between the small, spin-stabilized satellite and a TDRS satellite. The simulations were performed using Satellite Tool Kit (STK) version 3.0, an orbital analysis software program. STK was configured for the four vehicles representing the spin-stabilized satellite and three TDRS satellites, TDRS East, West, and TDRS Zone of Exclusion. A set of simulations were run in which the spinstabilized satellite was given orbital elements corresponding to an orbital altitude between 600 km and 1200 km. The orbital inclination angle for the set of simulations was also varied from 20° through 100° along with the antenna cone angle of 10° through 40° to account for the effective beamwidths. In each of the simulations, the access to each TDRS satellite in the SN constellation was examined as a function of orbital altitude, orbital inclination angle, and antenna cone angle.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / The Tracking and Data Relay Satellite System (TDRSS) Multiple Access (MA) Return Service provides a communication path that originates at a customer platform (either a spacecraft or other type of emitter) and is routed through a geosynchronous Tracking and Data Relay Satellite (TDRS) back to a customer control center or data acquisition location. Conventional operations provide Space Network (SN) customers with MA Service based on a schedule generated from user requests. The MA Service currently provides return link telemetry services to customer platforms with real-time, playback, and science data rates up to 100 kbps. This paper describes an integrated approach, using state-of-the-art technology and fault-tolerant architecture, to develop the next generation of TDRSS MA beamforming equipment. New designs will result in significant reduction in beamformer size and cost by at least an order of magnitude relative to the current MA equipment. This new equipment will provide the potential for increased usage of TDRSS MA services. The paper describes the in-development Demand Access (DA) Return Service that provides a new class of service using next generation technology.