The Tracking Data Relay Satellite System (TDRSS) Augmentation Service for Satellites (TASS) is a unique mission enabling service that could be provided by the current Space Network (SN) or the future Space Mobile Network (SMN). TASS will provide a global S-band beacon to disseminate global GPS differential corrections, GPS constellation status, Earth orientation parameters, space weather alerts, low rate forward commands, TDRS ephemeris, and a GPS compatible radiometric source to allow missions that receive TASS to improve the accuracy and reliability of on-board navigation and to allow for automation of many aspects mission operations. To date, work remains to finalize the TASS signal specification and to develop the necessary software/firmware to receive and process the signal.
Preliminary development of the TASS system concept and design included establishing mature ICDs with the various data sources, developing a TASS Data Integrator (TDI) unit to subscribe and collate the various data into the TASS message, and to combine the GSFC Navigator GPS receiver firmware with Space Network compatible TDRSS transponder firmware in a single FPGA platform.
This FY16 IRAD will build on the current success to further develop the end-to-end TASS system by meeting the following objectives:
Finalization of the TASS signal specification is necessary to proceed with further development of TASS. Once the GPS and TDRSS firmware is integrated into a common platform, the next step will be modification of the TDRSS waveform to both receive the TASS signal and to process the TASS data message. At the end of this FY16 IRAD, the TASS system (including both ground and user elements) will be considered TRL6.
This work is applicable to the S-band (2.0 to 2.2 GHz) forward and return space-to-space spectrum allocations held by NASA.More »
TASS, or a similar beacon service, will provide fundamental functions of the Space Mobile Network. The ability for users to reliably and accurately navigate autonomously is necessary for implementation of User Initiated (unscheduled, on-demand) Services, known as UIS; autonomous navigation and the exchange of self-generated state information will allow for pointing of laser communication terminals from the user spacecraft to laser ground terminals or a laser relay.
TASS also provides a channel for unscheduled forward commanding of users within the beacon coverage area to allow the UIS protocol to negotiate on-demand high rate service for science data delivery. Acknowledgement of service requests and then communication of service fulfillment will be executed using commands transmitted via the TASS beacon. Combined with the MA return Demand Access System (DAS), the current TDRS spacecraft could provide a ubiquitous, low to moderate data rate, on demand, TT&C capability.
Finally, TASS is a complementary navigation service to GPS that provides navigation performance enhancements for high accuracy users and an independent source of position, navigation, and timing (PNT) for users who desire resiliency.
|Organizations Performing Work||Role||Type||Location|
|Goddard Space Flight Center (GSFC)||Lead Organization||NASA Center||Greenbelt, MD|