by Charles Stelzried and Michael Klein
In the lead article of this issue, "Information Systems Standards Open New Opportunities", M. L. MacMedan, manager of Information Systems Standards, describes this important program. Close interaction with the program is vital for the Telecommunications and Mission Operations Directorate (TMOD) Technology Program to successfully transfer new developments to DSN Implementation. The Information Systems Standards program is applicable to multiple missions, as well as to TMOD, and balances the design flexibility needed for performance improvements with the design stability that is characteristic of standardized systems. Implementation and operational costs for functions common to multiple missions are minimized. This successful effort also includes active work in the international forum of the Consultative Committee for Space Data Systems (CCSDS). The standardization approach for deep-space communications is key to the considerable cost savings available through greater use of Commercial-Off-the-Shelf (COTS) instrumentation.
In issues 6 and 7, Nasser Golshan described the highly successful LEO-T (Low Earth Orbit Terminal) 3-m antenna, an automated ground station for tracking the low-Earth orbiting satellites. This concept is now being extended to deep-space mission tracking with the DS-T (Deep Space Terminal) demonstration. In the "DS-T Development" article, Golshan describes the new 34-m Beam Waveguide (BWG) antenna DSS-26, at Goldstone, that is being outfitted with LEO-T-derived instrumentation for this task. This demonstration provides another opportunity for lower-cost DSN services with autonomous, unattended operations, and direct data delivery to the investigator.
George Lutes gives an account of the progression of 'remoting' in the article "DSN Photonic Antenna Remoting". Introduction of the beam waveguide (BWG) antenna into the DSN permitted equipment that was formerly located on the antenna's structure to be moved to the ground. The next logical step is to move as much of this equipment as possible to the Signal Processing Center (SPC). This requires a Fiber Optics (FO) system with sufficient dynamic range to handle the expected signal levels of a variety of missions over the required tens-of-kilometers distance. The DSN currently uses FO systems for remoting at receiver Intermediate Frequencies. Remoting directly at the DSN-received microwave frequencies could provide further advantages. George describes a new FO system, for this application, that relies on high-efficiency microwave optical modulators, high-power semiconductor lasers, and high-power microwave photodetectors. Also discussed, is an upcoming demonstration of direct microwave transmission over an FO link, directly from the low-noise amplifiers in the Goldstone R/D 34-m antenna pedestal room to the control room. This capability will enable further migration of equipment presently in the antenna area of the DSSs to the SPC.
In the DSN Science contribution for this issue, "Jupiter's Synchrotron Radiation: Observed Variatons Before, During, and After the Impacts of Comet SL-9", Michael Klein reports the long-term effects on the microwave emission from Jupiter's inner magnetosphere following the fragment impacts of Comet Shoemaker-Levy 9, in July 1994. Klein describes the sudden increase and the slow decline in Jupiter's radio emission, as detected by the NASA/JPL Jupiter Patrol observations at 2295 MHz. The observational data are being used to test computer models that will explain the nature of the intense radiation belt that surrounds the planet and extends beyond the inner moons, Io and Europa.
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