RESUMO
The Sky Survey observing program is one of two complementary strategies that NASA plans to use in its microwave Search for Extraterrestrial Intelligence (SETI). The primary objective of the Sky Survey is to search the entire sky over the frequency range 1000-10,000 MHz for evidence of narrow band signals of extraterrestrial, intelligent origin. Spectrum analyzers with upwards of 10 million channels and data rates in excess of 10 gigabits per second are required to complete the survey in less than 7 years. To lay the foundation for the operational SETI Sky Survey, a prototype system has been built to test and refine real time signal detection algorithms, to test scan strategies and observatory control functions, and to test algorithms designed to reject radio frequency interference. This paper presents a high level description of the prototype hardware and software and reports on the preparations to deploy the system to the 34-m antenna at the research and development station of NASA's Deep Space Communication Complex, Goldstone, California.
Assuntos
Exobiologia/instrumentação , Meio Ambiente Extraterreno , Micro-Ondas , Comunicação , Desenho de Equipamento , Exobiologia/métodos , Exobiologia/tendências , Ondas de Rádio , Processamento de Sinais Assistido por Computador/instrumentação , Software , Estados Unidos , United States National Aeronautics and Space AdministrationRESUMO
Investigations are carried out at JPL on radiofrequency interferences at very low levels (-130 to -180 dBm) in various bands, especially the 1-2 GHz band. Extrapolation of interferences in the years to come is attempted.
Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno , Micro-Ondas , Comunicação , Planeta Terra , Ondas de Rádio , Estados Unidos , United States National Aeronautics and Space AdministrationRESUMO
Radio astronomical observations of Uranus show that the radio emission spectrum is evolving in time. Ammonia vapor must be depleted in the Uranian atmosphere as Gulkis and his co-workers previously suggested. Since 1965, ammonia either has been decreasing in time or is a decreasing function of latitude, or both, provided that the radio emission is atmospheric in origin. If Uranus has an observable low-emissivity "surface," these trends may be reversed. The microwave observations made in 1965, at the time when the spin axis of Uranus was nearly perpendicular to the sun-Uranus line, are consistent with an atmospheric opacity profile that would be produced by saturated ammonia vapor in a predominantly hydrogen atmosphere. At the present time, when the spin axis of Uranus is nearly aligned with the sun-Uranus line, the measurements require an opacity that would be produced by saturated water vapor. A large thermal gradient between the pole and equator is ruled out.