The microwave region of the electromagnetic spectrum, a plausible regime for signals from extraterrestrial intelligences, is largely unexplored. With new technology, particularly in data processing ...and low-noise reception, surveys can be conducted over broad regions of frequency and space with existing antennas at flux densities plausible for interstellar signals. An all-sky, broad-band survey lasting perhaps 5 years can be structured so that even negative results would establish significant boundaries on the regime in which such signals may be found. The technology and techniques developed and much of the data acquired would be applicable to radio astronomy and deep-space communications.
Fundamental information about the Universe is encoded in anisotropies of the
Cosmic Microwave Background (CMB) radiation. To make full use of this
information, an experiment must image the entire sky ...with the angular
resolution, sensitivity, and spectral coverage necessary to reach the limits
set by cosmic variance on angular scales >~10'. Recent progress in detector
technology allows this to be achieved by a properly designed space mission that
fits well within the scope of NASA's Medium-class Explorer program. An
essential component of the mission design is an observing strategy that
minimizes systematic effects due to instrumental offset drifts. The detector
advances make possible a `spin chopping' approach that has significant
technical and scientific advantages over the strategy used by COBE, which
reconstructed an image of the sky via inversion of a large matrix of
differential measurements. The advantages include increased angular resolution,
increased sensitivity, and simplicity of instrumentation and spacecraft
operations. For the parameters typical of experiments like the Primordial
Structures Investigation (PSI) and the Far InfraRed Explorer (FIRE), we show
that the spin-chopping strategy produces images of the sky and power spectra of
CMB anisotropies that contain no significant systematic artifacts.
Fundamental information about the Universe is encoded in anisotropies of the Cosmic Microwave Background (CMB) radiation. To make full use of this information, an experiment must image the entire sky ...with the angular resolution, sensitivity, and spectral coverage necessary to reach the limits set by cosmic variance on angular scales >~10'. Recent progress in detector technology allows this to be achieved by a properly designed space mission that fits well within the scope of NASA's Medium-class Explorer program. An essential component of the mission design is an observing strategy that minimizes systematic effects due to instrumental offset drifts. The detector advances make possible a `spin chopping' approach that has significant technical and scientific advantages over the strategy used by COBE, which reconstructed an image of the sky via inversion of a large matrix of differential measurements. The advantages include increased angular resolution, increased sensitivity, and simplicity of instrumentation and spacecraft operations. For the parameters typical of experiments like the Primordial Structures Investigation (PSI) and the Far InfraRed Explorer (FIRE), we show that the spin-chopping strategy produces images of the sky and power spectra of CMB anisotropies that contain no significant systematic artifacts.
PDF
