Astropulse - Scientific Research

Scientific Research

Astropulse searches for both single pulses and regularly repeating pulses. This experiment represents a new strategy for SETI, postulating microsecond timescale pulses as opposed to longer pulses or narrowband signals. They may also discover pulsars and exploding primordial black holes, both of which would emit brief wideband pulses. The primary purpose of the core Astropulse algorithm is coherent de-dispersion of the microsecond radio pulses for which Astropulse is searching. Dispersion of a signal occurs as the pulse passes through the interstellar medium (ISM) plasma, because the high frequency radiation goes slightly faster than the lower frequency radiation. Thus, the signal arrives at the radio-telescope dispersed depending upon the amount of ISM plasma between the Earth and the source of the pulse. Dedispersion is computationally intensive, thus lending itself to the distributed computing model.

Astropulse utilizes the distributed computing power of SETI@home, delegating computational sub-tasks to hundreds of thousands of volunteers' computers, to gain advantages in sensitivity and time resolution over previous surveys. Wideband pulses would be "chirped" by passage through the interstellar medium; that is, high frequencies would arrive earlier and lower frequencies would arrive later. Thus, for pulses with wideband frequency content, dispersion hints at a signal's extraterrestrial origin. Astropulse searches for pulses with dispersion measures ranging from 50 pc/cm3 to 800 pc/cm−3 (chirp rates of 7,000 Hz to 400 Hz per microsecond), allowing detection of sources almost anywhere within the Milky Way.

Project proponents believe that Astropulse will either detect exploding black holes, or establish a maximum rate of 5×10−14 pc−3yr−1, a factor of 104 better than any previous survey.