The Square Kilometre Array (SKA) radio telescope project has not reached the construction phase of the work yet. However, the SKA design is fully completed and the first construction phase should start in 2018, with the “first light” date set for 2020. There is still some time to go until then. In the meantime, ideas describing how the new telescope could be used are being actively discussed.
The technical capabilities of SKA are very promising indeed. The continuous operational frequency of the telescope should cover a range from 50 MHz to 14 GHz, with up to 30 GHz after the third construction phase is completed. According to the current calculations, its sensitivity should exceed any other radio instrument available by approximately 50 times. Undoubtedly, such impressive features attract the attention of astronomers from all the world, so it probably shouldn’t be very surprising to see a name of SETI among them.
Yesterday arXiv.org published a paper describing a potential application of SKA in the search for extraterrestrial intelligence by employing it in several experimental programs. “From a SETI perspective, we envision an observing system in which multiple phased array beams can be independently steered within the primary field-of-view and fed to dedicated signal processing hardware where SETI specific algorithms are implemented”, the authors discuss the basic idea of their approach. They also note that the entire technical concept has already been tested in smaller scale, including a previously designed mode of operation on the Allen Telescope Array (the principle is illustrated in the diagram above).
For this purpose a SETI observer could use an independent beamforming capability of SKA to form phased-array beams within the current primary field of observation. Data obtained from a single beam could be copied, and each copy directed to a separate signal processor. Similarly, parallel SETI analyses could be performed on raw data obtained from other observations.
“The combination of raw sensitivity, flexible electronics and increased computational capacity will enable orders-of-magnitude improvement in the speed, depth and breadth of previous SETI experiments”, the scientists say. For example, in a five year Phase 1 campaign, the performance of SKA should be enough to survey every star in its declination range within 60 pc, or more than ten thousand stars. In comparison, the most thorough SETI survey targeted “only” 1000 stars over 1-3 GHz frequency range to a luminosity limit of ~2 x 1019 ergs/sec. According to conservative estimations, in ten years SKA should be able to detect every star within 60 pc in its field of view more than a hundred times fainter than any earlier SETI study could achieve.
Why such extreme magnitudes of sensitivity are needed? Well, the more sensitive radio telescope you use, the weaker source of signal you can detect. Emission of even narrow-band beacon-like signals requires tremendous amounts of energy for them to travel across the vast cosmic distances. Therefore, having equipment like SKA either increases the observable distance for the signals of similar strength, or increases the range of potentially detectable signal sources and signal types.
Written by Alius Noreika