Human civilization emits radio waves in a huge range – from the spark of an internal combustion engine to communication systems. Radio astronomers have long accepted this and have found ways to mitigate the influence of the human factor on signals from space. Unfortunately, these methods do not eliminate the influence completely and not in all cases. But there is good news: methods for compensating for false signals are becoming better, allowing scientists to continue their work on listening to the Universe.
Image source: Murchison Widefield Array
Scientists from Brown University in the US have made an unexpected move to filter out signals of anthropogenic origin. Back in 2013, the Australian radio telescope Murchison Widefield Array (MWA) detected a strange signal whose origin was unexplained.
The MWA antenna array is located in a remote area of the country in a special radio silence zone. It is even forbidden to enter the territory in cars with gasoline engines, only diesel fuel. The signal was almost immediately identified as television, but it should not have been there in principle. But it was very strong, which baffled scientists.
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Scientists have developed a method for recording signals in the near field by creating a corresponding directional diagram of the radio array. The proposed solution made it possible to amplify television broadcasts reflected from aircraft, which opened up the possibility of excluding them from radio observation data of the Universe without compromising scientific results. Flight data for 2013 are missing, but the method, tested today, has shown the ability to record passing aircraft and even determine the source of the broadcast.
It is clear that the new technique will help in future observations, although radio astronomers face another problem – the deployment of thousands of satellite constellations in low orbit. This problem has no solution yet, but that is another story.