New radio signal excited alien hunters – but scientists are still skeptical
Ways forward
One way forward would be to abandon the traditional approach of using large single dishes for SETI. While a parabolic dish has the useful property of being sensitive to a fairly large area of sky, if a candidate signal is detected, there is no way of knowing exactly where it came from. So, while the Parkes telescope was nominally pointing at Proxima Centauri, literally hundreds of thousands of other galactic stars were also present in the field of view. Ultimately, any one of them could potentially be the source of the BLC-1.
We can overcome this problem by observing with several large dishes simultaneously, preferably separated by hundreds and even thousands of kilometers. By combining their signals using a powerful technique known asVery Long Baseline Interferometry, we can pin-point the position of a signal with exquisite accuracy, such as to a single star.
For nearby systems such as Proxima Centauri, we can achieve a precision of approximately one-thousandth of an astronomical unit (the distance between the Sun and Earth). This should allow us to identify not just the stellar system but the associated planet that transmitted the signal.
With such an approach, the motion on the sky of most signals could be measured in a year or even less. There areother advantagesto observing with an interferometric array of telescopes, such as having many completely independent telescopes detecting the same signal.
In addition, radio interference from Earth wouldn’t be registered by telescope sites separated by hundreds of kilometers. So thehuman-madeinterference that has contributed to so many false positives for SETI, and has included orbiting satellites and evenmicrowave ovens, would completely disappear.
This kind of interferometry is a well-established technique that has been around since the late 1960s. So why are we not doing SETI with it systematically? One reason is that combining data together from an array of telescopes requires more effort in almost all regards, including greater computing resources. An observation of a few minutes would generate many terabytes of data (1 terabyte is 1,024 gigabytes).
But none of these issues are showstoppers, especially as technology continues to advance at unprecedented rates. Perhaps a more important factor is human inertia. Until recently, the SETI community has been quite conservative in its approach, with staff traditionally drawn fromsingle-dish telescopes. These scientists aren’t necessarily familiar with the quirks and foibles of interferometric arrays.
Luckily, that’s finally changing. Breakthrough Listen now looks towards incorporating arrays such asMeerKAT, theJansky Very Large Telescope(JVLA), and eventually theSquare Kilometer Array (SKA)in their future survey programs. In the meantime, prepare for a rising tide of ambiguous radio events – and hopefully the reappearance of BLC-1. Determining the precise location and motion of these signals may be the only way of reaching unequivocal conclusions.
This article byMichael Garrett, Sir Bernard Lovell chair of Astrophysics and Director of Jodrell Bank Centre for Astrophysics,University of Manchesteris republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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