by Stelio Montebugnoli

How many times, watching the sky in amazement and pushed by an atavistic fear of both darkness and loneliness, have men asked themselves "Are we alone in the Universe?". A negative answer to this question would lead to incredible, unprecedented changes in the scientific and philosophical environment. The recent discovery of extra-solar planets and the detection of complex molecules in space, accomplished with spectroscopic techniques, leads us to believe that life as we know it could be a less peculiar event than we we had expected. At this point, since the available technology allows us to do it, it makes sense to look for evidences of the existences of life in the universe.

The international scientific community has created a Bioastronomy international group that has planned a large scale research programme. This interdisciplinary group is aiming to study:

1) the conditions that made the development and evolution of life possible on our planet;
2) whether those conditions exist in other parts of our galaxy;
3) if other technologically advanced civilizations are trying to communicate with us.

The discovery of prebiotic molecules (basic for life) in the interstellar medium and of several planets orbiting around other stars has stimulated a new enthusiasm towards Bioastronomy. In particular, the search for artificial radio signals coming from extraterrestrial civilizations has received more attention. This programme goes under the name of SETI (Search for ExtraTerrestrial Intelligence): it was born at NASA back in the '70s and it is now carried out, being called Phoenix, by the Seti Institute. This is an Institute that relies on the economic contributions of private donors and of several hi-tech industries situated in the Silicon Valley (Ca), where the Institute itself is located.

The detection of these extremely weak radio signals needs very sophisticated digital spectrum-analysers like the one that we use, SERENDIP IV (fig.1). This system is connected to the big antennas used in Radioastronomy like the VLBI antenna located in Medicina -Italy (fig.2).

Fig. 1: The SERENDIP IV System.

Fig. 2: The 32m antenna in Medicina (Italy).

At present the radio signal that is being looked for is a monochromatic one, which means it is one that is made up of a single frequency (radio carrier). If anybody out there wants to be "heard" they would probably use that kind of signal because it's very easy to generate and it can be easily discerned, using a spectrum-analyser, from the many broadband signals of natural origin coming from space. Radio telescopes are huge and expensive devices, and as a consequence the observing time allowed to any programme turns out to have a high cost. Since the SETI has a very low probability of leading to a positive result, it would not be cost-efficient or the best use of resources to dedicate observing time exclusively to one type of experiment.

The "Istituto di Radioastronomia" (Bologna) a division of the Italian National Research Council, has found a way to perform SETI observations at a very low cost, using the Radio astronomy Station located in Medicina. This is made possible thanks to the cooperation with Berkeley University (California) which has provided an extremely powerful real-time analysis system, aimed at detecting very weak artificial signals hidden amongst the crowd of natural radio sources. This "monster", which is able to compute several billion calculations every second, is called SERENDIP IV, and it is already in use.

At present it is paired to the 32 m VLBI antenna, but in the future it'll be connected to the Northern Cross telescope too, because the latter has dimensions of 600x600m and its collecting surface of 30,000 square metres it represents one of the largest antennas in Europe. A great feature that distinguishes the SERENDIP IV system from others is its capability to work in piggyback mode; this means that it works in parallel with other radio astronomy observations while at the same time avoiding dedicating time to just one experiment. Since we don't know where to point our antenna and which frequency to be tuned to it seems reasonable to choose the targets randomly, and process them using SERENDIP IV utilizing the signals coming from other experiments conducted by various astronomers using the antenna.
In this way, we achieve the double-goal of not requesting dedicated observation time (and as a consequence of saving money) and of increasing the observations up to 100% of the available time. Moreover the system does not need manpower, since it performs a first post-processing directly online and completely automatically.

It is planned, within a period of less than 6 years, to survey at least a 50% of the sky observable from Medicina. There will be enormous technical difficulties to be faced and solved, but this is an enterprise we have to try, mainly considering that, in case nothing was detected, "the absence of an evidence" could not imply "the evidence of the absence".

Stelio Montebugnoli

Chief Engineer of the Radio Astronomical Station in Medicina (Italy)

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