SETI researchers can now scan all Very Large Array data for any evidence of extraterrestrial transmission


February 14thand, 2020, the SETI Institute and the National Radio Astronomy Observatory (NRAO) announced a new partnership, which they appropriately named the Commensal Open-Source Multimode Interferometer Cluster Search for Extraterrestrial Intelligence (COSMIC SETI). This partnership will allow the Karl G. Jansky Very Large Array (VLA) to participate in the Search for Extraterrestrial Intelligence (SETI) for the first time in its history.

In recent weeks, the project has taken a big step forward with the installation of fiber optic amplifiers and splitters on all VLA antennas, which give COSMIC access to data streams from across the VLA. Once this digital backend is online, COSMIC will have access to all the data provided by the 27 radio antennas of the VLA, which will be able to carry out observations 24/7. In the process, COSMIC SETI will examine around 40 million stars in the Milky Way to detect possible signs of intelligent life.

Located in the deserts of New Mexico, the Karl G. Jansky Very Large Array is the largest array of radio telescopes in the world capable of operating at microwave frequencies. It was featured in the 1997 film “Contact” (based on Carl Sagan’s original novel), where Dr. Eleanor Arroway (played by Jodie Foster) and her colleagues received the first extraterrestrial communication. Interestingly enough, the VLA has never been part of a real-life SETI effort, but that’s about to change.

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The final results of the EDFA/Cosmic fiber work. Credit: SETI Institute

Jack Hickish, head of digital instrumentation for COSMIC SETI, explained in a press release from the SETI Institute:

“Having all VLA digital signals available for the COSMIC system is a major milestone, involving close collaboration with the NRAO VLA engineering team to ensure that the addition of COSMIC hardware does not affect the existing VLA infrastructure in any way. .

“It is fantastic to have overcome the challenges of prototyping, testing, sourcing and installation – all conducted during both a global pandemic and a shortage of semiconductors – and we are delighted to be able to move on to the next task of processing the many Tb/s of data to which we now have access.

As part of this collaborative effort, the VLA will make observations while SETI Institute scientists analyze this data to look for evidence of technological activity (aka “technosignatures”). The VLA provides many important features for SETI, not the least of which is size. Each of its 27 antennas is 25 m (82 ft) in diameter, giving a collection area equivalent to a single satellite dish measuring 130 m (426 ft) in diameter.

This surface and large amounts of metal mesh allow for almost unparalleled levels of sensitivity, which is always a plus for SETI surveys (where signals are likely to be weak). Additionally, each VLA antenna has eight cryogenically cooled receivers that continuously monitor the sky at frequencies ranging from 1 to 50 GHz in the radio spectrum. Some receivers can operate between 1 GHz and 54 MHz, corresponding to the frequencies used for television broadcasts.

SETI Institute postdoctoral researchers Dr. Savin Varghese and Dr. Chenoa Tremblay in front of one of the 82-foot-diameter dishes that make up the Very Large Array. Credit: SETI Institute

To exploit these capabilities, VLA engineers installed a “splitter” that transmits a copy of the data stream provided by the VLA’s 27 antennas to locally installed SETI equipment. This equipment consists of software and hardware that calculates 64 different beams, which sorts cosmic statics into hundreds of millions of narrowband frequency channels. Says Cherry Ng, a SETI Institute COSMIC project scientist:

“I am excited about COSMIC’s ability to conduct the most comprehensive technosignature search ever conducted in the Northern Hemisphere. We will be able to monitor millions of stars with a sensitivity high enough to detect an Arecibo-type emitter up to a distance of 25 parsecs (81 light-years), covering a range of observation frequencies from 230 MHz to 50 GHz, which includes many parts of the spectrum that have not yet been explored for ETI signals.

The COSMIC SETI program, which should be operational in early 2023, will observe around forty star systems in our galaxy for two years. This will be the most comprehensive SETI survey undertaken in the Northern Hemisphere, a record previously held by Breakthrough Listen. Its first major observation campaign will be conducted in parallel with the ongoing VLA Sky Survey (VLASS), which relies on the VLA to survey 82% of the sky in the 2-4 GHz S bands.

“We look forward to partnering with the SETI Institute on this exciting initiative and are excited to see this important milestone in the technical work that will make this new science possible,” said NRAO Director Tony Beasley.

Further reading: SETI Institute


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