Here’s an image that brings out the philosopher in me, or maybe the poet. It’s Voyager 1, as detected by a new processing system called COSMIC, now deployed at the Very Large Array west of Socorro, New Mexico. Conceived as a way of collecting data in the search for technosignatures, COSMIC (Commensal Open-Source Multimode Interferometer Cluster) taps data from the ongoing VLASS (Very Large Array Sky Survey) project and shunts them into a receiver designed to spot narrow channels, on the order of one hertz wide, to spot possible components of a technosignature.
Technosignatures fire the imagination as we contemplate advanced civilizations going about their business and the possibility of eavesdropping upon them. But for me, the image below conjures up thoughts of human persistence and a gutsy engagement with the biggest issues we face. Why are we here, and where exactly are we in the galaxy? In the cosmos? Spacecraft like the Voyagers were part of the effort to explore the Solar System, but they now push into realms not intended by their designers. And here we have the detection of doughty Voyager 1, still working the mission, somehow still sending us priceless information.
Image: The detection of the Voyager I spacecraft using the COSMIC instrument on the VLA. Launched in 1977, the Voyager I spacecraft is now the most distant piece of human technology ever sent into space, currently around 14.8 billion miles from Earth. Voyager’s faint radio transmitter is difficult to detect even with the largest telescopes, and represents an ideal human “technosignature” for testing the performance of SETI instruments. The detection of Voyager’s downlink gives the COSMIC team high confidence that the system can detect similar artificial transmitters potentially arising from distant extraterrestrial civilizations. Credit: SETI Institute.
Voyager 1 is thus a dry run for a technosignature detection, and COSMIC is said to offer a sensitivity a thousand times more comprehensive than any previous SETI search. The detection is unmistakable, combining and verifying the operation of the individual antennas that comprise the array to show the carrier signal and sideband transmissions from the spacecraft. The most distant of all human-made objects, Voyager 1 is now 24 billion kilometers from home. For one participant in COSMIC, the spacecraft demonstrates what can be done by combing through the incoming datastream of VLASS. Thus Jack Hickish (Real Time Radio Systems Ltd):
“The detection of Voyager 1 is an exciting demonstration of the capabilities of the COSMIC system. It is the culmination of an enormous amount of work from an international team of scientists and engineers. The COSMIC system is a fantastic example of using modern general-purpose compute hardware to augment the capabilities of an existing telescope and serves as a testbed for technosignatures research on upcoming radio telescopes such as NRAO’s Next Generation VLA.”
COSMIC is the result of collaboration between The SETI Institute (working with the National Radio Astronomy Observatory) and the Breakthrough Listen Initiative. The key here is efficiency – the technosignature search draws on data already being taken for other reasons, and given the challenge of obtaining large amounts of telescope time, an offshoot method of tracking pulsed and transient signals simply makes use of existing resources, with approximately ten million star systems within its scope.
Technosignatures are fascinating, but I come back to Voyager. We’ve gotten used to the scope of its achievement, but what fires the imagination is the details. It wasn’t all that long ago, for example, that controllers decided to switch to the use of the spacecrafts’ backup thrusters. The reason: The primary thrusters, having gone through almost 350,000 thruster cycles, were pushing their limits. When the backup thrusters were fired in 2017, the spacecraft had been on their way for forty years. The “trajectory correction maneuver,” or TCM, thrusters built by Aerojet Rocketdyne (also used on Cassini, among others), dormant since Voyager 1’s swing by Saturn in 1980, worked flawlessly.
In his book The Interstellar Age (Dutton, 2015), Jim Bell came up with an interesting future possibility for the Voyagers before we lose them forever. Bell worked as an intern on the Voyager science support team at JPL starting in 1980, and he would like to see some of the results of the mission stored up for a potentially wider audience. Right now there is nothing aboard each spacecraft that tells their stories. Bell quotes Jon Lomberg, who worked on the Voyager Golden Records and has advanced the idea of a digital message to be uploaded to New Horizons:
‘One thing I wish could have been on the Voyager record… is that I wish we could have had something of ‘here’s what Voyager was and here’s what Voyager found,’ because it’s one of the best things human beings have ever done. If they ever find Voyager they won’t know about its mission. They won’t know what it did, and that’s sad.’
And Bell goes on to say:
…let’s try to upload the Earth-Moon portrait; the historic first close-up photos of Io’s volcanoes and Europa and Ganymede’s cracked icy shells; the smoggy haze of Titan; the enormous cliffs of Miranda; the strange cantaloupe and geyser terrain of Triton; the swirling storms of Jupiter, Saturn and Neptune; the elegant, intricate ring systems of all four giant planets; the family portrait of our solar system. Let’s arm our Voyagers with electronic postcards so they can properly tell their tales, should any intelligence ever find them.
Could images be uploaded to the Voyager tape recorders at some point before communication is lost? It’s an intriguing thought about a symbolic act, but whether possible or not, it reminds us of the distances the Voyagers have thus far traveled and the presence of something built here on Earth that will keep going, blind and battered but more or less intact, for eons.