4 mins read 24 Oct 2019

Parkes to follow up exoplanet survey for alien signals

The Parkes radio telescope will be used to scan for techno-signatures around exoplanets, discovered by NASA’s orbiting spacecraft, TESS.

The Parkes Dish. Credit: Shaun Amy/CSIRO

In an announcement made at the 70th International Astronautical Congress in Washington D.C., the Breakthrough Listen Initiative has announced a new collaboration with the team from NASA’s Transiting Exoplanet Survey Satellite (TESS), utilising the CSIRO’s Parkes radio telescope to follow up any potential exoplanet candidates that might harbour extra-terrestrial societies.

Breakthrough Listen currently uses an array of global instruments as part of its primary facilities (such as the Parkes Dish) however bring on board a range of new telescopes around the world, including the CSIRO’s Murchison Widefield Array in Western Australia.

This new collaboration with TESS will expand Breakthrough Listen’s target list (adding over 1,000 “objects of interest” identified by TESS); refine Listen’s analysis strategy (for example, utilising new knowledge about planetary alignments to predict when transmissions might be more likely to occur); and provide more meaningful statistics in the event of non-detections.

“It’s exciting that the world’s most powerful SETI search, with our partner facilities across the globe, will be collaborating with the TESS team and our most capable planet-hunting machine,” remarked Dr. Worden from Breakthrough Listen. “We’re looking forward to working together as we try to answer one of the most profound questions about our place in the Universe: Are we alone?”

NASA’s Transiting Exoplanet Survey Satellite (TESS)

Launched in April 2018, TESS has four wide-field cameras, each monitoring a region of sky 24 degrees across (about the width of the span of your hand when held at arm’s length). Light-curves for 20,000 stars are measured every 2 minutes, and in addition, the brightness of every pixel in the cameras is recorded every 30 minutes.

The mission measures “light-curves” (how the brightness of stars changes over time) to look for tell-tale dips caused by “transits” – where a planet passes in front of the star as viewed from Earth. The cutting-edge instruments on TESS are sensitive enough to detect small, rocky planets similar to Earth. Such planets are prime targets for follow-up by NASA programs, such as the James Webb Space Telescope, that seek to measure planetary atmospheres. Careful measurements of atmospheric composition could result in the detection of “biosignatures” – indicators that biological processes may be taking place on worlds other than Earth.

In the past three decades over 4,000 exoplanets have been discovered – many by TESS’s predecessor, the Kepler spacecraft. According to recent estimates, the average number of planets per star is greater than one. As a result, techno-signature searches operate in a “target-rich” environment, observing stars whether or not confirmed planets are known to exist around them. Nevertheless, as the haul of confirmed exoplanets continues to grow, the additional information about these systems is very useful for optimizing SETI strategies.

The Search for SETI

As well as looking for biosignatures, astrobiologists search for “techno-signatures” – indicators of technology that may have been developed by advanced civilizations. Also known as SETI (the Search for Extra-terrestrial Intelligence), techno-signature searches use powerful telescopes to look for signals coming from space that appear to have arisen from transmitters, propulsion devices, or other engineering.

No unambiguous techno-signatures have been seen to date.

Breakthrough Listen at Parkes

The Parkes telescope (the second-largest steerable dish in the southern hemisphere at 64m diameter, compared to its nearby companion DSS-43 in Canberra, which is 70m) can be used to scan 13 different patches of the sky simultaneously using its multibeam instrument. This makes it an ideal candidate for the Breakthrough Listen project, especially since the ultra-wideband receiver is now in place, with the ability to scan 0.7 to 4.2 GHz frequencies.

Due to its southern location, Parkes is within an excellent range of listening for signals from the Milky Way galaxy and several southern hemisphere galaxies.

Breakthrough Listen Program

Breakthrough Listen is a scientific program in search for evidence of technological life in the Universe. It aims to survey one million nearby stars, the entire galactic plane and 100 nearby galaxies at a wide range of radio and optical bands.

Along with Breakthrough Listen, they include Breakthrough Watch, an optical search for Earth-like planets in the habitable zones of nearby stars; and Breakthrough Starshot, the first significant attempt to design and develop a space probe capable of reaching another star.