Prototype radar image zoom-in of Tycho Crater floor in 5-meter resolution detail. (Credit: Raytheon Technologies)
Everyone loves taking pictures of the Moon. Whether it’s with their phones or through the wonders of astrophotography, photographing the Moon reminds us about the wonders and awesomeness of the universe. But while we can take awesome images of the whole Moon from the Earth, it’s extremely difficult to get close-up images of its surface given the enormous distance we are from our nearest celestial neighbor at 384,400 km (238,855 mi). This is because the closer we try to zoom in on its surface, the blurrier, or more pixelated, the images become. Essentially, the resolution of the images becomes worse and worse. But what if we could take high-resolution images of the Moon’s surface from Earth instead of relying on satellites presently in lunar orbit to take them for us?
Artist’s impression of Green Bank Telescope connected to a machine learning network. Credit: Breakthrough Listen/Danielle Futselaar.
For over sixty years, astronomers and astrophysicists have been engaged in the Search for Extraterrestrial Intelligence (SETI). This consists of listening to other star systems for signs of technological activity (or “technosignatures), such as radio transmissions. This first attempt was in 1960, known as Project Ozma, where famed SETI researcher Dr. Frank Drake (father of the Drake Equation) and his colleagues used the radio telescope at the Green Bank Observatory in West Virginia to conduct a radio survey of Tau Ceti and Epsilon Eridani.
Since then, the vast majority of SETI surveys have similarly looked for narrowband radio signals since they are very good at propagating through interstellar space. However, the biggest challenge has always been how to filter out radio transmissions on Earth – aka. radio frequency interference (RFI). In a recent study, an international team led by the Dunlap Institute for Astronomy and Astrophysics (DIAA) applied a new deep-learning algorithm to data collected by the Green Bank Telescope (GBT), which revealed eight promising signals that will be of interest to SETI initiatives like Breakthrough Listen.
Artist view of an active supermassive black hole. Credit: ESO/L. Calçada
Black holes are gluttonous behemoths that lurk in the center of galaxies. Almost everybody knows that nothing can escape them, not even light. So when anything made of simple matter gets too close, whether a planet, a star or a gas cloud, it’s doomed.
But the black hole doesn’t eat it at once. It plays with its food like a fussy kid. Sometimes, it spews out light.
When the black hole is not only at the center of a galaxy but the center of a cluster of galaxies, these burps and jets carve massive cavities out of the hot gas at the center of the cluster called radio bubbles.
CHIME consists of four metal "half-pipes", each one 100 meters long. Image Credit: CHIME/Andre Renard, Dunlap Institute.
In 2017, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) began to gather light from the Universe to address some of the biggest questions and astrophysics and cosmology. Located at the Dominion Radio Astrophysical Observatory (DRAO) in British Columbia, this interferometric radio telescope has been a game-changer for studying Fast Radio Bursts (FRBs), which remain one of the most mysterious cosmic mysteries facing astronomers today.
In the near future, CHIME will be getting an expansion that will help it more accurately identify where FRBs are coming from. This will consist of a new radio telescope outrigger located at the SETI Institute’s Hat Creek Radio Observatory (HCRO), new outriggers near Princeton, British Columbia, and at the Green Bank Observatory in West Virginia. These will work with the main CHIME telescope to localize CHIME-detected FRBs precisely in the night sky.
In February 2016, Gravitational Waves (GWs) were detected for the first time in history. This discovery confirmed a prediction made by Albert Einstein over a century ago and triggered a revolution in astronomy. Since then, dozens of GW events have been detected from various sources, ranging from black hole mergers, neutron star mergers, or a combination thereof. As the instruments used for GW astronomy become more sophisticated, the ability to detect more events (and learn more from them) will only increase.
For instance, an international team of astronomers recently detected a series of low-frequency gravitational waves using the International Pulsar Timing Array (IPTA). These waves, they determined, could be the early signs of a background gravitational wave signal (BGWS) caused by pairs of supermassive black holes. The existence of this background is something that astrophysicists have theorized since GWs were first detected, making this a potentially ground-breaking discovery!
Observational astronomy is dependent on its data, and therefore also dependent on the instruments that collect that data. So when one of those instruments fails it is a blow to the profession as a whole. The collapse of the Arecibo Telescope last year after it was damaged by Hurricane Maria in 2017 permanently deprived the radio astronomy world of one of its primary observational tools. Now a team at the National Radio Astronomy Observatory (NRAO) hopes to upgrade an existing telescope at the Green Bank Observatory in West Virginia to replace the failed Puerto Rican one and provide even more precise images of near Earth objects in the radio spectrum.
When a star reaches the end of its life cycle, it will blow off its outer layers in a fiery explosion known as a supernova. Where less massive stars are concerned, a white dwarf is what will be left behind. Similarly, any planets that once orbited the star will also have their outer layers blown off by the violent burst, leaving behind the cores behind.
For decades, scientists have been able to detect these planetary remnants by looking for the radio waves that are generated through their interactions with the white dwarf’s magnetic field. According to new research by a pair of researchers, these “radio-loud” planetary cores will continue to broadcast radio signals for up to a billion years after their stars have died, making them detectable from Earth.
In 2016, Russian-Israeli billionaire Yuri Milner launched Breakthrough Initiatives, a massive non-profit organization dedicated to the search for extra-terrestrial intelligence (SETI). A key part of their efforts to find evidence of intelligent life is Breakthrough Listen, a $100 million program that is currently conducting a survey of one million of the nearest stars and the 100 nearest galaxies.
In keeping with their commitment to making the results of their surveys available to the public, the Listen team recently submitted two papers to leading astrophysical journals. These papers describe the analysis of Listen’s first three years of radio observations which resulted in a petabyte of radio and optical data, the single largest release of SETI data in the history of the field.
The Karl G. Jansky Very Large Array, located in central New Mexico. Credit: NRAO
In July of 2015, Russian billionaire Yuri Milner announced the creation of Breakthrough Listen, a decade-long project that would conduct the largest survey to date for signs of extra-terrestrial communications (ETI). As part of his non-profit organization, Breakthrough Initiatives, this survey would rely on the latest in instrumentation and software to observe the 1,000,000 closest stars and 100 closest galaxies.
Using the Green Bank Radio Telescope in West Virginia, the Listen science team at UC Berkeley has been observing distant stars for over a year now. And less than a week ago, they observed 15 Fast Radio Bursts (FRBs) coming from a dwarf galaxy located three billion light-years away. According to a study that described their findings, this was the first time that repeating FRBs have been seen coming from this source at these frequencies.
The team’s study, titled “FRB 121102: Detection at 4 – 8 GHz band with Breakthrough Listen backend at Green Bank“, was recently published in The Astronomers Telegraph. Led by Dr. Vishal Gajjar – a postdoctoral researcher at the University of California, Berkeley – the team conducted a detailed survey of FRB 121102. This repeating FRB source is located in a dwarf galaxy in Auriga constellation, some 3 billion light-years from Earth.
The NSF’s Arecibo Observatory, which is located in Puerto Rico, is the world largest radio telescope. Credit: NAIC
To clarify, FRBs are brief, bright pulses of radio waves that are periodically detected coming from distant galaxies. This strange astronomical phenomena was first detected in 2007 by Duncan Lorimer and David Narkovic using the Parkes Telescope in Australia. To honor their discovery, FRBs are sometimes referred to as “Lorimer Bursts”. Many FRB sources have been confirmed since then, some of which were found repeating.
The source known as FRB 121101 was discovered back on November 2nd, 2012, by astronomers using the Arecibo radio telescope. At the time, it was the first FRB to be discovered; and by 2015, it became the first FRB to be seen repeating. This effectively ruled out the possibility that repeating FRBs were caused by catastrophic events, which had previously been theorized.
And in 2016, FRB 121102 was the first FRB to have its location pinpointed to such a degree that its host galaxy could be identified. As such, the Listen science team at UC Berkeley was sure to add FRB 121102 to their list of targets. And in the early hours of Saturday, August 26th, Dr. Vishal Gajjar – a postdoctoral researcher at UC Berkeley – observed FRB 121102 using the Green Bank Radio Telescope (GBRT) in West Virginia.
Using the Digital Backend instrument on the GBRT, Dr. Gajjar and the Listen team observed FRB 121102 for five hours. From this, they accumulating 400 terabytes of data in the entire 4 to 8 GHz frequency band which they then analyzed for signs of short pulses over a broad range of frequencies. What they found was evidence of 15 new pulses coming from FRB 121102, which confirmed that it was in a newly active state.
The Green Bank Telescope, located in West Virginia. Credit: NRAO
In addition, their observations revealed that the brightest of these 15 emissions occurred at around 7 GHz. This was higher than any repeating FRBs seen to date, which indicated for the first time that they can occur at frequencies higher than previously thought. Last, but not least, the high-resolution data the Listen team collected is expected to yield valuable insights into FRBs for years to come.
This was made possible thanks to the Digital Backend instrument on the GBRT, which is able to record several GHz of bandwidth simultaneously and split the information into billions of individuals channels. This enables scientists to study the proprieties and the frequency spectrum of FRBs with greater precision, and should lead to new theories about the causes of these radio emissions.
So even if these particular signals should prove to not be an indication of extra-terrestrial intelligence, Listen is still pushing the boundaries of what is possible with radio astronomy. And given that Breakthrough Listen is less than two years into its proposed ten-year survey, we can expect many more sources to be observed and studied in the coming years. If there’s evidence of ETI to be found, we’re sure to find out about it sooner or later!
And be sure to check out this video of the Green Bank Telescope and the surveys it allows for, courtesy of Berkeley SETI:
Breakthrough Listen will monitor the 1 million closest stars to Earth over a ten year period. Credit: Breakthrough Initiatives
In July of 2015, Breakthrough Initiatives – a non-profit dedicated to the search for extra-terrestrial intelligence, founded by Yuri Milner – announced the creation of Breakthrough Listen. A ten-year initiative costing $100 million, this program was aimed at using the latest in instrumentation and software to conduct the largest survey to date for extraterrestrial communications, encompassing the 1,000,000 closest stars and 100 closest galaxies.
On Thursday, April. 20th, at the Breakthrough Discuss conference, the organization shared their analysis of the first year of Listen data. Gathered by the Green Bank Radio Telescope, this data included an analysis of 692 stars, as well as 11 events that have been ranked for having the highest significance. The results have been published on the project’s website, and will soon be published in the Astrophysical Journal.
The Green Bank Telescope (GBT), a radio telescope located at the Green Bank Observatory in West Virginia. Credit: greenbankobservatory.org
While the results were not exactly definitive, this is just the first step in a program that will span a decade. As Dr. Andrew Siemion, the Director of the BSRC, explained in a BI press release:
“With the submission of this paper, the first scientific results from Breakthrough Listen are now available for the world to review. Although the search has not yet detected a convincing signal from extraterrestrial intelligence, these are early days. The work that has been completed so far provides a launch pad for deeper and more comprehensive analysis to come.”
The Green Bank Telescope searched for these signals using its “L-band” receiver, which gathers data in frequencies ranging from 1.1 to 1.9 GHz. At these frequencies, artificial signals can be distinguished from natural sources, which includes pulsars, quasars, radio galaxies and even the Cosmic Microwave Background (CMB). Within these parameters, the BSRC team examined 692 stars from its primary target list.
For each star, they conducting three five-minutes observation periods, while also conducting five-minute observations on a set of secondary targets. Combined with a Doppler drift search – a perceived difference in frequency caused by the motion of the source or receiver (i.e. the star and/or Earth) – the Listen science team identified channels where radio emission were seen for each target (aka. “hits”).
The Parkes radio telescope, one of the telescopes comprising CSIRO’s Australia Telescope National Facility. Credit: CSIRO/David McClenaghan
This led to a combined 400 hours and 8 petabytes worth of observational data. All together, the team found millions of hits from the sample data as a whole, and eleven events that rose above the threshold for significance. These events (which are listed here) took place around eleven distant stars and ranged from to 25.4 to 3376.9 SNR (Signal-to-Noise Ratio).
However, the vast majority of the overall hits were determined to be the result of radio frequency interference from local sources. What’s more, further analysis of the 11 events indicated that it was unlikely that any of the signals were artificial in nature. While these stars all exhibited their own unique radio “fingerprints”, this is not necessarily an indication that they are being broadcast by intelligent species.
But of course, finding localized and unusual radio signals is an excellent way to select targets for follow-up examination. And if there is evidence to be found out there of intelligent species using radio signals to communicate, Breakthrough Listen is likely to be the one that finds them. Of all the SETI programs mounted to date, Listen is by far the most sophisticated.
Not only do its radio surveys cover 10 times more sky than previous programs, but its instruments are 50 times more sensitive than telescopes that are currently engaged in the search for extra-terrestrial life. They also cover 5 times more of the radio spectrum, and at speeds that are 100 times as fast. Between now and when it concludes in the coming decade, the BSRC team plans to release updated Listen data once every six months.
Aerial view of the Automated Planet Finder at the Lick Observatory. Credit: Lick Observatory/Laurie Hatch
In the meantime, they are actively engaging with signal processing and machine learning experts to develop more sophisticated algorithms to analyze the data they collect. And while they continue to listen for extra-solar sources of life, Breakthrough Starshot continues to develop the first concept for a laser-driven lightsail, which they hope will make the first interstellar voyage in the coming years.
And of course, we here in the Solar System are looking forward to missions in the coming decade that will search for life right here, in our own backyard. These include missions to Europa, Enceladus, Titan, and other “ocean worlds” where life is believed to exist in some exotic form!
Breakthrough Listen‘s data analysis can be found here. Director Andrew Siemion also took to Facebook Live on Thursday, April 20th, to presents the results of Listen’s first year of study.And be sure to check out this video that marked the launch of Breakthrough Initiatives:
