The iconic Arecibo Radio Observatory has been a mainstay in science and science fiction. This Puerto Rico-based radio telescope was already in an uncertain level of funding. But now with the damage from Hurricane Maria, it might be shut down forever.
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Astronomers have been listening to radio waves from space for decades. In addition to being a proven means of studying stars, galaxies, quasars and other celestial objects, radio astronomy is one of the main ways in which scientists have searched for signs of extra-terrestrial intelligence (ETI). And while nothing definitive has been found to date, there have been a number of incidents that have raised hopes of finding an “alien signal”.
In the most recent case, scientists from the Arecido Observatory recently announced the detection of a strange radio signal coming from Ross 128 – a red dwarf star system located just 11 light-years from Earth. As always, this has fueled speculation that the signal could be evidence of an extra-terrestrial civilization, while the scientific community has urged the public not to get their hopes up.
The discovery was part of a campaign being conducted by Abel Méndez – the director of the Planetary Habitability Laboratory (PHL) in Peurto Rico – and Jorge Zuluaga of the Faculty of Exact and Natural Sciences at the University of Antioquia, Colombia. Inspired by the recent discoveries around Proxima Centauri and TRAPPIST-1, the GJ 436 campaign relied on data from Arecibo Observatory to look for signs of exoplanets around nearby red dwarf stars.
Arecibo Observatory, the world’s biggest single dish radio telescope, was and is still being used to image comet 45P/H-M-P. Courtesy of the NAIC – Arecibo Observatory, a facility of the NSF
In the course of looking at data from stars systems like Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex, and K2-18 – which was gathered between April and May of 2017 – they noticed something rather interesting. Basically, the data indicated that an unexplained radio signal was coming from Ross 128. As Dr. Abel Mendez described in a blog post on the PHL website:
“Two weeks after these observations, we realized that there were some very peculiar signals in the 10-minute dynamic spectrum that we obtained from Ross 128 (GJ 447), observed May 12 at 8:53 PM AST (2017/05/13 00:53:55 UTC). The signals consisted of broadband quasi-periodic non-polarized pulses with very strong dispersion-like features. We believe that the signals are not local radio frequency interferences (RFI) since they are unique to Ross 128 and observations of other stars immediately before and after did not show anything similar.”
They also conducted observations of Barnard’s star on that same day to see if they could note similar behavior coming from this star system. This was done in collaboration with the Red Dots project, a European Southern Observatory (ESO) campaign that is also committed to finding exoplanets around red dwarf stars. This program is the successor to the ESO’s Pale Red Dot campaign, which was responsible for discovering Proxima b last summer.
Images of the star systems examined by the GJ 436 Campaign. Credit: PHL/Abel Méndez
As of Monday night (July 17th), Méndez updated his PHL blog post to announced that with the help of SETI Berkeley with the Green Bank Telescope, that they had successfully observed Ross 128 for the second time. The data from these observatories is currently being collected and processed, and the results are expected to be announced by the end of the week.
In the meantime, scientists have come up with several possible explanations for what might be causing the signal. As Méndez indicated, there are three major possibilities that he and his colleagues are considering:
“[T]hey could be (1) emissions from Ross 128 similar to Type II solar flares, (2) emissions from another object in the field of view of Ross 128, or just (3) burst from a high orbit satellite since low orbit satellites are quick to move out of the field of view. The signals are probably too dim for other radio telescopes in the world and FAST is currently under calibration.”
Unfortunately, each of these possibilities have their own drawbacks. In the case of a Type II solar flare, these are known to occur at much lower frequencies, and the dispersion of this signal appears to be inconsistent with this kind of activity. In the case of it possibly coming from another object, no objects (planets or satellites) have been detected within Ross 128’s field of view to date, thus making this unlikely as well.
The stars currently being examined as part of the GJ 436 campaign. Credit: PHL/Abel Méndez
Hence, the team has something of a mystery on their hands, and hopes that further observations will allow them to place further constrains on what the cause of the signal could be. “[W]e might clarify soon the nature of its radio emissions, but there are no guarantees,” wrote Méndez. “Results from our observations will be presented later that week. I have a Piña Colada ready to celebrate if the signals result to be astronomical in nature.”
And just to be fair, Méndez also addressed the possibility that the signal could be artificial in nature – i.e. evidence of an alien civilization. “In case you are wondering,” he wrote, “the recurrent aliens hypothesis is at the bottom of many other better explanations.” Sorry, alien-hunters. Like the rest of us, you’ll just have to wait and see what can be made of this signal.
We’ve covered the Fermi Paradox many times over several articles on Universe Today. This is the idea that the Universe is huge, and old, and the ingredients of life are everywhere. Life could and should have have appeared many times across the galaxy, but it’s really strange that we haven’t found any evidence for them yet.
Very recently, a team of scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) achieved an historic first by being able to pinpoint the source of fast radio bursts (FRBs). With the help of observatories around the world, they determined that these radio signals originated in an elliptical galaxy 6 billion light years from Earth. But as it turns out, this feat has been followed by yet another historic first.
In all previous cases where FRBs were detected, they appeared to be one-off events, lasting for mere milliseconds. However, after running the data from a recent FRB through a supercomputer, a team of scientists at McGill University in Montreal have determined that in this instance, the signal was repeating in nature. This finding has some serious implications for the astronomical community, and is also considered by some to be proof of extra-terrestrial intelligence.
FRBs have puzzled astronomers since they were first detected in 2007. This event, known as the Lorimer Burst, lasted a mere five milliseconds and appeared to be coming from a location near the Large Magellanic Cloud, billions of light years away. Since that time, a total of 16 FRBs have been detected. And in all but this one case, the duration was extremely short and was not followed up by any additional bursts.
The NSF’s Arecibo Observatory, which is located in Puerto Rico, is the world largest radio telescope. Credit: NAIC
Because of their short duration and one-off nature, many scientists have reasoned that FRBs must be the result of cataclysmic events – such as a star going supernova or a neutron star collapsing into a black hole. However, after sifting through data obtained by the Arecibo radio telescope in Puerto Rico, a team of students from McGill University – led by PhD student Paul Scholz – determined that an FRB detected in 2012 did not conform to this pattern.
In an article published in Nature, Scholz and his associates describe how this particular signal – FRB 121102 – was followed by several bursts with properties that were consistent with the original signal. Running the data which was gathered in May and June through a supercomputer at the McGill High Performance Computing Center, they determined that FRB 121102 had emitted a total of 10 new bursts after its initial detection.
This would seem to indicate that FRBs have more than just one cause, which presents some rather interesting possibilities. As Paul Scholz told Universe Today via email:
“All previous Fast Radio Bursts have only been one-time events, so a lot of explanations for them have involved a cataclysmic event that destroys the source of the bursts, such as a neutron star collapsing into a black hole. Our discovery of repeating bursts from FRB 121102 shows that the source cannot have been destroyed and it must have been due to a phenomenon that can repeat, such as bright pulses from a rotating neutron star.”
The Parkes Telescope in New South Wales, Australia. Credit: Roger Ressmeyer/Corbis
Another possibility which is making the rounds is that this signal is not natural in origin. Since their discovery, FRBs and other “transient signals” – i.e. seemingly random and temporary signals – from the Universe have been the subject of speculation. As would be expected, there have been some who have suggested that they might be the long sought-after proof that extra-terrestrial civilizations exist.
For example, in 1967, after receiving a strange reading from a radio array in a Cambridge field, astrophysicist Jocelyn Bell Burnell and her team considered the possibility that what they were seeing was an alien message. This would later be shown to be incorrect – it was, in fact, the first discovery of a pulsar. However, the possibility these signals are alien in origin has remained fixed in the public (and scientific) imagination.
This has certainly been the case since the discovery of FRBs. In an article published by New Scientistsin April of 2015 – titled “Cosmic Radio Plays An Alien Tune” – writer and astrophysicist Sarah Scoles explores the possibility of whether or not the strange regularity of some FRBs that appeared to be coming from within the Milky Way could be seen as evidence of alien intelligence.
However, the likelihood that these signals are being sent by extra-terrestrials is quite low. For one, FRBs are not an effective way to send a message. As Dr. Maura McLaughlin of West Virginia University – who was part of the first FRB discovery – has explained, it takes a lot of energy to make a signal that spreads across lots of frequencies (which is a distinguishing feature of FRBs).
For decades, scientists have been exploring the possibility that radio bursts are signals from alien civilizations. Credit: AdamBurn/DeviantArt
And if these bursts came from outside of our galaxy, which certainly seems to be the case, they would have to be incredibly energetic to get this far. As Dr. McLaughlin explained to Universe Today via email:
“The total amount of power required to produce just one FRB pulse is as much as the Sun produces in a month! Although we might expect extraterrestrial civilizations to send short-duration signals, sending a signal over the very wide radio bandwidths over which FRBs are detected would require an improbably immense amount of energy. We expect that extraterrestrial civilizations would transmit over a very narrow range of radio frequencies, much like a radio station on Earth.
But regardless of whether these signals are natural or extra-terrestrial in origin, they do present some rather exciting possibilities for astronomical research and our knowledge of the Universe. Moving forward, Scholz and his team hope to identify the galaxy where the radio bursts originated, and plans to use test out some recently-developed techniques in the process.
“Next we would like to localize the source of the bursts to identify the galaxy that they are coming from,” he said. “This will let us know about the environment around the source. To do this, we need to use radio interferometry to get a precise enough sky location. But, to do this we need to detect a burst while we are looking at the source with such a radio telescope array. Since the source is not always bursting we will have to wait until we get a detection of a burst while we are looking with radio interferometry. So, if we’re patient, eventually we should be able to pinpoint the galaxy that the bursts are coming from.”
In the end, we may find that rapid burst radio waves are a more common occurrence than we thought. In all likelihood, they are being regularly emitted by rare and powerful stellar objects, ones which we’ve only begun to notice. As for the other possibility? Well, we’re not saying it’s aliens, but we’re quite sure others will be!
Where are these radio bursts coming from? Astronomers have heard these signals from the sky several times, but always with the same telescope (Parkes Observatory in Australia). There was debate about whether these were coming from inside or outside the galaxy, or even from Earth itself (given only the one observatory was detecting them.)
A new study with a different telescope, the Arecibo Observatory in Puerto Rico, concludes that the bursts are from outside the galaxy. This is the first time one of these bursts have been found in the northern hemisphere of the sky.
“Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin,” stated Victoria Kaspi, an astrophysics researcher at McGill University who participated in the research. “The radio waves show every sign of having come from far outside our galaxy – a really exciting prospect.”
Fast radio bursts are a flurry of radio waves that last a few thousandths of a second, and at any given minute there are only seven of these in the sky on average, according to the Max Planck Institute for Radio Astronomy. Their cause is unknown. They could be anything from black holes, to neutron stars coming together, to the magnetic field of pulsars (a type of neutron star) flaring up — or something else.
Arecibo Observatory in Puerto Rico. Credit: NAIC – Arecibo Observatory, a facility of the NSF
The pulse was found Nov. 2, 2012 in the constellation Auriga. Astronomers believe it is from quite far away from measuring its plasma dispersion, or the slowdown of radio waves as they crash into interstellar electrons. This particular source had triple the maximum dispersion than what would be found inside the galaxy, astronomers stated.
“The brightness and duration of this event, and the inferred rate at which these bursts occur, are all consistent with the properties of the bursts previously detected by the Parkes telescope in Australia,” stated Laura Spitler, who led the research. (She was at Cornell University when the study began, but is now at the Max Planck Institute for Radio Astronomy in Bonn, Germany.)
When Comet 209P/LINEAR — the comet that brought us the Camelopardalids meteor shower last weekend – was first discovered in February of 2004, astronomers initially thought it was an asteroid. However, subsequent images of the objects showed it had a tail, and so it was reclassified as a comet. Now, new images taken by the Arecibo Observatory planetary radar system reveal Comet 209P/LINEAR has complex surface features that will require more analysis to fully interpret. This mini world seems to be filled with ridges and cliffs along with its icy surface.
“This is the highest resolution radar image we have obtained of a comet nucleus,” said Dr. Ellen Howell from the Universities Space Research Association, who led the observations of the comet at Arecibo, located in Puerto Rico.
The Arecibo Observatory is taking advantage of the approaching close pass of Earth by Comet 209P/LINEAR, taking these new radar images which confirm this comet to be about 2.4 by 3 km kilometers (1.5 x 1.8 miles) in size and elongated in shape. Earlier optical observations suggested this size range, but now these radar observations are the first direct measurement of the nucleus dimensions.
Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel. Image credit: Arecibo Observatory/NASA/Ellen Howell
Comets very rarely come this close to Earth, but don’t worry: Comet 209P/LINEAR is not coming close enough to cause any problems or concerns.
“Comet 209P/LINEAR has no chance of hitting Earth,” said data analyst Alessondra Springmann from Arecibo. “It comes no closer than 8.3 million kilometers (5.2 million miles) to Earth, safely passing our planet.”
But this relatively close pass makes this an extraordinary opportunity to get images of the surface. As Dr. Howell noted, these observations of are some of the most detailed. Just six comet nuclei have been imaged by spacecraft, and a wide variety of surface features and structures have been observed on these icy objects.
“We are being cautious,” Howell told Universe Today. “Radar images are not regular “spatial” images, and one can easily be misled by treating them as a regular picture. But proper analysis will take weeks or months, not minutes. What these radar images show is certainly not ordinary, but we don’t really have anything to compare to. The image looks different than asteroids we have imaged, but I don’t know what is due to surface feature differences and what might be scattering differences by the surface material.”
Comets have a central nucleus made of ice, dust, and rocks, and a coma of dust and gas. Two tails, one made of ions and one of dust, form in the direction pointing away from the sun.
Other comets seen by Arecibo radar include 103P/Hartley 2 and 8P/Tuttle, and 73P/Schwassmann-Wachmann 3.
Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel. Image credit: Arecibo Observatory/NASA/Ellen Howell
Unlike long period comets Hale-Bopp and the late Comet ISON that swing around the Sun once every few thousand years or few million years, Comet 209P/LINEAR visits our neighborhood frequently, coming ‘round every 5.09 years. However, it will not be close enough to Earth again for radar imaging any time in the next 100 years.
With a rotation period of approximately 11 hours as determined by Carl Hergenrother at the University of Arizona using the 1.8 meter VATT telescope, this comet is one of the many Jupiter family comets, which orbit the Sun twice for every time Jupiter orbits once.
It was discovered by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) automated sky survey.
The Arecibo Observatory, located in Puerto Rico, is home to the world’s largest and most sensitive single-dish radio telescope at 305 meters (1000feet) across. This facility dedicates hundreds of hours a year of its telescope time to improving our knowledge of near-Earth asteroids and comets.
Dr. Howell specializes in studying comets and asteroids using radar, as well as passive radio and infrared spectroscopy techniques to determine the surface and coma properties of small solar system bodies. She was assisted in these observations of Comet 209P/LINEAR by Michael Nolan, Patrick Taylor, Alessondra Springmann, Linda Ford, and Luisa Zambrano.
Arecibo Observatory, and the complementary Goldstone Solar System Radar in California run by NASA’s Jet Propulsion Laboratory, are both observing comet 209P/LINEAR during its pass by Earth in May. These radar facilities are unique among telescopes on Earth for their ability to resolve features on comets and asteroids, while most optical telescopes on the ground would see these cosmic neighbors simply as unresolved points of light.
The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation, and in alliance with the Sistema Universitario Ana G. Méndez-Universidad Metropolitana and the Universities Space Research Association. The Arecibo Planetary Radar program is supported by NASA’s Near Earth Object Observation program.
Damage to the iconic Arecibo Observatory from an earthquake earlier this year has been repaired and the telescope is now back to full service. On January 13, 2014, the William E. Gordon radio telescope sustained damage following a 6.4 magnitude earthquake that was centered 37 miles northwest of Arecibo. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.
“In an abundance of caution, telescope motion had been very limited since the earthquake,” said Kerr in a press release issued today. “Nevertheless, the telescope continued its science mission, including participation in a 10-day global ionospheric study in late January and continuing a productive search for pulsars in the sky above Arecibo.”
The platform hangs above the Arecibo dish, supported by cables. Via Cornell University.
The cable that was damaged was one of 18 cables that supports the 900-ton focal platform of the telescope. This particular cable was actually a known potential problem, Kerr told Universe Today in a previous interview. He said that during original construction of the telescope in 1962, one of the original platform suspension cables that was delivered to the observatory was too short, and another short cable section was “spliced” to provide sufficient reach to the platform.
“That cable segment and splice near the top of one of the telescope towers was consequently more rigid than the balance of the suspension system,” Kerr said. “When the earthquake shook the site, just after midnight on January 13, it is that short cable and splice that suffered damage.”
“You might say that our structural Achilles heel was exposed,” Kerr added.
Inspectors from New York’s Ammann & Whitney Bridge Construction, who have been inspecting the Arecibo observatory site since 1972, were brought in to access the situation and Kerr said a relatively low-cost (less than $100,000) repair option was designed and carried out, bringing the telescope back into full service as of March 13, exactly two months from when the earthquake occurred.
The Arecibo Observatory is operated by SRI International, teaming with Universidad Metropolitana and the Universities Space Research Association, in a cooperative agreement with the National Science Foundation.
The Arecibo Observatory’s 305 meter (1,000 ft) radio telescope is undergoing emergency repair after being damaged during a 6.4 magnitude earthquake on January 13, 2014. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.
“A protocol structural survey following the January 13 earthquake revealed serious damage to [a] short cable section, with apparent breach of several cable strands,” Kerr told Universe Today via email. “An experienced structural engineering firm was brought to assess the damage, and to consider repair options.”
The earthquake’s epicenter was located in the ocean about 60 kilometers (37 miles) northwest of Arecibo and was one of the largest to hit Puerto Rico in several years. The quake caused some floor cracking in buildings and homes on the island, as well as power outages, but no major damages or injuries, officials said. There were, however, at least 70 aftershocks with at least three of a magnitude 3.5 or greater.
The platform hangs above the Arecibo dish, supported by cables. Via Cornell University.
The famous radio observatory is located near Puerto Rico’s north coast, and opened in 1963. It was built inside a depression left by a sinkhole and is the largest curved focusing dish on Earth. The dish’s surface is made of thousands of perforated aluminum panels, each about 1 by 2 meters (3 by 6 feet), supported by a mesh of steel cables. The receiver is on a 900-ton platform suspended 137 meters (450 feet) above the dish by 18 cables running from three reinforced concrete towers.
It was one of these 18 cables that was damaged, and this particular cable was actually a known potential problem. Kerr said that during original construction of the telescope in 1962, one of the original platform suspension cables that was delivered to the observatory was too short, and another short cable section was “spliced” to provide sufficient reach to the platform.
“That cable segment and splice near the top of one of the telescope towers was consequently more rigid than the balance of the suspension system,” Kerr said. “When the earthquake shook the site, just after midnight on January 13, it is that short cable and splice that suffered damage.”
“You might say that our structural Achilles heel was exposed,” Kerr added.
Inspectors from New York’s Ammann & Whitney Bridge Construction, who have been inspecting the Arecibo observatory site since 1972, were brought in to access the situation. Kerr said a relatively low-cost (less than $100,000) repair option was designed, and materials are now being procured to complete a repair that is expected to bring the telescope back into full service.
“While the project awaits full review by the National Science Foundation, necessary steel materials for the repair are being shipped to the Observatory at this writing,” Kerr said. “Our estimated completion date for this project is March 11, 2014.”
This repair is considered temporary, however, and Kerr said a more comprehensive long-term cable repair design is being developed.
But the repair to the cable is by no means easy. The Arecibo Observatory maintenance staff will be doing the repairs themselves, working high above the ground on the 900-ton steel suspension bridge-like suspension system.
Kerr said they hope to complete this emergency repair “as expeditiously and safely as possible,” and that “it is testimony to the remarkable expertise, capability, and bravery of the Arecibo staff. I am dubious that a parallel capability exists at any other U.S. science facility.”
In the meantime, the telescope is being used only sparingly and with an “abundance of caution,” using only limited motion of the telescope. Kerr said that despite the damage, the telescope was able to continue its science mission by participation in a ten-day global ionospheric study in late January, in addition to continuing a search for pulsars in the sky above Arecibo, and searching for fast radio bursts (FRBs). Because radio telescopes can work at all times of day and in all kinds of weather, the observatory normally operates 24 hours a day. The Angel Ramos Visitor Center at the Observatory was closed for a few days, but reopened on January 22, with normal access and visiting hours.
The Observatory is recognized as one of the most important national centers for research in radio astronomy, planetary radar and terrestrial aeronomy. During its 50-plus years of use, findings from Arecibo have contributed to better understanding of the Earth’s atmosphere, the Moon, asteroids, other planets, exotic stars, our galaxy, and the large-scale galactic structure of the universe. The facility was featured in the movies “Contact” and “Golden Eye,” as well as dozens or TV shows and books, and is one of the most popular tourist attractions in Puerto Rico.
It is operated by SRI International, teaming with The Universidad Metropolitana and the Universities Space Research Association, in cooperative agreement with the National Science Foundation.
The mighty Arecibo Radio Observatory is one of the most powerful radio telescopes ever built – it’s certainly the larger single aperture radio telescope on Earth, nestled into a natural sinkhole in Puerto Rico. We’re celebrating the 50th anniversary of the construction of the observatory with a special episode of Astronomy Cast.
An asteroid that recently passed by Earth is about twice as large as originally estimated, and it would have had serious global consequences if it had impacted Earth. Asteroid 2012 LZ1 was only discovered on June 10, 2012 by Rob McNaught at the Siding Spring Observatory in Australia. This Near Earth Object was thought to be fairly large, 502 meters (1,650 feet) wide, and quite bright. But astronomers using the planetary radar system at Arecibo Observatory were able to better determine the asteroid’s size, rotation rate and shape and found it to be about 1 kilometer (0.6 miles) wide and actually quite dark.
Scientists consider a kilometer-wide asteroid is at the size threshold that could set off an extinction-level event if it were to hit Earth.
“This object turned out to be quite a bit bigger than we expected, said Dr. Ellen Howell from Arecibo, “which shows how important radar observations can be, because we’re still learning a lot about the population of asteroids.”
2012 LZ1 sneaked by our planet at about 5.3 million km (3.35 million) miles away, or about 14 times the distance between Earth and the Moon on June 14, and it won’t be back in Earth’s vicinity again until June 12th, 2053, and then will be about 3 times as distant.
The Arecibo astronomers have determined it won’t be a threat to Earth for at least 750 years.
“The sensitivity of our radar has permitted us to measure this asteroid’s properties and determine that it will not impact the Earth at least in the next 750 years,” said Dr. Mike Nolan, Director of Planetary Radar Sciences at the Arecibo Observatory.
Several amateur astronomers were able to image 2012 LZ1, and the original thinking was that it was very bright. Instead, the new size determination suggests that 2012 LZ1 must be quite dark, reflecting only 2-4% of the light that hits it.
This is another reminder that we don’t know everything about all the potential asteroid threats that are out there, and more searches need to be done to find and track as many of the near Earth asteroid population as possible. Asteroid 2012 LZ1 has been classified as a Potentially Hazardous Asteroid, which are asteroids larger than approximately 100 meters that can come closer to our planet than 0.05 AU (7.4 million km, 4.65 million miles). As of now, none of the known PHAs is on a collision course with our planet, but both amateur and professional astronomers are finding new ones all the time, sometimes with just a few hours’ notice of a close approach.
Lead image caption: Asteroid 2012 LZ1 as seen by the Haleakala-Faulkes Telescope North on June 13, 2012. Credit: Nick Howes, Ernesto Guido & Giovanni Sostero.
