If humans want to travel about the solar system, they’ll need to be able to communicate. As we look forward to crewed missions to the Moon and Mars, communication technology will pose a challenge we haven’t faced since the 1970s.Continue reading “New Receiver Will Boost Interplanetary Communication”
A cluster of galaxies is nothing trivial. The shocks, the turbulence, the energy, as all of that matter and energy merges and interacts. And we can watch all the chaos and mayhem as it happens.
A team of astronomers are looking at the galaxy cluster Abell 2255 with the European Low-Frequency Array (LOFAR) radio telescope, and their images are showing some never-before-seen details in this actively merging cluster.Continue reading “Complete and Total Mayhem in a Distant Galaxy Collision”
Fast Radio Bursts (FRBs) have been one of the more puzzling and fascinating areas of astronomical study ever since the first was detected in 2007 (known as the Lorimer Burst). Much like gravitational waves, the study of these short-lived radio pulses (which last only a few milliseconds) is still in its infancy, and only a 33 events have been detected. What’s more, scientists are still not sure what accounts for them.
While some believe that they are entirely natural in origin, others have speculated that they could be evidence of extra-terrestrial activity. Regardless of their cause, according to a recent study, three FRBs were detected this month in Australia by the Parkes Observatory radio telescope in remote Australia. Of these three, one happened to be the most powerful FRB recorded to date.
The signals were detected on March 1st, March 9th, and March 11th, and were designated as FRB 180301, FRB 180309 and FRB 180311. Of these, the one recorded on March 9th (FRB 180309) was the brightest ever recorded, having a signal-to-noise ratio that was four times higher than the previous brightest FRB. This event, known as FRB 170827, was detected on August 27th, 2017, by the UTMOST array in Australia.
All three of these events were detected by the Parkes radio telescope, which is located in New South Wales about 380 kilometers (236 mi) from Sydney. As one of three telescopes that makes up the Australia Telescope National Facility, this telescope has been studying pulsars, rapidly spinning neutron stars, and conducting large-scale surveys of the sky since 1961. In recent years, it has been dedicated to the detection of FRBs in our Universe.
Considering how rare and short-lived FRBs are, recording three in the space of one month is quite the achievement. What’s more, the fact that the detections happened in real-time, rather than being discovered in archival data, is also impressive. Shortly after the event, Stefan Oslowski (of the Swinburne University of Technology) tweeted about this rather fortunate discovery (see below).
At present, none of the three events are believed to be “repeaters” – aka. Repeating Fast Radio Bursts. So far, only one FRB has been found to be repeating. This was none other than FRB 121102, which was first detected by the Arecibo radio telescope in Puerto Rico on November 2nd, 2012. In 2015, several more bursts were detected from this some source which had properties that were consistent with the original signal.
— Stefan Oslowski (@StefanOslowski) March 9, 2018
As noted, and in spite of all the events that have been detected, scientists are still not sure what causes these strange bursts. But with three more events detected, and the possibility that they could repeat in the near-future, scientists now have more events to pore over and base their theories on. And with next-generation arrays being constructed, a great many more events (and repeaters) are likely to be detected in the coming years.
These include the the Square Kilometer Array currently being built across Australia, New Zealand and South Africa, and the Five hundred meter Aperture Spherical Telescope (FAST) being build in China. With these telescopes joining observatories like the Very Large Telescope (VLT), the Atacama Large Millimeter/submillimeter Array (ALMA) and venerated observatories like Arecibo, FRBs may not be mysterious for much longer!
For decades, scientists have held that Supermassive Black Holes (SMBHs) reside at the center of larger galaxies. These reality-bending points in space exert a extremely powerful influence on all things that surround them, consuming matter and spitting out a tremendous amount of energy. But given their nature, all attempts to study them has been confined to indirect methods.
All of that changed beginning on Wednesday, April 12th, 2017, when an international team of astronomers obtained the first-ever image of a Sagittarius A*. Using a series of telescopes from around the globe – collectively known as the Event Horizon Telescope (EHT) – they were able to visualize the mysterious region around this giant black hole from which matter and energy cannot escape – i.e. the event horizon.
Not only is this the first time that this mysterious region around a black hole has been imaged, it is also the most extreme test of Einstein’s Theory of General Relativity ever attempted. It also represents the culmination of the EHT project, which was established specifically for the purpose of studying black holes directly and improving our understanding of them.
Since it began capturing data in 2006, the EHT has been dedicated to the study of Sagitarrius A* since it is the nearest SMBH in the known Universe – located about 25,000 light years from Earth. Specifically, scientists hoped to determine if black holes are surrounded by a circular region from which matter and energy cannot escape (which is predicted by General Relativity), and how they accrete matter onto themselves.
Rather than constituting a single facility, the EHT relies on a worldwide network of radio astronomy facilities based on four continents, all of which are dedicated to studying one of the most powerful and mysterious forces in the Universe. This process, whereby widely-space radio dishes from across the globe are connected into an Earth-sized virtual telescope, is known as Very Long Baseline Interferometry (VLBI).
As Michael Bremer – an astronomer at the International Research Institute for Radio Astronomy (IRAM) and a project manager for the Event Horizon Telescope – said in an interview with AFP:
“Instead of building a telescope so big that it would probably collapse under its own weight, we combined eight observatories like the pieces of a giant mirror. This gave us a virtual telescope as big as Earth—about 10,000 kilometers (6,200 miles) is diameter.”
All told, the network includes instruments like the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the Arizona Radio Observatory Submillimeter Telescope, the IRAM 30-meter Telescope in Spain, the Large Millimeter Telescope Alfonso Serrano in Mexico, the South Pole Telescope in Antarctica, and the James Clerk Maxwell Telescope and Submillimeter Array at Mauna Kea, Hawaii.
With these arrays, the EHT radio-dish network is the only one powerful enough to detect the light released when an object would disappear into Sagittarius A*. And from six nights – from Wednesday, April 5th, to Tuesday, April 11th, – all of its arrays were trained on the center of our Milky Way to do just that. By the end of the run, the international team announced that they had snapped the first-ever picture of an event horizon.
In the end, some 500 terabytes of data were collected. This data is now being transferred to the MIT Haystack Observatory in Massachusetts, where it will be processed by supercomputers and turned into an image. “For the first time in our history, we have the technological capacity to observe black holes in detail,” said Bremer. “The images will emerge as we combine all the data. But we’re going to have to wait several months for the result.”
Part of the reason for the wait is the fact that the recorded data obtained by the South Pole Telescope can only be collected when spring starts in Antarctica – which won’t happen until October 2017 at the earliest. As such, it won’t be until 2018 before the public gets to feast its eyes on the shadow region that surrounds Sagittarius A*, and it is not expected that the first image will be entirely clear.
As Heino Falcke – an astronomers from Radbound University who now chairs the Scientific Council of EHT (and was the one who proposed this experiment twenty years ago) – explained in a EHT press release prior to the observation being made:
“It is the challenge of doing something, that has never been attempted before. It is the start of an adventurous journey towards a black hole… However, I think we need more observation campaigns and eventually more telescopes in the network to make a really good image.”
Despite the wait, and the fact that repeated attempts will be needed before we can get our first clear look at a black hole, there is still plenty of reason to celebrate in the meantime. Not only was this a first that was a long time in he making, but it also represents a major leap towards understanding one of the most powerful and mysterious forces of nature.
Given time, the study of black holes may allow for us to finally resolve how gravity and the other fundamental forces of the Universe interact. At long last, we will be able to comprehend all of existence as a single, unified equation!
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.
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.”
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 Scientists in 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).
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!
Further Reading: McGill University
Given that our Solar System sits inside the Milky Way Galaxy, getting a clear picture of what it looks like as a whole can be quite tricky. In fact, it was not until 1852 that astronomer Stephen Alexander first postulated that the galaxy was spiral in shape. And since that time, numerous discoveries have come along that have altered how we picture it.
For decades astronomers have thought the Milky Way consists of four arms — made up of stars and clouds of star-forming gas — that extend outwards in a spiral fashion. Then in 2008, data from the Spitzer Space Telescope seemed to indicate that our Milky Way has just two arms, but a larger central bar. But now, according to a team of astronomers from China, one of our galaxy’s arms may stretch farther than previously thought, reaching all the way around the galaxy.
This arm is known as Scutum–Centaurus, which emanates from one end of the Milky Way bar, passes between us and Galactic Center, and extends to the other side of the galaxy. For many decades, it was believed that was where this arm terminated.
However, back in 2011, astronomers Thomas Dame and Patrick Thaddeus from the Harvard–Smithsonian Center for Astrophysics spotted what appeared to be an extension of this arm on the other side of the galaxy.
But according to astronomer Yan Sun and colleagues from the Purple Mountain Observatory in Nanjing, China, the Scutum–Centaurus Arm may extend even farther than that. Using a novel approach to study gas clouds located between 46,000 to 67,000 light-years beyond the center of our galaxy, they detected 48 new clouds of interstellar gas, as well as 24 previously-observed ones.
For the sake of their study, Sun and his colleagues relied on radio telescope data provided by the Milky Way Imaging Scroll Painting project, which scans interstellar dust clouds for radio waves emitted by carbon monoxide gas. Next to hydrogen, this gas is the most abundant element to be found in interstellar space – but is easier for radio telescopes to detect.
Combining this information with data obtained by the Canadian Galactic Plane Survey (which looks for hydrogen gas), they concluded that these 72 clouds line up along a spiral-arm segment that is 30,000 light-years in length. What’s more, they claim in their report that: “The new arm appears to be the extension of the distant arm recently discovered by Dame & Thaddeus (2011) as well as the Scutum-Centaurus Arm into the outer second quadrant.”
This would mean the arm is not only the single largest in our galaxy, but is also the only one to effectively reach 360° around the Milky Way. Such a find would be unprecedented given the fact that nothing of the sort has been observed with other spiral galaxies in our local universe.
Thomas Dame, one of the astronomers who discovered the possible extension of the Scutum-Centaurus Arm in 2011, was quoted by Scientific American as saying: “It’s rare. I bet that you would have to look through dozens of face-on spiral galaxy images to find one where you could convince yourself you could track one arm 360 degrees around.”
Naturally, the prospect presents some problems. For one, there is an apparent gap between the segment that Dame and Thaddeus discovered in 2011 and the start of the one discovered by the Chinese team – a 40,000 light-year gap to be exact. This could mean that the clouds that Sun and his colleagues discovered may not be part of the Scutum-Centaurus Arm after all, but an entirely new spiral-arm segment.
If this is true, than it would mean that our Galaxy has several “outer” arm segments. On the other hand, additional research may close that gap (so to speak) and prove that the Milky Way is as beautiful when seen afar as any of the spirals we often observe from the comfort of our own Solar System.
Astronauts, start your rover engines. Two astronauts recently remote-controlled a rover vehicle in California from their perch on the International Space Station — about 250 miles (400 kilometers) overhead.
The concept is cool in itself, but NASA has loftier aims. It’s thinking about those moon and asteroid and Mars human missions that the agency would really like to conduct one day, if it receives the money and authorization.
Potentially, say, you could have a Mars crew using rovers to explore as much of the surface as possible in a limited time.
Mars Curiosity and its predecessor rovers have found amazing things on Mars, but the challenge is the average 20-minute delay in communications between Mars and Earth. NASA deftly accounts for this problem through techniques such as hazard avoidance software so that Curiosity, say, wouldn’t crash into a big Martian boulder. (More techniques from NASA at this link.) But having astronauts above the surface would cut down on the time delay and potentially change Mars rover driving forever.
So about that test: two astronauts so far have run the K10 planetary vehicle prototype around a “Roverscape” at NASA’s Ames Research Center in California. NASA calls these runs the “first fully-interactive remote operation of a planetary rover by an astronaut in space.”
Expedition 36’s Chris Cassidy was first up on June 15, spending three hours moving the machine around in the rock-strewn area, which is about the size of two football fields. Then his crewmate Luca Parmitano took a turn on July 26, going so far as to deploy a simulated radio antenna. Another test session should take place in August.
“Whereas it is common practice in undersea exploration to use a joystick and have direct control of remote submarines, the K10 robots are more intelligent,” stated Terry Fong, human exploration telerobotics project manager at Ames.
“Astronauts interact with the robots at a higher level, telling them where to go, and then the robot itself independently and intelligently figures out how to safely get there,” added Fong, who is also director of Ames’ intelligent robotics group.
The tests simulated a mission to the moon’s L2 Lagrangian point, a spot where the combined gravity of the moon and Earth allow a spacecraft to remain virtually steady above the surface. One possibility for such a mission would be to deploy a radio telescope on the lunar side opposite from Earth, far from Earth’s radio noise, NASA said.
These tests also showcase a couple of technical firsts:
- NASA is testing a Robot Application Programming Interface Delegate (RAPID) robot data messaging system to control the robot from space, essentially working to strip down the information to the bare essentials to make communication as easy as possible. (RAPID has been tested before, but never in this way.)
- The agency is also using its Ensemble software in space for telerobotics for the first time. It describes this as “open architecture for the development, integration and deployment of mission operations software.”
Thanks to Channel 37, radio astronomers keep tabs on everything from the Sun to pulsars to the lonely spaces between the stars. This particular frequency, squarely in the middle of the UHF TV broadcast band, has been reserved for radio astronomy since 1963, when astronomers successfully lobbied the FCC to keep it TV-free.
Back then UHF TV stations were few and far between. Now there are hundreds, and I’m sure a few would love to soak up that last sliver of spectrum. Sorry Charley, the moratorium is still in effect to this day. Not only that, but it’s observed in most countries across the world.
So what’s so important about Channel 37? Well, it’s smack in the middle of two other important bands already allocated to radio astronomy – 410 Megahertz (MHz) and 1.4 Gigahertz (Gz). Without it, radio astronomers would lose a key window in an otherwise continuous radio view of the sky. Imagine a 3-panel bay window with the middle pane painted black. Who wants THAT?
Channel 37 occupies a band spanning from 608-614 MHz. A word about Hertz. Radio waves are a form of light just like the colors we see in the rainbow or the X-rays doctors use to probe our bones. Only difference is, our eyes aren’t sensitive to them. But we can build instruments like X-ray machines and radio telescopes to “see” them for us.
Every color of light has a characteristic wavelength and frequency. Wavelength is the distance between successive crests in a light wave which you can visualize as a wave moving across a pond. Waves of visible light range from one-millionth to one-billionth of a meter, comparable to the size of a virus or DNA molecule.
X-rays crests are jammed together even more tightly – one X-ray is only as big as an small atom. Radio waves fill out the opposite end of the spectrum with wavelengths ranging from baseball-sized to more than 600 miles (1000 km) long.
The frequency of a light wave is measured by how many crests pass a given point over a given time. If only one crest passes that point every second, the light beam has a frequency of 1 cycle per second or 1 Hertz. Blue light has a wavelength of 462 billionths of a meter and frequency of 645 trillion Hertz (645 Terahertz).
The higher the frequency, the greater the energy the light carries. X-rays have frequencies starting around 30 quadrillion Hertz (30 petahertz or 30 PHz), enough juice to damage body cells if you get too much exposure. Even ultraviolet light has power to burn skin as many of us who’ve spent time outdoors in summer without sunscreen are aware.
Radio waves are the gentle giants of the electromagnetic spectrum. Their enormous wavelengths mean low frequencies. Channel 37 radio waves have more modest frequencies of around 600 million Hertz (MHz), while the longest radio waves deliver crests almost twice the width of Lake Superior at a rate of 3 to 300 Hertz.
If Channel 37 were ever lost to TV, the gap would mean a loss of information about the distribution of cosmic rays in the Milky Way galaxy and rapidly rotating stars called pulsars created in the wake of supernovae. Closer to home, observations in the 608-614 MHz band allow astronomers track bursts of radio energy produced by particles blasted out by solar flares traveling through the sun’s outer atmosphere. Some of these can have powerful effects on Earth. No wonder astronomers want to keep this slice of the electromagnetic spectrum quiet. For more details on how useful this sliver is to radio astronomy, click HERE.
Just as optical astronomers seek the darkest sites for their telescopes to probe the most remote corners of the universe, so too does radio astronomy need slices of silence to listen to the faintest whispers of the cosmos.
Named after the nearby city in Puerto Rico, the Arecibo Observatory (or Arecibo Radio Telescope) is the largest single-aperture (radio) telescope ever built, 305 m in diameter.
Taking advantage of a karst sinkhole, Cornell University built a spherical reflector out of wire mesh, with receivers at the focus suspended by 18 steel cables strung from three concrete towers on the rim. It took three years to build, and was completed in 1963. Since then it has been upgraded several times; for example, in 1974 perforated aluminum panels replaced the wire mesh, and a Gregorian reflector system added to the receiver mechanism in 1997. Among other things, these upgrades have extended the range of radio wavelengths Arecibo can operate at, both as a radio telescope and for radar astronomy.
Such a visually interesting piece of scientific hi-tech has lead to Arecibo playing a role in many movies and TV shows, from James Bond’s Golden Eye to Contact to X-Files.
Everyone knows about [email protected], right? Well, it’s receivers on Arecibo that supply the data which the millions of PCs crunch!
Arecibo has played a key role in many astronomical discoveries, from the rotation period of Mercury (a radar astronomy application, in 1964), to the pulses of the Crab Nebula (1968), to studies of pulsars by Hulse and Taylor (1974) that lead to their Nobel Prize (1993), and to direct imaging of asteroids (another radar astronomy application, first done in 1989).
Due to budget cutbacks and changes in research priorities, the future of Arecibo is uncertain (most of its funding comes from the National Science Foundation); maybe you can find a way to save it?
Here’s the official Arecibo Observatory website; ALFA is a current large-scale astronomical survey being done at Arecibo, in case you don’t already know about [email protected], and click here to read more about planetary radar.
Calling All Amateur Astronomers: Help Comb Through Arecibo Data for Gems, Arecibo Spots Triple Asteroid, Arecibo Gets an Upgrade: just three of the many Universe Today stories featuring the Arecibo Observatory!
Source: National Astronomy and Ionosphere Center: Arecibo Observatory