Space and astronomy news
A team of researchers from the University of Nebraska–Lincoln recently conducted an experiment where they were able to accelerate plasma electrons to close to the speed of light. This “optical rocket”, which pushed electrons at a force a trillion-trillion times greater than that generated by a conventional rocket, could have serious implications for everything from space travel to computing and nanotechnology.
Continue reading “Optical Rocket Boosts Electrons to Nearly the Speed of Light”
In April of 2016, Russian billionaire Yuri Milner announced the creation of Breakthrough Starshot. As part of his non-profit scientific organization (known as Breakthrough Initiatives), the purpose of Starshot was to design a lightsail nanocraft that would be capable of achieving speeds of up to 20% the speed of light and reaching the nearest star system – Alpha Centauri (aka. Rigel Kentaurus) – within our lifetimes.
At this speed – roughly 60,000 km/s (37,282 mps) – the probe would be able to reach Alpha Centauri in 20 years, where it could then capture images of the star and any planets orbiting it. But according to a recent article by Professor Bing Zhang, an astrophysicist from the University of Nevada, researchers could get all kinds of valuable data from Starshot and similar concepts long before they ever reached their destination.
The article appeared in The Conversation under the title “Observing the universe with a camera traveling near the speed of light“. The article was a follow-up to a study conducted by Prof. Zhang and Kunyang Li – a graduate student from the Center for Relativistic Astrophysics at the Georgia Institute of Technology – that appeared in The Astrophysical Journal (titled “Relativistic Astronomy“).
To recap, Breakthrough Starshot seeks to leverage recent technological developments to mount an interstellar mission that will reach another star within a single generation. The spacecraft would consist of an ultra-light nanocraft and a lightsail, the latter of which would accelerated by a ground-based laser array up to speeds of hundreds of kilometers per second.
Such a system would allow the tiny spacecraft to conduct a flyby mission of Alpha Centauri in about 20 years after it is launched, which could then beam home images of possible planets and other scientific data (such as analysis of magnetic fields). Recently, Breakthrough Starshot held an “industry day” where they submitted a Request For Proposals (RFP) to potential bidders to build the laser sail.
According to Zhang, a lightsail-driven nanocraft traveling at a portion of the speed of light would also be a good way to test Einstein’s theory of Special Relativity. Simply put, this law states that the speed of light in a vacuum is constant, regardless of the inertial reference frame or motion of the source. In short, such a spacecraft would be able to take advantage of the features of Special Relativity and provide a new mode to study astronomy.
Based on Einstein’s theory, different objects in different “rest frames” would have different measures of the lengths of space and time. In this sense, an object moving at relativistic speeds would view distant astronomical objects differently as light emissions from these objects would be distorted. Whereas objects in front of the spacecraft would have the wavelength of their light shortened, objects behind it would have them lengthened.
This phenomenon, known as the “Doppler Effect”, results in light being shifted towards the blue end (“blueshift”) or the red end (“redshift”) of the spectrum for approaching and retreating objects, respectively. In 1929, astronomer Edwin Hubble used redshift measurements to determine that distant galaxies were moving away from our own, thus demonstrating that the Universe was in a state of expansion.
Because of this expansion (known as the Hubble Expansion), much of the light in the Universe is redshifted and only measurable in difficult-to-observe infrared wavelengths. But for a camera moving at relativistic speeds, according to Prof. Zhang, this redshifted light would become bluer since the motion of the camera would counteract the effects of cosmic expansion.
This effect, known as “Doppler boosting”, would cause the faint light from the early Universe to be amplified and allow distant objects to be studied in more detail. In this respect, astronomers would be able to study some of the earliest objects in the known Universe, which would offer more clues as to how it evolved over time. As Prof. Zhang explained to Universe Today via email, this would allow for some unique opportunities to test Special Relativity:
“In the rest frame of the camera, the emission of the objects in the hemisphere of the camera motion is blue-shifted. For bright objects with detailed spectral observations from the ground, one can observe them in flight. By comparing their blue-shifted flux at a specific blue-shifted frequency with the flux of the corresponding (de-blueshifted) frequency on the ground, one can precisely test the Doppler boosting prediction in Special Relativity.”
In addition, the frequency and intensity of light – and also the size of distant objects – would also change as far as the observer was concerned. In this respect, the camera would act as a lens and a wide-field camera, magnifying the amount of light it collects and letting astronomers observe more objects within the same field of view. By comparing the observations collected by the camera to those collected by a camera from the ground, astronomers could also test the probe’s Lorentz Factor.
This factor indicates how time, length, and relativistic mass change for an object while that object is moving, which is another prediction of Special Relativity. Last, but not least, Prof. Zhang indicates that probes traveling at relativistic speeds would not need to be sent to any specific destination in order to conduct these tests. As he explained:
“The concept of “relativistic astronomy” is that one does not really need to send the cameras to specific star systems. No need to aim (e.g. to Alpha Centauri system), no need to decelerate. As long as the signal can be transferred back to earth, one can learn a lot of things. Interesting targets include high-redshift galaxies, active galactic nuclei, gamma-ray bursts, and even electromagnetic counterparts of gravitational waves.”
However, there are some drawbacks to this proposal. For starters, the technology behind Starshot is all about accomplishing the dream of countless generations – i.e. reaching another star system (in this case, Alpha Centauri) – within a single generation.
And as Professor Abraham Loeb – the Frank B. Baird Jr. Professor of Science at Harvard University and the Chair and the Breakthrough Starshot Committee – told Universe Today via email, what Prof. Zhang is proposing can be accomplished by other means:
>“Indeed, there are benefits to having a camera move near the speed of light toward faint sources, such as the most distant dwarf galaxies in the early universe. But the cost of launching a camera to the required speed would be far greater than building the next generation of large telescopes which will provide us with a similar sensitivity. Similarly, the goal of testing special relativity can be accomplished at a much lower cost.”
Of course, it will be many years before a project like Starshot can be mounted, and many challenges need to be addressed in the meantime. But it is exciting to know that in meantime, scientific applications can be found for such a mission that go beyond exploration. In a few decades, when the mission begins to make the journey to Alpha Centauri, perhaps it will also be able to conduct tests on Special Relativity and other physical laws while in transit.
Further Reading: The Conversation, The Astrophysical Journal
In 2015, Russian billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to enhancing the search for extraterrestrial intelligence (SETI). In April of the following year, he and the organization be founded announced the creation of Breakthrough Starshot, a program to create a lightsail-driven “wafercraft” that would make the journey to the nearest star system – Proxima Centauri – within our lifetime.
In the latest development, on Wednesday May 23rd, Breakthrough Starshot held an “industry day” to outline their plans for developing the Starshot laser sail. During this event, the Starshot committee submitted a Request For Proposals (RFP) to potential bidders, outlining their specifications for the sail that will carry the wafercraft as it makes the journey to Proxima Centauri within our lifetimes.
As we have noted in several previous articles, Breakthrough Starshot calls for the creation of a gram-scale nanocraft being towed by a laser sail. This sail will be accelerated by an Earth-based laser array to a velocity of about 60,000 km/s (37,282 mps) – or 20% the speed of light (o.2 c). This concept builds upon the idea of a solar sail, a spacecraft that relies on solar wind to push itself through space.
At this speed, the nanocraft would be able to reach the closest star system to our own – Proxima Centauri, located 4.246 light-years away – in just 20 years time. Since its inception, the team behind Breakthrough Starshot has invested considerable time and energy addressing the conceptual and engineering challenges such a mission would entail. And with this latest briefing, they are now looking to move the project from concept to reality.
In addition to being the Frank B. Baird, Jr. Professor of Science at Harvard University, Abraham Loeb is also the Chair of the Breakthrough Starshot Advisory Committee. As he explained to Universe Today via email:
“Starshot is an initiative to send a probe to the nearest star system at a fifth of the speed of light so that it will get there within a human lifetime of a couple of decades. The goal is to obtain photos of exo-planets like Proxima b, which is in the habitable zone of the nearest star Proxima Centauri, four light years away. The technology adopted for fulfilling this challenge uses a powerful (100 Giga-watt) laser beam pushing on a lightweight (1 gram) sail to which a lightweight electronics chip is attached (with a camera, navigation and communication devices). The related technology development is currently funded at $100M by Yuri Milner through the Breakthrough Foundation.”
In addition to outlining BI’s many efforts to find ETI – which include Breakthrough Listen, Breakthrough Message and Breakthrough Watch – the RFP focused on Starshot’s Objectives. As was stated in the RFP:
“The scope of this RFP addresses the Technology Development phase – to explore LightSail concepts, materials, fabrication and measurement methods, with accompanying analysis and simulation that creates advances toward a viable path to a scalable and ultimately deployable LightSail.”
As Loeb indicated, this RFP comes not long after another “industry day” that was related to the development of the technology of the laser – termed the “Photon Engine”. In contrast, this particular RFP was dedicated to the design of the laser sail itself, which will carry the nanocraft to Proxima Centauri.
“The Industry Day was intended to inform potential partners about the project and request for proposals (RFP) associated with research on the sail materials and design,” added Loeb. “Within the next few years we hope to demonstrate the feasibility of the required sail and laser technologies. The project will allocate funds to experimental teams who will conduct the related research and development work. ”
The RFP also addressed Starshot’s long-term goals and its schedule for research and development in the coming years. These include the investment in $100 million over the next five years to determine the feasibility of the laser and sail, to invest the value of the European Extremely Large Telescope (EELT) from year 6 to year 11 and build a low-power prototype for space testing, and invest the value of the Large Hardon Collider (LHC) over a 20 year period to develop the final spacecraft.
“The European Extremely Large Telescope (EELT) will cost on order of a billion [dollars] and the Large Hadron Collider cost was ten times higher,’ said Loeb. “These projects were mentioned to calibrate the scale of the cost for the future phases in the Starshot project, where the second phase will involve producing a demo system and the final step will involve the complete launch system.”
The research and development schedule for the sail was also outlined, with three major phases identified over the next 5 years. Phase 1 (which was the subject of the RFP) would entail the development of concepts, models and subscale testing. Phase 2 would involve hardware validation in a laboratory setting, while Phase 3 would consist of field demonstrations.
With this latest “industry day” complete, Starshot is now open for submissions from industry partners looking to help them realize their vision. Step A proposals, which are to consist of a five-page summary, are due on June 22nd and will be assessed by Harry Atwater (the Chair of the Sail Subcommittee) as well as Kevin Parkin (head of Parkin Research), Jim Benford (muWave Sciences) and Pete Klupar (the Project Manager).
Step B proposals, which are to consist of a more detailed, fifteen-page summary, will be due on July 10th. From these, the finalists will be selected by Pete Worden, the Executive Director of Breakthrough Starshot. If all goes according to plan, the initiative hopes to launch the first lasersail-driven nanocraft in to Proxima Centauri in 30 years and see it arrive there in 50 years.
So if you’re an aerospace engineer, or someone who happens to run a private aerospace firm, be sure to get your proposals ready! To learn more about Starshot, the engineering challenges they are addressing, and their research, follow the links provided to the BI page. To see the slides and charts from the RFP, check out Starshot’s Solicitations page.
Further Reading: Centauri Dreams, Breakthrough Starshot
It’s a staple of science fiction, and something many people have fantasized about at one time or another: the idea of sending out spaceships with colonists and transplanting the seed of humanity among the stars. Between discovering new worlds, becoming an interstellar species, and maybe even finding extra-terrestrial civilizations, the dream of spreading beyond the Solar System is one that can’t become reality soon enough!
For decades, scientists have contemplated how humanity might one-day reach achieve this lofty goal. And the range of concepts they have come up with present a whole lot of pros and cons. These pros and cons were raised in a recent study by Martin Braddock, a member of the Mansfield and Sutton Astronomical Society, a Fellow of the Royal Society of Biology, and a Fellow of the Royal Astronomical Society. Continue reading “Pros and Cons of Various Methods of Interstellar Travel”
In the past decade, the rate at which extra-solar planets have been discovered and characterized has increased prodigiously. Because of this, the question of when we might explore these distant planets directly has repeatedly come up. In addition, the age-old question of what we might find once we get there – i.e. is humanity alone in the Universe or not? – has also come up with renewed vigor.
These questions have led to a number of interesting and ambitious proposals. These include Project Blue, a space telescope which would directly observe any planets orbiting Alpha Centauri, and Breakthrough Starshot – which aims to send a laser-driven nanocraft to Alpha Centauri in just 20 years. But perhaps the most daring proposal comes in the form of Project Genesis, which would attempt to seed distant planets with life.
This proposal was put forth by Dr. Claudius Gros, a theoretical physicist from the Institute for Theoretical Physics at Goethe University Frankfurt. In 2016, he published a paper that described how robotic missions equipped with gene factories (or cryogenic pods) could be used to distribute microbial life to “transiently habitable exoplanets – i.e. planets capable of supporting life, but not likely to give rise to it on their own.
Not long ago, Universe Today wrote about Dr. Gros’ recent study where he proposed using a magnetic sail to slow down an interstellar spacecraft. We were fortunate to catch up with Dr. Gros again and had a chance to ask him about Project Genesis. You can find our Q&A below, and be sure to check out his seminal paper that describes this project – “Developing Ecospheres on Transiently Habitable Planets: The Genesis Project“.
Exoplanets come in all sizes, temperatures and compositions. The purpose of the Genesis project is to offer terrestrial life alternative evolutionary pathways on those exoplanets that are potentially habitable but yet lifeless. The basic philosophy of most scientists nowadays is that simple life is common in the universe and complex life is rare. We don’t know that for sure, but at the moment, that is the consensus.
If you had good conditions, simple life can develop very fast, but complex life will have a hard time. At least on Earth, it took a very long time for complex life to arrive. The Cambrian Explosion only happened about 500 million years ago, roughly 4 billion years after Earth was formed. If we give planets the opportunity to fast forward evolution, we can give them the chance to have their own Cambrian Explosions.
What worlds would be targeted?
The prime candidates are habitable “oxygen planets” around M-dwarfs like TRAPPIST-1. It is very likely that the oxygen-rich primordial atmosphere of these planets will have prevented abiogenesis in first place, that is the formation of life. Our galaxy could potentially harbor billions of habitable but lifeless oxygen planets.
Nowadays, astronomers are looking for planets around M-stars. These are very different from planets around Sun-like stars. Once a star forms, it takes a certain amount of time to contract to the point where fusion begins, and it starts to produce energy. For the Sun, this took 10 million years, which is very fast. For stars like TRAPPIST-1, it would take 100 million to 1 billion years. Then they have to contract to dissipate their initial heat.
The planets around TRAPPIST-1 would have been very hot, because the star was very hot for a long time. All the water that was in their stratospheres, the UV radiation would have disassociated it into hydrogen and oxygen – the hydrogen escaped, and the oxygen remained. All surveys have showed that they have oxygen atmospheres, but this is the product of chemical disassociation and not from plants (as with Earth).
There’s a good chance that oxygen planets are sterile, because oxygen planets eat up prebiotic conditions. We believe there may be billions of oxygen planets in our galaxy. They would have no life, and complex life needs oxygen. In science fiction, you have all these planets that look alike. We could imagine that in half a billion years, we could have this because we seeded oxygen planets (only we couldn’t travel there quickly since we have no FTL).
What kind of organisms would be sent?
The first wave would consist of unicellular autotrophs. That is photo-synthesizing bacteria, like cyanobacteria, and eukaryotes (the cell type making up all complex life, that is animals and plants). Heterotrophs would follow in a second stage, organisms that feed on other organisms and can only exist after autotrophs exist and take root.
How would these organisms be sent?
That depends on the technology. If it can advance, we can miniaturize a gene factory. In principle, nature is a miniature gene factory. Everything we want to produce is very small. If it’s possible that would be the best option. Send in a gene bank, and then select the most optimal organism to send down. If that is not possible, you would have to have frozen germs. In the end, it depends on what would be the technically available.
You could also send in synthetic life. Synthetic biology is a very active research field, which involves reprogramming the genetic code. In science fiction, you have alien life with a different genetic code. Today, people are trying to produce this here on Earth. The end goal is to have new life forms that are based on a different code. This would be very dangerous on Earth, but on a far-distant planet, it would be beneficial.
What if these worlds are not sterile?
Genesis is all about life, not destroying life, so we’d want to avoid that. The probes would have to go into orbit, so we are pretty sure that from orbit, we could detect complex life on the surface. The Genesis Project was intended for planets that are not habitable for eternity. Earth is habitable for billions of years, but we are not sure about habitable exoplanets.
Exoplanets come in all kinds of sized, temperatures, and habitabilities. Many of these planets will only be habitable for some time, maybe 1 billion years. Life there will not have time to evolve into complex life forms. So you have a decision: leave them like they are, or take a chance at developing complex life there.
Some believe that all bacteria are worth saving. On Earth, there is no protection for bacteria. But bacteria living on different planets are treated differently. Planetary protection, why do we do that? So we can study the life, or for the sake of protecting life itself? Mars most likely had life at one time, but now not, except for maybe a few bacteria. Still, we plan manned missions to Mars, which means planetary protection is off. It’s a contradiction.
I am very enthusiastic about finding life, but what about the planets where we don’t find life? This offers the possibility about doing something about it.
Could humanity benefit from this someday (i.e. colonize “seeded” planets)?
Yes and no. Yes, because nothing would keep our decedents (or any other intelligence living on Earth by then), to visit Genesis planets in 10-100 million years (the minimal time for the life initially seeded to fully unfold). No, because the involved time spans are so long, that it is not rational to speak of a ‘benefit’.
How soon could such a mission be mounted?
Genesis probes could be launched by the same directed-energy launch system planned for the Breakthrough Starshot initiative. Breakthrough Starshot aims to send very fast, very small, very light probes of about 1 gram to another star system. The same laser technology could send something more massive, but slower. Slow is relative, of course. So the in the end it depends on what is optimal.
The magnetic sail paper I recently wrote was a sample mission to show that it was possible. The probe would be about the size of a car (1 tonne) and would travel at a speed of about 1000 km/s – slow for interstellar travel relative to speed of light, but fast for Earth. If you reduce the velocity by a factor of 100, the mass you can propel is 10,000 heavier. You could accelerate a 1-tonne Genesis Probe and it would still fit into the layout of Breakthrough Starshot.
Therefore, the launch facility could see dual use and you wouldn’t need to build something new. Once that is in place one would need to test the magnetic sail. A realistic time span would hence be in the 50-100 years window.
What counter-arguments are there against this?
There are three main lines of counter-arguments. The first is the religious counter-argument, which says that humanity should not play God. The Genesis project is however not about creating life, but to give life the possibility to further develop. Just not on Earth, but elsewhere in the cosmos.
The second is the Planetary protection argument, which argues that we should not interfere. Some people objecting to the Genesis Project cite the ‘first directive’ of the Star Trek TV series. The Genesis Project fully supports planetary protection of planets which harbor complex life and of planets on which complex life could potentially develop in the future. The Genesis project will target only planets on which complex life could not develop on its own.
The third argument is about the lack of benefit to humanity. The Genesis Project is expressively not for human benefit. It is reasonable to argue, from the perspective of survival, that the ethical values of a species (like humanity) has to put the good of the species at the center. Ethical is therefore “what is good for our own species”. Spending a large amount of money on a project, like the Genesis Project, which is expressively not for the benefit of our own species, would then be unethical.
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Our thanks go out to Dr. Gros for taking the time to talk to us! We hope to hear more from him in the future and wish him the best of luck with Project Genesis.
The number of confirmed extra-solar planets has increased by leaps and bounds in recent years. With every new discovery, the question of when we might be able to explore these planets directly naturally arises. There have been several suggestions so far, ranging from laser-sail driven nanocraft that would travel to Alpha Centauri in just 20 years (Breakthrough Starshot) to slower-moving microcraft equipped with a gene laboratories (The Genesis Project).
But when it comes to braking these craft so that they can slow down and study distant stars and orbit planets, things become a bit more complicated. According to a recent study by the very man who conceived of The Genesis Project – Professor Claudius Gros of the Institute for Theoretical Physics Goethe University Frankfurt – special sails that rely on superconductors to generate magnetic fields could be used for just this purpose.
Starshot and Genesis are similar in that both concepts seek to leverage recent advancements in miniaturization. Today, engineers are able to create sensors, thrusters and cameras that are capable of carrying out computations and other functions, but are a fraction of the size of older instruments. And when it comes to propulsion, there are many options, ranging from conventional rockets and ion drives to laser-driven light sails.
Slowing an interstellar mission down, however, has remained a more significant challenge because such a craft cannot be fitted with braking thrusters and fuel without increasing its weight. To address this, Professor Gros suggests using magnetic sails, which would present numerous advantages over other available methods. As Prof. Gros explained to Universe Today via email:
“Classically, you would equip the spacecraft with rocket engines. Normal rocket engines, as we are using them for launching satellites, can change the velocity only by 5-15 km/s. And even that only when using several stages. That is not enough to slow down a craft flying at 1000 km/s (0.3% c) or 100000 km/s (c/3). Fusion or antimatter drives would help a bit, but not substantially.”
The sail he envisions would consist of a massive superconducting loop that measures about 50 kilometers in diameter, which would create a magnetic field once a lossless current was induced. Once activated, the ionized hydrogen in the interstellar medium would be reflected off the sail’s magnetic field. This would have the effect of transferring the spacecraft’s momentum to the interstellar gas, gradually slowing it down.
According to Gros’ calculations, this would work for slow-travelling sails despite the extremely low particle density of interstellar space, which works out to 0.005 to 0.1 particles per cubic centimeter. “A magnetic sail trades energy consumption with time,” said Gros.”If you turn off the engine of your car and let it roll idle, it will slow down due to friction (air, tires). The magnetic sail does the same, where the friction comes from the interstellar gas.”
One of the advantages of this method is the fact that can be built using existing technology. The key technology behind the magnetic sail is a Biot Savart loop which, when paired with the same kind of superconducting coils used in high-energy physics, would create a powerful magnetic field. Using such a sail, even heavier spacecraft – those that weight up to 1,500 kilograms (1.5 metric tonnes; 3,307 lbs) – could be decelerated from an interstellar voyage.
The one big drawback is the time such a mission would take. Based on Gros’ own calculations, a high speed transit to Proxima Centauri that relied on magnetic momentum braking would require a ship that weighed about 1 million kg (1000 metric tonnes; 1102 tons). However, an interstellar mission involving a 1.5 metric tonne ship would be able to reach TRAPPIST-1 in about 12,000 years. As Gros concludes:
“It takes a long time (because the very low density of the interstellar media). That is bad if you want to see a return (scientific data, exciting pictures) in your lifetime. Magnetic sails work, but only when you are happy to take the (very) long perspective.”
In other words, such a system would not work for a nanocraft like that envisioned by Breakthrough Starshot. As Starshot’s own Dr. Abraham Loeb explained, the main goal of the project is to achieve the dream of interstellar travel within a generation of the ship’s departure. In addition to being the Frank B. Baird Jr. Professor of Science at Harvard University, Dr. Loeb is also the Chair of the Breakthrough Starshot Advisory Committee.
As he explained to Universe Today via email:
“[Gros] concludes that breaking on the interstellar gas is feasible only at low speeds (less than a fraction of a percent of the speed of light) and even then one needs a sail that is tens of miles wide, weighting tons. The problem is that with such a low speed, the journey to the nearest stars will take over a thousand years.
“The Breakthrough Starshot initiative aims to launch a spacecraft at a fifth of the speed of light so that it will reach the nearest stars within a human lifetime. It is difficult to get people excited about a journey whose completion will not be witnessed by them. But there is a caveat. If the longevity of people could be extended to millennia by genetic engineering, then designs of the type considered by Gros would certainly be more appealing.”
But for missions like The Genesis Project, which Gros originally proposed in 2016, time is not a factor. Such a probe, which would carry single-celled organisms – either encoded in a gene factory or stored as cryogenically-frozen spores – a could take thousands of years to reach a neighboring star system. Once there, it would begin seeding planets that had been identified as “transiently habitable” with single-celled organisms.
For such a mission, travel time is not the all-important factor. What matters is the ability to slow down and establish orbit around a planet. That way, the spacecraft would be able to seed these nearby worlds with terrestrial organisms, which could have the effect of slowly terraforming it in advance of human explorers or settlers.
Given how long it would take for humans to reach even the nearest extra-solar planets, a mission that last a few hundred or a few thousand years is no big deal. In the end, which method we choose to conduct interstellar mission will come down to how much time we’re willing to invest. For the sake of exploration, expedience is the key factor, which means lightweight craft and incredibly high speeds.
But where long-term goals – such as seeding other worlds with life and even terraforming them for human settlement – are concerned, the slow and steady approach is best. One thing is for sure: when these types of missions move from the concept stage to realization, it sure will be exciting to witness!
Further Reading: Goete University Frankfurt, Journal of Physics Communications
Proxima Centauri, in addition to being the closest star system to our own, is also the home of the closest exoplanet to Earth. The existence of this planet, Proxima b, was first announced in August of 2016 and then confirmed later that month. The news was met with a great deal of excitement, and a fair of skepticism, as numerous studies followed t were dedicated to determining if this planet could in fact be habitable.
Another important question has been whether or not Proxima Centauri could have any more objects orbiting it. According to a recent study by an international team of astronomers, Proxima Centauri is also home to a belt of cold dust and debris that is similar to the Main Asteroid Belt and Kuiper Belt in our Solar System. The existence of this dusty belt could indicate the presence of more planets in this star system.
The study, titled “ALMA Discovery of Dust Belts Around Proxima Centauri“, recently appeared online and is scheduled to appear in the Monthly Notices of the Astronomical Society. The study was led by Guillem Anglada from the Astrophysical Institute of Andalusia (CSIS), and included members from the Institute of Space Sciences (IEEC), the European Southern Observatory (ESO), the Joint ALMA Observatory, and multiple universities.
For their study, the team relied on data obtained by the Atacama Large Millimeter/submillimter Array (ALMA) at the ALMA Observatory in Chile. These observations revealed the glow of a cold dust belt that is roughly 1 to 4 AUs from Proxima Centauri – one to four times the distance between the Earth and the Sun. This puts it significantly further out than Proxima b, which orbits its sun at a distance of 0.0485 AU (~5% of Earth’s distance from the Sun).
Dust belts are essentially the leftover material that did not form into larger bodies withing a star system. The particles of rock and ice in these belts vary in size from being smaller than a millimeter across to asteroids that are many kilometers in diameter. Based on their observations, the team estimated that the belt in Proxima Centauri has a total mass that is about one-hundredth the mass of Earth.
The team also estimated that this belt experiences temperatures of about 43 K (-230°C; -382 °F), making it as cold as the Kuiper Belt. As Dr. Anglada explained the significance of these findings in a recent ESO press release:
“The dust around Proxima is important because, following the discovery of the terrestrial planet Proxima b, it’s the first indication of the presence of an elaborate planetary system, and not just a single planet, around the star closest to our Sun.”
The ALMA data also provided indications that Proxima Centauri might also have another belt located about ten times further out. In other words, Proxima Centauri may have two belts, just like our Solar System. If confirmed, this could indicate that this neighboring star also has a system of planets that fall within and between belts of unconsolidated material, which in turn is leftover from the early days of planet formation. As Dr. Anglada explained:
“This result suggests that Proxima Centauri may have a multiple planet system with a rich history of interactions that resulted in the formation of a dust belt. Further study may also provide information that might point to the locations of as yet unidentified additional planets.”
The very cold environment of this outer belt could also have some interesting implications, since its parent star is much dimmer than our own. Pedro Amado, who also hails from the Astrophysical Institute of Andalusia, was similarly enthusiastic about these findings. As he indicated, they are just the beginning of what is sure to be a long process of discovery about this system.
“These first results show that ALMA can detect dust structures orbiting around Proxima,” he said. “Further observations will give us a more detailed picture of Proxima’s planetary system. In combination with the study of protoplanetary discs around young stars, many of the details of the processes that led to the formation of the Earth and the Solar System about 4600 million years ago will be unveiled. What we are seeing now is just the appetiser compared to what is coming!”
This study is also likely to be of interest to those planning on conducting direct observations of the Alpha Centauri system, such as Project Blue. In the coming years, they hope to deploy a space telescope that will observe Alpha Centauri directly to study any exoplanets it may have. With a slight adjustment, this telescope could also take a gander at Proxima Centauri and aid in the hunt for a system of planets there.
And then there’s Breakthrough Starshot, the first proposed interstellar voyage which hopes to send a laser sail-driven nanocraft to Alpha Centauri in the coming decades. Recently, the scientists behind Starshot discussed the possibility of extending the mission to include a stopover in Proxima Centauri. Before such a mission can take place, the planners need to know what kind of dusty environment awaits it.
And of course, future studies will benefit from the deployment of next-generation instruments, like the James Webb Space Telescope (scheduled for launch in 2019) and the ESO’s Extremely Large Telescope (ELT) – which is expected to collect its first light in 2024.
In 2015, Russian billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to enhancing the search for extraterrestrial intelligence (SETI). In April of the following year, he and the organization be founded announced the creation of Breakthrough Starshot, a program to create a lightsail-driven “wafercraft” that would make the journey to the nearest star system – Alpha Centauri – within our lifetime.
This past June, the organization took a major step towards achieving this goal. After hitching a ride on some satellites being deployed to Low Earth Orbit (LEO), Breakthrough conducted a successful test flight of its first spacecraft. Known as “Sprites”, these are not only the smallest spacecraft ever launched, but prototypes for the eventual wafercraft Starshot hopes to send to Alpha Centauri.
The concept for a wafercraft is simple. By leveraging recent developments in computing and miniaturization, spacecraft that are the size of a credit card could be created. These would be capable of carrying all the necessary sensors, microprocessors and microthrusters, but would be so small and light that it would take much less energy to accelerate them to relativistic speeds – in the case of Starshot, up to 20% the speed of light.
As Pete Worden – Breakthrough Starshot’s executive director and the former director of NASA’s Ames Research Center – said in an interview with Scientific American:
“This is a very early version of what we would send to interstellar distances. In addition, this is another clear demonstration that it is possible for countries to work together to do great things in space. These are European spacecraft with U.S. nanosatellite payloads launching on an Indian booster—you can’t get much more international than that.”
Professor Abraham Loeb also has some choice words to mark this historic occasion. In addition to being the Frank B. Baird Jr. Professor of Science, the Chair of the Astronomy Department and the Director of the Institute for Theory and Computation at Harvard University, Prof. Loeb is also the chairman of the Breakthrough Starshot Advisory Committee. As he told Universe Today via email:
“The launch of the Sprite satellites marks the first demonstration that miniaturized electronics on small chips can be launched without damage, survive the harsh environment of space and communicate successfully with earth. The Starshot Initiative aims to launch similar chips attached to a lightweight sail that it being pushed by a laser beam to a fifth of the speed of light, so that its camera, communication and navigation devices (whose total weight is of order a gram) will reach the nearest planet outside the solar System within our generation.”
The craft were deployed on June 23rd, piggybacking on two satellites belonging to the multinational technology corporation OHB System AG. Much like the StarChips that Starshot is proposing, the Sprites represent a major step in the evolution of miniature spacecraft that can do the job of larger robotic explorers. They measure just 3.5 by 3.5 cm (1.378 x 1.378 inches) and weight only four grams (0.14 ounces), but still manage to pack solar panels, computers, sensors and radios into their tiny frames.
The Sprite were originally conceived by Zac Manchester, a postdoctorate researcher and aerospace engineer at Cornell University. Back in 2011, he launched a Kickstarter campaign (called “KickSat“) to raise funds to develop the concept, which was his way of bringing down the associated costs of spaceflight. The campaign was a huge success, with Manchester raising a total of $74,586 of his original goal of $30,000.
Now a member of Breakthrough Starshot (where he is in charge of Wafer design and optimization), Manchester oversaw the construction of the Sprites from the Sibley School of Mechanical and Aerospace Engineering at Cornell. As Professor Loeb explained:
“The Sprites project is led by Zac Manchester, a Harvard postdoc who started working on this during his PhD at Cornell. Sprites are chip-size satellites powered by sunlight, intended to be released in space to demonstrate a new technology of lightweight (gram-scale) spacecrafts that can communicated with Earth.”
The purpose of this mission was to test how well the Sprites’ electronics systems and radio communications performed in orbit. Upon deployment, the Sprites remained attached to these satellites (known as “Max Valier” and “Venta”) and began transmitting. Communications were then received from ground stations, which demonstrated that the Sprites’ novel radio communication architecture performed exactly as it was designed to.
With this test complete, Starshot now has confirmation that a waferocraft is capable of operating in space and communicating with ground-based controllers. In the coming months and years, the many scientists and engineers that are behind this program will no doubt seek to test other essential systems (such as the craft’s microthrusters and imagers) while also working on the various engineering concerns that an instellar mission would entail.
In the meantime, the Sprites are still transmitting and are in radio contact with ground stations located in California and New York (as well as radio enthusiasts around the world). For those looking to listen in on their communications, Prof. Loeb was kind enough to let us know what frequency they are transmitting on.
“The radio frequency at which the Sprites that were just launched operate is 437.24 MHz, corresponding to a wavelength of roughly 69 cm,” he said. So if you’ve got a ham radio and feel like tuning in, this is where to set your dials!
And be sure to check out Zac Manchester’s Kickstarter video, which showcases the technology and inspiration for the KickSat:
Further: 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.
Since 2016, Breakthrough Listen has been gathering data with the Green Bank Radio Telescope in West Virginia, the Lick Observatory’s Automated Planet Finder on Mt. Hamilton in California, and the Parkes Radio Telescope in Australia. This data is analyzed by the Listen science team at the Berkeley SETI Research Center (BSRC), who rely on a specially-designed data pipeline to scan through billions of radio channels for any sign of unique signals.
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”).
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.
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:
Further Reading: Breakthrough Initiatives, Berkeley SETI
You might think you’re reading an educational website, where I explain fascinating concepts in space and astronomy, but that’s not really what’s going on here.
What’s actually happening is that you’re tagging along as I learn more and more about new and cool things happening in the Universe. I dig into them like a badger hiding a cow carcass, and we all get to enjoy the cache of knowledge I uncover.
Okay, that analogy got a little weird. Anyway, my point is. Squirrel!
Fast radio bursts are the new cosmic whatzits confusing and baffling astronomers, and now we get to take a front seat and watch them move through all stages of process of discovery.
Stage 1: A strange new anomaly is discovered that doesn’t fit any current model of the cosmos. For example, strange Boyajian’s Star. You know, that star that probably doesn’t have an alien megastructure orbiting around it, but astronomers can’t rule that out just yet?
Stage 2: Astronomers struggle to find other examples of this thing. They pitch ideas for new missions and scientific instruments. No idea is too crazy, until it’s proven to be too crazy. Examples include dark matter, dark energy, and that idea that we’re living in a
Stage 3: Astronomers develop a model for the thing, find evidence that matches their predictions, and vast majority of the astronomical community comes to a consensus on what this thing is. Like quasars and gamma ray bursts. YouTuber’s make their videos. Textbooks are updated. Balance is restored.
Today we’re going to talk about Fast Radio Bursts. They just moved from Stage 1 to Stage 2. Let’s dig in.
Fast radio bursts, or FRBs, or “Furbys” were first detected in 2007 by the astronomer Duncan Lorimer from West Virginia University.
He was looking through an archive of pulsar observations. Pulsars, of course, are newly formed neutron stars, the remnants left over from supernova explosions. They spin rapidly, blasting out twin beams of radiation. Some can spin hundreds of times a second, so precisely you could set your watch to them.
In this data, Lorimer made a “that’s funny” observation, when he noticed one blast of radio waves that squealed for 5 milliseconds and then it was gone. It didn’t match any other observation or prediction of what should be out there, so astronomers set out to find more of them.
Over the last 10 years, astronomers have found about 25 more examples of Fast Radio Bursts. Each one only lasts a few milliseconds, and then fades away forever. A one time event that can appear anywhere in the sky and only last for a couple milliseconds and never repeats is not an astronomer’s favorite target of study.
Actually, one FRB has been found to repeat, maybe.
The question, of course, is “what are they?”. And the answer, right now is, “astronomers have no idea.”
In fact, until very recently, astronomers weren’t ever certain they were coming from space at all. We’re surrounded by radio signals all the time, so a terrestrial source of fast radio bursts seems totally logical.
About a week ago, astronomers from Australia announced that FRBs are definitely coming from outside the Earth. They used the Molonglo Observatory Synthesis Telescope (or MOST) in Canberra to gather data on a large patch of sky.
Then they sifted through 1,000 terabytes of data and found just 3 fast radio bursts. Three.
Since MOST is farsighted and can’t perceive any radio signals closer than 10,000 km away, the signals had to be coming outside planet Earth. They were “extraterrestrial” in origin.
Right now, fast radio bursts are infuriating to astronomers. They don’t seem to match up with any other events we can see. They’re not the afterglow of a supernova, or tied in some way to gamma ray bursts.
In order to really figure out what’s going on, astronomers need new tools, and there’s a perfect instrument coming. Astronomers are building a new telescope called the Canadian Hydrogen Intensity Mapping Experiment (or CHIME), which is under construction near the town of Penticton in my own British Columbia.
It looks like a bunch of snowboard halfpipes, and its job will be to search for hydrogen emission from distant galaxies. It’ll help us understand how the Universe was expanding between 7 and 11 billion years ago, and create a 3-dimensional map of the early cosmos.
In addition to this, it’s going to be able to detect hundreds of fast radio bursts, maybe even a dozen a day, finally giving astronomers vast pools of signals to study.
What are they? Astronomers have no idea. Seriously, if you’ve got a good suggestion, they’d be glad to hear it.
In these kinds of situations, astronomers generally assume they’re caused by exploding stars in some way. Young stars or old stars, or maybe stars colliding. But so far, none of the theoretical models match the observations.
Another idea is black holes, of course. Specifically, supermassive black holes at the hearts of distant galaxies. From time to time, a random star, planet, or blob of gas falls into the black hole. This matter piles upon the black hole’s event horizon, heats up, screams for a moment, and disappears without a trace. Not a full on quasar that shines for thousands of years, but a quick snack.
The next idea comes with the only repeating fast radio burst that’s ever been found. Astronomers looked through the data archive of the Arecibo Observatory in Puerto Rico and found a signal that had repeated at least 10 times in a year, sometimes less than a minute apart.
Since the quick blast of radiation is repeating, this rules out a one-time collision between exotic objects like neutron stars. Instead, there could be a new class of magnetars (which are already a new class of neutron stars), that can release these occasional shrieks of radio.
Or maybe this repeating object is totally different from the single events that have been discovered so far.
Here’s my favorite idea. And honestly, the one that’s the least realistic. What I’m about to say is almost certainly not what’s going on. And yet, it can’t be ruled out, and that’s good enough for my fertile imagination.
Avi Loeb and Manasvi Lingam at Harvard University said the following about FRBs:
“Fast radio bursts are exceedingly bright given their short duration and origin at distances, and we haven’t identified a possible natural source with any confidence. An artificial origin is worth contemplating and checking.”
Artificial origin. So. Aliens. Nice.
Loeb and Lingam calculated how difficult it would be to send a signal that strong, that far across the Universe. They found that you’d need to build a solar array with twice the surface area of Earth to power the radio wave transmitter.
And what would you do with a transmission of radio or microwaves that strong? You’d use it to power a spacecraft, of course. What we’re seeing here on Earth is just the momentary flash as a propulsion beam sweeps past the Solar System like a lighthouse.
But in reality, this huge solar array would be firing out a constant beam of radiation that would propel a massive starship to tremendous speeds. Like the Breakthrough Starshot spacecraft, but for million tonne spaceships.
In other words, we could be witnessing alien transportation systems, pushing spacecraft with beams of energy to other worlds.
And I know that’s probably not what’s happening. It’s not aliens. It’s never aliens. But in my mind, that’s what I’m imagining.
So, kick back and enjoy the ride. Join us as we watch astronomers struggle to understand what fast radio bursts are. As they invalidate theories, and slowly unlock one of the most thrilling mysteries in modern astronomy. And as soon as they figure it out, I’ll let you know all about it.
What do you think? Which explanation for fast radio bursts seems the most logical to you? I’d love to hear your thoughts and wild speculation in the comments.