Some of you may have noticed a blip in the comments moderation over the past 24 hours. I think all messages have now come through, but a software upgrade on my server is the culprit. Things seem to have gone back to normal now. On an unrelated matter, I won't be able to get off a post today or tomorrow. On Tuesday, I'll have some interesting information about Breakthrough Starshot. [I had originally promised this for Monday, having forgotten about the US holiday].
I want to be sure to get the first image from TESS, the Transiting Exoplanet Survey Satellite, into Centauri Dreams, given the importance of the mission and the high hopes riding on it as the next step in exoplanet exploration. Now we move from the Kepler statistical survey methodology to a look at bright, nearby stars, and plenty of them. TESS will cover an area of sky far larger than the amount of sky we see in this image, which looks out along the plane of the galaxy from a perspective that matches southern skies on Earth. Image: This test image from one of the four cameras aboard the Transiting Exoplanet Survey Satellite (TESS) captures a swath of the southern sky along the plane of our galaxy. TESS is expected to cover more than 400 times the amount of sky shown in this image when using all four of its cameras during science operations. Credits: NASA/MIT/TESS. Showing some 200,000 stars, the image is centered on the southern constellation Centaurus, with a bit of the Coalsack...
It's conceivable that getting humans to an interstellar object may not involve journeying all the way to another star. We've learned that wandering asteroids and comets move between stars, as the case of 'Oumuamua demonstrated, and early research offers the possibility that such objects exist in large numbers. Now we have (514107) 2015 BZ509, which is conceivably an interloper into our system of another sort. Two researchers believe that this asteroid near the orbit of Jupiter is not just passing through, but a captured object from another stellar system. A comparison with Triton seems apt. One of the most compelling pieces of evidence that Neptune's largest moon is actually a Kuiper Belt Object is its retrograde orbit. We see the same thing with 2015 BZ509, and for Fathi Namouni (Observatoire de la Côte d'Azur) and Helena Morais (Universidade Estadual Paulista), that sends a clear message. The researchers have offered their work in a new paper in Monthly Notices of the Royal...
Ronald Bracewell's name doesn't come up as often in these pages as I might like, but today James Jason Wentworth remedies the lack. Bracewell (1921-2007), active in radio astronomy, mathematics and physics for many years at Stanford University, developed the concept of autonomous interstellar probes. Such a craft would be capable not only of taking numerous scientific readings but of communicating with any civilizations it encounters. His original paper on these matters dates back to 1960 and relies on artificial intelligence, long-life electronics and propulsion methods that don't necessarily involve high percentages of c. Jason considers these factors from the perspective of 2018 and explains what a program sending such probes to numerous stars might look like. If you're recalling Arthur C. Clarke's 'Starglider' from The Fountains of Paradise, you're not alone, but as the author notes, there are quite a few directions in which to take these ideas. by J. Jason Wentworth The writer...
In Stephen Baxter’s novel Ark (Gollancz, 2009), a starship launched by an Earth in crisis reaches a planet in the 82 Eridani system, an ‘Earth II’ that turns out to have major problems. Whereas Earth has an obliquity, or tilt relative to its orbital axis, of about 23.5 degrees, the second ‘Earth’ offers up a whopping 90 degree obliquity. Would a planet like this, given what must be extreme seasonality, be remotely habitable? The crew discusses the problem as they watch a computerized display showing Earth II and its star. The planet’s rotation axis is depicted as a splinter pushed through its bulk, one that points almost directly at the star. But as the planet rotates, the axis keeps pointing at the same direction in space. After half a year, the planet’s north pole is in darkness, its south pole in light. One of Baxter’s characters explains the consequences: “Every part of the planet except an equatorial strip will suffer months of perpetual darkness, months of perpetual light. Away...
Although we've seen spectacular images from deep space with the help of Voyager, New Horizons and numerous other spacecraft, the view from 1 million kilometers out can still put our world in perspective. Below is what a CubeSat called Mars Cube One (MarCO-B), one of a pair of such diminutive spacecraft, saw from that distance as it turned its camera back toward Earth. At the sides of the image you can see bits of the thermal blanket, the high-gain antenna feed and the HGA itself at the right, but in the center is the place we call home, the Earth-Moon system. You may want to zoom in to see the Moon better. Image: The first image captured by one of NASA's Mars Cube One (MarCO) CubeSats. The image, which shows both the CubeSat's unfolded high-gain antenna at right and the Earth and its moon in the center, was acquired by MarCO-B on May 9. Credit: NASA/JPL-Caltech. I've been keeping an eye on the MarCO CubeSats because they are the first of their type to be sent into deep space. The...
Once again we take advantage of older databanks to tease out new information. Europa is the case in point this morning, with Galileo data -- magnetic field and plasma wave observations from 1997 -- being brought in as evidence for a water vapor plume rising from the surface. The Galileo flyby took the craft closer than 400 kilometers, where a brief spike in plasma density was detected along with a concurrent decrease in magnetic field magnitude and a bend in the direction of the field. The data are consistent with a plume interacting with Jupiter’s plasma outflow, and support earlier Hubble indications of possible plumes on the moon. We have no firm measurement of the thickness of Europa’s ice, but if we are to get to that fascinating ocean now known to exist below the surface, we have to contend with penetrating it. Plumes from the interior would be helpful indeed, as Enceladus showed us at Saturn. Flying a spacecraft through a plume lets us measure its ingredients and sample the...
How would an advanced society communicate its history and values to the stars? Bill St. Arnaud argues that just as we can uncover our own history through careful analysis of archaeological sites, so SETI might uncover traces of ETI cultures in the form of signals that take advantage of natural astrophysical processes. Read on for more on an idea Bill first broached in a Centauri Dreams post called Virtual Von Neumann Probes. A consultant and research engineer, Bill's work has involved everything from charging methods for electric vehicles to next generation Internet networks. But his interest in SETI continues to mesh with his expertise in networking in this examination of a novel way to speak from the deep past. by Bill St. Arnaud To date most SETI research has focused on the assumption that an advanced extra- terrestrial society will want to "communicate" with similar beings throughout the universe. But it is my belief that given the vast distances and time that communication via a...
The definition of a habitable zone is under constant refinement, an important line of research as we choose which exoplanets to focus on in our search for life. Centauri Dreams regular Alex Tolley today looks at the question as it involves the presence of methane. With planetary warming already known to vary depending on the spectral type of the host star, we now learn that the presence of methane can produce thermal inversions and surface cooling on M-star exoplanets, impacting the outer limits of the habitable zone. The work of Ramses Ramirez (Tokyo Institute of Technology) and Lisa Kaltenegger (Carl Sagan Institute, Cornell University), the paper also suggests a possible biosignature near the outer habitable zone edge of hotter stars, one of several results that Alex explores in today's essay. by Alex Tolley Alien world - still from 2001: A Space Odyssey. Credit: Metro-Goldwyn-Mayer (MGM) As noted in previous posts on biosignatures, especially in regards to life prior to...
Looking for biological products in planetary atmospheres is how we'll first study exoplanetary life, assuming it exists. The tools for characterizing atmospheres have already developed to the point that we are examining the gases surrounding some 'hot Jupiters,' and even talking about the movement of clouds -- exoplanet meteorology -- on giant worlds. The hope is that TESS will find targets that we can then investigate with new space telescopes. The way forward is exciting, but my guess is that as we start looking into the atmospheres of transiting planets around nearby red dwarfs, the most accessible targets in the near future, we're going to find ourselves awash in controversy. Did we just find oxygen? Maybe we're on the way to a biosignature detection, but then again, ultraviolet radiation can break down atmospheric water to produce oxygen. For that matter, UV can split carbon dioxide molecules. What about methane? Abiotic methane from geothermal activity on the surface could...
Our current depictions of conditions in the early Solar System involve titanic change, with the giant planets moving inward and then outward, creating gravitational havoc and scattering inner system objects in all directions. Such disruptions doubtless happen in other infant planetary systems and because of them, we can predict a large population of so-called ‘rogue’ planets that move through the galaxy dissociated from any star. Closer to home, there may well be small objects kicked into extreme orbits that bear evidence of these migrations. The ‘grand tack’ hypothesis sees Jupiter forming at around 3.5 AU, well in from its current 5.2 AU orbital position, with migration all the way in to 1.5 AU before a reversal of course and movement outward to its current position. Imagine Jupiter plowing through the asteroid belt -- twice -- and the chaos of its passage, producing a wide scattering in asteroid orbital inclinations and eccentricities. The ‘Nice model’ likewise involves gas giant...
The SETI effort run by Breakthrough Listen is beginning to hit on all cylinders. Yesterday came news that observations at the CSIRO Parkes Radio Telescope in New South Wales have been extended. You may recall that work at the site began in November of 2016, when Parkes joined the Green Bank Telescope (GBT) in West Virginia, USA, and the Automated Planet Finder (APF) at Lick Observatory in California in Breakthrough's search for extraterrestrial signals. Invariably, when I start talking about SETI, I recall James Gunn's masterful The Listeners, written in 1972 but made up of previously published stories on the topic that Gunn melded together with interesting transitions. Here we get a tale of the first detection of a genuine extraterrestrial civilization, the narrative mixing with not just news reports but quotes on SETI and related matters from scientists to philosophers (the technique always reminds me of Dos Passos, but as I've written before, a science fiction reference is John...
How big a role space travel will play in our future is a question with implications for our civilization's intellectual, economic and philosophical growth. It may even be the hinge upon which swings the survival of the planet. But as Centauri Dreams regular Nick Nielsen points out in the essay below, enthusiasts for spacefaring can overlook historical analogies that show us the many ways humans can shape their culture. Numerous scenarios swing into view. An interstellar future may not be in the cards, depending on the choices we make, which is why seeing space travel in perspective is crucial for shaping the exploratory outcome many of us hope to see. By J. N. Nielsen The Role of Spacefaring in Spacefaring Civilizations What is, and what will be, the role of spacefaring in spacefaring civilizations? If we count the present human spacefaring capability as constituting a contemporary spacefaring civilization, the question can be partly addressed by assessing the role of spacefaring in...
Scientists have been saying for some time now that helium should be readily detectable in the atmospheres of gas giant planets -- after all, this is the second-most common element in the universe, and we know it is plentiful at Jupiter and Saturn. The problem has been how to detect it, an issue which this morning's story brings into sharp relief. At the University of Exeter (UK), Jessica Spake has put data from the Hubble telescope's Wide Field Camera 3 to good use, finding an abundance of helium in the upper atmosphere. The planet in question is the puffy WASP-107b, and this marks the first helium detection of the inert gas on an exoplanet. Some 200 light years from Earth in the constellation Virgo, WASP-107b shows little similarity to anything in our own Solar System. It was discovered in 2017 and is one of the lowest density planets yet found, a world that, although roughly the same size as Jupiter, has only 12 percent of its mass. In a tight six-day orbit around its K-class...
Scaling up our space telescopes calls for new thinking. Consider this: The Hubble telescope has a primary mirror of 2.4 meters. The James Webb Space Telescope takes us to 6.5 meters. But as we begin to get results from missions like TESS and JWST (assuming the latter gets off safely), we're going to need much more to see our most interesting targets. Imagine what could be done with a 30-meter space telescope, and ponder the challenge of constructing it. This is what Cornell University's Dmitry Savransky has been doing, developing a NIAC study that looks at modular design and self-assembly in space. Savransky's notions take me back to a much earlier era, when people like Bob Forward talked about massive structures in space that dwarf any engineering project we've yet attempted. Forward saw these projects -- his vast Fresnel lens between the orbits of Saturn and Uranus 1000 kilometers in diameter, for example -- as ultimately achievable, but his primary concern was to be sure the...
Avi Loeb's always interesting work has recently taken us into the realm of target selection for exoplanet surveys. Where should we be putting our time and money in the search for life elsewhere, and what can we do to maximize both the credibility of the investigation and the funding that it demands? These sound like pedestrian matters compared to the excitement of discovery -- finding Proxima b was a lot more exciting than watching any congressional committee debate over NASA's priorities. But Proxima Centauri b, that fascinating world around the nearest star, fits neatly into this narrative, for reasons that contrast nicely with its own nearest neighbors, Centauri A and B. The Centauri stars are an obvious target, and one that Loeb has devoted considerable time to assessing, given his deep involvement with Breakthrough Starshot's study of a mission there. If we find planets around Centauri A or B, are they our priority? Just where does Proxima b fit in? And what of fascinating...
Water delivery to the inner Solar System is crucial for life to develop, for worlds like our own must have formed dry, well within the 'snowline.' We need a mechanism to bring volatiles from the ice-rich regions beyond 3 AU or so, and while much attention has been paid to comets, we've been learning more about asteroids as a second delivery option, for isotopic measurements have shown that Earth's water has similarities to water bound up in carbonaceous asteroids. Focusing on asteroid delivery, Pete Schultz (Brown University) and colleague Terik Daly, a postdoctoral researcher at Johns Hopkins University, have confronted the issues raised by early system impacts in a series of experiments. The results appear in the journal Science Advances. Says Schultz: "Impact models tell us that impactors should completely devolatilize at many of the impact speeds common in the solar system, meaning all the water they contain just boils off in the heat of the impact. But nature has a tendency to...
I usually get up while it’s still dark and take a walk. The idea is to shake the night’s dreams out of my head, listen to the birds waking up and pull in a lot of fresh air, all conducive to thinking about what I want to write that day. Last fall I kept noticing the glow before morning twilight that marked the zodiacal cloud, faint enough to be lost in moonlight and challenging to see when competing with city lights. But catch the right conditions and its diffuse glow is apparent, as in the photograph below, a striking example of zodiacal light’s effect. Image: Sometimes mistaken for light pollution, zodiacal light is sunlight that is reflected by zodiacal dust. It is most visible several hours after sunset on dark, cloudless nights surrounding the spring and fall equinoxes, when the Earth's equator is aligned with the plane of the solar system. Credit: Malcol. What we’re seeing, especially at times when the ecliptic is at its largest angle to the horizon, hence autumn and spring, is...
Back in the late 1970s I didn't know anything about star catalogs. I suppose that, if asked, I would have assumed they were out there -- how otherwise could astronomers do their jobs? But the first catalog of stars that came into my life emerged when I was writing an article about SETI, a field I developed an intense interest in and at that time knew very little about. For the article I needed to identify the closest stars, and thus I stumbled upon the Gliese Catalog of Nearby Stars, and over the course of time became absorbed by the idea of exoplanets. In many ways my first dip into the Gliese catalog began the journey that continues here, because that first SETI article was the forerunner of the kind of writing I have been doing since the turn of the century. In that time our catalogs have grown more and more interesting to me, but none can match today's, the all-sky view of almost 1.7 billion stars that is the result of the European Space Agency's Gaia mission. The second Gaia...
The detection of hydrogen sulfide just above the upper cloud deck of Uranus has received the nods you might expect to rotten eggs, H2S having the odor of such unappetizing objects. But this corrosive, flammable gas is quite an interesting find even if it makes a whiff of Uranian air more off-putting than it already was. Not that you'd live long enough to notice the scent if you happened to be there, as Patrick Irwin (University of Oxford, UK) is quick to note: "If an unfortunate human were ever to descend through Uranus's clouds, they would be met with very unpleasant and odiferous conditions. Suffocation and exposure in the negative 200 degrees Celsius atmosphere made of mostly hydrogen, helium, and methane would take its toll long before the smell." We can leave that excruciating end to the imagination of science fiction writers, among whom I want to mention my two favorite stories about this planet, Geoff Landis' "Into the Blue Abyss" (2001) and Gerald Nordley's "Into the Miranda...
