by Paul Gilster | May 31, 2010 | Missions
One of the most useful technologies the Project Daedalus team lacked when designing its interstellar probe back in the 1970s was the personal computer. Today’s effort to re-visit Project Daedalus can draw on the strength of intercontinental networking for fast communications and widespread computer availability to design a probe differently. It’s exciting to hear that the Project Icarus team plans vIcarus, a ‘virtual’ interstellar mission drawing on the completed Icarus design and ‘flown’ through ongoing computer simulation. Spun out in real time, vIcarus will give designers and the public a chance to follow the mission step by step.
Andreas Tziolas (Variance Dynamical Corporation) discussed the idea on the Project Icarus blog recently, noting that over the next few years, the Icarus team will be creating computational models for propulsion, fault repair, communications, flight through the interstellar medium and all the factors impinging upon the behavior and stability of the spacecraft. Putting all these models into a master program will allow Project Icarus to be launched through cyberspace. Tziolas says a graphical interface will allow visitors to view every detail of the mission.
Obviously, computers allow us to do what would otherwise be impossible. Icarus is not being designed as a vehicle that will be flown in the near future, but as a study that updates the pioneering work of the BIS Daedalus team to show us where the critical systems for an interstellar probe powered by fusion stand today. Tziolas notes how useful vIcarus will be:
The idea for vIcarus came while thinking of the power and computer subsystems, where we imagined the spacecraft making programmed decisions such as fine-tuning the fusion reaction rate and course corrections all while interacting with the interstellar medium. Visualizing this process in real time would be extremely rewarding. Scientifically we could run full system simulations, without the need for statistical analyses and averaging schemes. As an educational tool, we could demonstrate spacecraft operation to students of spacecraft design and visually search for ways of improving on our design. It would indeed be rewarding in itself if, after five years of dedication, our models could be put to the test, having them run in real time for the entire forty year duration of the mission.
From an educational perspective, vIcarus is of obvious interest, and the software could potentially take an open source route for further development after the scientific study of Icarus is complete, allowing competing ideas to be examined and shared. All the models and codes from the Icarus design study will feed back real time information on trajectory, speed, and current command and execution protocols, with the intention being to make vIcarus parallel the decades-long mission to another star that a real Project Icarus would undertake. Such a robust software tool could be inspirational and turn more than a few young minds in the direction of aerospace engineering.
Image: The image shows a mock-up of what the vIcarus web interface may look like, using a Daedalus model as a placeholder for the spacecraft graphic. A central animation depicts the current state of the spacecraft, showing appropriate background and damaged systems. Control panels to the right allow the user to focus on specific subsystems. A virtual mission control room is depicted beside a running graphic of Icarus within a star field. Clicking on various terminals within the mission control room brings up subsystem performance graphs, maps, fuel burn ratios, current speed, etc. In the mean time, a dashboard displays general mission information, such as current speed, location, mission time, current status, etc. The message bar at the bottom of the frame shows the current command and control sequence vIcarus is addressing. Credit: Andreas Tziolas / Project Icarus team.
vIcarus is also discussed in the first paper released by the design team, now available on the arXiv server. The original Project Daedalus reports were consolidated into a landmark final report that summarized the analysis. Icarus will do the same, with this first paper being the prelude to a series of studies by the design team on every issue applicable to the mission. The new paper runs through propulsion issues and explains the terms of reference for the project, noting in particular the team’s decision to explore deceleration of the spacecraft at destination in order to provide a longer encounter time with the planetary system there. Daedalus used mini-probes for this purpose, but magnetic sail braking remains a distinct possibility for Icarus.
Icarus means plenty of late hours for its designers. From the paper:
It has been estimated that with 20 volunteer designers Project Icarus will require around 35,000 total man hours spread over a five year research programme culminating in the final design. For comparison, Project Daedalus began on 10th January 1973 and the final reports were published 15th May 1978 taking just over 64 months or over 5 years. The study reports state that around 10,000 man hours were used by 13 core designers and several additional consultants.
The paper offers the overview, and is especially interesting in terms of fusion alternatives. Whereas Daedalus looked to mine the atmosphere of Jupiter for the needed helium-3 (Daedalus employed Deuterium/Helium-3 fusion), the Icarus team will consider planetary alternatives (Uranus is particularly interesting because of its lower gravity well). And while Daedalus was powered by inertial confinement fusion (ICF) driven by electron beam, Icarus will be considering options like Antimatter Catalyzed Micro Fusion, a beam of anti-protons injected into a fusion fuel. Researching all these ideas will help the team define the current state of the art.
The paper is Long et al., “Project Icarus: Son of Daedalus. Flying Closer to Another Star,” available here.
by Paul Gilster | May 28, 2010 | Astrobiology and SETI
Is there a ‘Galactic Club’ of civilizations to which our species might one day deserve admission? If so, the club’s members are being mighty quiet about their existence. But David Schwartzman (Howard University) thinks it might be out there. In that case, he finds three possible explanations for the ‘Great Silence,’ our failure to detect any signs of extraterrestrial intelligence in the last fifty years. He rejects the first, the notion that we are alone in the galaxy — life is, in his view, all but inevitable in the universe, and he’s keen on the idea of high levels of intelligence developing on many worlds, as he tells us in this article in Astrobiology Magazine:
I have argued that encephalization – larger brain mass in comparison to body mass — and the potential for technical civilizations are not very rare results of self-organizing biospheres on Earth-like planets around Sun-like stars. Biotically-mediated climatic cooling creates the opportunity for big-brained multicellular organisms, such as the warm-blooded animals we observe on our planet. Note that several such animals have now been shown to pass the “mirror test” for self-consciousness: the great apes, elephants, dolphins and magpies, and the list is growing.
The second explanation is that the advanced civilizations of our galaxy are simply unaware of our existence. But this seems unsound as well. Assume that but a single planet among the huge number of Earth-like worlds Schwartzman assumes fills the galaxy becomes home to an advanced technical civilization, one capable of spreading among the stars at sub-light speeds. Such a civilization would have had billions of years to develop and expand before life appeared on our planet, and if it set out to build the Encyclopedia Galactica by using Bracewell probes, it would have placed surveillance stations throughout the galactic disk. He’s careful to note that no faster-than-light technologies are assumed in any step of this expansion.
Back Into Quarantine
We’re left with option three, which is that the ‘Galactic Club’ is avoiding communicating with us on the grounds that our culture is too primitive, the so-called ‘quarantine’ explanation. Now you can read what you like into the notion of ‘primitive’ — the article is freighted with the author’s assumptions on the matter. The key question is this: IF an extraterrestrial civilization is aware of us and uncommunicative, what ramifications would this have for our SETI search? For it seems obvious that a culture explicitly avoiding contact will not set up a beacon specifically targeting our planet. Thus the basic premise of most observational SETI disappears.
Paul Davies has a take on this in his new book The Eerie Silence (Houghton Mifflin Harcourt, 2010), one that Schwartzman examines and I’ll also quote here:
“…we should search for any indicators of extraterrestrial intelligence, using the full panoply of scientific instrumentation, including physical traces of very ancient extraterrestrial projects in or near the solar system. Radio SETI needs to be re-oriented to the search for non-directed beacons, by staring toward the galactic center continuously over months or even years, and seeking distinctive transient events (‘pings’). This ‘new SETI’ should complement, not replace, traditional radio and optical SETI.”
That interesting shift of strategy is well examined in Davies’ book, which I can’t commend too highly. But Schwartzman’s notion is that there won’t be any non-directional beacons, either, assuming an extraterrestrial civilization that does not alert others to its presence. His answer, first proposed back in 1988 along with the radio astronomer Lee Rickard, is that SETI should go after leakage radiation from late-stage primitive civilizations like our own. Leakage radiation is very hard to detect and would presumably only appear in a brief window in a culture’s evolution, as appears to be happening in our own, but Schwartzman believes such a search at galactic scale could be productive:
The technical requirements for a galaxy-wide search are dictated by the size of the radio telescope, with the detection range proportional to the effective diameter of the telescope. A large enough radio telescope situated in space could potentially set meaningful upper limits on the rate of emergence of primitive Earth-like civilizations (‘N/L’ in the Drake equation), without ever actually detecting the leakage radiation of even one ET civilization.
The Aspirations of Conjectural Beings
That, of course, would be useful information, but unfortunately the 1988 paper goes into the costs of creating the needed dish, a telescope with a diameter of 500 kilometers that — in 1988 dollars! — weighs in at $10 trillion. It is not a project Schwartzman expects to be implemented, for obvious reasons, although he opines that a ‘newly mature’ world might one day choose to build it. But let’s assume that $10 trillion adjusted for inflation is too much to ask. We’re left with Davies’ notion (and that of Michael Papagiannis before him) that evidence of a Bracewell probe might be lurking in our own Solar System, if we have the wherewithal to find it.
Short of making that detection, contact with the ‘Galactic Club’ seems to be a matter of waiting for the Club to contact us; i.e., restructuring our own civilization so that extraterrestrials will find it to their liking. It’s a prospect unlikely to satisfy those with the restless urge to push SETI to its limits using buildable technology. And it’s hard to know how to re-structure a civilization so that it would satisfy the entrance requirements to a club populated by extraterrestrials whose existence is purely conjectural. Schwartzman thinks an end to war and poverty will do the trick, laudable goals, to be sure, but he assumes that ETI’s aspirations largely parallel our own.
by Paul Gilster | May 27, 2010 | Deep Sky Astronomy & Telescopes
We sometimes forget the conditions under which great images get made. A few years back, in one of the earliest posts on his systemic site, Greg Laughlin (UC-Santa Cruz) showed the image you see below, a famous shot made by the Hubble telescope of the ‘Sombrero Galaxy,’ M104. It’s obvious why this image is a classic. As Greg notes, “The glow of its halo makes the idea of 100 billion stars seem comprehensible.”
But look at the follow-up picture, which Greg made to demonstrate his point. While the Hubble image is a long CCD time-exposure to light gathered by a 240 cm mirror, your own eyes would deliver something considerably different. From 300,000 light years, M104 is noticeable only as a dim and lurking shape.
You can see the same effect for yourself if you find the Andromeda Galaxy, subtening an angle larger than the full Moon in our skies but as evanescent as smoke when viewed by the naked eye. The dim, fuzzy object is out there if you know where to look, but it’s not exactly impressive without a telescope.
The Intergalactic Wanderer
I used to imagine settings beyond the galaxy, where the great pinwheel of the Milky Way would dominate the sky, but you’d have to be a lot closer than Andromeda’s two million light years to get a true spectacle. Suppose, though, there were a way to leave the galaxy, something like what Ray Villard talks about in a recent article. We know that every 100,000 years or so the supermassive black hole at the galactic center ejects a star at speeds high enough to leave the galaxy. These ‘hyper-velocity’ stars are an interesting study in their own right, having velocities of over 1000 kilometers per second, compared to the more sedate 100 kilometers per second of the average star. What exactly causes a hyper-velocity star to move like this?
I checked in with the Hyper-Velocity Star Project to learn the following:
These stars are so fast that the gravitational pull of our galaxy is overcome. They reach the escape velocity and hurtle out of the galaxy. There are a few theories about what makes them achieve this velocity. They could be the result of a supernova as is believed to be the case of HVS #3 [see this article] that came from the Large Magellanic Cloud. They could be the result of a binary star system passing too close to the gravitational well of the super massive black hole at the center of our galaxy. One of the stars of the system gets caught by the huge gravity well and the other one is thrown free at very high speed achieving escape velocity.
We know of sixteen confirmed hyper-velocity stars, and the thinking is that there are about 1000 associated with the galaxy. The Hyper-Velocity Star Project is searching for more.
Into the Deepest Night
What captured Ray Villard’s attention was the idea that a Sun-like star in a binary system might be ejected, carrying its planetary system along with it. What would the civilization that arose on the surface of such a planet think about the night sky? As Ray notes, their sky would be largely black, for the receding planetary system would be near few stars as it moved beyond the halo. Ray talks about the center of the Milky Way looking like a ‘fuzzy headlamp,’ with the spiral arms, though covering a large part of sky, emerging ghostly and faint from the nucleus.
Alien sky lore would have no constellations in the absence of stars. All mythology would be built around the nighttime wispy pinwheel with its cycloptic “glowing eye.” Alien sky watchers would duly note the appearance of brilliant star-like novae and supernovae in the spiral disk. These might as first be construed as omens or messages from the gods, or fuel other superstitions. But fireworks in the galactic disk would be dutifully recorded.
As to technology, we can only speculate, but imagine what happens after this civilization develops telescopes and spectroscopy:
The development of telescopic astronomy would allow star clusters and nebulae to be resolved. It would be as big a revelation as when Galileo first observed the Milky Way in 1609. Bright blue stars would be seen sprinkled across in the Milky Way’s spiral arms. Spectroscopy would show that the pinpoints are made of the same stuff the alien’s parent star is. But it would take a great leap of imagination to connect the tiny pinpoints to the brilliant glowing orb of their star.
Emerging Science in the Void
Over the eons, our runaway civilization, bound ever outward, might notice that the galaxy that filled its skies was dimming, but would it ever be able to relate its single star to the billions on display through its newly developed instruments? Ray imagines such a society remaining pre-Copernican, but I’m not so sure. In any case, scientists that did figure out their place in the cosmos might wonder what living beings inside a galaxy would imagine, and how they would ever sort out the shape of the star swarm within which they found themselves.
Science finds its ways and I suspect our lonely intergalactic friends would eventually relate distant galaxies to the one nearest them, always wondering how they happened to be cast adrift and learning to question whether the great sky pinwheel was once home to their star. But ponder the idea of interstellar flight in this setting. Would it even be imagined? If the distance to Alpha Centauri seems almost inconceivably far to us, how much more so would the outcasts find the hundreds of thousands of light years back to the stellar city?
by Paul Gilster | May 26, 2010 | Deep Sky Astronomy & Telescopes
What a glorious image WISE has given us. The Wide-field Infrared Survey Explorer has finished three-quarters of its infrared map of the entire sky, with the final images scheduled for July, after which time the spacecraft will spend three months on a second survey before its solid-hydrogen coolant (needed to keep its infrared detectors chilled) runs out. The public WISE catalog will be released a little over a year from now, but we can already marvel at spectacles like the Heart and Soul nebulae, seen below. Be sure to click on the image, presented at the American Astronomical Society meeting in Miami, to enlarge it and spend some time among the newly forming stars.
Image: Located about 6,000 light-years from Earth, the Heart and Soul nebulae form a vast star-forming complex that makes up part of the Perseus spiral arm of our Milky Way galaxy. The nebula to the right is the Heart, designated IC 1805 and named after its resemblance to a human heart. To the left is the Soul nebula, also known as the Embryo nebula, IC 1848 or W5. The Perseus arm lies further from the center of the Milky Way than the arm that contains our sun. The Heart and Soul nebulae stretch out nearly 580 light-years across, covering a small portion of the diameter of the Milky Way, which is roughly 100,000 light-years across. Credit: NASA/JPL-Caltech/UCLA.
The beauty of WISE for this kind of study is that it’s working in the infrared, and thus able to penetrate into cool, dusty crevices in the dust surrounding these star factories. It’s important, then, to keep in mind that we’re not in visible light here. In this image, green and red (mostly light from warm dust) represents light at 12 and 22 microns, while blue and cyan show infrared at wavelengths of 3.4 and 4.6 microns (dominated by light from stars). With that caveat in mind, we can marvel anew at the prodigious spectacle that accompanies stars being born.
No word yet on the brown dwarf possibilities in nearby space, of particular interest to Centauri Dreams readers, but we’re getting no shortage of images, with some 960,000 having been beamed down to date. And let’s not forget WISE’s utility in spotting asteroids. The spacecraft has tagged 60,000 of them thus far, of which about 11,000 are newly discovered, and 50 of these are near-Earth objects, of obvious significance as we continue to identify potential impact threats. The NEOWISE program studies and catalogs the asteroids WISE is finding.
“Our data pipeline is bursting with asteroids,” said WISE Principal Investigator Ned Wright of UCLA. “We are discovering about a hundred a day, mostly in the Main Belt.”
Once identified, new asteroids are reported to the IAU’s Minor Planet Center in Cambridge MA, and a network of ground-based telescopes follows up and confirms the finds. Although it hasn’t yet found an asteroid that would be too dark for visible-light detection from the ground, WISE’s infrared capabilities give it more accurate measurements of an asteroid’s size. Researchers expect that by mission’s end, WISE will have found between 100 and 200 new near-Earth objects and will offer size and composition profiles for all.
Two aspects of the WISE mission particularly pique our interest at Centauri Dreams. Tracking down thus far unidentified brown dwarfs near the Sun is obviously consequential — a brown dwarf at 3 light years would make a tempting target for study and, one day, an interstellar probe, being closer to us than the Alpha Centauri trio. But WISE also investigates the Trojan asteroids, which track Jupiter’s orbit around the Sun in two groups, one in front of and one behind the giant planet. 800 Trojans have been observed thus far, and their study may offer insights into the formation of gas giants both in our system and in others.
In terms of protecting our planet, WISE is also a comet hunter, having seen more than 72 so far, a dozen of them new. This animation gives you a sense of WISE’s operation, showing as it does the objects that come near the Earth, along with the comets found thus far. Measuring cometary orbits helps us understand what triggers their movement from long-period orbits (or short-period orbits within the system) and pulls them in toward the Sun. The search for a large, hidden perturber, possibly a gas giant, in the Oort Cloud will benefit from this information, but even in its absence, we need to learn more about how comets move in order to understand how they shaped our Solar System and played a role in bringing volatiles to the Earth.
by Paul Gilster | May 25, 2010 | Exoplanetary Science
It’s AAS week in Miami, and the American Astronomical Society usually gives us plenty to talk about. Inclined orbits, for one thing. In our Solar System, the process of planetary formation seems relatively intuitive. The eight major planets orbit largely in the same plane, reinforcing the idea that the cloud of gas that collapsed to form the Sun contained leftover material that formed into a planet-yielding disk. We can point to outer system objects like Pluto (and certainly Sedna) as exceptions, but they’re much further out and subject to gravitational influences that this model can account for.
But as Barbara McArthur (University of Texas at Austin) and team told an AAS session yesterday, the star Upsilon Andromedae A has yielded a different result. We already knew that three Jupiter-class planets orbited the star, some 44 light years away and a bit younger and more massive than our Sun. But McArthur’s team now has determined the mass of two of the three known planets, and has produced the startling finding that the orbits of planets c and d are inclined by 30 degrees with respect to each other.
Image: An artist’s illustration of the Upsilon Andromedae A system, where three Jupiter-type planets orbit the yellow-white star Upsilon Andromedae A. Astronomers have recently discovered that not all planets orbit this star in the same plane, as the major planets in our solar system orbit the Sun. The orbits of two of the planets are inclined by 30 degrees with respect to each other. Such a strange orientation has never before been seen in any other planetary system. This surprising finding will impact theories of how planetary systems form and evolve, say researchers. It suggests that some violent events can happen to disrupt planets’ orbits after a planetary system forms. The discovery was made by joint observations with the Hubble Space Telescope, the Hobby-Eberly Telescope, and other ground-based telescopes. Credit: NASA, ESA and A. Feild (STScI) / B. McArthur (University of Texas at Austin).
This is a fascinating find, and represents the first time that the mutual inclination of two planets orbiting another star has ever been measured. And McArthur points to the work’s significance:
“Most probably Upsilon Andromedae had the same formation process as our own solar system, although there could have been differences in the late formation that seeded this divergent evolution. The premise of planetary evolution so far has been that planetary systems form in the disk and remain relatively co-planar, like our own system, but now we have measured a significant angle between these planets that indicates this isn’t always the case.”
The jury is out on the cause of the inclined orbits, but various scenarios emerge including planetary migrations inward toward the star and their accompanying interactions, or the ejection of planets from the system altogether. Complicating all this is the fact that Upsilon Andromedae has a companion binary, Upsilon Andromedae B. Rory Barnes (University of Washington) adds this:
“Our dynamical analysis shows that the inclined orbits probably resulted from the ejection of an original member of the planetary system. However, we don’t know if the distant stellar companion forced that ejection, or if the planetary system itself formed in such a way that some original planets were ejected. Furthermore, we find that the revised configuration still lies right on the precipice of instability: The planets pull on each other so strongly that they are almost able to throw each other out of the system.”
The Upsilon Andromedae A work combines astrometric data from Hubble with radial velocity data from several ground-based telescopes, enabling a determination of planetary masses that turns previous thinking on its head. We now learn that planet c has a minimum mass of 14 Jupiters, while planet d has 10, quite an upgrade from the earlier minimum masses of 2 and 4 Jupiters respectively. There are also hints of a fourth planet in a long-period orbit (still unconfirmed) and confirmation that Upsilon Andromedae is indeed a binary, its companion being a red dwarf in an orbit that has yet to be determined. An occasional close pass by such an object could provide the gravitational perturbation needed to adjust planetary orbits.
Also from the AAS meeting, Wired.com adds this interesting and much wider ranging speculation about the effect of planetary migration on habitable zones, based on computer simulations Barnes has run and will report on at the meeting:
Barnes’ simulations predicted more-dire consequences for extrasolar planets near the edge of their habitable zones, though. If the planet is on the cooler edge of the habitable zone, it could go through cycles of freezing and thawing. If it’s on the warmer side, the temperature could fluctuate from comfy to boiling from one millennium to the next.
“The inner edge is much more dangerous,” Barnes said. All the water could boil off and be lost forever, or the warming planet could experience a “runaway greenhouse” effect and end up a scorched wasteland like Venus.
But it’s not all bad news. Barnes suggests that some planets we might dismiss as snowballs could just be going through an eccentric phase.
“Our own Earth has gone through stages of glaciation — we call them snowball Earth phases — and we managed to pull out of it,” he said. “On a planet like that, on the outer edge, you will have reservoirs of life, and there will be habitats that will persist.”
Reservoirs of life and habitats that will persist in a system where planetary neighbors play havoc with a terrestrial world — there’s a science fiction setting for an ambitious writer to tackle! As for Upsilon Andromedae A, the work will appear in the Astrophysical Journal on June 1, where we’ll be able to go over it in more detail. Meanwhile, our notions of habitability experience yet another challenge, making us realize that even when we do start identifying seemingly terrestrial worlds around other stars, our early observations may not be sufficient to make the call on where and how a planet might support life.