Now that NASA’s Institute for Advanced Concepts (NIAC) is back in business, I’m reminded that it was through NIAC studies that both Gerald Jackson and James Bickford introduced the possibility of harvesting antimatter rather than producing it in huge particle accelerators. The idea resonates at a time when the worldwide output of antimatter is measured in nanograms per year, and the overall cost pegged at something like $100 trillion per gram. Find natural antimatter sources in space and you can think about collecting the ten micrograms that might power a 100-ton payload for a one-year round trip mission to Jupiter. Contrast that with Juno’s pace!
That assumes, of course, that we can gather enough antimatter to test the concept and develop propulsion systems — doubtless hybrids at first — that begin to draw on antimatter’s power. Bickford (Draper Laboratory, Cambridge MA) became interested in near-Earth antimatter when he realized that the bombardment of the upper atmosphere of the Earth by high-energy galactic cosmic rays should result in ‘pair production,’ creating an elementary particle and its antiparticle.
A planetary magnetic field can hold such particles in place, producing a localized source of antiprotons. The detection of antimatter in this configuration has now been confirmed by a team of researchers using data from the Pamela satellite (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics). In fact, Pamela picks up thousands of times more antiprotons in a region called the South Atlantic Anomaly than would be expected from normal particle decays.
Image: A cross-sectional view of the Van Allen radiation belts, noting the point where the South Atlantic Anomaly occurs. Credit: Wikimedia Commons.
We could go so far as to talk about an ‘antimatter belt’ around the Earth, as the paper on this work explains:
Antiprotons are… created in pair production processes in reactions of energetic CRs [cosmic rays] with Earth’s exosphere. Some of the antiparticles produced in the innermost region of the magnetosphere are captured by the geomagnetic field allowing the formation of an antiproton radiation belt around the Earth. The particles accumulate until they are removed due to annihilation or ionization losses. The trapped particles are characterized by a narrow pitch angle distribution centered around 90 deg and drift along geomagnetic field lines belonging to the same McIlwain L-shell where they were produced. Due to magnetospheric transport processes, the antiproton population is expected to be distributed over a wide range of radial distances.
The McIlwain L-shell referred to above describes the magnetic field lines under investigation. As to the South Atlantic Anomaly, it is here that the inner Van Allen radiation belt approaches the Earth’s surface most closely, which creates a higher degree of flux of energetic particles in the region. It turns out to be quite a lively place, as this Wikipedia article on the matter makes clear:
The South Atlantic Anomaly is of great significance to astronomical satellites and other spacecraft that orbit the Earth at several hundred kilometers altitude; these orbits take satellites through the anomaly periodically, exposing them to several minutes of strong radiation, caused by the trapped protons in the inner Van Allen belt, each time. The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. The Hubble Space Telescope does not take observations while passing through the SAA. Astronauts are also affected by this region which is said to be the cause of peculiar ‘shooting stars’ (phosphenes) seen in the visual field of astronauts. Passing through the South Atlantic Anomaly is thought to be the reason for the early failures of the Globalstar network’s satellites.
What we’re seeing in the new work is that the Van Allen belt is indeed confining antiparticles in ways that the earlier NIAC work suggested. The antiprotons eventually encounter normal matter in the Earth’s atmosphere and are annihilated, but new antiparticles continue to be produced. The question is whether there may be enough antimatter here for hybrid missions like Steven Howe’s antimatter sail, which uses tiny amounts of antimatter to induce fission in a uranium-infused sail. James Bickford, in his Phase II study at NIAC, talked about a collection scheme that could collect 25 nanograms per day, using a plasma magnet to create a magnetic scoop that could be deployed in an equatorial Earth orbit, one that would trap incoming antiprotons.
Antimatter trapped in Earth’s inner radiation belt offers us useful savings, if Bickford is right in thinking that space harvesting will prove five orders of magnitude more cost effective than antimatter creation here on Earth. I also noticed an interesting comment in his Phase II NIAC report: “Future enhanced systems would be able to collect from the GCR [galactic cosmic ray] flux en route to further supplement the fuel supply.” Obviously, exploiting antimatter trapped near the Earth and other Solar System worlds assumes a robust space-based infrastructure, but it may be one that will finally be able to bring antimatter propulsion into a new era of experimentation.
James Bickford’s Phase II report is titled “Extraction of Antiparticles Concentrated in Planetary Magnetic Fields” (online at the NIAC site). Back in 2007 I looked at this work in three connected posts, which may be useful in putting all this in context:
The Pamela work is found in Adriani et al., “The discovery of geomagnetically trapped cosmic ray antiprotons,” Astrophysical Journal Letters Vol. 37, No. 2, L29 (abstract / preprint). See also Gusev et al., “Antiparticle content in the magnetosphere,” Advances in Space Research, Volume 42, Issue 9, p. 1550-1555 (2008). Abstract available.
The Project Icarus team has founded a non-profit research organization called Icarus Interstellar, its goal being to ‘foster research into those necessary technologies which can make interstellar research a reality’ through the study of such topics as fusion, nanotechnology, advanced power sources and other critical drivers for interstellar flight. We’ve tracked Icarus here from the beginning, when it emerged as an ambitious attempt to update and re-think the original Project Daedalus starship design of the 1970s. Taking fusion as its propulsion mechanism, the Icarus team now seeks to analyze and design a probe in terms of recent advances in numerous fields.
How do you go about designing a starship? Something this speculative, which must of necessity rely on extrapolations of where technology is going, happens outside the normal 9-5 workday. Centauri Dreams readers know that the Icarus team is composed of volunteers, most of whom work and exchange ideas over the Internet — only a few have actually been in the same room together. But all this is about to change. The team is now launching a fundraiser with the goal of supporting students and researchers in traveling to the DARPA/NASA 100-Year Starship Symposium, which will be held from September 30 through October 2 in Orlando, FL.
The team’s Web page supporting this effort is here, and the video below, assembled by current project leader Andreas Tziolas, offers background information. It’s especially noteworthy that Icarus now includes an active student designer program that focuses on training future generations in interstellar spacecraft design. Any funds raised through the new site will flow first to student designers who may lack the financial ability to travel to Orlando for the event.
Watching the Icarus effort grow has been inspirational –the project is now up to 35 researchers who have dedicated thousands of hours to studying the scientific constraints on a spacecraft that must attain speeds far beyond anything we have ever flown. The challenge is to design a craft that could explore a solar system within 15 light years of Earth, which involves speeds of at least 10 percent of the speed of light. We can contrast that with the current state of the art. Voyager 1, as I write this, is some 17,630,411,456 kilometers from the Sun, making about 17 kilometers per second. At that rate, 77,000 years would pass before it could cover the distance to the Alpha Centauri stars. A flyby at 10 percent of lightspeed would take less than fifty years.
Conceived as a joint venture of the Tau Zero Foundation and the British Interplanetary Society, Project Icarus has managed six conference appearances as well as 60 reports and publications in the 18 months it has been in existence, a tribute to the entire team, but especially to its first three leaders, Kelvin Long, Richard Obousy and Andreas Tziolas. If you’re not familiar with the nuts and bolts of the Icarus effort, the breakdown of its 20 research modules is available online. We now look toward Orlando and the 100 Year Starship Symposium, where Icarus team members, Tau Zero practitioners and others in the interstellar community will soon gather.
The launch of the Juno spacecraft last Friday gets us back in business around the Solar System’s largest planet, but also has useful exoplanet implications. To understand why, consider just one of the instruments carried aboard the spacecraft. The Jupiter Energetic-particle Detector Instrument (JEDI) is designed to measure how energetic particles flow through Jupiter’s magnetosphere and interact with its atmosphere. Developed at Johns Hopkins Applied Physics Laboratory, JEDI will be looking at the interactions that produce the most powerful auroral phenomena in our system, and what we will learn has broad applications.
After all, new tools like the Low Frequency Array (LOFAR) are coming online, bringing hitherto unavailable sensitivity to radio frequencies below 250 MHz. Not so long ago, Jonathan Nichols (University of Leicester) proposed using LOFAR to look for aurorae similar to those on Jupiter in exoplanetary systems. In fact, his research shows that gas giants in orbits up to 50 AU might be detectable from Earth even if their host star is as far as 150 light years from our planet. That’s a useful addition to our toolkit, for gas giants in wide orbits take a long time to identify using radial velocity methods, which are much more sensitive to the massive tug of a closer in ‘hot Jupiter.’
Image: NASA’s Juno spacecraft is shown in orbit above Jupiter’s colorful clouds in this artist’s rendering. Juno will arrive at Jupiter in 2016 to study the giant planet from an elliptical, polar orbit. The spacecraft will repeatedly dive between the planet and its intense belts of charged particle radiation, coming only 5,000 kilometers (about 3,000 miles) from the cloud tops at closest approach. Credit: NASA/JPL-Caltech.
The first spacecraft designed explicitly for a magnetic mapping mission, Juno will be operating in a tough environment, one in which electrons, protons and ions are energized by the planet’s fast rotation. Other than the Sun, no other destination NASA has visited presents such radiation challenges. In this orbit, Juno will need to take advantage of a protective shield made of titanium to preserve its sensitive electronics. This ‘vault’ weighs about 200 kilograms and should dramatically extend the life of the spacecraft’s instruments. Juno will circle Jupiter’s poles for a year after arrival in the summer of 2016, the choice of orbit adding its own radiation protection — the spacecraft will spend little time in the intense radiation belts around Jupiter’s equator.
The elliptical orbit will bring Juno closer to the giant planet than any other spacecraft, its polar orbits covering the entire globe during the course of an Earth year. At its closest, the spacecraft will feel the full brunt of the magnetic field, some 10 to 12 Gauss (Earth’s field is about half a Gauss), while further out — Juno will range farther out than the orbit of Callisto — it should encounter a field 10 million times weaker. Each of its magnetometers is equipped with two star cameras to determine the sensor’s orientation in space, allowing exquisite accuracy in measurement. Variations in the magnetic field will help scientists visualize how the planet’s magnetic system operates and offer insight into the planetary dynamos of gas giants.
But back to the aurorae and how they are formed. Barry Mauk (JHU/APL) is lead investigator for JEDI:
“JEDI’s sensors will be trained on the higher-energy particles that help to generate Jupiter’s aurora, that heat and ionize Jupiter’s upper atmosphere, and that offer clues to the structure of Jupiter’s near-planet space environment. We really want to know what happens in the aurora that causes these particles to accelerate to such high energies, and Juno will be the first spacecraft to fly within the region where this acceleration actually takes place.”
The polar orbit will be traversed 33 times as the spacecraft uses JEDI and its eight other science instruments and numerous sensors to probe the atmosphere and magnetosphere while looking for signs of a solid planetary core. Steven Levin (JPL) explains how the polar orbiter will be able to do more than simply investigate Jupiter’s active aurorae:
“Mapping Jupiter’s magnetic field is one of the very few ways available to learn about Jupiter’s deep internal structure. That’s because Jupiter’s atmosphere is compressed so much by its powerful gravity field that it becomes impenetrable to most sensing techniques. In addition, Jupiter may be the best place in the solar system to study how planetary magnetic fields are generated.”
In addition to the science instruments, Juno carries three figurines onboard: A 1.5-inch likeness of Galileo Galilei, a statue of the Roman god Jupiter and one of his wife Juno. But a plaque dedicated to Galileo, also on the spacecraft, is what caught my attention. Provided by the Italian Space Agency, the diminutive plaque measures just 71 by 51 millimeters (2.8 by 2 inches) and is made of flight-grade aluminum with a weight of six grams. Bonded to Juno’s propulsion bay, the plaque depicts a self-portrait of the Italian astronomer and also includes a famous passage he wrote in 1610 recounting his observations of the giant planet and its largest moons:
“On the 11th it was in this formation — and the star closest to Jupiter was half the size than the other and very close to the other so that during the previous nights all of the three observed stars looked of the same dimension and among them equally afar; so that it is evident that around Jupiter there are three moving stars invisible till this time to everyone.”
Thus an account of the discovery of large Jovian moons is now on its way to the planet Galileo did so much to reveal to humanity. It’s also worth remembering that Juno will be equipped with three huge solar panels, making it the most distant probe ever to be powered by the Sun. Fully extended, the probe will be over 18 meters wide as it soaks up as many solar photons as possible from a distance of 800 million kilometers from the Sun. We’ll have to learn as much as we can from Juno in relatively short order, for the mission is designed to survive in its Jovian orbit for little more than a year.
It occurred to me, after I wrote the post on impartiality and read the resulting comments , that a few other perspectives need to be shared. These encompass the necessity of inspiring visions, playfulness, complimentary contrasts, and tolerance for imperfection. And following that, I realized it was about time for another status update on Tau Zero.
Perfectionism is a neurosis that runs in my family. My dad had it. I have it. My wife and her mom had it. And now my daughters are dealing with it. I see it in many colleagues too. Perfectionism is when striving for ultimate quality exceeds striving for utility. It occurs most when we succumb to rhetoric about ‘excellence’ instead of utility and creativity. At NASA, the term “gold brick” was used to describe this.
I mention this because I’ve been making those same mistakes again while trying to convert Tau Zero from a volunteer, donation-based network into a fully functioning nonprofit corporation. Many of you have noticed the lack of updates on our public Tau Zero web pages (www.tauzero.aero). We have also not yet succeeded in bringing in sufficient funds to implement our next-step plans. While some of this is due to external circumstances and my learning curve of transitioning from a government worker into an entrepreneur, some of these shortcomings are due to my own perfectionism. I’ve been focusing too much on getting our next-steps “just right” to the point where I have not gotten things done. My apologies to our supporters. With this posting, changes are underway.
While lamenting on our shortcomings, I took comfort in seeing that Tau Zero is not alone in dealing with such issues. The Journal of the British Interplanetary Society has fallen about a year behind schedule and is still catching up. SETI failed to plan for operational funds for their telescope array, even though they succeeded in getting funds to build the array. The Planetary Society did not succeed at launching their first solar sail mission. And then there is Congress’, the President’s, and NASA’s failing to devise a sustainable space program. This also brings back memories from NASA of meetings where more resources were spent trying to eliminate waste than the amount being wasted (comparing labor cost of those meetings to the topic’s dollars).
Such striving for increased efficiency is more prudent and attainable when producing the same product, over and over (Cola?), than it is in these other types of organizations where each are attempting something that has never been done before. Pioneering work and perfectionism are not a healthy combination.
Bottom line, such imperfections are common. I’ll even go so far as to assert that they are an unavoidable consequence of human endeavors, especially those that are charting new ground. That said, it is a part of our human condition that I am still trying to accept in myself. And with that, I appreciate your patience as I bring Tau Zero into a new, more active era.
Where Tau Zero is Today
Here now is a list of activities of Tau Zero and their status.
(1) GRADUATE STUDENT PROJECTS: One of the recent set of comments on Centauri Dreams was about whether to create an “Interstellar Institute.” Since Tau Zero is not yet bringing in the degree of resources needed to create an institute, and because such an entity might not be the most effective way to spur wide-spread progress, an intermediate, alternative tactic is being implemented. Rather than creating one institute, we are looking to encourage graduate students everywhere to take on some of the unsolved, next-step issues of star flight as their thesis and dissertation topics (covering, “What’s out there?” “How to get there?” and “What does this mean for humanity?”). The first such thesis is already underway, at the USAF Institute of Technology.
Finding interested students is easy. Defining suitable thesis topics to consider and then getting my practitioners lined up to help get the students started, is challenging. Establishing working relations with the universities (their advisor must agree to the thesis topic) is even harder. I’ve started establishing working relations with other universities so that we can jointly apply for grants both for the student and to help pay for the services of our assisting practitioners. It is slow going, but things look promising. I feel this tactic will spur greater progress and broaden opportunities overall and for less cost and effort than creating a Interstellar Institute. I know a lot of students have asked about this. Bear with me as we work through the gory details of making it happen.
(2) MEMBERSHIPS: We are preparing to shift Tau Zero from a ‘Donation-only’ forum to one with annual memberships (est $55). This is to help both with revenue generation and to spur a more productively interactive community. Preparations are underway to: Set up the automatic database required for such actions, include volunteer coordination with that information, and create member benefits (newsletter, free downloads of practitioner presentations, and discounts on Tau Zero emblazoned merchandise).
(3) TAU ZERO STORE: In part to offer member goodies, and for revenue generation, and because we’ve been asked over and over again to offer t-shirts, mugs, and patches, we are setting up a store and designing products. We are also working to prepare “special reports” for sale that translate the journal papers that our practitioners publish into more accessible and readable documents for the non-specialist (this is NOT easy).
(4) REVAMPING TZF WEB: The glitch that blocked editing-access to our public website has been fixed, but creating new content is taking longer than expected. Producing content is easy. Producing digestible, meaningful content that is well organized is harder. We have created a private workspace where our practitioners can jointly prepare content in a wiki-style manner for later posting.
(5) ADVANCING THE STATE OF ART: Many of our practitioners keep making progress on interstellar challenges in their day jobs and on their own time. When they publish, Paul Gilster writes about their work, here, on Centauri Dreams. Related to that, we are asking several of the chapter authors from Frontiers of Propulsion Science to submit Centauri Dreams articles about those chapters and any follow-on work. This includes me writing about space drives.
(6) NETWORKING: Although Tau Zero has an abundant collection of space propulsion and power professionals, we are weak in areas of the humanities, and colony ship technology. I hope to meet more people in these disciplines at the 100-Year Starship Symposium. We are also weak regarding simple administrative support, but have recently made some headway there.
Here now is our current list of practitioners. For Tau Zero purposes, the word practitioner has a specific meaning. Practitioners of TZF work together to support the primary mission to pursue advances beyond the focus of other space organizations, using the challenge of interstellar flight as the driver for revolutionary progress. It is desired that practitioners follow their own instincts and make progress in their respective disciplines. When more than one practitioner shares the same interest/discipline, we urge collaboration to avoid duplication of effort. Better still, we suggest pooling of resources to make more of an impact.
ALSO – here is the opportunity to mix disciplines. For example, to convey complex sci-tech to the public in a responsible manner (factual, non-sensationalist, and absent hype or disdain), the journalists and artists on this list are willing to help the scientists and engineers. Reciprocally, the journalists want better content for their work and can call upon the scientists and engineers here for trustworthy content. Eventually, the suite of practitioners will cover the full gamut of topics pertinent to starflight, yet at present we are underrepresented in many key disciplines, such as colony ship requirements / technologies, the humanities, finance).
Tau Zero Practitioners
Karen Anderson: Humanities, science fiction community networking (widow of Poul Anderson, author of Tau Zero)
Dana Andrews: Technology, system level engineering and trend analysis
Greg Bear: Humanities, science fiction writer
James Benford: Technology, power beaming
David Brin: Humanities, science fiction writer, provocateur
Jean-Luc Cambier: Physics
Brice N. Cassenti: Mathematics and engineering
Adam Crowl: Mathematics and engineering
Eric W. Davis: Physics with specialties in FTL, general relativity and the quantum vacuum
Walter de Brouwer: Board member, fundraising, networking
Kathryn Denning: Humanities, anthropology
Robert H. Frisbee: Technology, comparative assessments
Pat Galea: Project Icarus IT support
Paul Gilster: Board member, Lead Journalist, and humanities, public education
George Hathaway: Experimentalist
Steven D. Howe: Technology, nuclear propulsion & power
Jonathan Hujsak: Admin assistance, lead IT for Tau Zero
Gerald P. Jackson: Physics, antimatter & nuclear
Les Johnson: Technology, sails and advanced propulsion, and humanities, writing books for public education
Jordin Kare: Technology, system level analyst
Larry Klaes: Humanities, journalism & social networking (TZF Facebook fan site maintenance)
Geoff Landis: Physics, and humanities, science fiction author
Michael R. LaPointe: Technology and physics, specialty in electromagnetics
Tim Lawrence: Liaison & assistance, USAF networking
Kelvin Long: Project Icarus founder, liaison British Interplanetary Society
Claudio Maccone: Mathematics (specialty in transforms & statistics), and project on statistical Fermi-Drake estimations as well as FOCAL mission studies
Jordan Maclay : Physics, specialty in quantum vacuum and Casimir experiments
Geoff Marcy: Astronomy, specialty in exoplanet hunt
Gregory Matloff: Technology, specialty in interstellar probes, and humanities, writing books for public education
William V. Meyer: Physics, experimental, small scale
Marc G. Millis: Board, founder and Executive Director, and physics, specialty in space drives
Frank P. Nagorney: Board, legal issues
Robert J. Noble: Technology, secondary propulsion
Richard Obousy: Project Icarus, physics
Tibor Pacher: Humanities, social networking, Faces from Earth project
Bob Romanofsky: Technology, specialty in sensors
Aldo Spadoni: Humanities, technology, art and documentaries
Alexandre Szames: Humanities, Lead Artist for Tau Zero, history, journalism
Martin Tajmar: Physics and advanced propulsion
Andreas Tziolas: Project Icarus, physics
Edward Zampino: Physics and mathematics
(7) FUND RAISING: The first solicitations to seek philanthropical support went out in 2010 and lessons were learned in that process. Changes are being applied now for future solicitations. I am new to this process and the learning curve is an uphill struggle.
(8) ETC: And lastly, we are responding to all the unexpected things that have come up, like the 100 Year Starship study, the reemergence of NIAC, various conferences, etc. More news on all these things will follow.
Stay with us — we plan to be here for the long haul.
Talking about Mason Peck’s notions of ‘swarm’ spacecraft — probes on a chip that might reach interstellar speeds — I’m inescapably drawn to the other end of the spectrum. A ‘worldship’ is a mighty creation that may mass in the millions of tons, a kilometer (or more) long vehicle that moves at a small fraction of the speed of light but can accommodate thousands, if not hundreds of thousands, of inhabitants. What promises to be the first scientific conference devoted solely to worldships is about to take place on Lambeth Road in London at the headquarters of the British Interplanetary Society. The day-long conference gets down to business on the morning of August 17. This BIS page offers a draft of the program.
As the BIS has done in the past, all presentations from the conference will be written up in a special issue of the Journal of the British Interplanetary Society, where much of the early speculation on worldships has taken place. Several of the Project Icarus team will be presenting papers and I notice that solar sail expert Gregory Matloff, one of the analysts of worldship ideas in the pages of JBIS back in the 1980s, will be represented with a paper on sail options for such a mission. Beyond that, the conference aims, in the words of its organizers, “to reinvigorate thinking on this topic and to promote new ideas.” It will “focus on the concepts, cause, cost, construction and engineering feasibility as well as sociological issues associated with the human crew.”
Image: A worldship may eventually take shape by drawing on the design of space habitats built closer to home. Credit: Don Davis.
Those of you who are familiar with The Starflight Handbook, Matloff’s seminal work on interstellar concepts (John Wiley & Sons, 1989) may recall a write-up on a mission called Sark-1, described as a ‘solar sail interstellar ark’ and named in honor not only of the sailing vessel Cutty Sark but the whiskey that now bears its image. The latter reference is a nod to the fact that a generous store of spirits would not go amiss for those involved in a journey scheduled to last at least a thousand years.
The Sark-1 would be, in comparison to some of the behemoth worldship concepts that have followed, a relatively small vessel, carrying a ‘modest’ crew of 1000 to the Alpha Centauri system. Working with Eugene Mallove, Matloff went on to allot roughly 40 square yards of living space for each person, lodged within a toroidal cabin structure that would weigh 2500 metric tons on the Earth’s surface. Now figure 1000 tons of atmosphere, supplies and power plant adding up to 2000 tons, giving you a basic 5500-ton space colony minus the essential sail. The authors then round the number up to 10,000 tons, thus providing for supplies needed upon arrival.
You make a lot of assumptions when trying to design something that only futuristic technology can deliver. Matloff and Mallove divide the colony into a fleet of six starships, each towed by a circular sail 380 kilometers in diameter, and assume micro-fine filaments of diamond for support cables. For propulsion, a close solar pass would involve an initial perihelion velocity of 0.0014 c, making travel time to Alpha Centauri about 1350 years. The sail — folded and stowed during the cruise phase — would be redeployed upon approach to the Centauri stars, electrically charged and used for deceleration. What the authors say next meshes nicely with the upcoming conference:
Missions by solar sail starship habitats lasting millennia may never be attractive to terrestrials. However, long-term residents of space colonies in the solar system or members of other spacefaring civilizations in the galaxy may not feel equally constrained. Furthermore, as we have seen, there may be undiscovered stars much closer than Alpha Centauri, so we may eventually discover destinations only a few centuries away via inhabited solar sail starships. So in addition to research on solar sail materials, starship dynamics, and logistics, it is not too soon to undertake sociological studies of the problems of maintaining interstellar colonies. Whether clipper ships of the galaxy will ply the interstellar ocean in the twenty-first century, as white-sailed Yankee clippers once did in the nineteenth, is a question our children may be able to answer.
Moving well beyond Sark-1, a true worldship would need to approximate a terrestrial environment inside a far larger vessel. The idea, after all, is to deliver a population of colonists who are not only equipped for the job but sane enough to accomplish it. That may well require structures on the scale of an O’Neill habitat, gigantic vessels housing many of the amenities we take for granted on a planetary surface — parks, lakes, farms — with ample room for living and carrying out a rewarding life as the interminable journey progresses. The typical Earth-dweller isn’t designed for such a mission, but long-term colony structures in the Solar System may one day breed a population for which living on a planetary surface is something of an anomaly. Will the descendants of this kind of habitat head out to become our first interstellar colonists?
For more, see Matloff and Ubell, “Worldships: Prospects for Non-nuclear Propulsion and Power Sources,” JBIS 38 (June 1985), pp. 253-261. See also Matloff and Mallove, “The First Interstellar Colonization Mission,” JBIS 33 (March, 1980), pp. 84-88.
In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).
If you'd like to submit a comment for possible publication on Centauri Dreams, I will be glad to consider it. The primary criterion is that comments contribute meaningfully to the debate. Among other criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language, and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. Centauri Dreams is emphatically not a soapbox for political or religious views submitted by individuals or organizations. A long form of the policy can be viewed on the Administrative page. The short form is this: If your comment is not on topic and respectful to others, I'm probably not going to run it.
