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The Asteroid and the Telescope

by Paul Gilster | May 3, 2012 | Asteroid and Comet Deflection | 20 Comments

One of the topics receiving fairly little coverage in the excitement of the Planetary Resources announcement is asteroid deflection. It seems clear that learning how to reach an asteroid and extract everything from water to platinum-group metals from it will also teach us strategies for changing an asteroid's trajectory, in the event we find one likely to hit the Earth. The recent report from the Keck Institute of Space Studies makes this point clearly in the context of its own mission study, a plan to retrieve a small (7 m) asteroid and park it in lunar orbit. What Asteroid Operations Can Teach Us Although Planetary Resources estimates there are more than 1500 asteroids that are as easy to get to as the Moon, we still have a long way to go in understanding basic facts about these objects and their composition. Take dust, which will probably vary from object to object, but which could cause problems for 'gravity tractor' concepts where a spacecraft is used to deflect an asteroid...

Bringing an Asteroid to Lunar Orbit

by Paul Gilster | May 2, 2012 | Asteroid and Comet Deflection | 23 Comments

Long before Planetary Resources was a gleam in the eye of its founders, John Lewis (University of Arizona) wrote a book that put asteroid mining into the public consciousness. Mining the Sky: Untold Riches from the Asteroids, Comets and Planets (Perseus Books, 1996) contains no shortage of wonders, as in the well publicized idea that a single one-kilometer asteroid could produce enough gold and silver to equal world production for a century. David Brin writes about this on George Dvorsky's Sentient Developments site, noting that while that would produce a collapse in gold and silver prices, it would also produce incalculable benefits in terms of raw materials production that could change the economic paradigm entirely. Lewis is a natural fit with Planetary Resources, the highly buzzed-about startup that plans to make asteroid mining a reality, and it's no surprise to see that he serves as one of its advisors. But remembering Mining the Sky, I was startled to discover that the idea of...

Advent of the ‘Belters’

by Paul Gilster | May 1, 2012 | Asteroid and Comet Deflection | 26 Comments

On the Trail of the Space Pirates was a 1953 adventure written by Carey Rockwell, a house pseudonym used by a Grosset & Dunlop writer who may or may not have been one Joseph Greene, an editor for the firm in that era. We don't know for sure who 'Carey Rockwell' was and no one has come forward to claim the title, but see the Tom Corbett Space Cadet website for another possible clue to authorship. In any case, On the Trail of the Space Pirates took readers such as my grade school self out into the asteroid belt, where all manner of adventures occur and uranium prospectors ply their trade harassed by evil doers. The asteroids became a lively analogue to the American wild west. Asteroid mining and the culture it spawns has a robust history in science fiction, but I couldn't help recalling this particular book when I read about Planetary Resources and its ambitious plan to mine asteroids. The company's intentions don't extend all the way to the main belt, but focus on asteroids much...

Our First Galactic Ambassador

by Paul Gilster | Apr 30, 2012 | Outer Solar System | 13 Comments

by Larry Klaes Larry Klaes is a long-time Centauri Dreams contributor, a practitioner of the Tau Zero Foundation and a serious devotee of space exploration and its history. Here he gives us a look at the Pioneer probes that first took us to the outer Solar System, journeys that foreshadowed the later exploits of the Voyagers and the more recent New Horizons mission to Pluto/Charon. It's hard to believe that it's been fully forty years since the Pioneers were launched. They came out of the era when thinking big was the order of the day, Apollo was putting astronauts on the Moon and human expansion into the cosmos seemed inevitable. When we ponder today's budget shortfalls and drifting public attention, it's heartening to recall that era even as we speculate about missions that will follow up on the findings of these two remarkable probes. The early 1970s was an exciting time for lunar and planetary exploration. On the Moon, Apollo was still placing pairs of astronauts on Earth's...

Another Way of Looking at Interstellar Probes

by Paul Gilster | Apr 27, 2012 | Culture and Society | 32 Comments

By Michael Michaud The following post is a distinct change of pace for Centauri Dreams, a work of fiction that gets at questions at the heart of SETI. We've considered many ideas about interstellar probes that humans may one day launch toward nearby stars. But the reverse could occur: A more advanced technological civilization could send a probe in our direction, particularly after detecting signs of life or technology on a rapidly developing Earth. This idea is a challenge to the dominant scientific paradigm of contact -- our detection of radio signals from a remote society. The short story below presents one of many possible scenarios. In this case, the probe is an intelligent machine. It lacks the omniscience so often assumed in films and television programs; this form of intelligence, like ours, can misunderstand evidence and is capable of making mistakes. This story avoids the two stereotyped film and television versions of contact: being saved by altruistic aliens, or being...

Titan’s Atmosphere Under Scrutiny

by Paul Gilster | Apr 26, 2012 | Outer Solar System | 2 Comments

Of all the probe targets in the outer Solar System, Titan is in many ways the most provocative. Not long ago we looked at two concepts -- Titan Mare Explorer (TiME) and AVIATR -- that would get instruments back into Titan's atmosphere and, in the case of TiME, onto one of its northern seas. The allure of this moon is surely what goes on in that atmosphere, a nitrogen brew mixed with methane that generates complex hydrocarbons. We're learning how these fall on the surface to form patterns of dunes made up of organic material, all of this mediated by a weather cycle that involves seasonal change the Cassini spacecraft has strikingly recorded. Kathleen Mandt (Southwest Research Institute) has been studying methane in Titan's atmosphere over time using data both from Cassini and the European Space Agency's Huygens probe (digression: can it really be seven years since Huygens parachuted down through those orange skies? Good grief...) Mandt's team is looking at heavy methane -- methane...

Coffee with Dr. Fermi

by Paul Gilster | Apr 25, 2012 | Exoplanetary Science | 129 Comments

I cannot live without good coffee, and that means fresh beans ground right before brewing, and either manual drip or French press extraction. Every morning after publishing Centauri Dreams I make a couple of cups and go out on the deck to rest my eyes and ponder the state of things before hitting the books for background research in the afternoon. Various thoughts about what to write next always come to me, but yesterday I mused about Enrico Fermi, the legendary Italian physicist who, among so much else, left us with a great unanswered question: Where are they? If it’s so easy for the universe to make intelligent species, why is SETI coming up so short? Where are they indeed? The day was gorgeous, the air filled with birdsong, temperatures in the mid-60s and a mild breeze. What better setting to be immersed in, thinking about where life emerges and when? I imagined Fermi sitting across from me with a cup of my Costa Rica Tres Rios in his hand, wondering what he might say about the...

100 Year Starship Site Launches

by Paul Gilster | Apr 24, 2012 | Culture and Society | 4 Comments

You'll want to bookmark the 100 Year Starship Initiative's new site, which just came online. From the mission statement: 100 Year Starship will pursue national and global initiatives, and galvanize public and private leadership and grassroots support, to assure that human travel beyond our solar system and to another star can be a reality within the next century. 100 Year Starship will unreservedly dedicate itself to identifying and pushing the radical leaps in knowledge and technology needed to achieve interstellar flight while pioneering and transforming breakthrough applications to enhance the quality of life on earth. We will actively include the broadest swath of people in understanding, shaping, and implementing our mission. And check here for news about the 2012 public symposium, which will be held in Houston from September 13-16. Quoting from that page: This year, 2012, DARPA gave its stamp of approval to and seed funded —100 Year Starship (100YSS)—a private...

The Proxima Centauri Planet Hunt

by Paul Gilster | Apr 24, 2012 | Exoplanetary Science | 24 Comments

Although we haven’t yet found any planets around Proxima Centauri, it would be a tremendous spur to our dreams of future exploration if one turned up in the habitable zone there. That would give us three potential targets within 4.3 light years, with Centauri A and B conceivably the home to interesting worlds of their own. And the issue we started to look at yesterday -- whether Proxima Centauri is actually part of the Alpha Centauri system or merely passing through the neighborhood -- has a bearing on the planet question, not only in terms of how it might affect the two primary stars, but also because it would tell us something about Proxima’s composition. A Gravitationally Bound System Greg Laughlin makes this case in the systemic post I referred to yesterday. It was Laughlin and Jeremy Wertheimer (UCSC) who used data from ESA’s Hipparcos mission to conclude that Proxima was indeed bound to Centauri A and B. Here I want to quote the conclusion of the duo’s paper on the matter,...

Proxima Centauri: Looking at the Nearest Star

by Paul Gilster | Apr 23, 2012 | Exoplanetary Science | 18 Comments

Let's start the week with a reminder about Debra Fischer's work on Alpha Centauri, which we talked about last week. There are several ongoing efforts to monitor Centauri A and B for planets and, given the scrutiny the duo have received for the past several years, we should be getting close to learning whether there are rocky worlds in this system or not. Fischer's continuing work at Cerro Tololo involves 20 nights of observing time that her grant money can't cover. Private donations are the key -- please check the Planetary Society's donation page to help if you can. While interest in the Alpha Centauri system is high, the small red dwarf component of that system has been getting relatively little press lately. But I don't want to neglect Proxima Centauri, which as far as we know is the closest star to the Earth (some 4.218 light years away, compared to Centauri A and B's 4.39 light years). From a planet around Centauri B, it would be hard to know that Proxima (also known as Alpha...

Habitable Zones in Other Galaxies

by Paul Gilster | Apr 20, 2012 | Astrobiology and SETI | 26 Comments

We often speak of habitable zones around stars, most commonly referring to the zone in which a planet could retain liquid water on its surface. But the last ten years has also seen the growth of a much broader idea, the galactic habitable zone (GHZ). A new paper by Falguni Suthar and Christopher McKay (NASA Ames) digs into galactic habitable zones as they apply to elliptical galaxies, which are generally made up of older stars and marked by little star formation. Ellipticals have little gas and dust as compared to spirals like the Milky Way and are often found to have a large population of globular clusters. Are they also likely to have abundant planets? The answer is yes, based on the authors’ comparison of metallicity -- in nearby stars and stars with known planets -- to star clusters in two elliptical galaxies. While many factors have been considered that could affect a galactic habitable zone, Suthar and McKay focus tightly on metallicity, with planet formation dependent upon the...

Closing in on Alpha Centauri

by Paul Gilster | Apr 19, 2012 | Deep Sky Astronomy & Telescopes | 40 Comments

Alpha Centauri is irresistible, a bright beacon in the southern skies that captures the imagination because it is our closest interstellar target. If we learn there are no planets in the habitable zones around Centauri A and B, we then have to look further afield, where the next candidate is Barnard's Star, at 5.9 light years. Centauri A and B are far enough at 4.3 light years -- that next stretch adds a full 1.6 light years, and takes us to a red dwarf that may or may not have planets. Still further out are Tau Ceti (11.88 light years) with its problematic cometary cloud, and Epsilon Eridani (10.48 light years), a young system though one thought to have at least one planet. A warm and cozy planet around the K-class Centauri B would be just the ticket, and the planet hunt continues. One thing we've learned in the past decade is that neither Centauri A or B is orbited by a gas giant -- planets of this size should have shown up in the data by now. We've also learned that stable orbits...

Neutrino Communications: An Interstellar Future?

by Paul Gilster | Apr 18, 2012 | Communications and Navigation | 24 Comments

The news that a message has been sent using a beam of neutrinos awakened a flood of memories. Back in the late 1970s I was involved with the Society for Amateur Radio Astronomers, mostly as an interested onlooker rather than as an active equipment builder. Through SARA’s journal I learned about Cosmic Search, a magazine that ran from 1979 through 1982 specializing in SETI and related issues. I acquired the entire set, and went through all 13 issues again and again. I was writing sporadically about SETI then for Glenn Hauser’s Review of International Broadcasting and later, for the SARA journal itself. Cosmic Search is a wonderful SETI resource despite its age, and the recent neutrino news out of Fermilab took me right back to a piece in its third issue by Jay Pasachoff and Marc Kutner on the question of using neutrinos for interstellar communications. Neutrinos are hard to manipulate because they hardly ever interact with other matter. On the average, neutrinos can penetrate four...

How Will Humans Fly to the Stars?

by Paul Gilster | Apr 17, 2012 | Missions | 69 Comments

by Andreas Hein The immense problems of time, distance and life support invariably mean that when we talk about an interstellar mission, we talk about robotics. But the imaginative team at Icarus Interstellar, which is now setting up projects on everything from beamed lightsails (Project Forward) to pulse propulsion engines (Project Helios), has pushed into the biggest what-if of all, the question of manned missions. And as project leader Andreas Hein reminds us in the following article, a variety of approaches have been suggested for this over the years from which a new concept study can grow. Andreas Hein received his master's degree in aerospace engineering at the Technische Universität München, and is doing his PhD at the same university in the area of space systems engineering at the Institute of Astronautics. He has participated in several mission studies: a lunar gravity measurement mission by EADS and a cubesat mission analysis. During his internship at ESA-ESTEC, he...

Lightsails: Safe Passage After All?

by Paul Gilster | Apr 16, 2012 | Sail Concepts | 22 Comments

Despite my best intentions, I still haven't put my hands on the exchange between Robert Forward and Ian Crawford on lightsails that ran back in 1986 in JBIS, nor have I managed to come up with the source of the 'lightsail on arrival' illustration I mentioned last week. This was the one showing a battered and torn sail docked in what I assume was a repair facility at the end of its long journey, and the effects of passage through the interstellar medium were all too obvious. It was a great image and I was frustrated about not being able to find the magazine it was published in, but an email from James Early quickly changed my mood. As opposed to the missing image that nagged at my memory, this was a case of having missed something perfectly obvious in the first place. I didn't know about the paper Jim did with Richard London on lightsails and the interstellar medium -- it was published in the Journal of Spacecraft and Rockets back in 2000, but somehow I didn't find it in the research...

Collisions in the Interstellar Medium

by Paul Gilster | Apr 13, 2012 | Interstellar Medium | 28 Comments

Memories play tricks on us all, but trying to recall where I saw a particular image of a laser lightsail is driving me to distraction. The image showed a huge sail at the end of its journey, docked to some sort of space platform, and what defined it were the tears and holes in the giant, shredded structure. It presupposed long passage through an interstellar medium packed with hazards, and although I assumed I would have seen it on the cover of some science fiction magazine, I spent an hour yesterday scanning covers on Phil Stephensen-Payne’s wonderful Galactic Central site, but all to no avail. The image must have run inside a magazine, then, but if so, I’m at a loss to identify it other than to say it would have appeared about twenty years ago. I had hoped to reproduce it this morning because our talk about starship shielding necessarily brought up the question of whether an enormous lightsail -- some of these are conceived as being hundreds of kilometers in diameter -- wouldn’t be...

Lasers: Protecting the Starship

by Paul Gilster | Apr 12, 2012 | Interstellar Medium | 23 Comments

Interesting new ideas about asteroid deflection are coming out of the University of Strathclyde (Glasgow), involving the use of lasers in coordinated satellite swarms to change an asteroid's trajectory. This is useful work in its own right, but I also want to mention it in terms of a broader topic we often return to: How to deal with the harmful effects of dust and interstellar gas on a fast-moving starship. That's a discussion that has played out many a time over the past eight years in these pages, but it's as lively a topic as ever, and one on which we're going to need a lot more information before true interstellar missions can take place. Lasers and the Asteroid But let's set the stage at Strathclyde for a moment. The idea here is to send small satellites capable of formation flying with the asteroid, all of them firing their lasers at close range. The university's Massimiliano Vasile, who is leading this work, says that the challenge of lasers in space is to combine high power,...

The Largest Solar System Yet

by Paul Gilster | Apr 11, 2012 | Exoplanetary Science | 21 Comments

The Kepler mission's exoplanet discoveries have been so numerous that an extension of the mission seemed all but inevitable. At the same time, bureaucracies can be unpredictable, which is why it was such a relief to have the Senior Review of Operating Missions weighing in with an extension recommendation, one followed up by NASA with extensions not just for Kepler but also for the Spitzer telescope and the US portion of ESA's Planck mission. Kepler's extension runs through fiscal 2016 (subject to review in 2014), allowing for plenty of time to home in on Earth-sized planets in the habitable zone around stars like our Sun. While Kepler's scheduled mission duration was 3.5 years, the mission was intended to be extendible to 6 years or more and this news is more than satisfying. But of course while we continue to monitor the Kepler work, we're following numerous other exoplanet stories including the European Southern Observatory's observations of the prolific star HD 10180, a Sun-like...

Splashdown on Titan?

by Paul Gilster | Apr 10, 2012 | Outer Solar System | 14 Comments

Getting to the stars may involve a sudden breakthrough -- we can't rule out disruptive technologies, nor can we predict them -- but my guess is that interstellar flight is going to be a longer, more gradual process. I can see a sort of tidal expansion into the outer system, forays to Mars, for example, followed by reassessment, retrenchment, then one day deeper study of Jupiter's moons with advanced robotics that can get under Europa's ice. The search for life may become so provocative that we have to explore Titan and Enceladus with human crews, and the imperative for planetary protection may help us further tune up our deep space technologies. The thing is, one wave of exploration inevitably begets another. Let's put no timeframe on that kind of expansion because, like the tides, it may surge at times and then fall back, hostage to budgetary problems and waves of public interest that can as easily ebb. But I could see an eventual civilization that extends throughout the Solar...

Reasons for a Human Future in Space

by Paul Gilster | Apr 9, 2012 | Outer Solar System | 38 Comments

I closed last week with two posts about the AVIATR mission, an unmanned airplane that could be sent to Titan to roam its skies for a year of aerial research. It’s a measure of Titan’s desirability as a destination that it has elicited so many mission proposals, and I want to get into the Titan Mare Explorer (TiME) as well, but let’s pause a moment to consider the nature of what we’re doing. Out of necessity, all our missions to the outer system have been unmanned, but as we learn more about long-duration life-support and better propulsion systems, that may change. The question raised this past weekend in an essay in The Atlantic is whether it should. Ian Crawford, a professor of planetary sciences at Birkbeck College (London) is the focus of the piece, which examines Crawford’s recent paper in Astronomy and Geophysics. It’s been easy to justify robotic exploration when we had no other choice, but Crawford believes not only that there is a place for humans in space, but that their...

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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).

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