Astrobiology and Sustainability

As the Thanksgiving holiday approaches here in the US, I'm looking at a new paper in the journal Anthropocene that calls the attention of those studying sustainability to the discipline of astrobiology. At work here is a long-term perspective on planetary life that takes into account what a robust technological society can do to affect it. Authors Woodruff Sullivan (University of Washington) and Adam Frank (University of Rochester) make the case that our era may not be the first time "...where the primary agent of causation is knowingly watching it all happen and pondering options for its own future." How so? The answer calls for a look at the Drake Equation, the well-known synthesis by Frank Drake of the factors that determine the number of intelligent civilizations in the galaxy. What exactly is the average lifetime of a technological civilization? 500 years? 50,000 years? Much depends upon the answer, for it helps us calculate the likelihood that other civilizations are out there,...

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Our Best View of Europa

Apropos of yesterday's post questioning what missions would follow up the current wave of planetary exploration, the Jet Propulsion Laboratory has released a new view of NASA's intriguing moon Europa. The image, shown below, looks familiar because it was published in 2001, though at lower-resolution and with considerable color enhancement. The new mosaic gives us the largest portion of the moon's surface at the highest resolution, and without the color enhancement, so that it approximates what the human eye would see. The mosaic of images that go into this view was put together in the late 1990s using imagery from the Galileo spacecraft, which again makes me thankful for Galileo, a mission that succeeded despite all its high-gain antenna problems, and anxious for renewed data from this moon. The original data for the mosaic were acquired by the Galileo Solid-State Imaging experiment on two different orbits through the system of Jovian moons, the first in 1995, the second in 1998....

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Rosetta: Building Momentum for Deep Space?

Even though its arrival on the surface of comet 67P/Churyumov-Gerasimenko did not go as planned, the accomplishment of the Rosetta probe is immense. We have a probe on the surface that was able to collect 57 hours worth of data before going into hibernation, and a mother ship that will stay with the comet as it moves ever closer to the Sun (the comet's closest approach will be on August 13 of next year). What a shame the lander's 'docking' system, involving reverse thrusters and harpoons to fasten it to the surface, malfunctioned, leaving it to bounce twice before it landed with solar panels largely shaded. But we do know that the Philae lander was able to detect organic molecules on the cometary surface, with analysis of the spectra and identification of the molecules said to be continuing. The comet appears to be composed of water ice covered in a thin layer of dust. There is some possibility the lander will revive as the comet moves closer to the Sun, according to Stephan Ulamec...

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Slingshot to the Stars

Back in the 1970s, Peter Glaser patented a solar power satellite that would supply energy from space to the Earth, one involving space platforms whose cost was one of many issues that put the brakes on the idea, although NASA did revisit the concept in the 1980's and 90's. But changing technologies may help us make space-based power more manageable, as John Mankins (Artemis Innovations) told his audience at the Tennessee Valley Interstellar Workshop. What Mankins has in mind is SPS-ALPHA (Solar Power Satellite by means of Arbitrarily Large Phased Array), a system of his devising that uses modular and reconfigurable components to create large space systems in the same way that ants and bees form elegant and long-lived ecosystems on Earth. The goal is to harvest sunlight using thin-film reflector surfaces as part of an ambitious roadmap for solar power. Starting small -- using small satellites and beginning with propulsion stablization modules -- we begin scaling up, one step at a...

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TVIW: From Wormholes to Orion

People keep asking what I think about Christopher Nolan's new film 'Interstellar.' The answer is that I haven't seen it yet, but plan to early next week. Some of the attendees of the Tennessee Valley Interstellar Workshop were planning to see the film on the event's third day, but I couldn't stick around long enough to join them. I've already got Kip Thorne's The Science of Interstellar queued up, but I don't want to get into it before actually seeing the film. I'm hoping to get Larry Klaes, our resident film critic, to review Nolan's work in these pages. Through the Wormhole Wormholes are familiar turf to Al Jackson, who spoke at TVIW on the development of our ideas on the subject in science and in fiction. Al's background in general relativity is strong, and because I usually manage to get him aside for conversation at these events, I get to take advantage of his good humor by asking what must seem like simplistic questions that he always answers with clarity. Even so, I've asked...

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Building Large Structures in Space

One thing the Tennessee Valley Interstellar Workshop did not offer was a lot of spare time. Les Johnson told attendees at the beginning that we would be working straight through. Between presentations and workshop sessions, that was pretty much the case, with no break at all between an 8:00 start and lunch, and afternoon sessions punctuated by breakout workshop sessions on four topics: communications and SETI; biology in small ecosystems; safety issues for interstellar missions; and a competition to reverse-engineer famous starships from science fiction literature. I finished up the after-dinner workshop session around 9:30 that first night. An Encounter with 'Dr. SETI' It was a pleasure to finally meet the SETI League's Paul Shuch in Oak Ridge. Paul and I have exchanged email for some time now, mostly about material we might use on our respective sites, and I've long admired the engineering and leadership skills he brings to a SETI all-sky survey that coordinates the efforts of 127...

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TVIW: Caveats for Long-Duration Missions

When he opened the Tennessee Valley Interstellar Workshop in Oak Ridge last week, Les Johnson told the audience that sessions would begin and end on time. Punctuality is a trait that I assume works well in Johnson's day job at Marshall Space Flight Center, and it certainly was appreciated in Oak Ridge, where the delays and overruns that mar so many conferences just didn't occur. That kept the pace brisk and the presenters solidly on topic throughout. That sense of pace and direction is making TVIW into one of my favorite gatherings. Today I'm going to run through some of the presentations from the first day, beginning with the multidisciplinary note with which I closed yesterday's post. What we gain by keeping a wide range of background in play among the presenters is a chance to spot hidden assumptions, some of which can prove deadly when not properly evaluated. Monday's TVIW talks helped clarify what we've learned about the human presence in space and just how much we have yet to...

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Going Interstellar at Oak Ridge

When I was last in Oak Ridge, TN for the Tennessee Valley Interstellar Workshop in 2011, I arrived late in the evening and the fog was so thick that, although I had a map, I decided against trying to find Robert Kennedy's house, where the pre-conference reception was being held. This year the fog held off until the first morning of the conference (it soon burned off even then), and I drove with Al Jackson out to the Kennedy residence, finding the quiet street surrounded by woods still lit with fall colors and the marvelous clean air of the Cumberland foothills. A house full of interstellar-minded people makes for lively conversation almost anywhere you turn. I quickly met the SETI League's Paul Shuch, with whom I've often corresponded but never spoken to in person, and our talk ranged over SETI's history, the division into a targeted search and a broader survey (the latter is the SETI League' bread and butter), and why looking for signals through a very narrow pipe (Arecibo) should...

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The Transition from Rocky to Non-Rocky Planets

As I decompress from the Tennessee Valley Interstellar Workshop (and review my notes for next week's report), I have the pleasure of bringing you Andrew LePage's incisive essay into a key exoplanet question. Are some of the planets now considered potentially habitable actually unlikely to support life? Recent work gives us some hard numbers on just how large and massive a planet can be before it is more likely to be closer to Neptune than the Earth in composition. The transition from rocky to non-rocky planets is particularly important now, when our instruments are just becoming able to detect planets small enough to qualify as habitable. LePage, who writes the excellent Drew ex Machina, remains optimistic about habitable planets in the galaxy, but so far the case for many of those identified as such may be weaker than we had thought. A prolific writer, Drew is also a Senior Project Scientist at Visidyne, Inc., where he specializes in the processing and analysis of remote sensing...

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Tennessee Valley Interstellar Workshop

I'm at the Tennessee Valley Interstellar Workshop in Oak Ridge for the next few days. As I've done at past conferences, I'll need to spend my time taking the notes that will be turned into next week's entries here. That means no further posts until Friday, though I'll try to keep the comment moderation going, perhaps with a few delays. TVIW 2014 has lined up a good group of speakers including, besides MSFC's Les Johnson himself (TVIW's founder), exoplanet hunter Sara Seager, beamed sail specialist Jim Benford, the SETI League's Paul Shuch and TZF founder Marc Millis, along with a healthy representation from Icarus Interstellar. I'm also looking forward to the workshop tracks and will be participating in one called "Language as Reality: A Near-Term Roadmap for Exploiting Opportunities and Natural Experiments Here on Terra Firma to Inform *C*ETI." Expect a complete report when I get back.

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Interstellar Arrival: Slowing the Sail

Some final thoughts on hybrid propulsion will wrap up this series on solar sails, which grew out of ideas I encountered in the new edition of the Matloff, Johnson and Vulpetti book Solar Sails: A Novel Approach to Interplanetary Travel (Copernicus, 2014). The chance to preview the book (publication is slated for later this month) took me in directions I hadn't anticipated. Solar Sails offers a broad popular treatment of all the sail categories and their history, as you'd expect, but this time through I focused on its four technical chapters on sail theory that helped me review the details. And because I kept running into the idea of multiple modes of propulsion, my thoughts on avoiding doctrinaire solutions continue to grow. In fact, I'd venture to say that probing into the possibilities of multimodal propulsion may offer a serious opportunity for insights. Centauri Dreams regular Alex Tolley came up with one of these yesterday, asking whether a sail mission to Jupiter space might...

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Hybrid Strategies for Deep Space

On Monday I touched on the topic of multi-modal spacecraft, wondering whether future deep space missions might carry twin or even triple systems of propulsion. The example I want to tinker with is an interstellar craft driven by beamed energy, akin to some of Robert Forward's designs in the 1980s. Forward went through enormous challenges trying to decelerate at the destination, though as we'll see, he did come up with more than one solution. A beamed laser sailcraft runs into this problem because the power source is in a close solar orbit, while the craft is reaching speeds that make a human crossing to another star possible. How to slow it down from behind? Deceleration is going to take a long time no matter what the method, but if we factor in a second mode of propulsion, a magnetic sail, we can brake against the destination star's stellar wind. I mentioned on Monday as well that the Venture Star, the starship that got James Cameron's crew to Alpha Centauri in the film Avatar, was...

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A Near-Term Sail Niche

When Les Johnson spoke to a session on sail technologies at the 100 Year Starship symposium in Houston last September, he startled some in the audience by going through a list of how many solar sail missions are now in the works. The European Space Agency's Gossamer program accounts for one of these, which is already built and waiting for launch, but three are in the pipeline. The University of Surrey (UK) is a surprisingly active entrant, with three CubeSat sails set for flight in the next three years. We also have the Planetary Society's LightSail to contend with, a CubeSat design with a 32 square meter sail when deployed. There are other missions as well, with names like NEA [Near Earth Asteroid] Scout, Lunar Flashlight, and although it is now in limbo at least for several years, NASA's Sunjammer. The surge in interest in CubeSats is hard to miss here. They're cheap, small, and ideal for trying out sail experiments as we try to figure out how best to use this technology in space....

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Sailcraft: Concepts, Design, Lab Work

Although we can trace the growth of research into interstellar flight all the way back to the days of Konstantin Tsiolkovsky, the effort has often operated outside of government channels. Scientists and engineers whose day job might take in aspects of rocketry were hard pressed to find time for studying trips to the stars when the proximate needs were better communications satellites or improved designs for reaching low Earth orbit. Nonetheless, work continued, marked by the enthusiasm of the practitioners for what was clearly the ultimate mission. Official or unofficial, small groups hammering on ideas have continued to debate the core concepts. When the Jet Propulsion Laboratory in Pasadena turned Aden and Marjorie Meinel loose on a mission concept aimed at reaching 1000 AU back in the 1970s, the duo looked at two propulsion options. As the new edition of Solar Sails: A Novel Approach to Interplanetary Travel (Copernicus, 2014) points out, the first of these was a nuclear-electric...

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An Updated Look at Space Sailing

It was back in 2008 that Copernicus Books published an excellent introduction and reference to space sail technologies. Now the work of Gregory Matloff, Giovanni Vulpetti and Les Johnson, Solar Sails: A Novel Approach to Interplanetary Travel is about to be released in a new edition that I've been reviewing for the past month (Note: the 2nd edition is not yet up on the book sites, but publication is slated for later in November). The new version preserves the older edition's structure but inserts three new chapters covering recent developments, one of which -- the cancellation of the Sunjammer sail mission -- is too current to have made it into the text. [Addendum: My mistake! Although the text I saw didn't have the Sunjammer news, Les Johnson tells me that the authors were able to insert it into the final version]. So let's start with that to get up to speed, and then I want to use Solar Sails as a guide through a series of posts covering not just sails themselves, their variants...

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Driggers on The Space Show

Aerospace engineer and science fiction novelist Gerald Driggers will be a guest on The Space Show, hosted by David Livingston, tomorrow (Monday) at 5 PM Eastern US time (2200 UTC). You can listen to the show here. Centauri Dreams readers know Gerald as a champion of space colonization efforts going back to the days of the L-5 Society in the 1960s and 1970s, but of late he's been chronicling our prospects on Mars with novels like The Earth-Mars Chronicles Vol. 1 Hope for Humanity. He's also just released an Amazon short called Butterscotch Dawn. On Livingston's show, expect discussion of the large-scale settlement of Mars and the role of the Red Planet in our species' colonization of the larger Solar System. The show will be archived at http://www.thespaceshow.com.

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Charter

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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