by Marc Millis
Here is a holiday gift from Tau Zero as compiled by TZF’s founding architect Marc Millis. It’s part of Marc’s continuing effort to find earlier references to the interstellar concepts — many of them in fiction — that we routinely ponder today. Some of these go back to the early 20th Century and in some cases the 19th. Compilations like this are always works in progress, as we found when putting together a list of interstellar propulsion concepts for the first chapter of the book Marc and Eric Davis edited, Frontiers of Propulsion Science, where one memory triggered another and the list kept growing. Readers are encouraged, then, to add other references to older material, as those of us who delight in prowling through old science fiction magazines have access to a mother lode of fictional precedents. I’ll also mention that this post will be the last of 2011 — as I did last week, I’ll skip the Friday and Monday posts in honor of the holiday, with the next post appearing on Tuesday, January 3.
I am indebted to the following volunteers who helped me finish these lists of inspirational starflight visions, both fictional and engineered: Brandon Vernon, Curtis Wilbur, Tatiana Covington, Yusif Nurizade, and Geoff Landis.
These lists of noteworthy fiction and engineered interstellar ships are not complete lists, but rather those that had more influence than the rest. In some cases I’ve added my personal reactions. Enjoy!
Year, Concept / “term” / “Ship name,” Author / Designer, Name of reference.
1880, “Antigravity” term coined, Percy Greg, Across the Zodiac.
1928, Faster-than-light first mentioned, E.E. ‘Doc’ Smith, Skylark series.
1931, “Hyperspace” term coined, John Campbell, Islands of Space.
1932, “Space Drive” term coined, John Campbell, “The Electronic Siege,” Wonder Stories.
1935, “Space Warp” term coined, N. Schachner, “The Son of Redmask,” Astounding Stories.
1941, First colony ship (multi-generation), R. A. Heinlein, “Universe” / “Common Sense” / Methuselah’s Children.
1950, “FTL” as acronym coined, Fritz Leiber, “Enchanted Forest,” Astounding Science Fiction.
1951, “Warp Drive” term coined, M. Gibbs, Letter in Marvel Science Stories.
1951, “Klaatu” saucer, Harry Bates, Edmund North, Robert Wise, The Day the Earth Stood Still.
1956, “United Planets Cruiser C57-D,” Irving Block & A. A. Adler, C. Hume, F. M Wilcox, Forbidden Planet.
Millis comment: I did not see this movie until long after Star Wars had been out (some time in the 1980s). When I did finally see it and knowing its creation date, I was seriously impressed. Even the opening narrative makes sense. The ship dealt with the differences in FTL and slower flight well, and I was delighted that it did NOT use rockets. Landing scene done well (image courtesy Metro-Goldwyn-Mayer).
1956, “Twin Paradox” used in literature, “Torchship,” Robert Heinlein, Time for the Stars.
1958, “Matter Transmitter,” Poul Anderson, The Enemy Stars.
1963, “TARDIS” (Time And Relative Dimensions In Space), Sydney Newman, D. Wilson, C. E. Webber, Dr. Who.
Millis comment: To me, the most stimulating part of this vehicle is that it is larger on the inside than outside – good fodder for pondering. I did not discover Dr. Who until the late 1980’s.
1966, “Starship Enterprise NCC-1701,” Matt Jefferies and Gene Roddenberry, Star Trek.
Millis comment: I grew up watching Star Trek after the Apollo Moon landings when I was at that impressionable age. This was the fiction that provoked much of my early thinking about physics and star flight. The occasional logical inconsistencies (e.g “Wink of an Eye”) fueled as much thought as the unknowns that needed to be to solved. I remember being frustrated by not being able to find out which parts of the ship’s technology were just fiction and which were based on extensions of works in progress. That unfulfilled desire led me to some of the thoughts behind Tau Zero.
1967, “Galileo Seven” shuttle, Matt Jefferies (interior) and Gene Winfield (exterior), Star Trek.
Millis comment: This specific vehicle has an even fonder place in my memory than the starship Enterprise, since this ship was on the scale I could imagine owning and operating myself. And even more than that, this ship was THE major icon for my childhood ponderings for how to make such a vehicle real. In my early teens I would imagine this ship hovering over my driveway, and then I would imagine throwing rocks at it and poking it with a stick to try and decipher how it might be hovering (typical boy way of analyzing things, eh?) The trajectory of the rocks would vary depending on the levitation method. These mental exercises led me to realize what I would have to study in school to figure these things out on my own. I have yet to write down and share such ponderings in open publications, but look forward to doing so some day.
1970, Runaway relativistic speed and collapse of time, (via Bussard Ramjet), Poul Anderson, Tau Zero.
1971, “Valley Forge,” Deric Washburn, Michael Cimino, Steven Bochco, Douglas Trumbull, Silent Running (PG note: Be sure to read Larry Klaes’ essay on this movie in The Space Review).
1971 “Boom Tube” (interdimensional portal/transporter), Jack Kirby, Waves of the Mind.
1977, “Millennium Falcon,” George Lucas, Star Wars.
Millis comment: When this vehicle hit the screens it helped reenergize my enthusiasm, but I was not impressed by its operations. Unlike Star Trek, which hit me in my impressionable years, Star Wars emerged when I was already studying physics in college. It became clear after a few minutes of watching the movie that Star Wars was more about entertainment than speculation, and was absent the kind of provocations of Star Trek, the Outer Limits, and the Twilight Zone. As much as that Falcon looked cool, it was NOT thought-provoking. I was entertained and energized, but it did not stimulate my imagination.
1978, “Infinite improbability drive” / “Heart of Gold,” Douglas Adams, The Hitchhiker’s Guide to the Galaxy.
Millis comment: Finally, a different space engine than the ubiquitous warp drives and hyperspace! In addition to the great humor of the Hitchhiker series, I really like this propulsion concept. It was fun, funny, and intellectually provocative.
1984, “Laser-pushed sail,” Robert Forward, Rocheworld.
1984, “3-man thermal pod,” Earl Mac Rauch and W. D. Richter, The Adventures of Buckaroo Banzai.
Millis comment: I am one of the few people who love this movie because of its delightful, complex absurdity. Regarding inspirations, there is a moment near the end of the movie when our hero, Buckaroo Banzai, connects jumper cables to a car battery to get the “thermal pod,” in which he is plummeting to suddenly start levitating. That cause-effect moment hit me hard. The notion of a car battery powering the levitation propulsion on a little pod was heart warming, in a delightfully absurd way.
1985, Bubble of isolated inertial space, Eric Luke and Joe Dante, Explorers.
Millis comment: There was a scene where a pre-teen is riding inside a transparent-invisible sphere that flies around in all directions and goes right through objects (like the ground) while the pre-teen remains protected. Although not explained in the movie, the behavior of that device was as if the internal inertial and gravitational environment is disconnected from the external inertial and gravitational environment. It matched several of my prior imaginative sessions.
1985, Wormhole Generator, Carl Sagan [Kip Thorne], Contact.
1986, “Trimaxian Drone,”(morphing spacecraft) Mark H. Baker, Michael Burton Disney, Flight of the Navigator.
1994, “Wormhole networks,” Roland Emmerich and Dean Devlin, Stargate.
Image: A screenshot from the science fiction television series Stargate Atlantis, one of several TV spinoffs from the film.
1999, “Planet Express,” Matt Groening, Futurama.
1999, “Protector,” Howard, Gordon, Dean Parisot, Galaxy Quest.
Millis comment: I thoroughly enjoyed this parody, in particular the role of the enthusiastic, believing fan, and the contrast between fiction fandom and reality (albeit the movie’s ‘reality’ is fiction too).
2009, “ISV Venture Star,” (It’s noteworthy for having thermal radiators), James Cameron, Avatar.
ENGINEERED INTERSTELLAR SPACECRAFT
Year, “Ship Name” Ship Type, Author/engineer, name of reference, Publisher.
1958, “Project Orion” using nuclear detonation propulsion, S. Ulam, T. Taylor, & F. Dyson, “Nuclear Pulse Space Vehicle Study,” General Atomic.
1960, “Bussard Ramjet” using on-the-fly-fusing of indigenous space protons, R. Bussard, “Galactic Matter and Interstellar Flight,” Astronautica Acta.
1977, “Voyager 1 & 2” using a chemical rocket, JPL et al (http://voyager.jpl.nasa.gov/spacecraft/index.html), Jet Propulsion Laboratory.
1978, “Project Daedalus,” using a nuclear fusion rocket, Alan Bond, et al, British Interplanetary Society.
1984, Laser-beamed sail, Robert Forward, “Roundtrip Interstellar Travel Using Laser-Pushed Lightsails,” Journal of Spacecraft & Rockets.
1985, “Starwisp” using beamed microwave energy to sails, R. Forward, “Starwisp: an Ultralight Interstellar Probe,” American Institute of Aeronautics and Astronautics.
1987, “VISTA” using a nuclear fusion rocket, Charles D. Orth, “VISTA – A Vehicle for Interplanetary Space Transport Application Powered by Inertial Confinement Fusion,” Lawrence Livermore National Lab.
1987, “TAU (Thousand Astronomical Units)” using nuclear-electric ion propulsion, JPL, et al, “Tau — A Mission to a Thousand Astronomical Units,” Jet Propulsion Laboratory.
1988, “Project Longshot” using nuclear pulse propulsion, Beals, K. A., M. Beaulieu, F. J. Dembia, J. Kerstiens, D. L. Kramer, J. R. West and J. A. Zito, “Project Longshot: An Unmanned Probe To Alpha Centauri,” U. S Naval Academy.
1999, “AIMStar” using antimatter catalyzed nuclear propulsion, Raymond A. Lewis, Kirby Meyer, Gerald A. Smith and Steven D. Howe, “AIMStar: Antimatter Initiated Microfusion For Pre-cursor Interstellar Missions,” Pennsylvania State University.
2003, “Innovative Interstellar Explorer” using nuclear electric rocket, Ralph McNutt, “Mission Design for the Innovative Interstellar Explorer Vision Mission” NASA (ongoing).
2009, “Project Icarus,” using nuclear fusion rocket, Icarus Interstellar (numerous papers, ongoing).
A paper in the December 24 issue of Physical Review Letters goes to work on the finding of supposed faster-than-light neutrinos by the OPERA experiment. The FTL story has been popping up ever since OPERA — a collaboration between the Laboratori Nazionali del Gran Sasso (LNGS) in Gran Sasso, Italy and the CERN physics laboratory in Geneva — reported last September that neutrinos from CERN had arrived at Gran Sasso’s underground facilities 60 nanoseconds sooner than they would have been expected to arrive if travelling at the speed of light.
The resultant explosion of interest was understandable. Because neutrinos are now thought to have a non-zero mass, an FTL neutrino would be in direct violation of the theory of special relativity, which says that no object with mass can attain the speed of light. Now Ramanath Cowsik (Washington University, St. Louis) and collaborators have examined whether an FTL result was possible. Neutrinos in the experiment were produced by particle collisions that produced a stream of pions. The latter are unstable and decayed into muons and neutrinos.
What Cowsik and team wanted to know was whether pion decays could produce superluminal neutrinos, assuming the conservation of energy and momentum. The result:
“We’ve shown in this paper that if the neutrino that comes out of a pion decay were going faster than the speed of light, the pion lifetime would get longer, and the neutrino would carry a smaller fraction of the energy shared by the neutrino and the muon,” Cowsik says. “What’s more, these difficulties would only increase as the pion energy increases. So we are saying that in the present framework of physics, superluminal neutrinos would be difficult to produce.”
This news release from Washington University gives more details, pointing out that an important check on the OPERA results is the Antarctic neutrino observatory called IceCube, which detects neutrinos from a far different source than CERN. Cosmic rays striking the Earth’s atmosphere produce neutrinos with energies that IceCube has recorded that are in some cases 10,000 times higher than the neutrinos from the OPERA experiment. The IceCube results show that the high-energy pions from which the neutrinos decay generate neutrinos that come close to the speed of light but do not surpass it. This is backed up by conservation of energy and momentum calculations showing that the lifetimes of these pions would be too long for them to decay into superluminal neutrinos. The tantalizing OPERA results look more than ever in doubt.
Image: The IceCube experiment in Antarctica provides an experimental check on Cowsik’s theoretical calculations. According to Cowsik, neutrinos with extremely high energies should show up at IceCube only if superluminal neutrinos are an impossibility. Because IceCube is seeing high-energy neutrinos, there must be something wrong with the observation of superluminal neutrinos. Credit: ICE.WUSTL.EDU/Pete Guest.
As we continue to home in on what happened in the OPERA experiment, it’s heartening to see how many physicists are praising the OPERA team for their methods. Cowsik himself notes that the OPERA scientists worked for months searching for possible errors and, when they found none, published in an attempt to involve the physics community in solving the conundrum. Since then, Andrew Cohen and Sheldon Glashow have shown (in Physical Review Letters) that if superluminal neutrinos existed, they would radiate energy in the form of electron-positron pairs.
“We are saying that, given physics as we know it today, it should be hard to produce any neutrinos with superluminal velocities, and Cohen and Glashow are saying that even if you did, they’d quickly radiate away their energy and slow down,” Cowsik says.
The paper is Cowsik et al., “Superluminal Neutrinos at OPERA Confront Pion Decay Kinematics,” Physical Review Letters 107, 251801 (2011). Abstract available. The Cohen/Glashow paper is “Pair Creation Constrains Superluminal Neutrino Propagation,” Physical Review Letters 107, 181803 (2011), with abstract available here.
I hope everyone is having a happy holiday season and looking forward to the upcoming New Year’s festivities. In the intervening window, let’s look at the outer Solar System. No other spacecraft has ever come as close to Pluto as New Horizons now has, already halfway between the Earth and the distant dwarf planet. It’s also worth mentioning that New Horizons is only the fifth spacecraft to venture so deep into the Solar System, following the two Voyagers and the Pioneer spacecraft. July of 2015 will be an extraordinary time as we wait for data return from the mission and begin to find answers to some of the many questions that await us there.
But studies from closer to home are continuing to reveal more about Pluto/Charon as well. The Cosmic Origins Spectrograph aboard the Hubble Space Telescope has found evidence for complex hydrocarbon and/or nitrile molecules on the planetary surface. Alan Stern, principal investigator for New Horizons, is behind the study, whose work was recently published in the Astronomical Journal. It’s assumed that what we’re seeing on Pluto’s surface is the result of interactions between sunlight or cosmic rays with methane, carbon monoxide and nitrogen ices.
Image: The Cosmic Origins Spectrograph aboard NASA’s Hubble Space Telescope recently discovered a strong ultraviolet-wavelength absorber on Pluto’s surface. Credit: NASA/STScI.
“This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color,” said Stern.
Also more than a little interesting in light of New Horizons’ upcoming encounter is the fact that the team found evidence for changes in Pluto’s ultraviolet spectrum as compared to earlier Hubble measurements from the 1990s. Whether this is the result of differing terrains being observed in the two studies or surface changes related to atmospheric pressure variations during the time period involved is not known. New Horizons, it’s hoped, will tell us much more.
The paper is Stern et al., “First Ultraviolet Reflectance Spectra of Pluto and Charon by the Hubble Space Telescope Cosmic Origins Spectrograph: Detection of Absorption Features and Evidence for Temporal Change,” Astronomical Journal Vol. 143, No., 1 (9 December 2011), p. 22. Abstract available.
The most interesting thing about the worlds known as KOI 55.01 and KOI 55.02 is not just the fact that they are — if current thinking holds — the smallest planets yet detected around an active star other than our Sun, but that they are evidently survivors of the most extreme kind of experience. KOI 55, their host star, is of subdwarf B class, the exposed core of a red giant that has lost most of its gaseous envelope. The two planets that circle it are in such tight orbits that they would have been engulfed when the central star went through its red giant expansion.
What a scenario, one we’ve often contemplated in these pages as we look toward the future of our own Sun. We tend to think in terms of planets that survive the red giant phase by orbiting far enough from the primary not to be swallowed up in it — smaller worlds like Mercury, Venus and the Earth would not survive the experience. But KOI 55.01 and KOI 55.02 evidently were swallowed, and probably represent the remains of gas giants that underwent the plunge. At present, they are thought to have radii 0.76 and 0.87 times the Earth’s radius.
Elizabeth Green (University of Arizona) explains:
“When our sun swells up to become a red giant, it will engulf the Earth. If a tiny planet like the Earth spends 1 billion years in an environment like that, it will just evaporate. Only planets with masses very much larger than the Earth, like Jupiter or Saturn, could possibly survive.”
Green participated in this work as a member of a team led by Stephane Charpinet (Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse-CNRS). The team’s findings make an intriguing case for the proposition that planets may directly influence the development of their host stars in this late phase of stellar evolution. Here they seem to have done it by contributing to the mass loss that is necessary for a subdwarf B star to form.
Here’s Green again on how this would work:
“As the star puffs up and engulfs the planet, the planet has to plow through the star’s hot atmosphere and that causes friction, sending it spiraling toward the star. As it’s doing that, it helps strip atmosphere off the star. At the same time, the friction with the star’s envelope also strips the gaseous and liquid layers off the planet, leaving behind only some part of the solid core, scorched but still there.”
Finding remnant planets around a stellar core, planets that have passed through the maelstrom of red dwarf expansion, is surprising enough, but the work also came from an unexpected direction. The team’s objective had been to use Kepler data to study astroseismology, examining the rhythmic expansions and contractions that pressure and gravitational forces produce inside a star as it burns. It’s useful stuff because with enough data, astronomers can estimate the star’s mass, temperature and size, as well as learning something about its internal structure.
Astroseismology takes time as researchers accumulate information about the star’s variations in brightness and compare these to theoretical models of stellar interiors. Green had already been studying hot subdwarf stars in the galactic plane and had accumulated spectra of KOI 55 with instruments on Kitt Peak before the Kepler mission was launched. Kepler was able to show the star’s pulsational modes with great clarity and it was in the midst of examining the Kepler data that periodic modulations occurring every 5.76 and 8.23 hours began to turn up. The researchers were able to show that the modulations could not have been caused by internal pulsations.
Two planets were the best explanation, each orbiting closer to their star than Mercury is to the Sun. Conditions on these worlds today must be hellish, as KOI 55 is much hotter than the Sun, but their tight orbits tell us that things were once worse still, when the planets would have been engulfed during the star’s expansion.
“I find it incredibly fascinating that after hundreds of years of being able to only look at the outsides of stars, now we can finally investigate the interiors of a few stars – even if only in these special types of pulsators – and compare that with how we thought stars evolved,” Green said. “We thought we had a pretty good understanding of what solar systems were like as long as we only knew one – ours. Now we are discovering a huge variety of solar systems that are nothing like ours, including, for the first time, remnant planets around a stellar core like this one.”
The paper is Charpinet, “A compact system of small planets around a former red-giant star,” Nature 480, 496–499 (22 December 2011). Abstract available. This University of Arizona news release offers further details.