The space elevator concept has been in the public eye since the publication of Arthur C. Clarke's The Fountains of Paradise in 1979. Its pedigree among scientists is older still. With obvious benefits in terms of moving people and materials into space, elevators seize the imagination because of their scale and the engineering they would require. But we needn't confine space elevators to Earth. As Alex Tolley explains in today's essay, a new idea being discussed in the literature explores anchoring one end of the elevator to the Moon. Balanced by Earth's gravity (and extending all the way into the domain of geosynchronous satellites), such an elevator opens the possibility of moving water and materials between Earth and a lunar colony, though the engineering proves as tricky as that needed for a system anchored on Earth. Is it even possible given the orbital characteristics of the Moon? Read on. by Alex Tolley Image: Space elevator connecting the moon to a space habitat. Credit:...

Some names seem to carry a certain magic, at least when we’re young. I think back to all the hours I used to haunt St. Louis-area libraries when I was growing up. I would go to the astronomy section and start checking out books until over time I had read the bulk of what was available there. Fred Hoyle’s name was magic because he wrote The Black Cloud, one of the first science fiction novels I ever read. So naturally I followed his work on how stars produce elements and on the steady state theory with great interest. Willy Ley’s name was magic because he worked with Chesley Bonestell (another magic name) producing The Conquest of Space in 1949, and then the fabulous Rockets, Missiles, and Space Travel in 1957, a truly energizing read. Not to mention the fact that he had a science column in what I thought at the time was the best of the science fiction magazines, the ever-engaging Galaxy. It still stuns me that Ley died less than a month before Apollo 11 landed on the Moon. My list...

Let’s start the year with a look back in time to 1957, a time when nuclear bombs were being tested underground for the first time at the Nevada test site some 105 kilometers northwest of Las Vegas. If this seems an unusual place to launch a discussion on interstellar matters, consider the story of an object that some argue became the fastest manmade artifact in history, an object moving so fast that it would have passed the orbit of Pluto four years after ‘launch,’ in the days of Yuri Gagarin and Project Mercury. I’m bringing it up because the tale of the nuclear test known as Plumbob Pascal B is again active on the Internet, and it’s a rousing tale. Operation Plumbob involved a series of 29 nuclear tests that fed the development of missile warheads both intercontinental and intermediate. The history of such underground nuclear testing would make for an interesting book and indeed it has, in the form of Caging the Dragon (Defense Nuclear Agency, 1995), by one James Carothers. But...

As I write, Voyager 1 is almost 166 AU from the Sun, moving at 17 kilometers per second. With its Voyager 2 counterpart, the mission represents the first spacecraft to operate in interstellar space, continuing to send data with the help of skilled juggling of onboard systems not deemed essential. Despite communications glitches, the mission continues, and it seems a good time to reprise a piece I wrote on the future of these doughty explorers back in 2015. Is there still time to do something new with the two probes once the demise of their plutonium power sources makes further communications impossible? The idea is hardly mine, and goes back to the Sagan era, as the article below explains. It's also a notion that is purely symbolic, and for those immune to symbolism (the more practical-minded among us) it may seem trivial. But those with a poet's eye may see the value of an act that can offer a futuristic finish to a mission that passed all expectations and will inspire generations...

It’s not often that I highlight the work of anthropologists on Centauri Dreams. But it’s telling that the need to do that is increasing as we continue to populate the Solar System with human artifacts, which are after all the province of this discipline. I’ve often wondered about the fate of the Apollo landing sites, originally propelled to do so by Steven Howe’s novel Honor Bound Honor Born and conversations with the author ranging from lunar settlement to antimatter. Long affiliated with Los Alamos National Laboratory, Howe is deeply involved in antimatter research through his work as CEO and co-founder of Hbar Technologies. In my conversations with Howe almost twenty years ago while writing my original Centauri Dreams book, he was asking what would happen if commercial interests decided to exploit historical sites from the early days of space exploration. The question is still pertinent. Imagine Armstrong and Aldrin’s Eagle subjected to near-future tourists prying off souvenirs or...

Bear with me today while I explore the pleasures of the Infinite Monkey Theorem. We’re all familiar with it: Set a monkey typing for an infinite amount of time and eventually the works of Shakespeare emerge. It’s a pleasing thought experiment because it’s so visual and involves animals that are like us in many ways. Now we learn from a new paper that the amount of time involved to reproduce the Bard is actually longer than the age of the universe. About which more in a moment, but indulge me again as I explore infinite monkeys as they appear in fictional form in the mid-20th Century. In "Inflexible Logic," which ran in The New Yorker's February 3, 1940 issue, Russell Maloney tells the tale of a man named Bainbridge, a bachelor, dilettante and wealthy New Yorker who lived in luxury in a remote part of Connecticut, "in a large old house with a carriage drive, a conservatory, a tennis court, and a well-selected library." He has about him the air of an English country gentlemen of the...

One night a few years back I had a late night call from a friend who was involved in Breakthrough Starshot, the attempt to design a probe that could reach nearby stars and return data with transit times of decades rather than centuries. His news was surprising. The Parkes radio dish in Australia, then being used by the Breakthrough Listen SETI project, had detected a signal that seemed to come from Proxima Centauri. “What’s interesting,” said he, “is that when you move the dish off Proxima, the signal disappears.” You probably remember this episode, which had a brief moment in the news and may well live on among the conspiracy-minded in the wackier regions of cyberspace. We know now that the signal was some form of radio frequency interference, commonly abbreviated RFI. In any case, our conversation was relatively tame because the idea of a terrestrial explanation seemed inevitable, no matter how tantalizing the first look at this signal. After all, with all the years of SETI effort...

"We were dreamers, dreaming greatly, in the man-stifled town; We yearned beyond the sky-line where the strange roads go down. Came the Whisper, came the Vision, came the Power with the Need…" -- Kipling, from "The Song of the Dead" We’re lucky that science fiction fans are such packrats. They not only keep beloved books and magazine issues from their past but also catalog them relentlessly. Because of both these traits, I can turn to my own bookshelf and pull out the November, 1957 issue of Astounding Science Fiction to see P. Schuyler Miller’s review of John Campbell’s Islands of Space, in which he described the novel as “very characteristic of the best ‘hard’ science fiction of its day.” Miller had a lot to do in subsequent book reviews for the magazine with establishing ‘hard SF’ as a category. Campbell’s book, extensively revised from its original appearance in the spring, 1931 issue of Amazing Stories Quarterly, is an interesting curiosity in being the first appearance of a...

Transients have always been intriguing because whether at optical, radio or other wavelengths, they usually flag an object worth watching. Consider a supernova, or a Fast Radio Burst. But non-repeating transients can have astronomers both professional and amateur tearing their hair out. What was Henry Cordova, for instance, seeing in the Florida sky back in 1999? The date seems significant, as we were moving toward the Y2K event, and despite preparation, there was some concern about its effects in computer coding. Henry, a retired map maker and geographer as well as a dedicated astronomer, had a transient that did repeat, but only for a short time, and one that may well have been entangled in geopolitical events of the time. I’m reminded of our reliance on electronics, and the fact that some 60,000 commercial flights have encountered bogus GPS signals, according to The New York Times (strikingly, the U.S. has no civilian backup system for GPS). What goes on in orbit may keep us...

Studying the rich history of interstellar concepts, I realized that I knew almost nothing about a figure who is always cited in the early days of beamed sail papers. Whereas Robert Forward is considered the source of so many sail concepts, the earliest follow-up to his 1962 paper on beamed sails for interstellar purposes is by one G. Marx. The paper is “Interstellar Vehicle Propelled by Terrestrial Laser Beam,” which ran in Nature on July 2, 1966. Who is this G. Marx? My ever reliable sources quickly came through when I asked if any of them had known the man. None had, though all were familiar with the paper, but Al Jackson sent me a copy of it along with another by J. L. Redding (Bishop’s University, Canada), who published a correction to the Nature paper on February 11, 1967. It didn’t reduce my confusion that Redding’s short contribution bears the exact same title as Marx’s. My other contacts on Marx had no personal experience with him either but were curious to learn more. Image:...

Larry Klaes began developing a following for his deep dives into science fiction cinema long ago on Centauri Dreams, through memorable looks at films like The Thing from Another World, Forbidden Planet and The Day the Earth Stood Still. Although he delves into recent films as well, Larry's frequent focus on the 1950s always intrigues me, as he places these movies in the context of our developing, rapidly changing ideas about the spacefaring future. How did our views of space travel change over time as we went from Sputnik to Apollo, and where are they heading today? All of that is a subtext in today's look at Conquest of Space, an odd and irritating take on interplanetary travel with an unusual pedigree and cultural echoes that persist. by Larry Klaes Imagine if the iconic ground (and space) breaking science fiction film 2001: A Space Odyssey, first released into theaters in early 1968, had actually been put together over one decade earlier – in the mid-1950s, to be more precise. Now...

An old pal from high school mentioned in an email the other day that he had an interest in Adam Frank’s work, which we’ve looked at in these pages a number of times. Although my most recent post on Frank involves a 2022 paper on technosignatures written with Penn State’s Jason Wright, my friend was most intrigued by a fascinating 2018 paper Frank wrote for the International Journal of Astrobiology (citation below). The correspondence triggered thoughts of other, much earlier scientists, particularly of Charles Lyell’s Principles of Geology (1830-1833), which did so much to introduce the concept of ‘deep time’ to Europe and played a role in Darwin’s work. Let’s look at both authors, with a nod as well to James Hutton, who largely originated the concept of deep time in the 18th Century. Adam Frank is an astrophysicist at the University of Rochester, and one of those indispensable figures who meshes his scientific specialization (stellar evolution) with a broader view that encompasses...

John Barrow has been on my mind these past few days, for reasons that will become apparent in a moment. In my eulogy for Barrow (1952-2020), I quoted from his book The Left Hand of Creation (Oxford, 1983). I want to revisit that passage for its clarity, something that always inspired me about this brilliant physicist. For it seemed he could render the complex not only accessible but encouragingly pliable, as if scientific exploration always unlocked doors of possibility we could use to our advantage. His was a bright vision. The notion that animated him was that there was something in the sheer process of research that held its own value. Thus: Could there be any shortcuts to the answers to the cosmological questions? There are some who foolishly desire contact with advanced extraterrestrials in order that we might painlessly discover the secrets of the universe secondhand and prematurely extend our understanding. Such a civilization would surely resemble a child who receives as a...

The wish that humans will one day walk on exoplanets is a natural one. After all, the history of exploration is our model. We look at the gradual spread of humanity, its treks and voyages of discovery, and seamlessly apply the model to a future spacefaring civilization. Science fiction has historically made the assumption through countless tales of exploration. This is the Captain Cook model, in which a crew embarks on a journey into unknown regions, finds new lands and cultures, and returns with samples to stock museums and tales of valor and curiosity. Captain Cook didn’t have a generation ship, but HMS Endeavour was capable of voyages lasting years, stocking itself along the way and often within reach of useful ports of call. A scant 250 years later, however, we need to consider evolutionary trends and ask ourselves whether our ‘anthropocene’ era will itself be short-lived. Even as we ask whether human biology is up for voyages of interstellar magnitude, we should also question...

Suspended animation shows up early in science fiction after a long history in prior literature. In Shakespeare, it’s the result of taking a "distilling liquor" (thus Juliet’s ‘sleep,’ which drives Romeo to suicide). In the SF realm, an early classic is John Campbell’s 1938 story “Who Goes There?”, which became the basis for the wonderful “The Thing from Another World" (1951). Here an alien whose spacecraft has crashed remains in frozen suspension for millennia, only to re-emerge as the barely recognizable James Arness. In the essay below, Don Wilkins points us toward a new study that could have implications for achieving the kind of suspended animation that one day might get a crew through a voyage lasting centuries. A frequent contributor to Centauri Dreams, Don is an adjunct instructor of electronics at Washington University, where the work took place. Echoes of van Vogt’s “Far Centaurus”? Read on. I'll have another take on this topic in the next post. by Don Wilkins Humans have...

One of the pleasures of writing and editing Centauri Dreams is connecting with people I’ve been writing about. A case in point is my recent article on Freeman Dyson’s “Gravitational Machines” paper, which has only lately again come to light thanks to the indefatigable efforts of David Derbes (University of Chicago Laboratory Schools, now retired). See Freeman Dyson’s Gravitational Machines for more, as well as the follow-up, Building the Gravitational Machine. I was delighted to begin an email exchange with Dr. Derbes following the Centauri Dreams articles, out of which emerges today’s post, which presents elements of that exchange. I run this particularly because of my continued fascination with the work and personality of Freeman Dyson, who is one of those rare individuals who seems to grow in stature every time I read or hear about his contributions to physics. It was fascinating to receive from Dr. Derbes not only the background on how this manuscript hunter goes about his craft,...

Colonies on other worlds are a staple of science fiction and an obsession for rocket-obsessed entrepreneurs, but how do humans go about the business of living long-term once they get to a place like Mars? Alex Tolley has been pondering the question as part of a project he has been engaged in with the Interstellar Research Group. Martian regolith is, shall we say, a challenge, and the issue of perchlorates is only one of the factors that will make food production a major part of the planning and operation of any colony. The essay below can be complemented by Alex’s look at experimental techniques we can use long before colonization to consider crop growth in non-terrestrial situations. It will appear shortly on the IRG website, all part of the organization’s work on what its contributors call MaRMIE, the Martian Regolith Microbiome Inoculation Experiment. by Alex Tolley Introduction: Food Production Beyond Hydroponics Conventional wisdom suggests that food production in the Martian...

Interstellar flight poses no shortage of ethical questions. How to proceed if an intelligent species is discovered is a classic. If the species is primitive in terms of technology, do we announce ourselves to it, or observe from a distance, following some version of Star Trek's Prime Directive? One way into such issues is to ask how we would like to be treated ourselves if, say, a Type II civilization - stunningly more powerful than our own - were to show up entering the Solar System. Even more theoretical, though, is the question of panspermia, and in particular the idea of propagating life by making panspermia a matter of policy. Directed panspermia, as we saw in the last post, is the idea of using technology to spread life deliberately, something that is not currently within our power but can be reasonably extrapolated as one path humans might choose within a century or two. The key question is why we would do this, and on the broadest level, the answer takes in what seems to be...

Larry Klaes is well known in these parts for his extraordinary reviews of classic science fiction films. Today, however, he steps back from cinema to consider how we will expand into space. The crews on our deep space missions will doubtless be a lot different than some of those old black-and-white movies would suggest. Just how will our species adapt to the environments it will soon be exploring? There's nothing quite so lush as our own blue and green planet, yet the imperative to move ever outward is a driver for our species. Mars is a case in point, but the long-range picture is that we're looking off-planet and already pondering destinations beyond the Solar System. Re-shaping our expectations will be a part of what drives the scientists and engineers who equip us for the next steps. An earlier version of this essay was published by The Mars Society. by Larry Klaes In 1972, singer, pianist, and composer Sir Elton Hercules John (born 1947) released a song titled "Rocket Man". This...

Taking a long walk in the early morning hours (and I do mean ‘early,’ as I usually walk around 4 AM – Orion is gorgeously high in the sky this time of year in the northern hemisphere), I found myself musing on terminologies. The case in point: The Fermi Paradox. Using that phrase, the issue becomes starkly framed. If there are other civilizations in the galaxy, why don’t we have evidence for them? Much ink, both physical and digital, has been spilled over the issue, but I will argue that we should soften the term ‘paradox.’ I prefer to call the ‘where are they’ formulation the Fermi Question. I prefer ‘question’ rather than ‘paradox’ because I don’t think we have enough data to declare what we do or do not see about other civilizations a paradox. A paradox is a seemingly self-contradictory statement that demands explanation. But is anything actually demanded here? There are too many imponderables in this case to even frame the contradiction. How can we have a paradox when we are...