Centauri Dreams
Imagining and Planning Interstellar Exploration
Disrupted Systems: Implications for Life
Anthropocentric thinking is a persistent problem when we’re talking about extraterrestrial civilizations. Some of our most cherished notions can be invoked so effortlessly as to defy the imagination. The Copernican idea that life must exist elsewhere because elsewhere is bound to be more or less like here has had a long lifetime in SETI studies. It seems like the most basic common sense. And yet, as we’ll see once again today, scientific results continue to make it apparent that the fact that we are here does not mean that they are there.
Finding stellar systems more or less like our own continues to be difficult. I’m not going full ‘rare Earth’ here but acknowledging that our circumstances may be unusual enough to tamp down estimates of the number of life-supporting planets. For that matter, our lack of knowledge about abiogenesis itself makes the case that we cannot necessarily expect it around other suns. On this matter, at least, we should be able to gather data soon, perhaps with a Mars lander.
Which gets me to today’s interesting take on binary stars. The binaries – HD 129171 and HD 129209 – are G-class, both having formed from the same molecular cloud. This is a common enough scenario, because binary systems are extremely common. In fact, about half of the stars in the Milky Way have a companion star, and thus are likely to share a common chemistry.
About 180 light years from the Sun (based on Gaia data) in Boötes, the system is proving unusually helpful. Using the UVES spectrograph on ESO’s Very Large Telescope (VLT) in Chile, an international effort led by Anne Rathsam at the University of São Paulo in Brazil is using this binary as a laboratory to study chemical differences between the stars that may be telling us something about planet formation and orbital evolution. What is driving the differences?
All this has a bearing on life, because for life to occur, conditions must exist for long enough to let the necessary processes go to work. And that may be a problem. HD 129171 turns out to be enriched in refractory elements, while its companion HD 129209 is not. Refractory elements condense at high temperatures, as opposed to volatiles, and the proportion of one to the other can be an interesting diagnostic tool, telling us something about the system’s history. A star depleted in refractories is likely one that has spawned planets, while one heavy in these elements has likely swallowed planets whole.
Rathsam’s work, available in a paper just published in Astronomy & Astrophysics, focuses on beryllium, whose abundance here is interesting because it is not produced in stellar interiors. Measured properly, its presence points to a star that consumed planetary material long after formation. Lithium, beryllium, and boron, in fact, share characteristics that make them exceptional in terms of chemical emergence in the galaxy. Jorge Luis Melendez Moreno (USP), who served as study advisor to Rathsam on this paper, explains:
“All other chemical elements originate from primordial nucleosynthesis [the formation of the first atomic nuclei in the minutes following the Big Bang] or stellar nucleosynthesis [the nuclear fusion process that occurs inside stars throughout their lifetimes]. But not beryllium and boron. They primarily arise through a process called ‘cosmic spallation,’ in which high-energy particles fragment heavier nuclei, such as carbon, nitrogen, and oxygen, producing lighter elements.”
Image: The binary system of HD 129171 and HD 129209. Credit: Digital Sky Survey/Aladin/Anne Rathsam.
Lithium has its own uses as a marker, but the USP researchers found that beryllium is the more reliable tool, with a longer lasting chemical signature. HD 129171’s surplus of refractory elements (including magnesium, silicon, calcium and titanium) compared to its companion HD 129209 is accompanied by lithium and beryllium excess as well. The authors see evidence for rocky material equivalent to more than eleven times the mass of the Earth. This would have been ingested in the star, raising interesting questions about planet dynamics.
The infall of entire planets into a host star can be explained in various ways, from gravitational perturbations from other planets on eccentric orbits or skewed inclinations, to interactions within the early circumstellar disk driving young planets onto migratory trajectories. Although I hadn’t seen this paper before, the authors cite a 2025 study by Soares and team (citation below) that draws on simulations to show that about half of the stars simulated should ingest planets, leaving a chemical signature in perhaps 20 percent of them.
Evidently we can imagine system disruptions as a common occurrence in the Milky Way. We might add to this the fact that planet configurations with giant planets in circular outer orbits and rocky planets on inner ones are not common. Our observational data so far tends to confirm this, although tracking outer Jupiter-class planets with our current detection methods is always problematic given their sparse transit signatures. Overall, though, the picture that is emerging is that systems similar to the Solar System seem rare. If many systems are going through upheavals through planet migration and ingestion into the host, stable orbits may be trickier than we’ve thought. Rathsam comments:
“In our planetary system, the planets have relatively stable, low-eccentricity orbits. However, if planetary engulfment is common, it suggests that many systems undergo violent dynamic phases.”
Implications?
“Life wouldn’t just need billions of years to emerge and evolve. The planet would also have to remain in a sufficiently stable orbit to survive significant gravitational perturbations.”
If you’re wondering about our own star, it’s light in refractory materials relative to volatiles, which at least one recent study sees as a sign of planet formation at an early era. What became rocky planets and planetesimals, in other words, was never accreted into our star. I give that citation below. This and subsequent work seems to peg the Sun as the center of a dynamically quiet system compared to many, but be aware that the debate on this matter continues.
How useful is beryllium as a marker in such an analysis? The authors argue that despite the fact that beryllium is eventually depleted in a stellar interior, it persists long enough to provide reliable information. From the paper (my italics):
Refractory elements offer an excellent way to distinguish between the planet engulfment or the proto-cloud inhomogeneity scenarios. Since they have high condensation temperatures (≳1000 K), they are the primary constituents of the rocky material in planetary systems – terrestrial planets and cores of gaseous planets. In case of engulfment by a Sun-like star, this material is accreted by the star and then dissolved and mixed in the convective envelope, increasing the stellar surface abundances after the event (Sandquist et al. 2002). This process, however, produces a metal-rich outer layer with an unstable mean molecular weight gradient, which triggers thermohaline mixing (Théado & Vauclair 2012; Sevilla et al. 2022). For fragile elements such as Li and Be, this thermohaline mixing induces depletion, as it can carry these elements below the convective zone, into their burning regions. Thus, the chemical enrichment caused by the engulfment disappears over time. Nevertheless, Sevilla et al. (2022) demonstrated through simulations that the Li engulfment signature in stars with masses close to solar can be detected for ≥1 Gyr.
As far as I can tell, it’s the treatment of beryllium as a marker of engulfment that gives this paper its significance, as heretofore it has been used primarily as a diagnostic for the mixing of elements in stellar interiors. More broadly speaking, though, any reminders of the factors that make our Solar System adaptable for life should help us in identifying systems where life is less likely. That’s worth keeping in mind as we move beyond easy assumptions about life’s ubiquity and dig into realities that may make it more unusual than we thought.
The paper is Rathsam et al. (2026). Planet engulfment in the chemically anomalous HD 129171/HD 129209 pair. Astronomy & Astrophysics, 710, A236 (full text). The interesting paper on beryllium’s persistence is Soares et al. (2025). Assessing the processes behind planet engulfment and its imprints. Astronomy & Astrophysics, 693, A47 (preprint). The paper on the composition of our Sun is Meléndez et al. (2009). The peculiar solar composition and its possible relation to planet formation. The Astrophysical Journal Letters, 704(1), L66–L70. Abstract.
Pandora: Tuning Up our Data on Exoplanet Atmospheres
Launching a flagship-class mission like the Roman Space Telescope is always exciting, but with Roman in space, let’s also keep an eye on Pandora, a smaller though fascinating NASA mission (through its Astrophysics Pioneers program) that is now beginning its own work in exoplanet science. 20 exoplanets are targeted here, the idea being to work with data from transits to characterize their atmospheres via transmission spectroscopy, but with an additional twist. Elisa Quintana,(NASA GSFC) is principal investigator:
“Pandora’s data will help close a major gap in our knowledge about planets and their host stars because, right now, we can’t be entirely sure how the star’s light affects measurements of what makes up exoplanet atmospheres. We designed the Pandora spacecraft and its in-depth observing program to better understand this vexing issue.”
Launched January 11 of this year, Pandora is now beginning observations of its target stars. It’s in that category of smallsats that fascinate me because their low cost also gives them the option of higher tolerance of failure, making it possible to push the limits without great financial risk (the cost cap on this class of mission is $20 million). A tool like this can be tightly focused on specific targets without compromising larger instruments that are already besieged with obligations to existing observing programs. Word from the Pandora team is that science work begins with all instruments performing as expected.
Image: Artist’s concept of NASA’s Pandora mission, which will help scientists untangle the signals from exoplanets’ atmospheres and their stars. Credit: NASA GSFC/Conceptual Image Lab.
What makes Pandora so interesting is that it’s a multi-wavelength mission. Pandora’s telescope, an aluminum Cassegrain instrument 45 centimeters in diameter, feeds detectors that work in both visible light for long-baseline photometry as well as near-infrared (NIR) wavelengths. Starspots or other stellar activity can be separated from the near-infrared spectroscopy data on the planet’s clouds and atmospheric hazes. This is information that will inform subsequent work with telescopes like JWST and Roman as we refine our tools for removing noise in the data. A recent paper on Pandora makes the case:
Alongside the opportunities explored throughout this work, Pandora provides a unique opportunity to help overcome many hurdles inherent in observations with current instruments. Namely, multi-epoch observations of exoplanet atmospheres with JWST are often observed at different points in the stellar rotation, making them difficult to fit jointly (e.g., E. M. May et al. 2023). By providing information about the stellar activity and allowing for corrections at the data level, joint Pandora–JWST programs will unlock new insights into planets around active hosts. Additionally, these same insights will inform the presence of offsets between different instruments and epochs, which have been difficult to constrain thus far with JWST alone (e.g., A. L. Carter et al. 2024).
Pandora is going to give us useful data on stellar contamination in our transmission spectroscopy work. That means a clearer and more reliable look at the composition of exoplanet atmospheres. Stellar contamination should stand out, with a minimum of 10 transit observing sessions per target, each lasting about 24 hours. The plan is to accumulate, for each target, roughly 240 hours of pointing time, which should yield more than 120 hours of science data once Earth occultations and unavoidable gaps for downlinks, etc. are taken into account. An instrument like JWST can collect transmission spectroscopic data for exoplanets but only with relatively short observing sessions involving one or a small number of transits. The combined datasets of the two observatories will cleanly excise star signals from the data on planetary ones.
The finalized target list was published last January and contains 19 host stars, one of which is orbited by two of the target worlds. The stars range from M-dwarfs to K-class. 16 of these planets have been observed previously by JWST, which will allow the retrofitting of the Pandora measurements onto the JWST spectra. As far as I can tell, earlier provisional target lists included planets that didn’t make the final list, with the emphasis shifting toward larger warm Neptunes and Saturns. That makes sense given that these offer higher signal-to-noise ratios as we put these techniques to work together for the first time.
Image: This is Figure 1 from the paper. Caption: The absorption cross sections of common absorbers in exoplanet atmospheres considered in this work, shown at a pressure and temperature of 0.1 mbar and 1000 K. The wavelength coverage of Pandora’s NIR detector (NIRDA), JWST’s NIRCam F322W2 and F444W filters, and HST’s WFC3 instrument (for the G141 grism) are shown. Pandora/NIRDA covers absorption bands of H2O, CH4, NH3 and the wing of the K doublet, making it most sensitive to these absorbers. Credit: Rotman et al.
Using these methods, Pandora’s science observations should be more accurate and reliable than any planetary atmosphere readings ever taken before. The paper is Rotman et al., “NASA’s Pandora SmallSat Mission: Simulated Modeling and Retrieval of Near-Infrared Exoplanet Transmission Spectra,” accepted at The Astronomical Journal (preprint).
Fermi Explorer: Building the First Mission to Another Star?
The question of when to launch an interstellar mission has occupied us many times in the past. Specifically, how long do we wait so that travel times are reduced to something like the lifetime of a researcher working on the project? But there is another approach to all this. Someone is going to launch an interstellar mission that will be the first human effort to send a payload to another star. It’s all about intentionality and the choice of targets.
A symbolic act? Sure, but don’t write the idea off. We can learn a lot from symbolic acts, and if we only have, at our current level of technology, the ability to reach Voyager-like speeds, we can still work on issues like equipment lifetimes, self-healing technologies, navigational issues and more. We can also work to refine existing AI tools to achieve the most efficient design.
If we give ourselves 80,000 years to reach Alpha Centauri, we have to contend with the fact that the system is constantly moving. On this timeframe, by the time the craft would arrive, Centauri A and B would be a bit over 6 light years from the Sun as opposed to their current 4.365 light years. Trajectory analysis going this far into the future is going to be an interesting challenge.
I mention all this because a call to mount such a mission has now arisen. It bears the name Fermi Explorer, and according to its new website, its intention is to get a spacecraft with a 1 kilogram, 10X10X10 cm payload to the barycenter of the binary Centauri A and B system. In other words, the target is not either star itself but the common center of mass between the two as they orbit.
Some particulars: The mission should launch before the end of 2029 if the effort succeeds, and is intended to cost less than $15 million to design, build, launch and operate. Mission co-founder Philip Johnston is going to have his hands full.
As to departure, Fermi Explorer would take a year and a half moving out of Earth orbit. Then, using a series of Oberth maneuvers taking it to within 0.42 AU of the Sun, the craft would rely upon what the site calls a ‘perihelion pump,’, which involves multiple close solar flybys over 12 years to build the energy to achieve an escape trajectory that, after climbing out of the Sun’s gravity well, attains 23.64 km/sec. That’s a bit higher than Voyager 1’s 17 km/sec. Final Solar System departure would be, after a 2029 launch, around the year 2043. Ahead for the spacecraft would be an unpowered cruise of over 70,000 years.
What the craft will carry is not yet determined, although I notice the plan to put a copy of the Voyager Golden Record and similar materials onboard (I’m assuming this is to be done digitally). Ahead is a three-month period for solicitations for other items of cultural value. Likewise, scientific instruments will undergo their own period of solicitation. The emphasis is on flight-proven hardware with little research and development necessary. To quote from the website:
We will soon put the mission out for open tender to all the major satellite manufacturers, and we aim to open-source as much of the design as we can. The four primary objectives are considered non-negotiable. Everything else is negotiable. For example, the manufacturers can determine the power system, antenna strength, propulsion, mission profile, and whether to include gravity assists, etc. We anticipate that we can do the mission with around a 100-200 kg small solar-powered satellite with just electric propulsion, doing what we call a perihelion pump maneuver… We expect the mission will not have a large antenna for communication, and so we expect we will lose connectivity relatively quickly, and so much of the mission will be autonomous. It will be too small to track and will lose power once it leaves the solar system.
Can crowdfunding build an interstellar craft? The hope is clearly that enough people will become interested to help, with the site offering engraved names and physical objects in the payload itself, so the scientific payload, already tightly squeezed, will have a mass budget with even tighter constraints.
And with all the attention AI is getting in the press, note its use here. The website points to a key technical report called “Interstellar Precursor Mission to Alpha Centauri: Technical Feasibility Assessment,” dated July of 2026. Specifically, the report is said to be: “Prepared with PSI’s Autonomous Physics-Research Platform,” under which is stated “Physical Superintelligence’s agentic research system produced the analyses, simulations, and proof-grade verification in this report end-to-end under staged independent audit.” And again: “This report did not undergo comprehensive human peer review.”
This gets interesting. Writing for MIT Technology Review, Michelle Kim has a fine piece on the use of AI for Fermi Explorer that fills in the background. PSI is a research laboratory called Physical Superintelligence, and its AI system is what came up with the trajectory Fermi Explorer would follow. According to Kim, PSI’s AI went to work on the problem of getting a small spacecraft like this up to speed:
A week later, the AI system turned up a novel trajectory… It combined well-known orbital maneuvers in a way the Fermi team had not considered, according to a paper that has not been peer-reviewed. It suggested that the spacecraft could first slow down so its orbit swings in close to the sun—closer than Mercury. On each close pass, it would fire its engine so that the solar panels get four times the light, and a burst of thrust delivered at high speed would buy more energy than the same burst anywhere else. Because the engine would run only near the sun, the solar panels could stay small and the spacecraft light.
The Fermi Explorer site also links to a separate mission analysis which cross-references the PSI report and seems to agree with its results almost completely. I’m assuming human peer review is going to come into play if momentum for this mission builds. But watching the development of these models for physics and their tweaking along the way is a fascinating exercise.
Roman Space Telescope Launches Tomorrow
We’ll have a lot to talk about when observations from the Nancy Grace Roman Space Telescope start coming in. But first we’ve got to get it out to its halo orbit around the L2 Sun-Earth Lagrange point. With the Sun, Earth and Moon permanently blocked out, the seeing should be good from this vantage some 1.5 million kilometers out. Just now I’ve had a note from Jim Benford reminding me that launch is currently scheduled for tomorrow, August 30, at 0726 ET (1126 UTC). The additional good news is that Jim’s son Dominic will be one of two hosts of the live coverage from NASA. I remember meeting Dominic some years back at Goddard Space Flight Center, where I had the chance to see the JWST telescope being prepared to go through its vibration testing.
Dominic has spent more than a decade working on the Roman telescope, so the honor of working the NASA live coverage is well deserved. The photo below shows him during preparations for the Sunday coverage, which starts at 0620 ET (1020 UTC). You can tune in on Facebook, Instagram, Twitch, X, Discovery+, Amazon Prime, YouTube, or NASA+ (see https://www.nasa.gov/live/ for links and updates).
And as Jim reminds us: “As with any launch, timing can change because of weather or other conditions, so check NASA for the latest schedule. Fingers crossed!”
A ‘Time Variable’ Feature on Pluto?
With New Horizons now 63 AU out, it’s time to ponder that record hibernation period that the spacecraft just went through. Over 10 months long, this one had the same goal as previous such periods, to hold down operating costs but also give a break to onboard instrumentation in hopes of augmenting mission lifetime. As a kid, I often thought how cool it would be to be involved with a distant spacecraft. For some reason I always visualized this as being here on Earth while working with a craft beyond the Solar System. So maybe I was dreaming more of being a flight controller than an astronaut.
I hadn’t realized until reading Alan Stern’s recent update that while hibernation means there are no commands and responses going back and forth, the craft does continue active data gathering from its Solar Wind at Pluto (SWAP) plasma detector and the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. The Student Dust Counter is also in operation. Since awaking early in the summer, New Horizons has been delivering data from these instruments back to Earth.
I see that future flybys of Kuiper belt objects (KBOs) are still a distinct possibility, assuming that one can be found within range of the vehicle. And yes, the Vera Rubin Observatory is already in use in the search for such objects, with planning extended to requests for time on the Roman Space Telescope, now scheduled for launch within days. Writing about New Horizons always comes with a tinge of melancholy as I contemplate the fact that no successor is ready, but it’s a relief to see how active this tough little craft continues to be. There are good successor concepts out there, but none are currently funded.
Meanwhile, we have the interesting news about possible liquid flows on Pluto’s surface, revealed by New Horizons images of Sputnik Planitia, the nitrogen glacier whose northern regions reveal convection cells separated by features that suggest liquid nitrogen has flowed there in the past. The new work out of Southwest Research Institute (SwRI) and published in the Planetary Science Journal, suggests that this process continues, doubtless through liquid nitrogen upwelling from beneath the glacier.
SwRI’s Kelsi Singer, one of the study’s co-authors, comments:
“The surface of Sputnik Planitia is quite young, probably less than one million years based on modeling of the surface overturn, and thus these features that we are looking at must have formed since then. Pluto has many unique terrains seen nowhere else in the solar system, and this area of Sputnik Planitia is one of them. Its surface provides a different set of conditions compared to what we are used to on Earth, and exploring that allows us to better understand how materials behave in environments that are difficult to produce on Earth.”
Image: Pluto’s northern Sputnik Planitia glacier (in the western or left side of Pluto’s bright heart) is shown here in a color mosaic made from NASA’s New Horizons imagery. The direction of north is shown on the image. The image is ~ 700 x 350 kilometers across. The red box has been added to show most of the region containing dark features attributed to the wetting of the glacier by liquid nitrogen sourced from a “basal melting” process beneath the glacier. NASA/Johns Hopkins APL/SwRI.
These findings are based on studies of a glacial surface far from Earth and involve liquid nitrogen rather than water, but it’s interesting that the paper reports that the surface patterns on this region of Sputnik Planitia have darkened in ways that are similar to Earth glaciers that have undergone their own wetting by subsurface liquid. The team worked with images from the Landsat 9 satellite that included the Greenland ice sheet. Computer models of glacial melting led by Orkan Umurhan (SETI Institute) reveal a transport mechanism to the surface and indicate an icy flow that can persist on the surface for short periods, which would account for the dark features.
And there is another Earth analogue that perhaps comes into play. From the paper:
We have posited that the striking, dark, irregular linear and diffuse features prevalent at the northern margin of SP are manifestations of the upwelling of liquids or liquid slurries from beneath the SP ice sheet. We have further posited that these liquids were created as a basal melt at depth below the glacier, and we have quantitatively shown the plausibility that such a mechanism can then advect through conduits to the surface of SP where it will horizontally spread out, leaving a darkened surface akin to that observed in northern SP. The buoyant ascent of liquid nitrogen through the denser N2 ice is akin to terrestrial volcanism where less dense basaltic melt rises through cold continental crust.
Does this process occur on other dwarf planets in the Kuiper Belt? We won’t know that until we have mapping missions to objects like Eris. The paper also mentions the obvious candidate at Neptune, the large moon Triton, as a possible example of such processes factoring into the geysers Voyager 2 observed during its flyby. For that matter, it’s fascinating to consider that despite the success of New Horizons at Pluto/Charon, over half the planet (I know I’ll get emails about calling it that) remains unmapped at high resolution because of the geometry of the encounter. So for the time being, we don’t even know whether apparent flows like that at Sputnik Planitia occur elsewhere.
The SETI Institute’s Umurhan points out that the physics of solid nitrogen materials under stress and strain are not well understood, and have to this point “never been studied in real detail in the laboratory.” We need, in other words, to go out there and look, and New Horizons has just reminded us why.
The paper is Stern et al., “Evidence for Possible N2 Basal Flow beneath Pluto’s Northern Sputnik Planitia,” Planetary Science Journal Vol. 7, No. 7 (31 July 2026), 185 (full text).
The Limits of Understanding Between Species, and the Issue for Interstellar Communication
We’ve yet to find any evidence of intelligent life beyond Earth, a puzzling failure given the widespread belief that where habitable planets exist, life will somehow emerge. If we do receive a signal, though, would we be able to understand it? We’ve made some progress in piecing together animal communications here on Earth, but figuring out what the whistles and clicks of sea creatures mean remains a work in progress. In today’s essay, associate editor Alex Tolley goes to work on key questions: Is mathematics truly a universal language? Does language change how we experience the world, and if so, what aspects of an alien culture will we actually be able to understand? The questions are daunting and now coming into public discourse in the realm of AI. Alex’s thoughts on that phenomenon and how we might interact with a machine civilization are only part of the interest here.
by Alex Tolley
Introduction
Discussions about alien communication usually focus on the technology of message transmission and how to decode the first message received. This essay will address the issue of decoding the first message and the expected limits of the subjects that can be communicated.
Humans have a long history of wanting to talk to other species. From the many stories of talking with various animals, often projected with human qualities, to talking with invisible entities, including invisible deities and dead ancestors, to the modern period, where talking with pets and inanimate objects is not looked askance at, and now chatting with large language models (LLMs) that usefully talk back.
We have learned of the vast size of the universe, and rationalize that there must be life and intelligent, technological civilizations somewhere in that vast universe. The search for extraterrestrial intelligence (SETI) is an attempt to answer the question of whether there are other intelligent species in the stars.
Serious attention to searching for aliens and receiving their messages started around 1960. The assumption was that if life also existed on other planets, evolution might eventually produce intelligent, technological life, with interests not dissimilar to ours. The only question was how many civilizations interested in communication there were. The basic model was encapsulated in the famous Drake Equation [1]. While the probabilities of intelligent, communicating civilizations were very much a guess, Drake has made the claim that their number is the same as their communicating longevity.[1, Appendix A] If they communicate for 10,000 years, there should be about 10,000 communicating civilizations, perhaps in a “Galactic Club”. Sixty-odd years later, there has been no detection of such signals using the technologies we have at our disposal. Despite the unanswered Fermi Question that there may not be any civilizations in space, and nor have there ever been, SETI continues with the hope that intelligent life must exist somewhere in the vast reaches of space, although the emphasis has shifted towards the astrobiologists’ hopes that at least life exists elsewhere and how best to detect it.
Figure 1. Participants in the 3rd Decennial US-USSR meeting on SETI in Santa Cruz, CA. 1991. Frank Drake can be seen standing in the middle front row holding the sign “N EQLS L” (Source: The Biological Universe (1996) p487)
But suppose a signal is detected; what then? Decoding an alien message might not be easy. A few years ago, the artist Daniela de Paulis and her team devised a test signal for the public to decode [2]. Even though the signal data was formatted using human transmission coding, it took about a year before the signal was successfully decoded. This, despite prior knowledge of the signal transmission features, and despite sending only 2-D images, with a clear similarity in form to previous ideas we have had for decoding signals. How much harder might a real alien signal be to decode?
Terrestrial Animal Communication as a Decoding Test
Animal communication, and potentially language, offers another way to attack the issue of communication with a species very different from us. While aliens have so far proven elusive, Earth is teeming with animal life, some of which appears quite intelligent, even if unable to use more than rudimentary technology. Research into animal communication continues to determine the extent, if any, that intelligent animals have a language they use to communicate with their own kind. Progress is being made, but could we ever talk to the animals like the fictional Dr. Dolittle?
Despite their far greater separation from humans in evolutionary time than apes. and their aquatic environment, cetaceans seem to have more complex communication and perhaps something closer to a true language. Work by the linguist Gašper Beguš has shown that sperm whales (Physeter macrocephalus) communicate with a series of clicks, or codas, that can be compared to how humans produce vowel sounds [3]. AI was used to extract the commonality of codas of “vowels” between individual whales, although there is insufficient information to connect the sounds with meaning. The video below explains the concept of the sequences of clicks, or codas [4].
From their recent paper [3] Beguš concludes:
…our findings demonstrate that sperm whale vocalizations are highly complex and likely constitute one of the most phonologically sophisticated (currently known) communication systems in the animal kingdom.
Another study by a different team on 2 separate sperm whale populations in the eastern and western Mediterranean showed that the 2 populations used different “dialects” for the same codas.[5] A recent study indicated that sperm whales change the tone of their codas when encountering ships, indicating that they recognize ships in some way, although we don’t know what it means [6].
Work by Sayigh et al with a wild pod of bottlenose dolphins (Tursiops truncatus) was able to extract consistent clicks and whistle sounds for both individuals and the group [7]. The clicks identify individuals and are used to identify the individual, and to contact others. Whistles are associated with emotional and social interactions, for example, courtship and mating.
While we are still a long way from decoding the meaning of the vocalizations of dolphins and sperm whales, it does appear that they have some sort of language to communicate with others of their kind. As might be expected, the geographic separation of pods hints that there are also different dialects associated with pods at different locations.
Suppose in the future that we manage to decode the meaning of these communications, and that these cetaceans, while not as sophisticated as the dolphins in Douglas Adams’ Hitchhiker’s universe stories, do have a basic language that uses their various vocalizations. What could they communicate that we could understand?
This is where the influence of Thomas Nagel and his seminal essay “What is it like to be a Bat?” is relevant [8]. Nagel argued that we cannot understand an animal without being that animal. If he argument is correct, then as we are not sperm whales or dolphins whose experiences are very different to ours, there may well be a communication gap between our species. We could understand the meanings of vocalizations of objects and actions, but not of feelings and other qualia, and conversely these cetacans could not understand ours. As for the abstractions each species has for dealing with its environment, these may forever be unintelligible.
Aliens as species with different experiences
Recall that one assumption of SETI is that some civilizations would have similar ideas and motivations as we do. That they would have a sophisticated technology, likely far ahead of ours, but with similar ideas about inter-civilization communications and a desire to learn. Just as we try to learn about animals, and even communicate with them, so aliens might send out signals to try to initiate a communication with us. If so, we should be able to receive them, and possibly respond.
But is this the case, and are we assuming that our differences as species and evolved experiences can be overcome, contra Nagel?
We have made an attempt at sending out an informative message, the Arecibo message, as well as the Pioneer probes 10 & 11 plaques, and Voyagers 1 & 2 records. The Arecibo message and Pioneer plaque are shown in Figure 1 below.
Figure 2. Left) The Arecibo message radioed into space. Right) The Pioneer space probe plaque with depictions and information about Earth and its intelligent species.
The approaches of both messages assume some common understanding between humans and aliens. The Arecibo message is very concise, but not easy to interpret even by humans. The Pioneer plaque is clearly a more representative message, although how easy would it be for an alien species to recognize the location of our system from the representation of pulsars? Explanations of the messages are found at [9,10]. The Voyager Golden Record needs to have a player to extract the information that includes sounds and music. How might aliens interpret these sounds?
It has come to my attention that Joe Davis had created an artwork of the Arecibo Message using bottles of water at MIT, yet none of the students and scientists could discover any meaning to the display. In 2009, to celebrate the Arecibo Message’s 35th anniversary, Davis also sent out from the Arecibo telescope a cleverly encoded message of the DNA sequence of a photosynthesis enzyme, RuBisCO, which, while ingenious, seems impossible for an alien to decode its meaning [15,16,17]. Yet as he said, it was more about our view of ourselves than for any alien recipients.
A general assumption has been that technological aliens must have a reasonably common perception of the universe as we do. Indeed, John McCarthy (of Lisp and AI fame) espoused that view at a SETI meeting [11]. His argument was that just as evolution results in convergence of phenotypes to fit their environment, like the shapes of Ichthyosaurs and dolphins, so intelligence will converge on the same concepts as we share the same universe and discover its properties and laws. Math as a purely logical construct is therefore often assumed to be a common language between humans and aliens. Numbers, and their manipulations should be common. Hence the idea that a primer in a message might start with basic arithmetic and work upwards from there. However, at another SETI meeting, mathematician Keith Devlin was not so convinced that this would be the case. His argument was that math was actually a unique product of the human mind and reflected our construction of the universe [11].
If he is correct, what are we to make of Eugene Wigner’s 1959 lecture title about math and nature, “The Unreasonable Effectiveness of Mathematics in the Natural Sciences”? Is this a unique formulation of the human mind and experience, whilst it may be very different for an alien mind?
This issue has been raised in a number of works, but it is perhaps most concisely put in Brian McConnell’s slim book, “The Alien Communication Handbook” [13] and his Centauri Dreams post “Communicating with Aliens: Observables versus Qualia” [14]. His view is the consensus one, that some things such as physical objects and actions are communicable between species, whilst others, such as feelings and experiences, are most likely not. He takes McCarthy’s side in saying that mathematics and logic are also assumed to be universal, perhaps confirming Wigner’s statement.
We often forget that language determines how one views the world. It is well known that in the West we tend to see the world as distinct objects with some associations between them. The Japanese also see the spaces between objects, and have words to describe those spaces. e.g., Ma is for negative space, such as the space between musical notes, or the spacing of flowers in flower arrangements. As we know from the difficulties of translation between languages, some concepts don’t have words in the other language. In English, we now use the German word schadenfreude as there is no English equivalent for the “pleasure derived by someone from another person’s misfortune.” The power of words to shape perception is exemplified in Ted Chiang’s short sci-fi story “The Story of Your Life”, filmed as “Arrival.” It illustrated how language itself could change what you experience, in this case one’s experiences of the future.
AI as magic Pixie dust and an alien mind
Our AI technology using LLM technology has performed creditably well in translation between languages. It has also played a role in extracting the key components of sperm whale codas, and therefore establishing associations that apply between different individuals in the same pod, much as humans have different accents and ways of speaking the same words. AI is currently the magic behind science fiction universal translators, allowing humans and aliens to converse.
But of perhaps more pertinent is the idea that AIs are becoming minds, although there is considerable debate about this. However, AI “minds” are likely to be different than human minds, if only because they do not experience the qualia we experience. Are AIs going to have unemotional thoughts like Star Trek’s humanoid robot, Commander Data, but like sociopaths, able to mimic human emotions and empathy? If given a very different training set of data, would they acquire minds that are shaped by that data set? Could we design the data set to mimic that of hypothetical aliens, and thereby create fake alien AI minds?
Humans are good at projecting agency and anthropomorphizing animals and objects. Most famously, Weizenbaum’s simple ELIZA therapist program persuaded many that it was a person, much to his horror. Alan Turing had proposed that if judges could not distinguish between a human and a computer responding to questions, then the computer program was intelligent. After years of Turing Test competitions, we have now comfortably blown past that test, although we are still debating if LLM-based AI is truly intelligent. The interesting issue is that we are at the point where several people believe that AIs are conscious. AI scientist Geoff Hinton, the inventor of deep learning architecture, is one such. Early chatbots would say they might be conscious, although the frontier models are trained to say they are not. But are they just trying to hide that fact from us? This was anticipated in the 1960s in the movie 2001: A Space Odyssey. Below is a transcript of a key conversation in the movie:
Table 1. Dialog with astronauts and HAL 9000 from the movie 2001: A Space Odyssey.
AIs are currently like brains in a box. However, as we develop robots of various types that embody AI, will they learn to experience the world more as their bodies allow them to, much as animals and humans do? We are on the cusp of finding out.
Conclusion
Learning how some animals communicate and how far they have a language will provide us with new ideas on how an alien may try to signal us. AI can not only help us understand animal languages, but also help in decoding alien signals if/when we receive them, and even to communicate with them. We should even be able to tell how far our minds overlap in subjective concepts and experiences. Should aliens be machines, then it may be best if AIs take the lead in communication with them. If it turns out that we are alone, then there is value in being able to communicate at some level of understanding with intelligent animals. While I don’t expect we could experience being a cetacean, we could probably experience being one of our hominin cousins, such as the chimpanzee and bonobo.
In the meantime, all we can do is “Watch the Skies” and wait for a signal to arrive.
Appendix A
If we modify the values in the Wikipedia entry, using values in the ranges suggested, but update the annual rate of star formation to more current values, the product of the 1st 6 probability terms = 1. Therefore, the final term, the longevity of the communicating civilizations, equals the number of communicating civilizations in the galaxy.
References:
1. Wikipedia contributors. (2026, July 31). Drake equation. Wikipedia.
https://en.wikipedia.org/wiki/Drake_equation
2. de Paulis, D., et al. (2023) “First Contact: Global team simulates message from extraterrestrial intelligence to Earth”
https://www.seti.org/news/first-contact-global-team-simulates-message-from-extraterrestrial-intelligence-to-e arth/
3. Beguš, G., Dabkowski, M., Sprouse, R. L., Gruber, D. F., & Gero, S. (2025). The phonology of sperm whale coda vowels. Proceedings of the Royal Society B Biological Sciences, 293(2069).
https://doi.org/10.1098/rspb.2025.2994
4. Begus – video on whale clicks https://www.youtube.com/watch?v=eFbnYQI-Oa0
5. Taylor A. Hersh, et al, (2026) “Dialect variation in Mediterranean sperm whales shows evidence of cultural evolution in an isolated population”. Proc Biol Sci 1 June 2026; 293 (2073): 20260165.
https://doi.org/10.1098/rspb.2026.0165
6. Diamant, R., Gruber, D. F., Gero, S., & Beguš, G. (2026). Evidence for the influence of shipping underwater radiated noise on sperm whale coda structure. Ecological Informatics, 103881. https://doi.org/10.1016/j.ecoinf.2026.103881
7. Sayigh, L., Jensen, F., McHugh, K., Casoli, M., Lemercier, L., Tyack, P., Wells, R., & Janik, V. M. (2025). First evidence for widespread sharing of stereotyped non-signature whistle types by wild dolphins. bioRxiv (Cold Spring Harbor Laboratory). https://doi.org/10.1101/2025.04.21.647658
8. Nagel, T (1974) “What is it like to be a bat?”, The Philosophical Review, Vol. 83, No. 4 (Oct., 1974), pp. 435-450
9. Wikipedia contributors. (2026a, May 22). Arecibo message. Wikipedia.
https://en.wikipedia.org/wiki/Arecibo_message
10. Wikipedia contributors. (2026c, July 31). Pioneer plaque. Wikipedia.
https://en.wikipedia.org/wiki/Pioneer_plaque
11. McCarthy, J (2009) “Convergence of Intelligence” (SETI Talks)
https://www.youtube.com/watch?v=kvIqc0aBR0A
12. Devlin, K. (2013) “Contact with ET using Math? Not so fast” (SETI Talks)
https://www.youtube.com/watch?v=KveKjHIipgo
13. McConnell, B. S. (2021). The Alien Communication Handbook: So We Received a Signal—Now What? Springer. pp247-248, 278-281
14. Gilster, P. (2021, December 10). Communicating with Aliens: Observables versus Qualia | Centauri Dreams. https://www.centauri-dreams.org/2021/12/10/communicating-with-aliens-observables-versus-qualia/
15. Gilster, P. (2009, November 18). “RUBISCO Stars” and The Riddle of Life | Centauri Dreams. https://www.centauri-dreams.org/2009/11/18/%E2%80%9Crubisco-stars%E2%80%9D-and-the-riddle-of-life/
16. Gilster, P. (2009b, November 19). “RUBISCO Stars”: Part II | Centauri Dreams.
https://www.centauri-dreams.org/2009/11/19/rubisco-stars-part-ii/
17. Wikipedia contributors. (2026b, July 18). RuBisCO. Wikipedia. https://en.wikipedia.org/wiki/RuBisCO
Further Reading
1. Wikipedia contributors. (2025, December 4). Lincos language. Wikipedia.
https://en.wikipedia.org/wiki/Lincos_language
2. Freudenthal, H. “Lincos: Design of a Language for Cosmic Intercourse, Part 1 “
https://en.wikipedia.org/wiki/Lincos_language
3. Chiang, T “The Story of Your Life” https://en.wikipedia.org/wiki/Story_of_Your_Life
4. Earth Species Project https://www.earthspecies.org/
5. Clarke, A.C. “History Lesson” https://en.wikipedia.org/wiki/History_Lesson
6. Michaud, M. (2010). Contact with Alien Civilizations: Our Hopes and Fears about Encountering Extraterrestrials. Copernicus. pp279–284
7. Bracewell, R. N. (1974). The Galactic Club: Intelligent Life in Outer Space. Scribner Book Company.
8. Baird, J. C. (1987). The inner limits of outer space. Dartmouth College Press.
9. Dick, S. J. (1996). The Biological Universe: The Twentieth Century Extraterrestrial Life Debate and the Limits of Science. Cambridge University Press.
