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An active catalogue of ‘messages’ and other artefacts of material culture in local, interplanetary and interstellar space – recording the range of purposeful electromagnetic signals, space-time archives and other deposition activities sent for social, ceremonial and communicative applications.






Imagine finding a written cultural document, or detecting a strange encoded signal, that has been travelling through the vast expanse of space for centuries or perhaps far, far longer. What could the ‘message’ mean? Who sent it? Why? How could we glean anything useful from our minimal knowledge about it? Why is it relevant for humanity, given we have our own social and planetary problems? Was the artefact intended for us? Can we perhaps peer into the minds of a distant ‘other’? What could be reliably known, about something that is completely unknowable? Does this esoteric material culture speak for all others inhabiting the origin source, or just small cohorts of individuals? How do we ensure our interpretation doesn’t socially construct knowledge about others? We often pose these critical questions when contemplating reception of strange signals from ExtraTerrestrial Intelligence (ETI), or discovering purposeful material evidence bequeathed from our own species’ antiquity. However, seldom do we discuss how we are now authoring a chronological landscape of these communicative records ourselves, alongside other unanticipated material legacies while pioneering aerospace technologies; cultural documents which intend to operate far from the spatiotemporal shores of our planet for imaginative recipients, with agendas or partialities that are deeply seated within our own unique lived experiences on 21st Century Earth.



On the 9th of October 2008, a powerful narrow-band signal ‘A Message from Earth’ was transmitted by the RT-70 Yevpatoria radio telescope towards Gliese 581 (in the Libra constellation). Much like the lineage of other interstellar radio transmissions sent before from the Yevpatoria planetary radar, this publicly-compiled ‘message’ was composed of an eclectic array of bitmaps and written descriptions, with some emphasis placed upon the comprehensibility of the encoded cultural payload should it be intercepted. The signal, in essence, may be succinctly described as a symbolic act primarily intended for human audiences capable of recognising the broad contours of cultural perspectives and value judgements, alongside associated pictorial and lingual framing conventions and other terrestrial partialities contained within the ‘contents’. Despite this discrepancy, the strength and duration of the broadcast possesses significance for the electromagnetic profile continuously emanating from Earth into our wider surrounding interstellar neighbourhood. This ‘message’ is now over 15 light-years from Earth, arriving at Gliese 581 by 2029. An immediate ETI response for Earth may arrive by 2049.

As a ‘backup’ for this signal sequence, several CD-ROMs were created for each project stakeholder as a digital repository to secure the transmitted contents. Bebo, the stakeholder primarily responsible for accumulating public content, allegedly can’t locate the cache after multiple sales and shutdowns. According to our personal correspondences with several authoring agents, many of these digital archives have now been misplaced over the course of office upheavals and individual retirements, with the last [known] surviving copy of this disc residing within a Crimean space museum collection. Today, this material archive remains inaccessible according to several of our recent probes, with explanations ranging from the misplacement of an asset, to damage inflicted on the storage facility during the Russian invasion and annexation of the Crimean Peninsula in 2014. The Wikipedia project page has now even disappeared, with some details reshuffled under the 'Gliese 581c' page. This is one particular messaging legacy with a very tragic human twist; symbolism which perhaps speaks more candidly about the state of affairs on Earth today than the ‘best of us’ or goodwill sentiments shared as contents. Despite several arduous attempts to recover the message contents, just under 3 million (of over 60 million) ‘bits’ from the transmission sequence have been retrieved with assistance from the few journalists who reported on the transmission at the time. Moreover, the sequence of these selective ‘bits’ (i.e., the specific locations for each element in the signal stream) is indeterminable.

There are various moral, ethical, democratic, philosophical, political, social and existential challenges associated with what is informally known as the ‘Great Transmission Debate’ across interdisciplinary circles; literature which continues to generate an incredible array of disputes and counter arguments as humanity begins to recognise its growing profile of (sometimes, unintentional) electromagnetic signatures now reaching extraterrestrial shorelines. Proponents of METI (Messaging Extraterrestrial Intelligence) argue for the benefits of these signals to our cosmic, cultural, and political awareness granted by immediate experiments with neighbouring stellar systems, while opponents highlight the menu of diverse impracticalities, discord within implicit claims of ETI benevolence without verifiable evidence, prospective unknown risks, and wisdom of incorporating precautionary principles into this enigmatic enterprise. In the absence of any formal consensus or legislative agreements, the SETI community remains polarised on the wisdom of constructing and sending 

de novo messages from Earth, with both sides of the aisle contributing valid insights and positions to this dynamic debate. This rather brief account of ‘A Message From Earth’ however, draws into sharp relief yet another concern for METI; a challenge within accountability we refer to as ‘Remembering the Conversation’.


The issue raised above can best be explained as a very human problem – one of simply retaining information across intergenerational timeframes for use at an unspecified time. If ETI were to detect our likely indecipherable transmission, and choose to formulate a response to this found signal, should we as the initiating party not take precautions to ensure that any material dispatched to represent us, is still available at home to consult, scrutinise, and re-examine? After all, such materials will hold vital contextual indicators when contemplating how an ETI may have chosen to engage with any perceived ‘Message from Earth’. If we don’t remember how a conversation started, how can we expect to mount an intelligible re-response in the event of establishing contact from an old de novo METI signal? This unique rendition of the ‘incommensurability issue’ is readily apparent with ‘A Message from Earth’, but it arguably also manifests indirectly across the history of other transmission projects which seek to represent humanity for foreign and exotic audiences to contemplate, in addition to the plethora of other messaging activities broadcasting into the expanse. While the odds of ETI intercepting any signal is miniscule at best, acknowledging this does not preclude chance encounters altogether. By comparison, and as an example of best practice, the 1983 ‘Greetings to Altair’ message has been faithfully archived by successive researchers who recognised the significance of technological acts committed on behalf of our world without any established consensus. This is fortuitous for any radioastronomers now monitoring Altair for a response – a prospective ETI message we have been waiting to hopefully observe since 2016. Disregarding the short-term sensationalism of ‘contact’, or the ethics of whether we should engage in METI, archiving any unilateral outbound messages is crucial for ensuring the great silent majority – those who didn’t consent, yet will still inherit these legacies – have a factual basis to commit informed decisions for their world beyond the 21st Century (often amusingly referred to as the ‘unordered pizza’ argument).



What are the motives behind such projects? There are many applications that presently contribute to this growing property of our planetary system across different material domains in general; our desires to create secure ‘eternal memory’ libraries to preserve information beyond our terrestrial environment, rational communication attempts with extraterrestrial intelligences, expressions within ‘SpaceArt’, mission outreach initiatives, techno-colonialist propaganda objects as ideological claims in the ‘higher frontier’, questionable ‘lifeboat’ projects to conserve libraries of life beyond Earth, and also symbolic gestures devised to impart some profound heuristic about our observed position within the universe. Often such motives are intermeshed with other intents, making neat divides between categories difficult to ascertain. While many of these different types of messaging activities clearly do not represent equivalent degrees of ‘plausible risk’ as those frequently cited against METI, they can possess other significance for our enduring exoatmospheric archaeological record

scattered across the Sol System, alongside our increasing ‘bio-footprints’, and other residual legacies we may yet still need to uncover. Here we can observe a growing problem; technological activities seemingly far outpace ethical foresight and legislation not yet written – preemptive acts which may subsequently accumulate unintended repercussions across intergenerational time frames.

Despite these identifiable drawbacks, space messages have often been considered as intriguing, material representations both for and of humanity – artefacts which often furnish us with a pale reflection of what we intended to represent. They are designed, essentially, as a means of delivering ‘adequate’ information about present day generations of humanity to foreign extraterrestrial intelligences, or as a variant of time capsules; intent on conveying a snapshot of our contemporary societies to others far removed from today’s traditions and cultural histories. Often, these intentions are mixed, unwittingly or otherwise. More often than not, they are simply intended as immortalising ‘gestures to eternity’, intent on preserving material traces of their creator's minds and thoughts beyond their individual lifespans. However we choose to quantify or distil aspects of humanity, and our broader interactions across the Earth system, we may find that such mnemonic devices serve as an astute bridge to explore further aspects of the sender’s own social philosophies, value judgements, and defining worldviews committed on behalf of Earth’s heterogeneous populations. Messages can therefore be considered as deeply introspective appraisals of Earth; with post-creation examinations also revealing more between the lines of choices and intents than we think – often subconscious elements which are useful for studying such practices under the lens of disciplines within the humanities. They can also represent – by omission – the many cultures and traditions of those voices frequently not heard; the marginalised, oppressed, erased and forgotten cultures and other terrestrial organisms that typically do not directly benefit from our Space Age technologies.

Moreover, the litany of these early, conventional decisions in ‘Speaking for Earth’ have now become entrenched as a social history of crafting messages; customs that continue to reshape us in response. The Voyager Golden Records, while not the first physical extension of cultural resources dispatched into distant space, continues to be the source of much inspiration – and recognition for some human oversights – within semiotics, linguistics, and associated fields of the humanities and social sciences. We often overlook and sometimes perpetuate these partialities of humanity, and how they can tend to warp, and favourably intermix any rational interpretation of the media we use as representational signs for Earth. Recent research across the humanities and social sciences, which peripherally touch upon the information compiled for messaging practices (as an extension of material culture studies), also reveal other deeper schisms between disciplinary positions. For instance, how differences in evidence

acquisition, data interpretation, and subject orientations play key roles in contributing to the confusing reflections of humanity embedded in our messages. Such contexts from these practical experiments, however, has also proven to be a vital tool for designing prospective intelligible message constructs and associated ‘pidgins’ or ‘primers’ (for METI applications, but also as ideas for possible sanctioned responses to ETI signals, as outlined in the IAA Post-Detection Protocol).


Examples of other generally recognised partialities which may impact re-interpretations of message contents are also apparent through these interdisciplinary studies; the sensory limitations to extract information through human visual and other sensory channels; the cultural (or 'human’) partiality of contents that will prove challenging to recipients; often misplaced confidence in ‘the language of our science’ to intelligibly communicate aspects of semiotics; and a tendency to sanitise these accounts of Earth to represent an idealist version of [primarily] our species, and [secondly] our planet. This is not only apparent within messages intended for extraterrestrial intelligences, but also across the range of ‘space-time capsule’ artefacts, and other deposition activities which attempt to time-bind the human species across centuries or millennia – with archives left in orbit, on the Moon, or much further afield. How might these devices, one day, reflect our ages, values, attitudes, and varied social customs? Certainly, much about these unique material legacies still needs to be revealed through successive investigations; research necessitating the custodianship of contents for this future work.


Aside from these learning outcomes, there are of course other teething problems associated with this eclectic arena of messaging practices outside of content interpretive channels that warrant further scrutiny which may also be initially addressed by adequately documenting these legacies. In the case of METI and other purposeful de novo messages broadcast towards particular stellar systems, we can varyingly understand how each individual message intended to reach recipients with tales of humanity. However, documenting these outbound signals has already contributed towards the often latent legacies that follow hand in hand with our intentional messages. While the contents of any given transmission will likely be inaccessible for any number of the above reasons, simply encountering ‘recurrence’ within signals (i.e., patterns of transmissions arriving at a target star system over successive years) may certainly tell listening ETI more about our transmitting behaviours and practices than we may realise. For instance, transmissions have been independently sent to the star system HD 95128 three times; Teen Age Message (September 2001), and Cosmic Call 2 (July 2003), followed by an advert for Doritos tortilla chips (June 2008). How might the semiotics of inaccessible signals arriving years apart impact any reasonable interpretation made by ETI? What might ETI learn from waves of ‘contact’? An initial survey of such ‘recurrence’, and differing patterns apparent in these semiotic pathways, has been discussed elsewhere. However, simply noticing such inadvertent emerging patterns enables us to adapt metrics like the San Marino Scale to deduce any benefits and harms of repeatedly transmitting into specific space when signal values aggregate.


Given the interests of some parties in creating ‘messages’ as technological demonstrators, there is also an emerging preference for harnessing DNA – or complete microbes – as convenient [and small] storage vessels for datasets we would ideally like to preserve off-world. While such novel ideas are likely borne out of an intrigue in initiatives like the Frozen Zoo (preserving genetic materials from endangered or extinct species for future reanimation or ‘conservation backups’), alongside prevailing nuances of creating a personal or ‘second genesis’, it is unclear how such technological ventures attempt to navigate the long-held agreements on the ethics of planetary protection protocols, in addition to state obligations curtailing the emergence of privately-funded ‘space frontier-ism’. Launch parties are legally mandated to sterilise space hardware to varying standards depending upon where the spacecraft is intended to function – removing Earth microbes is considered a ‘best practice’ to safeguard all off-world sites of special scientific interest. Signatory states for the Outer Space Treaty (1967) are also liable for ensuring compliance of non-state actors resident based in their territories.

However, it is troubling to see an emerging practice of purposely forward-contaminating other environments outside of sanctioned activities and accidental circumstances, with questionable justifications or ethical oversight by those who contribute to mission engineering or scientific objectives. In the past few years, we have already seen at least one slippery precedent established in smuggling bio-payloads (i.e., Tardigrades placed aboard the Beresheet lander, and declared months after spacecraft's failed touchdown). For this reason, ‘cultur-able matter’ (i.e., microbes as dense living libraries documenting billions of years of phylogenetic evolution, mutations, and genetic mistakes with the potential to proliferate across new ecological niches on other planetary bodies) need to be accounted for as an integral part of any messaging archive.




Not all raised issues are problematic in nature, however keeping track of both electromagnetic and physical messaging practices has already aided in progressing a variety of debates, as well as responsibly keeping track of distant legacies that may, one day, impact our world. Moreover, the custodianship of these materials will likely be instrumental when probing the many future questions, innocuous or crucial, not yet asked about these intractable technological legacies. As part of the foundation's activities within this arena, we have developed an inaugural ‘A Profile of Humanity’ catalogue to survey the broad variety of messaging projects that collectively (and cumulatively) define our world at meaningful spatial and temporal distances. This particular catalogue was informally compiled and presented at the 2018 UK SETI Research Network symposium in Oxford University, before being later published in the International Journal of Astrobiology. However, documenting METI activities while tentatively drawing this practice under the purview of Long-Term Experiment praxis is not this catalogues sole function. The range of materials now representing the populations of Earth is vast and exponentially increasing which, in addition to the startling rise in contemporary proposals for alternative deposits to fulfil a range of applications, inherently tells us something about ourselves, our underlying intentions, behavioural patterns, customs, and frequent oversights committed in our desire to find exotic, imagined audiences to share our lives with. To complement this catalogue, the foundation is also cultivating an extended compendium of materials from these messaging projects, taking care to preserve the integrity of content sequences, in addition to cataloguing the strategies employed to ensure comprehension of these resources. Such strategies are crucial for advancing prospective long-term communication techniques; aspects of linguistics, semiotics, and commensurability studies explored in our ‘Companion Guide to Earth’.


Notes to the catalogue: The original catalogue was informally compiled and presented at the 2018 UK SETI Research Network symposium in Oxford University before being published in the International Journal of Astrobiology. This second edition has now been consolidated and expanded as an appendix for our volume ‘Messaging Beyond Earth: Speaking Across Deep Space and Cosmic Time. As a departure from the initial version, the revised edition attempts to re-contextualize the previously established categories to correspond with the taxonomic approach discussed in the above publication, re-presenting some of the initial messaging projects under alternative ‘motivation’ headings, while extensively building upon the previous quantity of documented materials. This catalogue now also documents some shorter-term artefacts that will likely decay into Earth’s atmosphere over successive years, while still maintaining a traditional emphasis upon outlining messages with moderate to protracted lifespans. Given the emerging relevance of purposeful microbial contamination in this exoatmospheric record, this catalogue documents examples of these intentional ‘bio-footprints’ launched as part of intentional messages or, in some instances, sites knowingly contaminated with biological matter (e.g., Apollo lunar sites). As with the first edition, this index does not feature mission-oriented infrastructure (e.g., satellite communications, physical space probes, launch vehicle components, scientific payloads, etc.), or technosignatures such as the radiosphere (i.e., the unintentional, electromagnetic ‘leakage’). Some cancelled and planned initiatives have also been included to document these activities for communal review and insights into our increasing aspirations to leave our marks across other astronomical bodies.

Page last updated: 10 May 2023.



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