"our future is in ruins"

Most commonly the term has been used by authors such as John Armitage (‘The prospect of astro-palaeontology’) to describe the study of prehistoric extraterrestrial life. Astropalaeontology in this sense is a sub-discipline of astrobiology, and in fact as Armitage argued it may be more likely that we will discover the remains of extinct extraterrestrial life before we discover a living example. Exopalaeontology and astropalaeobiology are synonyms, and I’ve also seen palaeoastrobiology. Xenopalaeontology doesn’t seem to have caught on in serious circles.

It’s worth noting again that astropalaeontology is a separate discipline from xenoarchaeology, as terrestrial palaeontology is from archaeology (although in both cases the fields share a blurry boundary). Archaeological fields are more concerned with cultural remains, which are created by sophonts.

Secondly the term has been used to describe the study of stellar evolution (as an analogy to palaeontology’s study of the evolution of life). See the paper ‘The evolution of the mass-metallicity relation in SDSS galaxies uncovered by astropaleontology’ by Asari et al. You also see terms like stellar palaeontology, or galactic palaeontology used to discuss this kind of research.

Here’s a summary of ‘galactic palaeontology’ from the University of Sydney:

Ultra metal-poor stars are the living fossils of the stellar kingdom. Although elements heavier than Helium only make up a tiny fraction of any star, they have a profound effect on the stellar structure.
Consequently stars born when the universe was substantially younger, before heavy elements were formed, should stand out from the crowd exhibiting dramatically different physical and thermal structure — or so the theoretical models tell us. Because these fossil stars are rare and far from Earth, nobody has ever been able to examine one in detail. Until now.

If this stellar use of the term was more common, I’d suggest that astropalaeobiology is the better word to describe the study of extraterrestrial fossils. The biology part would avoid confusion, and it ties in with astrobiology, the most common term for the study of extraterrestrial life in use.

Thirdly, I’ve seen one use of the term astropalaeontology to describe study of the way the evolution of life on earth has been affected by astronomical events. See this 2009 article in National Geographic which discusses the theory that a gamma-ray burst might have caused a mass extinction.

I mentioned in my last post some thoughts about the cultural heritage value of the planet Venus. To recap, I argued that Venus has been noted throughout history as one of the brightest objects in the night sky, prompting names such as the Morning or Evening Star. This distinguishing brightness has furthermore given Venus a special place in the mythology of many human cultures.

According to Wikipedia, Carl Sagan was the first person to propose terraforming Venus in 1961. Terraforming is, of course, the process of altering a planet to make it earthlike. There are other reasons to think twice about undertaking such a project, but here I’ll consider the cultural side of things.

I’d argue that the cultural significance of Venus for much of human history arose from its brightness in the night sky. That brightness is a product of the planet’s high albedo of 0.65. If the planet’s albedo is preserved, then cultural objections to the terraforming process could be mitigated.

Venus’ status as the second brightest object in the night sky was trumped last year when the International Space Station deployed sufficient solar panels to overtake it. Should its pre-eminence have been preserved? I don’t personally think so, but someone with more reverence for the planet might. I think the fact of its brightness is more important than its rank among celestial bodies visible from earth.

Of course, there may be other cultural objections. We occasionally hear cultural or religious objections to human activity on the Moon, based on beliefs about that body. Furthermore, since the planet Venus has become observable by telescope, its dense cloud layers have themselves gained some cultural significance through conjecture about what they could be concealing.

As it turns out, the albedo of Venus might actually be boosted by terraforming. The creation of oceans, or the seeding of the planet’s atmosphere with reflective materials have both been mooted as methods of reflecting solar heat. Would brightening Venus diminish its cultural value? I think not, that the significance lies in its being a remarkably bright object and not in a particular albedo of 0.65.

At the moment no Earth organisation has responsiblity for protecting space heritage, and no terraforming projects are being put in motion so this is a moot, but interesting point. Is the redness of Mars similarly valuable from a cultural perspective? How about the visibility and regularity of recurrence of bodies like Halley’s comet?

Craig Kalpakjian's proposal for a selenoglyph

Geoglyphs are large-scale drawings on the earth’s surface made by either adding or exposing different-coloured material. Historic and archaeological features such as the famous Nazca lines in Peru, or hill figures such as those found in England are examples. People are still making geoglyphs, including the Marree Man created by unknown artists (or vandals?) in the 1990s, and various works of the Land Art movement of the 1960s and 70s.

A recent story about Japanese plans to send an anthropomorphic robot to the Moon to draw a flag on the surface set me thinking about lunar geoglyphs. That term, like geology is derived from the Greek word for Earth, Ge. Selenoglyphs would be more appropriate, based on the Greek word for the moon, Selene. The discipline of lunar geology is called selenology, for example.

There are already selenoglyphs up there!
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Xenoarchaeology is the study of past alien cultures from their physical remains.  The prefix xeno- is from the Greek xenos, ‘stranger’.

Alien, in this instance, refers to members of any species other than that of the hypothetical xenoarchaeologist.  A human studying martian ruins is a xenoarchaeologist, as is a martian studying human ruins.

The term ‘alien’ always sounds a little pejorative to me (how about non-human person?), but I use it here instead of ‘extraterrestrial’ which could be taken as a spatial designation, and because in the future there could conceivably be terrestrial nonhuman cultures (say, from uplifted animals or artificial intelligences). Despite its connotations, the word ‘alien’ conveys the otherness of the culture to be studied.
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Journal of the British Interplanetary Society, vol. 30, pp. 466-9, 1976.

After it was published this paper seems to have fallen into utter obscurity. It was pure serendipity that led me to stumble across it.

All that I can determine about John Armitage is that he became a Fellow of the Royal Astronomical Society on 10 December 1976[1], and that the paper was also presented at the Second British Interplanetary Society Conference on Interstellar Travel and Communication, 4-5 April 1977.

In it the author argues, as I have, that it seems likely that the number of galactic extinct civilizations is greater than the number of galactic extant civilizations. Armitage makes the distinction that detectable civilizations are only apparently extant, given the relativistic gap between signal transmission and detection.
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In 1960 Freeman Dyson proposed that a sufficiently-motivated civilization might build an ‘artificial biosphere’ around a star in order to fully exploit its radiated energy. This concept has become known as a Dyson sphere.

The idea of enclosing a star seems incredible, but as Dyson later wrote: ‘there is nothing so big nor so crazy that one out of a million technological societies may not feel itself driven to do.’
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From the movie Blade Runner: an artificial snake's scales reveal clear evidence of intelligent design.

Anthropologist John Hawks has an interesting post on genomic SETI, responding to a Wall Street Journal essay by Paul Davies promoting The Eerie Silence.  

The rationale for genomic SETI is that terrestrial organisms might have been genetically modified or created from scratch by ancient extraterrestrials, and that evidence of this, even deliberate messages, might be found in their genomes.

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Are We Alone In The Universe / Renewing Our Search For Alien Intelligence
Illustrated. 242 pages. Allen Lane. $15.82 – $17.82 [Buy from Amazon.com].

There are two subtitles for different editions of this fine book by Paul Davies.  Subtle promotional reasons most likely dictated the variance for different markets, but ‘Renewing Our Search for Alien Intelligence’ is truer to the theme of the book. Published for the 50th anniversary of SETI, Davies, one of the best cosmological science writers of our day, uses this work to challenge the assumptions of the search for extraterrestrial intelligence.

‘How could something as bold and visionary as SETI become conservative?’ Davies asks in the first chapter. His answer: anthropocentrism (and later, what you might call ‘radiocentrism’). There’s a great sequence in the first chapter of examples of scientists basing their work on assumptions that stem from their own preoccupations, although I suppose that potential xenoarchaeologists aren’t immune to this.
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Alun Salt has written a thoughtful response to my previous post about space archaeology theory … so here’s my thoughts on his thoughts

My prior post featured a Venn diagram illustrating the conceptual space of the field and the interrelationships of its subfields of aerospace, xeno- and exo- archaeology. Alun asks whether this definition adds anything, and whether it’s necessary to draw boundaries around the field.

Should a definition add anything or should it describe and clarify? I think the diagram adequately encapsulates the subject, even though I wasn’t sure how to visually convey the way that space heritage and exogarbology permeate the subfields (perhaps some kind of hatching?).

Is the definition limiting? Perhaps I’m wrong, but the diagram seems to encompass all possible fields that could be considered space archaeology, and I’m fairly confident that even unthought-of fields would fit into the diagram (xeno-maritime archaeology?).
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