A Prelude To A Technosignatures Discussion
Technosignatures Workshop: Looking at Searching for Life Beyond Earth, NASA
“In April 2018, new interest arose in Congress for NASA to begin supporting the scientific search for technosignatures as part of the agency’s search for life. As part of that effort, the agency is hosting the NASA Technosignatures Workshop in Houston on Sept. 26-28, 2018, with the purpose of assessing the current state of the field, the most promising avenues of research in technosignatures and where investments could be made to advance the science. A major goal is to identify how NASA could best support this endeavor through partnerships with private and philanthropic organizations.”
Webcast
Keith’s note: Something worth watching in advance of this workshop (which will be webcast). Watch this on a large screen with the sound turned up.
Scavenger from Raphael Rogers on Vimeo.
A Stunning Short Video: “Scavenger”, Astrobiology.com
“In 1977 NASA launched two golden records into deep space on the Voyager I and II probes. Having left our solar system, they are the most distant human-made objects. The records carry sounds and images of our planet and human brainwaves.”
Yeah, I watched “Scavenger”. Dammit, someones been dicing onions in here again…….
What a great video!
At least one part ot the Drake Equation has been solved, we know planetary systems are fairly common, earthlike planets in stable orbits rare in relative terms but still present in great numbers in our galaxy. But our one example of intelligence required almost perfect conditions, a star at just the luminosity to provide adequate energy for an adequate period, and life appeared almost as soon as the planet could support it, yet intelligence appeared with only about 2% of the Earth’s habitable lifetime remaining, due to the inevitable increase in solar luminosity. Sheesh, that was close! Another 100 million years and we would have been toast!
As a thought experiment, someone once asked if we actually know we are first and only intelligent species on Earth. If, hypothetically, there had been an intelligent species of dinosaurs, with roughly our current level of civilization and technology, but living 150 million years ago, would we know it? Reportedly, there are essentially no sorts of archeological evidence which would survive. The best suggestion, if memory serves, would be looking for one of their lunar landers (space being a very benign environment when it comes to archeological preservation.)
I don’t buy this. That we find evidence of living creatures from that time (and, btw, dinos were still around 65 million years ago, and we have evidence of life going back ~3.8 billion years) suggests that at least some technological artifacts would likely be preserved, too, especially the ‘hard’ things. Rock formations from that time are still there (even footprints & trackways made in mud!); would building foundations, etc, actually disassociate completely alongside the rocks? I doubt this.
What I find rather more interesting is the paucity of robust fossils of early hominids as compared to much-older dinosaurs and other organisms (not to mention hominid-contemporary animals). What were our close-primate ancestors doing with their dead a few million years ago to prevent them from being preserved to such a degree? Or were they THAT rare that the preservation odds just weren’t in their favor?
The latter is actually the answer. It is really very, very rare for an organism to be preserved as a fossil. And it is just not proto-humans that are rare, we have almost no fossils on chimpanzees for example. Indeed the first one wasn’t found until 2005.
https://www.nature.com/news…
First chimp fossil unearthed
“Palaeontologists digging in the dusty wastelands of East Africa have discovered the first known chimpanzee fossil. The modest haul of just three teeth is the first hard evidence of the evolutionary path that led to today’s chimpanzees.”
The fossil record is extremely sparse. I picked a species, more or less at random but one of the more famous ones. Tyrannosaurus Rex was around for two million years (I assume related species were around much longer.) Under a hundred complete or mostly complete fossil skeletons have been found. Somehow, the age of those remains have been estimated, giving a lifespan or time between generations of about 20 years. Do the math. That means we have one fossil per thousand generations of that dinosaur species. That’s equivalent to one human skeleton found in the entire time our species has been around and obviously tool using and technically advanced.
Physical structures also decay. A sword from around 1000 AD is a rusted lump of iron and barely recognizable as what it was. It wouldn’t even be recognizable as a tool if if had been rusting away for a hundred million years. The same thing applies to roads and buildings. A hundred million years is an awfully long time.
The dinosaurs were around for a lot, lot longer than any proto-human. Also, when we say “dinosaur” we aren’t limiting ourselves very much to one form, we’re counting almost every land and sea animal. So the total number of bones that ever existed to potentially become part of the fossil record is immensely larger than the number of proto-hominid bones. It’s all a matter of odds.
Actually Gavin A. Schmidt and Frank Adam published a paper on that topic earlier this year. Here is a link to it
https://arxiv.org/abs/1804….
The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record?
“If an industrial civilization had existed on Earth many millions of years prior to our own era, what traces would it have left and would they be detectable today? We summarize the likely geological fingerprint of the
Anthropocene, and demonstrate that while clear, it will not differ greatly in many respects from other known events in the geological record. We then propose tests that could plausibly distinguish an industrial cause from an otherwise naturally occurring climate event.”
Also last year Jason T. Wright published a paper along similar lines, proposing that the only remains may be artifacts on other bodies of the Solar System, if the civilization had advanced that far.
https://arxiv.org/pdf/1704….
Both are very interesting readings and gives folks something to speculate on.
The question is of course, just how long would a spacecraft last on an world like the Moon or Mars?
How long would a spacecraft last on the Moon or Mars? It’s probably easier to estimate for the Moon. I don’t think there is much to destroy an artifact there, other than meteor impacts. UV light and radiation will degrade plastics, so I wouldn’t expect them to last. Thermal cycling and the resulting expansion and contraction would probably turn a spacecraft into a pile of metal fragments, but it should still be recognizably artificial. I think the same would be true of micrometeorite pitting. But a large impact on or near the object would probably be catastrophic. I’d have to look up the numbers, but the lunar maria aren’t saturation cratered. So the odds of a impact on any given spot are well under 100% after 3 billion years or so.
Mars is different. There, there would be seasons, weather (frost at least), wind and dust. Over Milankovitch cycles, I suppose an occasional wet season is possible. And, although the evidence for active geology is limited, it’s there. Just not much of it. All that would reduce the survivability of artifacts. But I’ve never seen any estimates of this sort of thing. The closest I can think of are estimates of infilling of small craters.
Great find on the video. Thanks