Noted first on Sentient Developments, this interesting video of Michio Kaku discussing the Kardashev scale and where we fit into it. Kaku believes we are living at the critical time when our Type 0 civilization becomes a Type 1. What can happen next gets dicey indeed, as the video makes clear, and it may well be that cultures playing with nuclear weaponry have scant chance of survival, never reaching the point where, as Type 1, they control the processes of their own world and build toward Type 2, the essentially indestructible species that manages all the power of its Sun.
It’s intriguing to speculate on how Kubrick and Clarke’s 2001: A Space Odyssey would have been received had the initial five minutes, in which scientists discussed the robotic seeding of the galaxy, been left in the film. As it was, the mysticism and rich symbolism of the ending left many scratching their heads even while appreciating the grandeur of the story. But Frank Tipler and others have shown long ago that it wouldn’t take that long in absolute terms for self-replicating robots to sweep through an entire galaxy. Where might they have left their beacon?
Tipler believed it would take self-replicating probes a million years to colonize the galaxy, ten million to colonize the Local Group and another hundred million to colonize the entire Virgo Cluster. But perhaps future civilizations would decide not to build such probes, deeming them too dangerous to future life. Carl Sagan and William Newman argued just this point in their paper “The Solipsist Approach to Extraterrestrial Intelligence,” Quarterly Journal of the Royal Astronomical Society 24 (1983), p. 113. The Tipler paper (which prompted the Sagan/Newman rebuttal) is “Extraterrestrial Intelligent Beings Do Not Exist,” Quarterly Journal of the Royal Astronomical Society 21 (1980), pp. 267-81.
Knowing where to point our future planet-hunter telescopes in space is crucial, because we’ll want to maximize observing time for the most likely stellar candidates. There are various ways to narrow the list, but one involves the study of existing spectroscopic data. Charles Lineweaver (Australian National University) calls it a ‘poor man’s technique,’ an inexpensive way to look at the elements within stars and calculate from their abundance the kind of planets that may have formed in that system.
The differences between the rocky terrestrial planets in our own Solar System and the outer gas giants are instructive. We can assume that planets form from the same raw materials as the stars they orbit. But the inner planets lack volatile gases like hydrogen and helium compared to the Sun, while maintaining the same abundances of heavier elements like silica and iron. The latter don’t vaporise easily in warmer inner orbits.
So a star heavy in iron is likely circled by inner planets abundant in the same element. The kind of elements involve may tell a fascinating tale. Lineweaver told Australia National Broadcasting’s Science Online that the ratio of carbon to oxygen, for example, could predict the formation of vastly different kinds of planets. Here’s a quote from the article:
“As the planetary disc cools, carbon and oxygen combine to form carbon monoxide, which gets blown away. If there is more oxygen than carbon, the oxygen that’s left combines with everything else and you’ll end up with a rocky planet like Earth… But if there’s more carbon, it combines with silica and magnesium and iron and you end up with all sorts of weird carbide planets that may have a diamond core.”
Hence a kind of element mapping may take place: The ratio of carbon to oxygen being higher near the center of the galaxy, such diamond carbide planets may be more abundant there. In any case, we have spectroscopic data in great quantity for nearby worlds we’ll be examining with future planet-finder missions. An upcoming Lineweaver paper will go into detail about how predictive the abundances of these elements may be.
We often talk about the need to find and track Earth-crossing objects, but what do we do if we find one that’s likely to hit us? We’re far from demonstrating our ability to deflect an incoming asteroid, making a precursor mission of some kind a necessity. The European Space Agency has been carrying out design studies with three industrial consortia — led by Alcatel Alenia Space, EADS Astrium and QinetiQ — for a precursor mission called Don Quijote that would involve two separate spacecraft.
What the ESA has in mind is to drive an impactor into an asteroid to assess the resulting deflection. The impactor vehicle, called Hidalgo, would hit the target asteroid at a relative speed in the area of ten kilometers per second. The orbiter, called Sancho, would measure the deflection with a high degree of precision and act as a data relay for the approaching impactor. It would also deploy instruments in the form of what ESA calls an ‘autonomous surface package’ to to study the asteroid’s composition and other properties.
Image: The moments before impact… The Impactor spacecraft (Hidalgo) heads towards the target asteroid. Credit: ESA – AOES Medialab.
The late word out of ESA is that a Sancho mission study has been completed that builds on the larger Don Quijote industrial study. As the idea evolves, the agency is talking about first flying a Sancho mission without accompanying impactor to demonstrate key technologies for rendezvous and close operations around the asteroid. At this early stage, both electric and chemical propulsion options are still in the mix, with a launch assumed somewhere between 2013 and 2015. The duration of the preliminary Sancho mission would be four years.
You can read more about Sancho and Hidalgo, the primary components of the Don Quijote mission, here. Based on conventional technologies (although the SMART-1 electrical thruster, if chosen, would need some tweaking for the required seven-year mission lifetime), Don Quijote would tell us a great deal about what is and isn’t possible with some classes of near-Earth objects. Let’s hope that’s knowledge we never have to use in a collision scenario, but the cratered face of the Moon is a nightly reminder that the Solar System is an active, frequently hostile place.
Those following the Gliese 581 story have been awaiting the results of the MOST observations with great interest. The Canadian mission put the red dwarf under study for six weeks after the recent flurry of speculation regarding a possible habitable planet, Gliese 581 c, in the system. If the planet made a transit, moving across the face of its star as seen from Earth, then we could learn more about its size and makeup.
The results are now in, and no transit occurred. But a second issue is a bit more satisfactory. During the observation period, Gliese 581 showed little change in brightness, indicating a level of stability that would prove beneficial to the growth of life, whether on Gliese 581 c or the more distant (and massive) Gl 581 d, which may orbit on the outer edge of the star’s habitable zone. Here’s Jaymie Matthews (University of British Columbia and a MOST mission scientist) on the matter:
“The climate there should not be a wild rollercoaster ride that would make it difficult for life to get a foothold. It also suggests the star is quite old, and settled in its ways, so that the planets around it have been around for billions of years. We know it took about three and a half billion years for life on Earth to reach the level of complexity that we call human, so it’s more encouraging for the prospects of complex life on any planet around Gliese 581 if it’s been around for at least as long.”
Note that phrase ‘any planet around Gliese 581.’ I assume it’s an oblique reference to the growing evidence that Gl 581 c is not the Earth-like world first suggested. In fact, recent work on the planet suggests it resembles Venus much more than Earth, a seething cauldron far too close to its primary to provide a reasonable foothold for life. But Gl 581 d may still be in the running, and it is encouraging in any case to know that a star like this can produce candidate planets near the needed limits. It won’t be long before we have another candidate, and a transiting one at that.
Bringing MOST to bear on this interesting system was useful in another regard. The observations rule out sunspots or other activity on Gliese 581’s surface that might have posed an alternative explanation for the 13-day cycle that has been interpreted as a planet. No such variations occur in the MOST findings, adding to our confidence that Gliese 581 c is indeed there. Whether it is habitable or not seems increasingly in doubt.
UK science minister Malcolm Wicks met yesterday with leading British astronomers in a London gathering whose subject was life in the universe. The researchers, drawn from UK universities and research institutes, proved quite optimistic about the chances of intelligent life elsewhere. An article in this morning’s Guardian quotes Glenn White, head of astrophysics at the Open University: “You can be pretty sure that if there’s life out there, we’ve a good chance of being able to say so.”
White’s optimism doubtless stems from his work on the Darwin project. The mission, scheduled for a 2015 launch, will deploy a set of telescopes to look for terrestrial worlds around other stars. And although the technology is still in the development stage, the hope is that Darwin’s capabilities will extend to conducting spectral analyses on the most interesting planets it finds. That makes detecting biomarkers like large amounts of oxygen along with methane or nitrous oxide a real possibility.
Of the seven scientists who met with Wicks, six believe life exists elsewhere, with one holding out for humans as the only intelligent beings in the universe. The latter vote was cast by astrophysicist Michael Perryman (European Space Agency), who also noted that “If there’s intelligent life out there, they sure as hell know we’re here,” a reference to stray radio signals from our planet that have penetrated perhaps as far as 80 light years into space. My thought on that is that the signal strength of old Jack Benny shows may be too low to justify the claim.
Meanwhile, Reuters reports on the SETI Institute’s plan to put 42 radio telescope dishes (the Allen Telescope Array) online 24 hours a day by the end of this year. Here again the notion is that stray radio signals may be detectable even at these extreme ranges. Says the Institute’s Scott Hubbard: “You don’t have to have somebody who is planning to broadcast a signal. You hope to pick up somebody’s old radio broadcast that left a different planet hundreds or thousands of years ago.”
Maybe, but a re-thinking of SETI’s core principles has been ongoing for some time now, one focusing less on radio and more on the various other ways an advanced civilization might communicate. As George Dvorsky notes in this interesting post on his Sentient Developments blog, the radio ‘window’ may already be closing here on Earth as we move away from the old broadcast model. What other forms of communication might an alien civilization use, and are there ways we might detect their signals?
For that matter, are there megascale engineering projects we might detect long before the reception of a radio signal? Dvorsky discusses all this in the context of the Singularity hypothesis and what civilizations on the other side of it may do that would make their presence known. My guess is that we’ll have hard data from Darwin or other planet-finder missions before we have a SETI detection of any kind. That data will tell us we’re looking at a living world, but whether its biomarkers flag high technology or single-cell organisms may take a long time to deduce.
And if we do find a megascale engineering project one day, let’s hope it doesn’t house a civilization that has, in the words of evolutionary psychologist Geoffrey Miller, disappeared up its own brainstem. Miller talks about the pleasure principle trumping the reality principle (what exactly goes on inside those matrioshka brains anyway)? It’s an alluring, perhaps deadly prospect:
This is the Great Temptation for any technological species — to shape their subjective reality to provide the cues of survival and reproductive success without the substance. Most bright alien species probably go extinct gradually, allocating more time and resources to their pleasures, and less to their children.
And again:
Technology is fairly good at controlling external reality to promote our real biological fitness, but it’s even better at delivering fake fitness — subjective cues of survival and reproduction, without the real-world effects. Fresh organic fruit juice costs so much more than nutrition-free soda. Having real friends is so much more effort than watching Friends on TV. Actually colonizing the galaxy would be so much harder than pretending to have done it when filming Star Wars or Serenity.
Thus Miller’s answer to the Fermi Paradox — SETI won’t work because alien civilizations are all addicted to computer games and runaway consumerism. Why even attempt communication with actual beings (who are in any case quite difficult to reach and perhaps impossible to understand), when you can create a virtual reality that’s so much more malleable and responsive to your needs? That’s a dark view indeed, but we’ve a long way to go before drawing any serious conclusions about Fermi’s ‘Where are they?’ question. And in the meantime, we have near-term planet finder missions to fly and biomarkers to detect.
In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).
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