by Paul Gilster | Sep 16, 2010 | Culture and Society |
NASA’s Human Research Program is all about risk reduction, finding ways to counter fatigue and mitigate radiation damage, among other potential issues in space travel. But what if a different kind of program had evolved? After all, back in the 1960s the agency was looking into the much broader question of how a human being might be adapted for space. The notion grew out of a 1960 article by Manfred Clynes and Nathan Kline called “Cyborgs and Space,” suggesting that re-creating the environment of Earth aboard a space vehicle was not as useful an option as adapting a human being at least partly to the conditions he or she would face.
The idea was a bold one in its day. From the paper (the italics are in the original):
The task of adapting man’s body to any environment he may choose will be made easier by increased knowledge of homeostatic functioning, the cybernetic aspects of which are just beginning to be understood and investigated. In the past evolution brought about the altering of bodily functions to suit different environments. Starting as of now, it will be possible to achieve this to some degree without alteration of heredity by suitable biochemical, physiological and electronic modification of man’s existing modus vivendi.
Altering Physiology to Suit Space
Thus the concept of altering human biology (and, doubtless, psychology) to adapt to this truly extreme environment. It’s one that NASA historian Roger Launius (Smithsonian National Air and Space Museum) looks into in a recent magazine article, pointing to his own use of medical equipment to sustain his existence as an example of one such transformation. Is Launius a cyborg? He calls himself one, perhaps partly in jest, but certainly to make the point that while humans cannot survive in space for more than a minute and a half without major help, deep space missions are going to require adaptations that help us weather the long voyage.
This Astrobiology Magazine article gets into the debate, noting Stephen Hawking’s belief that the long-term future of the human species is in space. Assuming we find one way or another to reach nearby stars, colonizing any terrestrial planets there will make huge demands:
If humans are to colonize other planets, Launius said it could well require the “next state of human evolution” to create a separate human presence where families will live and die on that planet. In other words, it wouldn’t really be Homo sapien sapiens that would be living in the colonies, it could be cyborgs—a living organism with a mixture of organic and electromechanical parts—or in simpler terms, part human, part machine.
And Launius himself points to the large number of people with uncontroversial tweaks such as pacemakers and cochlea ear implants whom we pass on the street every day. How many people are, in fact, alive precisely because of technological interventions they carry about in their bodies? The notion of the cyborg, then, shouldn’t really be quite as daunting as it appears, but my guess is that public reaction to a human being altered almost beyond recognition so as to allow survival in an alien biosphere would be considerably different. Such a being calls up ethical questions that make us think not so much of 2001: A Space Odyssey but Mary Shelley’s Frankenstein.
Bioengineering: A Step Too Far?
It was the Clynes and Kline paper that originally coined the term ‘cyborg,’ and NASA’s ‘The Cyborg Study: Engineering Man for Space’ followed in 1963, discussing issues like organ replacement and hibernation for deep space journeys before concluding that the technologies required were out of reach at the time. Poking around the Net on this issue, though, I came across an earlier article on the Astrobiology Magazine site looking at implementation:
The development of artificial organs is not too far advanced from what was available when NASA commissioned its cyborg study. Although artificial hearts and lungs are now more compact and better at the jobs they were designed for, they are used mainly as temporary replacements to help patients survive until appropriate donor organs become available. Artificial kidneys – dialysis machines – have posed the greatest challenge, partly due to the need to filter large amounts of fluid. In the 60s, artificial kidneys were the size of a refrigerator.
We have a long way to go, in other words, before we can achieve the kind of bioengineering that this kind of adaptation would demand. But the work continues, and accelerates:
Today, the smallest devices are still not implantable, but a recent prototype can be worn as an extremely bulky utility belt. Artificial bones, blood, skin, eyes, and even noses are now all being developed, and each could conceivably help man cope with the conditions of space. So long as the resulting entity still had a human brain, it could be considered a cyborg rather than an android (a robot that looks like a human).
Ethics of the Cyborg
From an ethical perspective, we also have to weigh the advantages of cyborg-style bioengineering against other possibilities. Assuming we eventually find and travel to a planet that could sustain human life (and assume as well that no sentient species lives there), which would be the superior moral choice: 1) Terraforming the entire world so as to suit our kind of life; or 2) Bioengineering our colonists so that they adapt to the environment they find themselves in?
The question may be resolved in a different way. It’s always possible that interstellar travel will prove so treacherous and lengthy for biological beings that our expansion into the galaxy will be managed by artificial intelligence. Paul Davies’ book The Eerie Silence again comes to mind: “I think it very likely – in fact inevitable – that biological intelligence is only a transitory phenomenon, a fleeting phase in the evolution of the universe. If we ever encounter extraterrestrial intelligence, I believe it is overwhelmingly likely to be post-biological in nature.”
I can’t close this without mention of Freeman Dyson’s notions on the subject, as found in Disturbing the Universe (New York: Harper & Row, 1979), p. 234:
In the long run, the only solution that I see to the problem of diversity is the expansion of mankind into the universe by means of green technology. Green technology pushes us in the right direction, outward from the Sun, to the asteroids and the giant planets and beyond, where space is limitless and the frontier forever open. Green technology means that we do not live in cans but adapt our plants and our animals and ourselves to live wild in the universe as we find it. The Mongolian nomads developed a tough skin and a slit-shaped eye to withstand the cold winds of Asia. If some of our grandchildren are born with an even tougher skin and an even narrower eye, they may walk bare-faced in the winds of Mars. The question that will decide our destiny is not whether we shall expand into space. It is: shall we be one species or a million? A million species will not exhaust the ecological niches that are awaiting the arrival of intelligence.
The Clynes and Kline article is “Cyborgs and Space,” Astronautics September 1960, pp. 29-33.
by Paul Gilster | Sep 15, 2010 | Exoplanetary Science, Missions |
Debra Fischer (Yale University) takes a brief look at the next thirty years as part of a Discover Magazine 30th anniversary section, an appearance notable more for what Fischer doesn’t say than what she does. Any hint of how her radial velocity studies of the Alpha Centauri system are proceeding? I wouldn’t have expected any, I’ll admit, and Fischer says nothing about it, but the betting here is that we’ll have an announcement within the next year either by Fischer or Michel Mayor’s team either giving us a planetary discovery or sharply constraining the alternatives.
What Fischer does speculate on beyond the notion that we’ll detect life in exoplanetary atmospheres is that interstellar probes will eventually fly. You may recall Robert Freitas’ notion of interstellar probes loaded with artificial intelligence and as tiny as sewing needles, scattered into the galaxy in their hordes to investigate potentially habitable worlds. Fischer, too, likes miniaturization, which does so much to mitigate the huge propulsion issues:
Outside the gravitational field of Earth, we could launch robotic spacecraft to other destinations in our solar system. Further ahead I’d like to see tiny spacebots – smaller than your cell phone—travel outside our solar system to the nearest star system, Alpha Centauri. By keeping the mass of those spacebots low, we could more easily accelerate them. We could launch an army of these tiny bots and have them do what your cell phone does: take pictures and phone home.
Yes, and just maybe we could use them to create the kind of communications station at the Alpha Centauri gravitational lensing distance that Claudio Maccone envisages, using it to communicate at extremely low power with a comparable robotic relay at our Sun’s gravitational focus. That would set up tremendous bandwidth opportunities for tiny transmitters and allow valuable scientific studies to flourish.
Meanwhile, we’ll all keep speculating on the big question for the immediate future — when will the first habitable extraterrestrial planet be discovered? Greg Laughlin (UC-Santa Cruz) and Samuel Arbesman (Harvard University) have a go at this with a new paper that attempts a sociometric analysis of the question. The researchers create a metric of habitability that can be applied to already discovered planets and use a boostrap analysis to extrapolate discoveries into the immediate future. The prediction that emerges from this is near-term: The first Earth-like planet will be discovered (with high probability) by mid-year 2011. The method will likely be planetary transit or radial velocity (Debra Fischer’s Alpha Centauri work again comes to mind).
Will Kepler find the first habitable planet? Don’t count on it. For one thing, the next Kepler results we get will be of planets that are probably too hot to sustain life:
While the initial results of Kepler were released on June 15, 2010, the Kepler team has delayed publication of 400 of the most promising extrasolar planetary candidates until February 2011. Within this large pool of withheld candidates, it is virtually certain that some have radii that are observationally indistinguishable from Earth’s radius. It is likely, however, that because of the limited time base line of the mission to date, the Kepler planet candidates to published in February 2011 may be too hot to support significant values for H [habitability].
Laughlin and Arbesman re-ran their analysis using only those planets discovered via the transit method, learning that the method cannot determine a likely date of discovery because we have relatively few planets found by transits, and all rank very low on the habitability scale. But the authors’ habitability metric curve deployed on a larger population of 370 well-characterized known exoplanets continues to point to as early as May of 2011 and very likely by the end of 2013 for that first habitable planet. The method, fully described in the paper, is fascinating. What’s more, with target dates this close, we’ll have an early read on how prescient its authors really are.
Interestingly enough, the authors note that the habitability factor for most of the 370 planets in their study is zero, but of course Gliese 581d is an exception, recently examined by other authors and found to be potentially habitable. Laughlin and Arbesman disagree with the assessment, pointing out that the planet’s mass should be close to ten Earth masses. The paper describes Gl 581d’s ‘…possibly water-dominated composition more akin to an ice giant planet such as Uranus or Neptune than to a terrestrial planet like the Earth.’
The paper is Arbesman and Laughlin, “A Scientometric Prediction of the Discovery of the First Potentially Habitable Planet with a Mass Similar to Earth,” accepted by PLoS ONE (preprint). Re Gliese 581d, the paper is Wordsworth et al., “Is Gliese 581d Habitable? Some Constraints from Radiative-Convective Climate Modeling” (preprint).
by Paul Gilster | Sep 13, 2010 | Astrobiology and SETI |
A symposium celebrating the first fifty years of NASA’ exobiology program takes place on October 14 in Arlington, Virginia. ‘Seeking Signs of Life’ looks all the way back to 1959, when NASA funded its first exobiology investigation, an experiment for a future spacecraft to detect life on Mars. The actual exobiology program was established in 1960, and led to the three Viking experiments that eventually flew. Exobiology has these days morphed into ‘astrobiology,’ as we look at topics as diverse as chemical evolution in interstellar space and planetary formation.
For those in range of Arlington, more information is available here. Be aware as well of a workshop on SETI that is now taking place at the National Radio Astronomy Observatory in Green Bank, WV, marking the 50th anniversary of Frank Drake’s first search for extraterrestrial signals. Webcasts begin at 0830 EDT (1230 UTC), and will include Drake’s views on ‘SETI in 2061 and Beyond’ at that time on September 15. Further information is available from NRAO.
Thinking about astrobiology has me turning to an interesting notion put forward by Caleb Scharf last week on his Life, Unbounded site. It has to do with what we mean by habitability, a necessary term in searching for life on other worlds that has to be defined to help us narrow our search, but one that may be misleading. Scharf (Columbia University) is wondering whether habitability is only part of a template that may be just a bit too tidy to be truly descriptive:
If there is one inevitable thing about life it is that particular variants, species, modes of existence, are all prone to extinction. A new work by Drake & Griffen in Nature this week makes this point rather succinctly. They show, by subjecting water flea populations to a series of unfortunate events, how the population dynamics of a species can fundamentally shift due to environmental changes. Fluctuations in population numbers occur even in stable environments, but the character and size of these fluctuations changes in degrading environments, and beyond a certain point there is no recovery. Long before it all goes down the tube there are clear statistical indicators that things are not well – population sizes drop as the tree begins to fall.
We do indeed know that extinction events are an unfortunate fact of life on planets like ours — at least, they have been on this one. Right now we’re looking to a near-term future when we can go to work on planetary atmospheres, eventually subjecting terrestrial planets to scrutiny with space-based spectroscopy. But if we do find biomarkers in an alien atmosphere, what will they mean? Scharf argues that any planet we find with these methods will most likely be one in which life is moving toward instability, a fertile but dangerous period pointing to catastrophe:
We are most likely to be able to sniff out the signs of life on a terrestrial-type planet when it’s in full swing. Suppose a world is having a particularly fertile episode, chock-a-block with organisms, but not a stable situation. It’s prime for collapse. Relative populations will swing high and swing low. At the high point for some, a planet may show the greatest bio-signatures, and make itself far more tasty for our prying telescopic eyes. Without running the numbers it’s impossible to give a precise answer, but it would seem that the odds will be shifted. We may be most likely to find not the signs of normality, but the signs of a system approaching some kind of biological collapse – just like the stock market, it’s all about the fluctuations.
Evolutionary success may wind up creating all the conditions for sudden, catastrophic change, a delicate balance that, once put out of whack, quickly degrades. We may detect, then, signs of planets overrun by particular kinds of life, with populations in a state of fluctuation over timescales as low as thousands or even hundreds of years. Must it always be so? Of course not, but what Scharf is saying is that our limited detection sensitivity will hamper us in the early going, and we’d better be careful about the kind of conclusions we draw from the evidence.
Which brings me to the closing panel at the upcoming astrobiology conference in Arlington. It’s titled “Homing in on ET Life: Where, and How, To Look.” With our one example of planetary life to go on, the ‘how’ gets increasingly important. We aim for the most recognizable life scenarios but must keep in mind that what Scharf calls ‘convenient truths’ can mislead us. Stable, long-term life may not show as strong a signal as biological collapse, so that as is the case with ‘hot Jupiters,’ we start off by seeing extreme examples of a much more evenly distributed phenomenon. We’ll want to learn from that lesson if it’s one we observe in spectroscopy, and avoid drawing too many conclusions from the outliers that our early instrumentation may reveal.
by Paul Gilster | Sep 13, 2010 | Asteroid and Comet Deflection |
A manned mission to an asteroid sounds, on first hearing, like a true deep-space venture, and in the days when we thought of the asteroids as largely confined to a belt between Mars and Jupiter, so it would have been depicted. But today we know that a large population of near-Earth objects (NEOs) is out there, close enough to make one of them the most obvious target for a mission beyond the Earth-Moon system. Moreover, they’re a necessary target given our need to understand their composition in case we ever have to change an asteroid trajectory.
Even so, you don’t send a human team to a completely unknown destination, which is why robotic asteroid exploration continues to loom large. Two missions — Japan’s Hayabusa and NASA’s Near Earth Asteroid Rendezvous (NEAR) — have actually orbited and landed on an asteroid. Now the Applied Physics Laboratory at Johns Hopkins University is proposing a follow-on to the NEAR mission that would give us the needed insights for later human visits.
James Garvin is chief scientist at NASA’s Goddard Space Flight Center, which is working with APL and the Johnson Space Flight Center on what the trio are calling ‘Next Gen NEAR,’ a robotic precursor mission to a near-Earth asteroid. Garvin sizes up Next Gen NEAR this way:
“We’ve learned a lot about NEOs using telescopes, Earth-based radar and two robotic missions, but we’d have to get up close and personal with a specific asteroid again, and learn much more about its environment, before we could send human explorers. But there is nothing intuitive about operating at an asteroid; in fact, sending humans to an asteroid would be one of the most challenging space missions ever. So to make sure we really understand that challenge, we’ve paired NASA experts in small-body robotic and human spaceflight with the only team in the U.S. to design, build and operate an asteroid-orbiter mission.”
Image: Artist’s impression of the Next Gen NEAR spacecraft approaching a near-Earth object, or NEO. A concept based on the successful Near Earth Asteroid Rendezvous mission, Next Gen NEAR could serve as a robotic ‘precursor’ for a human visit to a near-Earth asteroid. Credit: Johns Hopkins University Applied Physics Laboratory.
If Next Gen NEAR lives up to its predecessor’s standards, we’ll be doing well. NEAR was able to produce more than 160,000 images of asteroid 433 Eros, studying its geology, geophysics and composition. Next Gen NEAR would be what APL is calling a ‘workhorse of a mission’ that can launch in 2014 and return a similar windfall of data at a cost lower than a Discovery-class mission. As proposed, the spacecraft would run on commercially available subsystems, carrying lightweight scientific instruments including a surface-interaction experiment and composition-measuring spectrometers, and would be launched by a medium-class rocket.
Next Gen NEAR is an interesting and evidently cost-effective mission concept that takes us another step toward meeting the goal of a manned mission to an asteroid. The more experience the better with this kind of operation — landing on a body with infinitesimal gravity and no atmosphere is a different kind of operation than putting a payload on a planetary surface. The operations in close orbit and in contact with the surface that NEAR and Hayabusa have already demonstrated can be tuned up further in a mission like this. We’ll see how this concept is greeted at a time when expanding our knowledge of Earth-crossing asteroids is becoming a more visible priority.
by Paul Gilster | Sep 10, 2010 | Exoplanetary Science |
Globular clusters held an early fascination for me, and I guess anyone who encounters these rich cities of stars for the first time wonders what it would be like to be on a planet deep inside one of them. The clusters appear to be distributed in a spherical halo around the galactic center, ancient collections of stars much lower in heavy elements than stars in the galactic disk (although globular clusters in some other Local Group galaxies seem younger). The thought of the night sky on a planet embedded in such a place makes the mind reel, star upon star upon star filling the view.
Image: The globular cluster 47 Tucanae, the second brightest globular cluster orbiting the Milky Way (behind Omega Centauri). Imagine the night sky deep within such a cluster. Credit: South African Astronomical Observatory.
But a new paper suggests that at least one category of planets may be rare in such clusters. It follows up on an earlier survey of the cluster 47 Tucanae which examined some 34,000 stars and came up empty. The theory here is that the high density of stars in globular clusters disrupts planetary orbits. Even more significant, tidal effects upon planets much closer to their star than Mercury is to our Sun eventually cause ‘hot Jupiters’ to experience orbital decay and an early demise. Add this to the low metallicity (few elements heavier than hydrogen and helium) in globular clusters and you have an environment not conducive to planet building in the first place.
Brian Jackson (NASA GSFC) puts it this way: “Globular clusters turn out to be rough neighborhoods for planets, because there are lots of stars around to beat up on them and not much for them to eat.” Working with colleague John Debes, Jackson argues that any ‘hot Jupiters’ in globular clusters would be destroyed quickly by tidal effects if nothing else, their orbits gradually moving closer to their star until the planet is torn apart by the star’s gravity or crashes into it.
Thus we can explain the dearth of planets in 47 Tucanae. The researchers’ simulations using tidal effects and the proximity of nearby stars showed that hot Jupiters would be unlikely to survive even when metallicity is left out of the equation. In fact, Debes and Jackson have found that approximately one third of hot Jupiters won’t survive the first billion years of a cluster’s life, not to mention the eleven billion years 47 Tucanae has been in existence. The simulations suggest that at 47 Tuc’s age, at least 96 percent of the hot Jupiters would have perished.
Here Kepler becomes a relevant tool. The mission has four open clusters (much less dense than globular clusters) in its survey field, in a range of ages from less than half a billion to nearly 8 billion years old. All of these clusters appear to have the raw materials from which planets are formed, making them a good test for the tidal decay model. The new work suggests that Kepler should find up to three times more Jupiter-class planets in the youngest cluster than in the oldest one. Fewer expected hot Jupiters, in other words, as cluster age increases and, as a corollary, increasingly tight orbits for detected planets. We should have some answers soon.
And this is interesting, from the paper on this work, on the results of a planet being consumed by its star:
If planets are engulfed, one would expect a signature of pollution in the stellar atmosphere… or an increase in stellar rotation rates… If the process strips just the envelope but leaves a dense core, there might be an excess of ?5-10 ME planets with short periods above that expected through orbital migration alone. There might even be a mass-period relationship for the remnant cores, analogous to that observed for tidally-stripped white dwarfs… Although transit surveys may have difficulty detecting these small stranded remnant cores, their detection would provide an important clue to the fate of close-in gaseous planets.
As to other planets in globular clusters, we’re forced to look for smaller worlds in far more distant orbits. Says Debes: “The big, obvious planets may be gone, so we’ll have to look for smaller, more distant planets. That means we will have to look for a much longer time at large numbers of stars and use instruments that are sensitive enough to detect these fainter planets.” Personally, I hope we start finding them, if only to validate those spectacular sky scenes I’ve long imagined.
The paper is Debes and Jackson, “Too Little, Too Late: How the Tidal Evolution of Hot Jupiters affects Transit Surveys of Clusters,” accepted by The Astrophysical Journal (preprint).
