Forging the Future of Space Science The Next 50 Years (2010) / Chapter Skim
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The Possibility of Life Elsewhere in the Universe--Christopher F. Chyba
The Possibility of Life Elsewhere in the Universe--Christopher F. Chyba
Pages 77-89
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From page 77... ...
This Earth required placing Earth in its solar system context. is not true for a great deal of subsurface life, much of In this sense the IGY can also be seen as a harbinger which directly or indirectly depends on the energy of what is now called "astrobiology." Writing in 1974, harvested from sunlight at Earth's surface -- e.g., beshortly after the Moon landings, Carl Sagan asserted cause it depends on the organic molecules produced by that we could, for the first time, try to understand life photosynthesis, or depends on the oxidized molecules on Earth in its cosmic context.
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From page 78... ...
In the out there -- this was largely exploratory science, not case of Jupiter's moon Europa, which likely harbors a hypothesis-testing science. But as a result of explorasubsurface ocean of liquid water, it seems unlikely that tion, it seems more likely that carbon will be the basis there were hospitable surface conditions for more than for chemical life elsewhere in the universe, should any a fleeting moment, if that, early in solar system history.
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From page 79... ...
There is a page in his Arundel Codex on which he lists the contradic tory characteristics of water -- he considers only liquid water -- noting that sometimes it's yellow, sometimes FIGURE 5.2 Ribonucleic acid (RNA) mediates between deoxy green, sometimes muddy; sometimes bitter, sometimes ribonucleic acid (DNA)
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From page 80... ...
Definitions payoff of lunar samples returned to Earth -- primardo not answer scientific questions about the world. On ily by the Apollo missions but also by Soviet robotic the other hand, it may be impossible to devise a general Luna missions -- has been huge.
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From page 81... ...
Spacecraft flybys, orbiters, landers and Europa harbors an ocean of liquid water beneath its rovers have made it clear than ancient Mars once had extremely cold outermost layer of ice (Figure 5.6)
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From page 82... ...
The Outer Space Treaty, which entered into may be the most intriguing site for extraterrestrial life force in 1967 and is best known for forbidding the in our solar system. It appears that Jupiter's Mercury- placement of "weapons of mass destruction" in outer sized moons, Ganymede and Callisto, harbor deeper space, requires space-faring nations to avoid the "harmsubsurface liquid water oceans as well.
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From page 83... ...
another world by a big impact, or in a controlled way, The current international interpretation of the as samples brought back by a dedicated spacecraft. But Outer Space Treaty requirement is that microorgan both cases involve hands-on investigations for the presisms carried to other planets must not be allowed to ence of life in the solar system.
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From page 84... ...
and atmosphere, a highly oxidizing atmosphere flooded therefore their distances from their stars. With knowl- with ultraviolet light that should not permit organics edge of the stars, we will know which, if any, of these to exist for long, contains patches of the simple organic worlds lie in the right range of distances for liquid water molecule methane -- at about the 10 parts per billion oceans to be possible on their surfaces.
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From page 85... ...
. Radio frequencies are the natu- the fact that SETI radio searches have been carried out ral frequency to use for interstellar communications, since the first search was conducted by Frank Drake because of the so-called microwave window where nearly 50 years ago.
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From page 86... ...
lar distances are more rare than one in every hundred The Drake equation summarizes this way of looking thousand stars, even the ATA will not be successful at the problem. Frank Drake wrote down his equation anytime soon.
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From page 87... ...
The aver- Encephalization is typically expressed as a quotient age value of L in the galaxy might well be anywhere (hence, encephalization quotient, or EQ) that quantiin this interval, although even a small number of very fies how much smaller or larger a particular animal's long-lived civilizations could make the average quite brain is compared to the expected (via a regression over long indeed.
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From page 88... ...
Just as studies of microscopic life on Earth intool-users Homo erectus and the earlier Homo habilis had form thinking about the prospects for microorganisms EQ values of about 5.3 and 4.3, respectively. elsewhere, so can rigorous exploration of the evolution These results suggest that the evolution of human of intelligence on Earth inform our thinking about the intelligence on Earth is not an entirely exceptional prospects for intelligence elsewhere.
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From page 89... ...
We should not exaggerate the ease or casualness new opportunities, if mishandled, for destruction. with which substantial genetic manipulation of human Astrobiology is defined as "the study of the living unibeings will be done, but as Robert Carlson has shown, verse." If so, then the discipline must also speak to the basic measures of human bioengineering power, such future of human civilization, a thing uniquely precious as the time or cost required to sequence or synthesize regardless of whether it is entirely alone or one of many short sequences of DNA, show that biotechnology in the galaxy.
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