Reflection

Life on Venus

Harold Morowitz

In the early days of NASA, much of the planning for spacebiology came before a group I belonged to, The Planetary

Biology Subcommittee. Before Sputnik, the idea of experi-mental space biology had been an abstraction so that the‘‘experts’’ were scientists from several domains who had aninterest in the subject or were recruited for their expertise asbiological generalists. Many of the early discussions, whichtook place in Washington DC, Cape Canaveral, Florida,Mountain View, California, and Houston, Texas, focused onwhich astral body was the most likely choice to search forextraterrestrial life. No one believed that the Moon was apossibility. The discussion tended to focus on the two mostaccessible planets, Mars and Venus, Mars being the heavychoice. One evening, after a day of discussion, four of thecommittee members thought that Venus might have beenpassed over too quickly, so we arranged to meet for dinner atthe hotel. As the only survivor of that group, I feel that thetime has come to reveal the results of that meeting.

The foursome consisted of Wolf Vishniac, then of theUniversity of Rochester; Carl Sagan, then of Harvard; Kim-ball Atwood, then of the University of Illinois; and myself,then of Yale. The topic during the first cocktail was whetherliving forms were able to float in the dense atmosphere in azone where the temperature might permit the stability of thecovalent bonds and other structures we all felt were neces-sary for life. Very little was known about the extremely hotsurface of our neighboring planet, including the amount andstatus of water in the atmosphere.

As the second cocktail appeared, someone began to worrythat except for the four of us the biology of Venus mightdisappear as a subject of interest. (Through the haze of time Ican’t exactly recall who said what, so all attributions must becollective.) We decided to forestall any lessening of interestby forming a society dedicated to the study of life on Venus.The first suggestion was that it be called ‘‘The Society ofVenutian Biologists.’’ This seemed like an awkward name,lacking a certain rhetorical power.

We considered ‘‘The Society of Cytherean Biologists.’’ Thistitle was rejected as being too snobbish. We paused to orderdinner, decided on another round of cocktails, and returnedto the naming problem. I wish I could recall who offered

‘‘Society of Venereal Biologists.’’ The name immediately wonunanimous approval. Elections were held, and each com-panion was awarded high office by acclaim. I have never putit on my resume, fearing that promotion and tenure com-mittees would not understand, and now that my fellow of-ficers are no longer with us I would deem it improper toclaim honor for myself. It was truly a collective enterprise.

Although the society never met again, Carl Sagan and Icontinued to examine the Venus issue, and in September1967 we published a brief analysis of the subject as a letter tothe journal Nature (an abstract is shown next page). AlthoughI have not followed this subject in any detail, I do notice anoccasional article in the astrobiology literature in which thepossible biology of the planet is reexamined. I don’t thinkthat we can rule out the possibility of Venusian life.

A few years later, Wolf Vishniac was in Antarcticasearching for extremophilic microbial life in a Mars-like en-vironment. While exploring in the dark he fell 500 feet from acliff and died. In an obituary, Carl Sagan noted, ‘‘He is thusthe first person since Bruno to lose his life in the pursuit ofextraterrestrial life.’’ Space biology lost one of its earliest andmost brilliant devotees. Kimball Atwood moved from Illinoisto Columbia, where he continued his distinguished career inseveral domains of biology. He passed away in October 1992.Carl Sagan, the leader of space biology and chief represen-tative of that discipline to both the community of scientistsand the broader public, died in 1996. His name is virtuallysynonymous with the search for life in the Cosmos.

And now, as last surviving officer of the Society of VenerealBiologists, I feel that the time has come to tell this story and tohonor my fellow society members. They were pioneers ofastrobiology and a wonderful group to have dinner with.

Address correspondence to:Harold Morowitz

The Krasnow Institute for Advanced StudyGeorge Mason University

Fairfax, VA 22030United States

E-mail: morowitz@gmu.edu

(continued next page)

The Krasnow Institute for Advanced Study, Fairfax, Virginia, United States.

ASTROBIOLOGYVolume 11, Number 9, 2011ª Mary Ann Liebert, Inc.DOI: 10.1089/ast.2011.9270

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Life in the Clouds of Venus?

Harold Morowitz1 and Carl Sagan2

Abstract

While the surface conditions of Venus make the hypothesis of life there implausible, the clouds of Venus are adifferent story altogether. As was pointed out some years ago1, water, carbon dioxide and sunlight—the pre-requisites for photosynthesis—are plentiful in the vicinity of the clouds. Since then, good additional evidence hasbeen provided that the clouds are composed of ice crystals at their tops2,3, and it seems likely that there are waterdroplets toward their bottoms4. Independent evidence for water vapour also exists5. The temperature at thecloud tops is about 210�K, and at the cloud bottoms is probably at least 260–280�K (refs. 4 and 6). Atmosphericpressure at this temperature level is about 1 atm.7. The observed planetary albedo falls steeply in the violet andultra-violet8, which accounts for the pale lemon yellow colour of Venus. The albedo decline would not beexpected for pure ice particles, and must therefore be caused by some contaminant. Dust, ozone, C3O2 and othergases may possibly explain these data but, whatever the explanation, the ultra-violet flux below the clouds islikely to be low. If small amounts of minerals are stirred up to the clouds from the surface, it is by no meansdifficult to imagine an indigenous biology in the clouds of Venus. What follows is one such speculation.

Abstract reprinted by permission from Macmillan Publishers Ltd: Nature 215, 1259–1260 (16 September 1967). Availableonline at http://www.nature.com/nature/journal/v215/n5107/pdf/2151259a0.pdf.

1Department of Molecular Biophysics, Yale University, New Haven, Connecticut.2Harvard College Observatory, Smithsonian Astrophysical Observatory, Cambridge, Massachusetts.

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