National Aeronautics and Space Administration

www.nasa.gov

Produced in 2010 by the 

NASA Astrobiology Program 

to commemorate 50 years of 

Exobiology and Astrobiology 

at NASA.

#1

Issue
Astrobiology

A History of Exobiology and Astrobiology at NASA

This is the story of life in the Universe—or at least the story as we know it so far. As 

scientists, we strive to understand the environment in which we live and how life relates to this environment. As astrobiologists, we study an environment that includes 

not just the Earth, but the entire Universe in which we live.

The year 2010 marks 50 years of Exobiology and Astrobiology research at the National Aeronautics and Space Administration (NASA). To celebrate, the Astrobiology 

Program commissioned this graphic history. It tells the story of some of the most 

important people and events that have shaped the science of Exobiology and Astrobiology. At only 50 years old, this field is relatively young. However, as you will 

see, the questions that astrobiologists are trying to answer are as old as humankind.

Concept & Story

Mary Voytek

Linda Billings

Aaron L. Gronstal

Artwork

Aaron L. Gronstal

Script

Aaron L. Gronstal

Editor

Linda Billings

Layout

Jenny Mottar

Copyright 2010, NASA Astrobiology Program
Issue #1—The Origin of a Science

This year marks the 50th anniversary of NASA’s Exobiology Program, established 

in 1960 and expanded into a broader Astrobiology Program in the 1990s. To commemorate the past half century of research, we are telling the story of how this 

field developed and how the search for life elsewhere became a key component 

of NASA’s science strategy for exploring space. This issue is the first in what we 

intend to be a series of graphic history books. Though not comprehensive, the 

series has been conceived to highlight key moments and key people in the field as 

it explains how Astrobiology came to be.

-Linda Billings, Editor
In scientific circles, many people use these 

terms interchangeably. But what do they 

mean? In short, they are used to describe 

the study of life’s potential in the Universe and the origin and history of life on 

our own planet. Astrobiologists study anything and everything about life on Earth in 

order to understand how life might arise 

and survive elsewhere in the Universe.

Astrobiologists are also interested in how Earth life is able to 

survive and adapt when leaving 

our planet. They are studying life 

forms like algae and other Earth 

microorganisms, and trying to 

figure out if they could live on 

other planets like Mars. So really, 

astrobiologists study how life 

might begin and survive anywhere 

in the Universe.

Astrobiology.

Exobiology.

Background Image: 30 

Doradus Nebula (1)
Astrobiology as a field of 

science includes many disciplines, 

from astronomy to biology. But 

all astrobiologists work to understand the origin of life on Earth 

and potential for life on other 

worlds (2).

Astrobiology can include 

everything from studying the 

fundamental principles of how 

living cells form to searching 

the skies for Earth-like planets 

around distant stars. This broad 

range of scientific pursuits can 

make Astrobiology difficult 

to explain.

Earth is the only example we have 

of a habitable planet for life as we 

know it. So how do astrobiologists 

do their work? 

When searching for life in the 

Universe, what do we look for and 

how do we look for it? 

If we haven’t found ‘aliens’ 

yet... what do they study?
Humans have long been fascinated with the potential for life in 

the Universe—even before people knew what the Universe was. 

Ancient cultures had a variety of explanations for what the stars 

and planets were, but nearly all of them believed in the possibility 

of life forms much different from those they saw on Earth.

Twenty-three centuries ago, 

the Greek philosopher Epicurus 

wrote about the existence 

of other worlds in a letter to 

Herodotus (300 BCE).

Astronomers have played an important role in helping us 

understand that Earth is not the only world in the Universe. 

The discovery of other planets and moons helped to spark 

ideas that the Earth might not be the only world with life.

In fact, Galileo had discovered Jupiter’s largest moons. He 

later identified Io, Europa, Callisto and Ganymede. This is 

why we refer to them as ‘Galilean’ satellites today.

Christiaan Huygens 

(1629-1695) discovered 

Saturn’s moon, Titan.

Giovanni Cassini 

(1625-1712) was the 

first to observe four 

of Saturn’s moons, 

including Iapetus.

Epicurus 341 BCE–270 BCE

Galileo 1564-1642

Galileo Galilei is one of the most famous 

astronomers in history. He perfected 

the early telescope and made some truly 

profound observations of the Solar 

System. In 1610, he observed:

There are many different translations and 

interpretations of Epicurus’ words, but it is 

clear that he did not believe the Earth was 

the only inhabited world in existence.

 

“There are an 

infinite number 

of worlds, some 

like this world, 

others unlike 

it.”

“I have seen Jupiter 

accompanied by three fixed 

stars, totally invisible by their 

smallness... The planets are 

seen very rotund, like 

little full moons (3).”

“The bodies 

of the planets are 

solid like that of 

our Earth.” “These 

new Earths may 

be stocked 

with plants and 

animals (4).” 

“With 

regard to living 

things, it cannot be 

proven that the seeds 

from which animals, 

plants and other 

things originate are 

not possible on any 

particular worldsystem.”
In the 1920s, scientists like the Russian 

Aleksandr Oparin and Englishman J.B.S. 

Haldane were trying to determine how 

life began on Earth.

Through independent 

research, they both 

proposed somewhat 

similar ideas.

The theories of Oparin and Haldane would later influence one of 

the most important origin of life 

experiments to date...

*Translated from Russian 

**Translated from British

I believe the early Earth had 

a reducing atmosphere*

Composed of methane, 

ammonia, hydrogen and 

water vapor.

I believe it was CO2, 

ammonia and water vapor. CO2

provided the source of carbon 

for life my good chap. Da, but methane 

could also provide 

carbon for life.

And prebiotic life 

most likely began with 

molecules in the atmosphere 

that were then deposited 

in the oceans.

Increasingly complex 

organic molecules were 

created in the presence of 

ultraviolet radiation.”

Nyet. Life arose in 

the process of the evolution 

of matter. Basic organic molecules 

organized into localized systems—

like primitive cells.

Agreed.**

Agreed.
Stanley Miller was a young 

graduate student working 

under Nobel Laureate 

Harold C. Urey

1952. The University of Chicago

Using Urey’s calculations 

for the constituents of the 

early Earth’s atmosphere 

along with Oparin and 

Haldane’s theories...

First, I’ll seal 

gases that were thought 

to be present on the early 

Earth in an airtight 

container.

These chemicals 

are sealed in sterile tubes 

and flasks that create 

a loop.

Methane... 

Ammonia... Hydrogen...

The water is heated...

No oxygen.

I am going to attempt 

to synthesize molecules 

necessary for life by simulating 

conditions on the early Earth—

thereby testing the theory of 

chemical evolution.

This simulates the 

oceans and atmosphere 

of the early Earth.
But the real trick is to 

simulate the energy provided by 

flashes of lightning in the ancient 

atmosphere of the Earth (5).

We do this with 

sparks of electricity.

This allows water to 

condense inside the bottles 

and trickle down through 

the tubes...

After our 

little ‘lightning storm,’ 

we let the atmosphere 

inside our bottles cool 

off again.

Amazingly, we get 

organic compounds that contain 

carbon. These compounds include 

things like amino acids, sugars, lipids 

and other molecules that are vital 

for living cells.

...where we can 

collect samples to see what 

has happened.

“Just turning on the spark in a basic pre-biotic 

experiment will yield 11 out of 20 amino acids” used 

by life on Earth (5). 
“You look at science (or at least talk of it) as some 

sort of demoralising invention of man, something 

apart from real life, and which must be cautiously 

guarded and kept separate from everyday existence. 

But science and everyday life cannot and should 

not be separated. Science, for me, gives a partial 

explanation for life. In so far as it goes, it is based 

on fact, experience and experiment (7).”

Other key steps in the 20th century were major advances in the fields 

of biology and chemistry that would later provide astrobiologists with 

the tools they needed to examine life at the molecular level.

British scientist Rosalind Franklin was a key figure in 

biology. Her work with x-ray diffraction would provide 

clues to the structure of one of life’s most important 

molecules—DNA.

Franklin’s data was the foundation for the work 

of James D. Watson and Francis Crick, who put 

forward their theory of the DNA helix in 1953.

In 1962, Watson and Crick, along 

with molecular biologist Maurice 

Wilkins, were awarded the Nobel 

Prize for this invaluable contribution 

to molecular biology.

Sadly, Rosalind Franklin passed away in 1958 without 

receiving the proper credit for her contribution.

DNA is a big helix in several 

chains. Phosphates on the outside... 

phosphate-phosphate inter-helical 

bonds disrupted by water (6).

Watson and Crick provided the world with a visual understanding of how nucleotide base pairs fit together to ultimately provide the fundamental blueprint 

for life as we know it. Their paper hit the stands in 1953, following their now 

infamous announcement at the Eagle Pub in Cambridge, England. Only three weeks 

later, Stanley Miller and Harold Urey published their equally famous paper on the 

chemical building blocks of life.

We have found the 

secret of LIFE!!!
Exobiology really began to develop when humankind 

first gained access to space...

The race to launch people off our planet had begun... and nobody 

knew what would we find – or what would happen to Earth’s first 

space travelers when they left home.

Space was still the realm of speculation. 

Early telescopes had led the likes of astronomers like Percival Lowell to theorize about 

canal systems on Mars carved by intelligent 

civilizations...

...Science fiction authors speculated 

even further about strange societies 

on other planets in our solar system.

All these visions of bizarre life forms, 

both benign and dangerous, were still 

fresh in the minds of the public.

Sputnik, 1957

Voskhod, 1963

Skylab 4, 1973

Explorer I, 1958

The main players at 

the time were the 

United States and 

the Soviet Union.
At that time, key figures and critical meetings drove the creation of Exobiology. 

One such moment came in 1957, when the young microbiologist Joshua Lederberg 

traveled from the U.S. to meet with J.B.S. Haldane in India.

Lederberg had made a name for himself by demonstrating 

how bacteria exchange genetic information—research that 

helped give birth to the field of bacterial genetics.

Both men saw a potential for ‘reckless’ use of space technologies. 

Lederberg, with his knowledge of microbiology, was fearful of 

humans contaminating other celestial bodies with Earth microbes 

that could damage potential ecosystems on other planets and 

prevent further scientific study of them (8).

While watching a lunar eclipse 

from Haldane’s home, they 

speculated about the effects 

that human access to space 

could have on other planets 

and moons in our solar system.

Lederberg also grew concerned about space 

explorers bringing harmful, alien bacteria back to 

Earth—thereby contaminating our own planet.

*See page 4.

Lederberg and Haldane were 

in awe of the two recent 

Sputnik satellite launches 

from the Soviet Union.

Following his work in England on the origins of life*, 

Haldane had relocated to Calcutta.
As we grew more confident in our ability to access 

space, concerns over our impact on the other planets 

and moons in the Solar System also continued to grow.

Achievements in the new ‘Space Race’ 

between the USA and the USSR came in 

rapid succession. In a matter of months, 

rockets grew larger and larger, allowing 

for more and more complicated missions.

The animals’ space flights culminated in the 

mission of Soviet cosmonaut Yuri Gagarin, the 

first human being to leave the atmosphere.

On April 12, 1961, the day 

of his flight, life on Earth 

had truly left home.

Laika the dog (c. 1954—November 3, 1957), was the 

first animal sent to space. The Soviet Union launched 

Laika on a one-way trip in 1957 to test the effects of 

space flight on a living organism.

Ham the chimp (c. July 1956—January 19. 

1983), the first hominid in space. In 1961, 

he spent 16 minutes and 39 seconds in 

flight before returning to Earth.
On July 29, 1958, US President Dwight D. Eisenhower 

signed the National Aeronautics and Space Act.

In the fall of 

1958, Lederberg 

was awarded 

the Nobel Prize 

in Physiology or 

Medicine, but it 

didn’t slow his 

interest in the 

science he called 

‘Exobiology.’

Joshua Lederberg, fresh from his meeting with 

Haldane in Calcutta, immediately approached 

NASA’s first deputy administrator...

Dryden quickly appointed 

Lederberg the head of the 

Space Science Board’s panel on 

extraterrestrial life.

Lederberg quickly set about assembling scientists 

concerned with life beyond Earth. He recruited 

talented members of the science community, including 

Melvin Calvin, Wolf Vishniac, Norman Horowitz, Harold 

Urey and the young Carl Sagan.

Calvin

Horowitz

Urey

Vishniac

Sagan

...Hugh Latimer Dryden.

NASA was born.

Sir, I believe 

there is a need to 

prevent extraterrestrial 

contamination of Earth in 

our endeavors to 

reach space.

Also, the search 

for native life on the 

moons and planets of the 

Solar System must be 

a priority.

“...for their discovery that 

genes act by regulating 

definite chemical events...”

“...and for his discoveries 

concerning genetic recombination 

and the organization of the genetic 

material in bacteria...”(9)

Yes, I see.
Sagan had already gained an interest in ‘Exobiology’ when sitting in lectures by Harold Urey at the University of Chicago—just as he and Stanley Miller were making headlines with their origin of life experiments.

Lederberg’s plea to consider the implications of life 

beyond Earth struck a chord with Dryden, and soon the 

young biologist was involved in decision-making at NASA. 

He was the one who coined the term ‘Exobiology.’

The enthusiasm of Lederberg’s panel 

for exobiology ensured that, from 

NASA’s very beginnings, core questions 

in the study of the origin, evolution and 

distribution of life in the Universe were 

at the heart of space exploration plans. 

Lederberg quickly set up dedicated study 

teams—dubbed EASTEX and WESTEX—

on both coasts of the United States.

Background image: Hubble 

Space Telescope (12)

Harold Urey

Melvin Calvin

Gunther Stent

Salvador Luria

Bruno Rossi Wolf Vishniac

Fred Whipple

Keffer Hartline

Stanley Miller

Carl Sagan

Italian biologist Salvador Luria chaired the 

EASTEX group, which included Bruce Billings, 

Dean Cowie, Richard Davies, George Derbyshire, 

Paul Doty, Herbert Freeman, Thomas Gold, H. 

Keffer Hartline, Martin Kamen, Cyrus Levinthal, 

Stanley Miller, E.F. Mac Nichol, Bruno Rossi, W. 

R. Sistron, John W. Townsend, Wolf Vishniac, 

Fred Whipple and Richard S. Young.

Lederberg chaired the WESTEX group, which 

included Melvin Calvin, Richard Davies, Norman 

Horowitz, A.G. Marr, Daniel Mazia, Aaron Novick, 

Carl Sagan, William Stinton, Roger Stanier, Gunther Stent, C.S. van Niel and Harold F. Weaver.

I would like to get

some help from a young 

astronomer at Yerkes Observatory [named Carl Sagan] who is well 

informed and deeply interested in 

planetary biology (10).

My mission in 

science is nothing 

less than ‘extending 

Miller’s results to 

astronomy (11).’
In 1959, NASA awarded the first grant for 

Exobiology research to an EASTEX member, the 

microbiologist Wolf Vishniac of Yale University. 

He received $4500 to develop the “Wolf Trap,” 

a device to detect microorganisms in the soil of 

another planet.

NASA created a Life Sciences office on March 1, 

1960. Thanks to the work of scientists like Lederberg, an Exobiology program was established as an 

important element of this office. The NASA Jet 

Propulsion Laboratory in Pasadena, California, and 

the NASA Ames Research Center in Mountain View, 

California, quickly developed strong Exobiology 

research groups.

NASA Ames (14) began to recruit new postdoctoral 

researchers, including Cyril Ponnamperuma and George 

Akoyunoglou, to focus on Exobiology. Soon, “postdocs” 

were working alongside staff scientists at NASA 

Ames. This development was a major step in recruiting new scientists to the field.

Many researchers joined Vishniac in receiving support from NASA in 

the early days of Exobiology, including several Nobel Prize winners (15). 

By 1963, NASA had become a significant funding source for life science research in the USA. NASA money also helped build new facilities 

for universities, including UC Berkeley and Stanford. Below are a few 

examples of projects funded by the first NASA Exobiology Grants.

Harrison Brown, “Problems of Lunar 

and Planetary Exploration (16)”.

Samuel Silver, “Biochemistry of 

terrestrial microbes in simulated 

planetary environments (16).”

Joshua Lederberg, “Development of 

the Multivator biochemical lab (16).”

Sidney Fox, “Study of proteinoid 

microspheres (16).”

Gilbert Levin, “Development of 

the Gulliver life detector (16).”

Pretty soon, 

you’ll be ready for a 

trip to Mars (13).
Questions about life’s potential in the Universe 

have been on NASA’s science agenda since the 

very beginnings of the agency, making Exobiology 

and Astrobiology research essential to meeting 

NASA’s goals. In 1976, NASA would launch the 

first planetary exploration mission dedicated to 

searching for evidence of life on another world, 

and the work of Exobiology and Astrobiology would 

truly take off.

Next issue... 

Astrobiology travels the Solar System

18

17
Astrobiology

A History of Exobiology and Astrobiology at NASA

Further Resources and References cited in this issue:

1. The background image on Page 1 is of the 30 Doradus Nebula of the Large Magellanic Cloud. This is one of the most active star-forming regions discovered thus 

far in our region of the galaxy. This image combines ultraviolet, visible, and red 

light captured by the Hubble Space Telescope’s Wide Field Camera 3. Credit: 

NASA, ESA, and F. Paresce (INAF-IASF, Bologna, Italy), R. O’Connell (University of Virginia, Charlottesville), and the Wide Field Camera 3 Science Oversight 

Committee photo. Image available online at: http://www.astrobio.net/index.

php?option=com_galleryimg&task=imageofday&imageId=216&pageNo=24

2. See the Astrobiology Roadmap at: http://Astrobiology.nasa.gov/roadmap

3. Drake, S. (1978) Galileo at Work: His Scientific Biography, University of 

Chicago Press

4. Huygens, C. (1968) Cosmostheoros: Book 1

5. “EXOBIOLOGY: An interview with Stanley L. Miller”. Accessexcellence.org

6. Lecture Notes of Franklin, “Colloquium Nov. 1951.” The report is typewritten, 

dated 7 Feb. 1952, in A Sayre, Rosalind Franklin and DNA (1975), 128.

7. Letter to Ellis Franklin, possibly summer 1940 whilst Rosalind Franklin was an 

undergraduate at Cambridge. Cited in Brenda Maddox (2002) The Dark Lady of 

DNA, HarperCollins Publishers, 380p.

8. Morange, M. (2007) What history tells us: X. Fifty years ago: the beginnings of 

Exobiology. J. Biosci. 32(6), September 2007, 1083–1087

9. www.nobelprize.org

10. http://www.njhn.org/Humanist_Candle_in_the_Dark.html

11. Sagan to Lederberg, 1959, Lederberg Papers, National Library of Medicine. 

Available at: http://profiles.nlm.nih.gov/BB/Views/Exhibit/narrative/exobio.html

12. Image from the Hubble Space Telescope entitled, “A Five Quasar Gravitational 

Lens”. Credit: K. Sharon (Tel Aviv U.) and E. Ofek (Caltech), ESA, NASA. 

Available from www.hubblesite.org and www.nasaimages.org

13. Wolf Vishniac’s instrument, the Wolf Trap, would later become one of four 

instruments selected to fly on NASA’s Viking Mars lander mission.

14. This aerial photograph of what is now the NASA/Ames Research Center was 

captured by the Navy NAS on May 1, 1936. The distinctive large dirigible 

hanger can still be seen today when driving past NASA Ames in Mountain 

View, CA, on California Highway 101. From the Ames Research Center Image 

Library Collection, Image A93-0073-8

15. Nobel Prize winning scientists involved in early Astrobiology projects with 

support from NASA included the likes of Lederberg, Calvin, Urey, H.J. Muller, 

Fritz Lipmann, George Wald, M. Keffer Hartline and Manfred Eigen (Dick and 

Strick 2005, p. 30)

16. Dick, S.J. and Strick, J.E. (2005) The Living Universe: NASA and the development of Astrobiology. Rutgers University Press, New Brunswick, New Jersey, 

and London

17. Images captured by the Viking Orbiters: (1) Image of the Mars surface from 

Viking 1 (1976) (2) Mars’ moon Deimos as captured by Viking 2 (1977) (3) The 

infamous ‘face’ on Mars captured by Viking 1 (1976) (4) Channels and Craters 

on Mars. Captured by Viking 2 (1976)

18. The comet Tempel 1 as viewed by the NASA Deep Impact mission (2005).

NP-2010-09-681-HQ