1

National Aeronautics and Space Administration

www.nasa.gov

Produced by the NASA 

Astrobiology Program to 

commemorate 50 years of 

Exobiology and Astrobiology 

at NASA.

#3

Issue

2nd EDITION
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 marked 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

Special thanks to Leslie Mullen and Daniella Scalice

Copyright 2017, NASA Astrobiology Program. First Edition printed 2012
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Issue #3

Missions to the inner Solar System!

The year 2010 marked 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 third 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
Astrobiology has focused on 

Mars* since the early years 

of space exploration. But 

Mars is by no means the only 

place in our solar system 

for astrobiology.

Issue 3—Missions to

the inner Solar System!

It all began in the 

1950’s with the launch 

of Sputnik (see Issue 1).

With access to space,

scientists from around

the globe set their sights 

on visiting other worlds.

The first target was,

of course, the Moon. The early years of lunar exploration saw many

failures, but the successes soon followed.

Luna 2 (1959—USSR) was the 

first to reach the Moon’s surface, east of Mare Serenitatis.

Luna 3 (1959—USSR) gave us

our first glimpse of the far 

side of the Moon.

With access to the Moon a reality, 

astrobiologists prepared to test 

their theories about life’s potential 

in the Universe by visiting locations 

throughout the Solar System with 

robotic missions.

The USSR’s** lunar program

had many ‘firsts’, including

the first spacecraft to reach

the Moon’s vicinity. Luna 1 (1959)—USSR

Explorer 1—first US

satellite (1959)

*see Issue 2: 

Missions to Mars!

**Union of Soviet Socialist Republics

2
3

NASA scrambled to catch up with the USSR while 

astrobiologists anxiously awaited science results from 

every mission—regardless of its country of origin.

Of course, there was no life—no ‘man in the 

Moon.’ What we found was a world of impact 

craters, fine dust and geological features.

Remnants of ancient lava flows hinted at 

the Moon’s origins... origins that could 

reveal information about the formation of 

Earth and the processes that allowed our 

planet to become habitable. The flurry 

of Moon missions continued.

...a human sample return, 

a robotic sample return 

and automated rovers.

Soft Landers... ...Orbiters...

There are many links 

between the Earth 

and the Moon that 

interest astrobiologists. The Moon 

might affect the 

Earth’s climate

and habitability by 

influencing ocean 

tides and stabilizing 

Earth’s rotational 

axis. Even sampling 

efforts at the 

Moon could have 

implications for 

astrobiology.

Long ago, rocks from the ancient

Earth may have been kicked

toward the Moon by impacts.

These remnants of Earth’s history could

still be on the Moon—like pieces of

buried treasure waiting to be found.

Pioneer 4 (1959), NASA’s first 

mission on a lunar trajectory

Ranger 7 (1964—NASA)—

first closeup photos. Ranger 

9 (1965–NASA) - first

high quality images

Surveyor 1 (1966—NASA)

Luna 9 (1966—USSR)

Apollo 8 

(1968—NASA)

Luna 10 (1966—USSR)

Apollo 11 (1969—NASA)

Luna 16 

(1970—USSR)

Lunokhod 1 

(1970—USSR)
4

By studying lunar craters,

scientists may also learn

about the types of impacts 

that affected early Earth.

These missions have improved 

our understanding of the origin 

and evolution of the Moon...

...and they also laid the foundation 

for missions further from Earth.

Pioneer 5 (1960—NASA) 

drifted between the orbits 

of Earth and Venus...

The first visit to another 

planet came in 1962 with 

Mariner 2 to Venus (NASA).

Scientists were already speculating 

about the possibility of life on Earth‛s 

shimmering sister planet.

...conducting the first study

of interplanetary space.

Lunar missions have now

been undertaken by many

countries—and the list

continues to grow!

Hiten (Muses A)

(1990—Japan)

Lunar Reconnaissance 

Orbiter (2009—NASA)

Lunar Atmosphere and

Dust Environment Explorer 

(LADEE) (2013—NASA)

Clementine (1994—NASA)

Acceleration, Reconnection, Turbulence and Electrodynamics of 

the Moon‛s Interaction with the 

Sun (ARTEMIS) (2010—NASA).

Kaguya (SELENE)

(2007—Japan)

Smart 1 (2003—European 

Space Agency (ESA)

Chang’e 1 and 2 (2007—

Chinese National Space 

Administration (CNSA))

The Gravity Recovery And

Interior Laboratory

(GRAIL) (2011—NASA)

Lunar Crater Observation and Sensing 

Satellite (LCROSS) (2009—NASA)
5

Venus is similar in size to Earth, and 

many scientists believed its thick 

atmosphere could harbor life. (1)

Following early failures, the 

USSR accomplished some 

great feats in exploring 

the mysterious planet.

In 1965, the Venus 3

mission became the first

to reach the surface of

Venus with an impact, but

it failed to return data.

Venera 4 (1967) made it 

to Venus and released a 

descent capsule into the 

planet’s atmosphere.

The success continued with 

Venera 5 and 6 (1969).

In 1970, Venera 7 made the 

first soft landing on Venus and 

returned 23 minutes of data.

Venera 7 revealed that

Venus was hostile to life.

These missions

set the stage

for an incredible

set ofaccomplishments that would 

change our view of

Venus forever.

Temperatures reached 475°C and 

pressures were 90 times greater 

than at the Earth’s surface. (2)

Humankind had its first signal from 

the surface of another planet.

Sputnik 19-21 (1962), 

Venus flyby attempts.

Sputnik 7 (1961), Venus 

impact attempt.

Venera 1 (1961), Venus 

flyby—contact lost.

Venera 4 (1967)
6

Mariner 5 (1967—NASA) revealed more 

about the harsh venutian environment...

... and Mariner 10 (1973—NASA) 

added to the story as it passed 

by on its way to Mercury.

Extreme conditions on Venus made it 

look uninhabitable, but scientists were 

still interested in the dynamic planet.

At Venus, scientists could perform 

comparative planetology.

Studying phenomena like the greenhouse effect on Venus has helped 

us understand Earth’s climate.

Before missions to Venus, scientists could only 

learn about Earth‛s climate by studying Earth.

Venus provided us with a glimpse 

of what global warming could do 

to our own planet.

The Soviets

forged ahead.

The Venera 8 (1972) probe made 

it to the surface and returned 50 

minutes and 11 seconds of data.

(3)
7

The USSR achieved 

two major milestones 

at Venus in 1975.

A lander separated

from the orbiter...

The lander survived 

the treacherous 

descent...

...from the surface

of another planet.

...and Venera 9 

became the first to

return an image...

Humankind glimpsed a planet other than 

Earth from the ground level—viewing 

our first ‘alien’ horizon.

Venera 10 also returned photographs that visually 

confirmed Venus as a scorched and barren land.

Shortly thereafter, the Venera 10 lander 

separated from its orbiter and landed 2200 

kilometers (km) away from Venera 9.

...and made its way 

to the surface.

Venera 9 was the first spacecraft

to orbit around Venus.

Venera 9 & 10

images (4)
8

Venera 11 and 12 (1978—USSR) performed

flybys of Venus as they studied things like

gamma ray bursts and the solar wind. They also delivered landers that 

fleshed out views of Venus.

Surprisingly, the landers detected lightning, thunder and 

carbon monoxide at low altitudes in the atmosphere.

NASA returned to Venus

in 1978 with the Pioneer 

Venus mission, which dropped 

probes to the planet and 

mapped the surface.

Another “first” 

came in 1982 when 

Venera 13 and 14 

(USSR) touched 

down on Venus 

and conducted the 

first soil analysis 

on a planet other 

than Earth. The 

landers quickly 

sent data back to 

Earth before they 

melted under the 

extreme venutian 

heat.

Venera 15 and 16 (1983—USSR) 

followed, capturing thermal maps 

of the northern hemisphere and 

high resolution images of the 

polar regions. Venera 15 and 16 

mapped an area of 115 million km2

at a resolution of one to two km 

by the end of their main missions 

in 1984. (5)

In 1984, the USSR led the Vega 1 and 2 missions—an 

effort that included many European partners.

They dropped probes toward the planet 

as they passed by en route to their true 

target... but more on that in later pages.

Venera 15 & 16 

Vega 1 & 2

(6)
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Although NASA had great success at 

Mars.* Venus proved more elusive.

It wasn’t until 1989 that NASA attempted a 

return to Venus, when the Magellan spacecraft 

was deployed from the space shuttle Atlantis.

As our view became clearer, scientists

came to a general consensus that life as 

we know it could not survive in the blistering conditions Venus had to offer.

In the 1990s activity at Venus fell 

quiet as space agencies turned their

attention to other targets of astrobiological interest—such as Mars.

...but none stayed for 

an extended visit.

Many missions captured photos or

data as they passed by Venus on

the way to other destinations...

“Venus suffers from a runaway

greenhouse at a temperature of

hundreds of degrees, far too hot 

for any life to survive.” (7)

*See Issue 2

Carl Sagan

MESSENGER (2004)

Cassini (1997)

Galileo (1989)

(8)
10

It wasn’t until 2005 that Venus received 

another dedicated mission.

Venus Express entered orbit in 2006,

The mission spent more than eight years 

providing new and fascinating information 

about the enigmatic world. 

On December 9th, the probe entered it’s 

intended orbit at Venus and began its 

original 2-year science operations! (10)

Although it is still considered an unlikely 

habitat for life, Venus is providing invaluable 

information for astrobiologists, planetary

scientists and climatologists.

As the Earth’s global temperatures 

continue to rise, scientists will keep 

their eyes trained on our celestial 

‘twin’ and try to determine how we 

can prevent Earth from turning into 

a similar, furnace-like world.

ESA’s Venus Express was based on

the hugely-successful Mars Express.

The Japanese space agency (JAXA) attempted 

to join Europe at Venus with the lauch of the 

Venus climate orbiter, AKATSUKI.

In 2010, AKATSUKI failed to enter 

orbit around Venus. However, the 

probe got a second chance in 2015. 

(9)

(11)
11

NASA’s most recent visitor to Venus 

was the MESSENGER spacecraft, which 

made two separate flybys of the planet.

MESSENGER’s final target, however,

was the next planet on our road

toward the Sun—fiery little Mercury.

On the other side of the planet,

however, temperatures drop 

dramatically to -173oC (-278oF)!

From Earth, the tiny

planet appears as little

more than a speck of dust 

against the Sun. Mercury 

is only about 15,329 km 

in diameter (compared to 

Earth’s 40,030 km), and is 

so close to our solar system’s bubbling and boiling 

sun that temperatures can 

reachup to 427oC (801oF) 

on its sun-facing side. (12)

Few missions have braved the dangerous

journey to Mercury, where the proximity to

the Sun means they are cooked by heat...

...and battered by

intense solar wind.

To date, only Mariner 10*

(1973) and MESSENGER

have made the journey. *see page 6
12

MESSENGER began a yearlong

science orbit of Mercury in March 

of 2011 and has provided amazing

views of the tiny planet.

Comparing Mercury to 

Earth can also help us

determine why our 

planet is so special in 

its ability to support

life as we know it.

Europe and Japan are working together 

on a new mission, dubbed BepiColombo.

Mercury, the world obscured from view by the glare of the 

Sun, will continue to reveal its secrets in the years to come.

The inner Solar System includes everything from Mercury 

to the asteroid belt between Mars and Jupiter. Humankind 

has sent robotic explorers to all of the inner-solar-system 

planets, and also to the moons of Earth and Mars.

But planets and moons are not the only things in this region 

of space that capture the attention of astrobiologists.

Mercury may look similar to

the Moon, with its barren

and crater-scarred surface,

but it has different lessons

to teach astrobiologists.

Mercury is the Solar System’s smallest terrestrial planet. Studying how it formed and evolved can 

teach astrobiologists about the many different types of rocky planets that can exist around stars.
13

Asteroids and comets also move 

through the inner Solar System. 

Occasionally, they come close 

enough to Earth to visit with 

dedicated spacecraft.

In the mid 80’s, as it journeyed around the 

Sun, the majestic Halley’s comet made a 

rare visit to the inner Solar System.

Space agencies around the world

launched a flotilla of spacecraft to

observe Halley‛s comet close up.

After Earth formed, comets and asteroids may

have also delivered molecules and material that

were essential for the origins of life on our planet.

Studying comets and asteroids up 

close provides astrobiologists with 

clues about how the Solar System 

formed and evolved...

...and how life on our planet began!

...how Earth developed

into a habitable world...

These objects are like small samples from the early Solar System. Scientists are interested 

in studying them because they provide a record of conditions during a time when planets 

were still forming from the rock and dust that spun around our infant sun.

Comets and asteroids are remnant 

chunks of material left over from 

the formation of the Solar System.

(13)
14

The Halley‛s comet encounter of 1986 included spacecraft 

from the USSR, Japan and Western Europe.

After delivering their

probes to Venus*, the

Soviet-led Vega 1 and

2 spacecraft sped to

catch Halley’s comet.

Japan and Europe also joined 

in. Giotto (1985—ESA) encountered Halley in 1986 and then 

traveled onward to the Comet 

P/Grigg-Skjellerup in 1992.

NASA helped by using existing 

spacecraft that were already in 

space. Instruments from missions 

like Pioneer 7, Pioneer Venus 1 

and ICE were re-directed to 

observe Halley. All together, 

the spacecraft became popularly 

known as the ‘Halley Armada.”

The data gathered from 

Halley’s comet proved that 

small bodies were more than

just rocks or snowballs.

Suisei (Japan)

Vega 1 and Vega

2 (USSR)

Pioneer Venus 1

(USA)

Giotto (ESA)

Sakagaki (1985),

Japan’s first interplanetary probe.

Pioneer 7 (USA)

*see page 8

International

Cometary

Explorer (ICE)

Vega probes at Venus.

(15)

(14)
15

Of the many “postcards” that NASA’s Galileo 

mission sent back to Earth during its long 

journey to the outer Solar System (more on 

that later) were snapshots of Venus...

These were the first

asteroids to be visited up 

close by a robotic mission.

...and 951 Gaspra

(in 1991)...

Impact events have shaped

the history of life on Earth.

They may have been responsible for some of 

the planet’s largest mass extinction events. 

Scientists realized that objects from space 

could pose a threat to our own future.

In 1994 humankind also got a reminder of 

the dangers that asteroids and comets could 

bring when Asteroid XM1 passed within 

65,000 miles of our planet. (18)

Tracking potentially dangerous

near-Earth objects (NEOs) also 

meant that we could identify 

the easiest ones to visit with 

robotic missions.

In 1996, NASA launched the 

Near Earth Asteroid Rendezvous 

(NEAR) mission.

The spacecraft passed the asteroid Mathilde (1997) en route to a

rendezvous with 433 Eros.

...and the asteroids

243 Ida (in 1993)...

(16)

(17)
16

NEAR flew within 2400 miles of 433 Eros in 

1998 and photographed two-thirds of its surface. On its first visit to the asteroid, NEAR 

failed to enter orbit, but it was successful on 

a second attempt in 2000.

Missions to asteroids and comets 

have also helped scientists test new 

technologies that can pave the way for 

larger missions. Deep Space 1 (1998) 

used an ion engine to leave Earth and 

rendezvous with the Asteroid Braille.

After flying within 16 miles of the asteroid, the

mission was extended and Deep Space 1 was able to

make a spectacular flyby of the comet 19P/Borrelly.

In 1999, while Deep 

Space 1 was making 

its observations, 

NASA launched the 

Stardust mission.

Stardust was NASA’s 

first mission to return 

comet samples. (20) After a passing visit to the 

asteroid Annefrank, Stardust 

arrived at its primary target, 

comet Wild 2, in 2004.

In fact, it was the first

sample return from space 

since Apollo.

After orbiting the asteroid, NEAR made a soft 

impact onto 433 Eros in 2001—and managed to 

send back data following its landing. (19)

Like comets, asteroids proved to have unique 

compositions—and could have carried many 

materials for life to the early Earth.
17

The first pictures that Stardust

returned were stunning.

Wild 2 had a much more dynamic

surface than expected... What Stardust did not

see were impact craters

on the surface of Wild 2.

Stardust opened its Aerogel Collector

Grid and began catching samples of

comet and interstellar dust.

Tiny particles impacted

the collector and were 

embedded in the Aerogel

material. Stardust then 

turned back toward Earth.

...with features like overhanging 

cliffs, flat-topped hills, and jets 

of gas escaping into space.

“What we saw, even in

the very first picture

sent back, was quite

dramatic.” (22)

“The lack of impact

craters indicates

the surface is new, the

old cratered surface is

gone.” (22)

(21)
18

When Stardust returned

home, its precious cargo of

cometary and interstellar

samples parachuted safely

to a nightime landing in a

muddy field in Utah.

Stardust yielded a plethora of amazing discoveries 

that have helped to refine our knowledge of how 

the Solar System formed and evolved.

With the discovery

glycine in the samples...

...Stardust also showed that comets 

could have delivered at least one 

amino acid to the early Earth.

Samples were sent to

more than 200 scientists

around the world.

“These comet

sample studies have provided

a direct look at the nature and

origin of the building blocks of

planets, materials that were sprayed

all over the young Solar System and

must have been incorporated

into all planets and

moons.” (22)

“Because most stars

have comets it suggests that

all Earth-like planets obtain

important pre-biotic molecules

from space.” (22)

Principal Investigator, 

Don Brownlee (University of Washington)
19

In 2002 NASA suffered 

a setback with the

Comet Nucleus Tour 

(CONTOUR) spacecraft.

CONTOUR launched into orbit, 

but was never heard from again.

As the impactor approached

Tempel 1, onboard cameras

captured images of the

comet nucleus.

Deep Impact was composed 

of two spacecraft, one of 

which was an ‘impactor’ 

roughly the size of a washing machine, made of 49% 

copper, and weighing 770 

pounds. (23)

On the 4th of July,

2005, the two spacecraft separated.

NASA had success with the launch of Deep 

Impact in 2005. Deep Impact was unique in that 

it was the first experiment to probe beneath the 

surface of a comet. (23)

“I’m trying to

solve the mystery of

what conditions were like

in the early Solar System,

how things got

made...”

“...My tools are comets

and asteroids.” (24)

Principal Investigator,

Michael F. A’Hearn

(25)
20

Twenty-four hours after separation,

travelling at 23,000 miles per hour, the 

impactor slammed into comet Tempel 1.

From 300 miles away, Deep Impact’s 

second ‘flyby’ spacecraft observed

the collision and studied the ejected

material that blasted from the crater.

Deep Impact yielded the first definitive 

evidence of water ice on a comet’s surface.

The mission increased our understanding 

of comets, from their compositions to 

their geological properties.

The story of Tempel

1 wasn’t over.

After Stardust returned its 

samples of Wild 2, the spacecraft 

cruised past the Earth and was 

redirected toward Tempel 1.

In a stunning extended mission (dubbed

‘Stardust-NExT’) the spacecraft showed

scientists how the Deep Impact experiment

had altered the comet’s surface. (28)

The collision provided clues about how we 

might be able to ‘deflect’ dangerous, Earthbound comets and asteroids in the future.

Stardust then performed a final 

engine burn in 2011. (28)

...were fixed upon Tempel

1 in an unprecedented

coordination campaign.

In addition, more than 

60 telescopes on Earth...

...and in space...

Submillimeter Wave

Astronomy Satellite.

Hubble Space

Telescope.

(26)

(27)
21

Deep Impact also continued 

to provide scientific data 

well beyond its primary 

mission timeline.

EPOXI is using the Deep 

Impact cameras to hunt for 

extrasolar planets, but the 

craft has also taken scientific 

observations of Mars, Earth...

After successfully observing 

the collision with comet Tempel 

1, Deep Impact was ‘reborn’ as 

the EPOXI mission.

...and the ‘hyperactive’, boneshaped 

comet Hartley 2.

With the early success of missions like Giotto, 

Europe continued to develop dedicated missions to these unique celestial bodies.

ESA’s Rosetta mission 

launched in 2004.

En route, Rosetta practiced its 

science observations by performing 

flybys of two asteroids in the Main 

Asteroid Belt, Steins and Lutetia.

Rosetta even used one of its cameras 

to solve a mystery surrounding the 

object P/2010 A2. Scientists once 

Rosetta had one of the most complicated thought this object was a comet...

trajectories of any mission to date, and 

includeed three gravity assists from 

Earth and one from Mars. (32)

Rosetta entered into orbit around the comet 

67P/ Churyumov-Gerasimenko in 2014.

...but viewing from its unique vantage 

point, Rosetta identified the object as the 

debris from a pair of colliding asteroids.

(30)

(31)

(33)

(29)
22

When Rosetta arrived at 67P/ChuryumovGerasimenko, the spacecraft mapped the 

surface of the comet from orbit.

Rosetta also delivered the Philae 

lander, which made the first-ever, 

albeit difficult, controlled landing 

on a comet. (34)

NASA’s Dawn mission

launched in 2007.

Ceres and Vesta are big asteroids—so large 

that they are considered ‘protoplanets.’

In the early days of the Solar System, these asteroids were building 

themselves from the same material 

as planets like Mars and Earth.

The primary goal of Dawn was to orbit 

Vesta, an asteroid in the Main Asteroid 

Belt, and then travel to a second, Ceres. 

However, they didn’t get 

quite big enough to become 

full-fledged planets.

Studying these large bodies will help

astrobiologists understand how rocky

planets like Earth came into existence.
23

We think the 

materials were 

delivered from 

space.

Back when the 

Solar System was 

rich in fine dust. Over time, the tiny, 

water-containing dust 

built up.

Unlike the Moon, 

areas with hydrated 

minerals on Vesta 

are not tied to 

sunlight! 

It’s a 

different process 

entirely, and might 

provide clues about the 

formation of planets 

like Earth.

(38)

Maria Cristina De Sanctis, 

Italian National Institute 

for Astrophysics

(35)

(36)

In August of 2011, Dawn became 

the first spacecraft to orbit an 

object in the main asteroid belt 

(Vesta). The mission returned 

surprising images of Vesta’s 

bizarre surface features. 

Suprisingly, Dawn found minerals that were 

hydrated, or have water incorporated into 

their crystaline structure. (37)
24

Curved gullies and fanshaped deposits in Cornelia 

might also be evidence of 

liquid water! (40)

We can’t definitively 

prove that they formed this 

way yet. Dry materials can also 

create similar shapes. But it 

goes to show...

...Vesta has features 

we never thought we’d 

see on such a small 

body!

And water 

could come from subsurface ice heated 

during impacts.

Just small 

amounts of water 

could mobilize sand 

and rocks!

Jennifer Scully, NASA JPL

Mark Sykes, Dawn Investigator, 

Planetary Science Institute

Vesta also showed signs of geological 

processes that we thought only happened 

on larger objects, like planets.

The water would have explosively gassed into 

space, leaving pot-hole-like structures. (39)

Cornelia crater had ‘pitted terrain’ 

inside of it. Heat from big impacts 

could have released the water 

from hydrated minerals.

After Vesta, Dawn flew on to Ceres. 

The spacecraft entered orbit of its 

second target on March 16, 2015.

Ceres brought surprises as well. Even 

from far away, bright white spots were 

seen dotting the dwarf planet’s surface.
25

(36)

*Origins-Spectral Interpretation Resource 

Identification-Security-Regolith Explorer.

Next up for NASA is the 

OSIRIS-REx* mission.

Studying numerous comets and 

asteroids has helped astrobiologists 

understand the incredible diversity 

of these small celestial bodies.

OSIRIS-REx will fly to the 

asteroid 1999 RQ36 and 

map its surface from orbit.

It’s also NASA’s first attempt to collect 

and return samples from an asteroid.

1999 RQ36 is of interest 

because it could be headed 

for Earth in the year 2182!

In a death-defying maneuver, 

a robotic arm will scoop up 

regolith from the surface.

Samples brought back to Earth will also 

help us determine the role of asteroids 

in life’s origins on our planet. (43, 44)

The spots might be salt 

deposits, but how they got 

there is unclear. (41, 42)

An impact could have dredged 

up a briny mixture of salt and 

water ice from the subsurface.

When the ice quickly sublimated away, salt deposits 

would have been left behind.
26

Earth is the only planet known to support 

life—but questions still remain about 

whether or not rocky planets like Mars 

could have been habitable in the past.

The smaller bodies—dwarf 

planets, asteroids, and 

comets—have shed light on 

the early Solar System, the 

formation of the planets, 

and the molecules that 

could have seeded life’s 

origins on the early Earth.

Gathering data on the rocky 

planets has allowed astrobiologists to compare their 

environments to Earth, 

providing clues about what 

makes our planet capable of 

supporting life.

Beyond the Main Asteroid Belt lie 

planets that are vastly different 

from the rocky bodies that orbit 

closer to the Sun. The outer Solar 

System is a realm of gas giants and 

frozen balls of ice and rock.

Pioneer 10, launched in 1972, was

the the first spacecraft to punch

through the asteroid belt, and

ushered in the exploration of our

solar system’s furthest and

darkest corners...

Next issue...

Missions to the Outer

Solar System!
27

Astrobiology

A History of Exobiology and Astrobiology at NASA

Further Resources and References cited in this issue:

1. Woese, C.R. 1979. A proposal concerning the origin of life on the planet earth. 

Journal of Molecular Evolution, Vol. 13, p. 95-101.

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