“The successful orbiting of Explorer I in 1958 is one of the landmarks in the technical and scientific history of the human race. Its instrumentation revealed the existence

of radiation belts of the Earth and opened up a massive new field of scientific exploration in space. It inspired an entire generation

of young men and women in the United States to higher achievement and propelled the Western world into the space age.”

— James A. Van Allen

EXPLORER 1

ww

w.n

asa.

gov

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

EX

PLO

RE

R 1

Expl

orer

1 w

as th

e fir

st U

.S. s

atel

lite

in

spac

e an

d th

e fir

st s

atel

lite

to c

arry

sci

ence

in

stru

men

ts. L

aunc

hed

on a

Jup

iter-C

ro

cket

from

Cap

e C

anav

eral

, Flo

rida,

on

Jan.

31,

195

8 by

the

U.S

. Arm

y Ba

llistic

M

issi

le A

genc

y un

der t

he d

irect

ion

of

Wer

nher

von

Bra

un, t

he s

atel

lite

was

de

sign

ed a

nd b

uilt

by th

e Je

t Pro

puls

ion

Labo

rato

ry in

less

than

thre

e m

onth

s.

The

sate

llite

carri

ed a

mic

rom

eteo

rite

dete

ctor

, tem

pera

ture

sen

sors

and

a

cosm

ic ra

y ex

perim

ent d

esig

ned

by J

ames

A.

Van

Alle

n of

the

Uni

vers

ity o

f Iow

a.

Rev

ealin

g a

muc

h lo

wer

cos

mic

ray

coun

t th

an e

xpec

ted,

Van

Alle

n th

eoriz

ed th

at

the

inst

rum

ent m

ay h

ave

been

sat

urat

ed

by v

ery

stro

ng ra

diat

ion

from

a b

elt o

f ch

arge

d pa

rticl

es tr

appe

d in

spa

ce b

y Ea

rth’s

mag

netic

fiel

d. T

he e

xist

ence

of

thes

e ra

diat

ion

belts

was

con

firm

ed b

y th

e la

unch

of E

xplo

rer 3

two

mon

ths

late

r, an

d th

ey b

ecam

e kn

own

as th

e Va

n Al

len

belts

in

hon

or o

f the

ir di

scov

erer

.

Expl

orer

1 u

sher

ed in

a n

ew u

nder

stan

ding

of

our

pla

net’s

inte

rcon

nect

ed s

yste

ms

thro

ugh

spac

e-ba

sed

obse

rvat

ions

and

in

spire

d de

cade

s of

ach

ieve

men

t in

Earth

an

d sp

ace

scie

nce.

Willi

am P

icke

ring,

Jam

es A

. Van

Alle

n an

d W

ernh

er v

on B

raun

(lef

t to

right

) hol

d up

a m

odel

of

the

Expl

orer

1 s

atel

lite

at a

pre

ss c

onfe

renc

e an

noun

cing

its

succ

essf

ul o

rbit.