Danandfoundhimselfgazingatthe
AuroraAustralisripplinginreds,
purplesandgreensacrossthepolar
sky.Thiswasin1958,ayearafter
theRussianslaunchedSputnikand
thesameyearNASAwasfounded.
O’Brienbegantodreamofputtinga
satelliteintoorbittostudyhow ener-
gisedprotonsandelectrons
gaverisetothesouth-
ernlights.Hegothis
chancethefollow-
ing year, when
James Van Al-
len,discoverer
oftheVanAllen
belts,gothima
jobattheUni-
versityofIowa.
O’Brienanda few
studentsbuilta sat-
elliteinfivemonths.
Otherlaunchesfollowed,
andin 1963 O’Brienwas
offeredapost inRice
University’snewspace
science department.
NOTLONGAFTER,hegota callfrom
NASA.Theagencyhopedtohire
himasanastronautinstructor,but
italsoinvitedhimtosubmita pro-
posalfora scienceexperimenttogo
tothemoon.Hesuggesteda device
- theChargedParticleLunarEnvi-
ronmentExperiment(CPLEE)– that
wouldmeasuretheenerg yspectra
ofchargedparticlesastheyrained
downonthelunarsurface. From a
fieldof 90 submissions,hiswasoneof
seventhatgotthegreenlight.NASA
toldhimthattheexperimentshould
includea dustcover.Nooneknewat
thisstagejusthowpeskymoondust
wouldbe,butO’Brienfiguredthatif
theagencywasgoingtothetroubleof
installingdustcovers,itshouldalso
includea dustdetector.
At first, NASA
baulked.Itwouldbe
toodifficult,they
believed,tocon-
structa detector
thatwas light
enoughtomeet
t h e m i s s i o n
specsandsim-
pleenoughthat
itwouldn’t take
upanyoftheastro-
nauts’limited time.
O’Briencameupwitha
designtoallaytheircon-
cerns– threetinysolar
cellsmountedona box,
paintedwhitetoref lect
sunlight.Asdustsettledonthecells,
theirpoweroutputwoulddrop,pro-
vidinga clearrecordofaccumulation
overtime.O’Brienthrewinafew
temperaturesensorsforgoodmeas-
ure,bringingtheexperiment’stotal
weightto 280 grams.Becausethe
DDEwassosmall,it couldbebolted
ontotheseismometerthatAldrinand
NeilArmstrongweresettingupto
measuremoonquakes.NASArelent-
ed: the DDE could go to the moon.O’Brienwithhis
Apollo 13 ChargedParticle
LunarEnvironment
Experiment (CPLEE)114 March 2020
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