Table Of ContentDeep Space Propulsion
K.F. Long
Deep Space Propulsion
A Roadmap to Interstellar Flight
K.F.LongBsc,Msc,CPhys
VicePresident(Europe),IcarusInterstellar
FellowBritishInterplanetarySociety
Berkshire,UK
ISBN978-1-4614-0606-8 e-ISBN978-1-4614-0607-5
DOI10.1007/978-1-4614-0607-5
SpringerNewYorkDordrechtHeidelbergLondon
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This book is dedicated to three people who
have had the biggest influence on my life.
My wife Gemma Long for your continued
love and companionship; my mentor
Jonathan Brooks for your guidance and
wisdom; my hero Sir Arthur C. Clarke
for your inspirational vision – for Rama,
2001, and the books you leave behind.
Foreword
We live in a time of troubles. It is easy to name a few of them: endless wars,
clashesofcultures,nuclearproliferation,overpopulation,globalclimatewarming,
economicrecession,politicaldisarray. Itisalsoeasytogiveupandconcludethat
allishopelessforourcivilizationandpossiblyforallhumanity.
However,issuchpessimismtrulywarranted?Theyear2010witnessedthefirst
reasonablysoliddetectionofpotentiallyhabitableworldscirclingnearbystars.Our
understanding of the variety of life forms that could inhabit these worlds has also
beenbroadened.
Perhaps more significantly, another milestone of 2010 was the first successful
flighttestofanon-rocketpropulsionsystemthatcouldsomedayevolveintoastar
drive.True–thesolarsailsthatmayevolvefromthesuccessfulinterplanetarytest
flight of the Japanese Ikaros probe will never achieve the performance of Star
Trek’smythicalEnterprise–buttheyrepresentastart.
Progresstowardscontrolledthermonuclearfusioncontinues.AndattheCERN
laboratory on the Italian-Swiss border, the Large Hadron Collider is now opera-
tional. It is not impossible that advances in our understanding of particle physics
promptedbyexperimentsatthisnewfacilitywillultimatelyleadtoourtamingof
theantimatter/matterannihilation.Maybesometheoreticalbreakthroughwillactu-
ally lead to a warp drive or a means of tapping the enormous energies of the
universalvacuum.
It is impossible to know which of these new technologies – sails, fusion, or
antimatter – will lead to the first human probes and ships capable of crossing the
interstellar gulfs. But if you are interested in participating in the adventure of
expanding the terrestrial biosphere into new realms, this book is an excellent
placetohoneyourskills.
The author is a major contributor to the British Interplanetary Society Project
Icarus, which is investigating near-term techniques that might lead to probes
capable of reaching our Sun’s nearest stellar neighbors. As well as reviewing the
current state of interstellar propulsion technologies, Kelvin Long provides an
extensive bibliography that will be an invaluable aid to the novice researcher.
vii
viii Foreword
Chapter exercises are also included so that young engineers and physicists can
practicetheirskills.
Historical discussions regarding the evolution of flight within and outside
Earth’s atmosphere will be of great interest to the casual reader. References to
science fiction demonstrate the significance of literature in inspiring much of the
scientific inquiry that has led us to the threshold of galactic citizenship. And the
colorplatespresentthebeautifulworkofspaceartistsandillustrators.
Onlyafewhumanshavefeltthecrunchoflunarsoilsbeneaththeirbootedfeet.
Asomewhatlargernumberhaveremotelycontrolledtheirrovingvehiclesasthey
crossthedesertsofMarsorcommunicatedwithVoyagerprobesnowonthefringe
ofgalacticspace.Inalllikelihood,onlyafewwillcontrolourinterstellarrobotsand
fewerstillwillridethegalactichighroadtoournextstellarhomes.Butthisbook
allowsmanytocontributetoandshareintheadventure.
Just maybe today’s interstellar pioneers will help stem the tide of pessimism.
Perhaps, just perhaps, books like this may help develop a welcome sense of
optimismandfeelingofhopeamongthereaders.
NewYorkCityCollegeofTechnology,CUNY Dr.GregMatloff
Preface
Twolightsforguidance.Thefirst,ourlittleglowingatomof
community,withallthatitsignifies.Thesecond,thecoldlight
ofthestars,symbolofhypercosmicalreality,withitscrystal
ecstasy.Strangethatinthislight,inwhicheventhedearestlove
isfrostilyassessed,andevenpossibledefeatofourhalf-waking
worldiscontemplatedwithoutremissionofpraise,thehuman
crisisdoesnotlosebutgainssignificance.Strange,thatitseems
more,notless,urgenttoplaysomepartinthisstruggle,this
briefeffortofanimalculesstrivingtowinfortheirracesome
increaseofluciditybeforetheultimatedarkness.
OlafStapledon
This book is about robotic exploration of the nearby stars and the prospects for
achievingthiswithinthenextcentury.Inparticular,wewillfocusonthepropulsion
technology that will be used to accomplish such an ambitious objective. This is
so called ‘game changing’ technology that goes beyond conventional chemical
rockets, using exotic fuels and more efficient engines for the purpose of an
interstellar mission. This includes ideas for engines based upon harnessing the
emittedenergyoftheSun,usingfusionreactionsoreventappingtheenergyrelease
from matter-antimatter annihilation reactions. This book serves as an essential
primerfor anyone new tothis field who wishes to become familiar with the ideas
thathavealreadybeendevelopedandhowtoattainthenecessarytheoreticaltools
tocreatesimilarideasforthemselves.If,bytheendofthisbook,youarethinkingof
your own ideas for how machines can be propelled across the vastness of space,
thenthisbookwillhavebeensuccessfulinitsultimateaim.
Atthedawnofthisnewmillenniumwecan lookback ontheprevious century
with pride, knowing that humanity took its first steps into space and even walked
upon the surface of the Moon. We have collected a wealth of data on the many
planets and moons of our Solar System, and our robotic ambassadors are still
pioneering the way so that one day humans may hope to follow where they lead.
TheMoonandMarsarethecurrentfocusofhumanambitionsinspace,andthisis
ix
x Preface
rightfortheshort-termgoalsofourspecies.Butinthelongterm,missionstoplaces
muchfurtherawaywillbecomenotjustaspirationsbutvitaltooursurvival.
From the outset of thistext, we must betruthfulandadmitthat the technology
toenable human transporttootherstarsis currently immature.Thephysics,engi-
neeringandphysiologicalrequirementsareunlikeanythingwehaveeverencoun-
tered,andthisuniqueproblemdemandsourfullattentionifwearetoevercrossthe
enormous gulfs of space that separate the stars in our galaxy and become a truly
spacefaringcivilization. But if we are bold andeventually attemptthis, the scien-
tific,economicandspiritualrewardswillbemany,andourcivilizationwillbecome
enriched for the attempt. Until then, we must be content with robotic exploration
and to push that technology to its limit. We must continue to launch missions to
theouterplanetsofourSolarSystemtoexplorethosecoldbutinterestingworlds.
Eventually, our robotic probes will break through the termination shock of the
solar heliosphere and pass out into the Kuiper Belt to explore many strange new
dwarf planets, some perhaps yet undiscovered. Then they will be sent to much
further distances out into the Oort Cloud to investigate the myriad of comets that
orbit our Solar System in large period trajectories. Finally those same robots will
entertheouterreachesoftheinterstellarmedium,thediffusenebulaofspacethatis
dispersedbetweenthestars,andforthefirsttimeinhistoryahumanmademachine
wouldhavefullyleftthegravitationalcradleofourSun.
Bythistime,thetechnologyperformanceofourmachinesshouldhaveimproved
by many orders of magnitude so that missions to the nearest stars will become
possible and scientific data return will become common. What will those probes
discover?Perhapsunusualplanetswithoceansmadeofmaterialsthoughtimpossi-
blewherelifemightbeswimmingamongitsdepths.Theastronomicalknowledge
gained will be highly valuable; the chance to be so close to another star and its
orbiting worlds will enrich our knowledge of the universe and give us a better
understandingofitsstructure,evolutionandorigin.
Afew momentsspent thinking about the interstellar transportproblem quickly
leadstotherealizationthattherearetwomainextremestoreachingthestars.We
canbuildverylightweightvehicleswithalimitedpayloadsizeinthehopethattheir
smallmassallowsforlargespeeds,suchasasolarsail.Alternatively,wecanbuild
massivevehiclesthesizeofsmallmoons,whichwillmoveslowlyandtakeperhaps
thousands of years to reach their destination; these are so called world ships. For
any form of human exodus to another world, clearly the latter option is the only
credibleapproach.However,asonedigsintotheinterstellarliteraturewefindthat
thereareapproachestothisproblemthatlaybetweenthesetwoextremes.Wefind
that physicists have invented clever theoretical (and some practical) means of
allowing a large mass scientific payload to be delivered to a destination at a
speed of a few to tens of percent of light speed, thus getting to the target within
decades. It is then just a matter of the engineering technology progressing to an
acceptablereadinesslevel.Manyoftheseschemesarediscussedinthisbook.
In reading this book it will be clear that the author favors the nuclear pulse
propulsionapproachforinterstellarmissions.Thisisalongthelinesofthehistorical
OrionandDaedalusconcepts.Itshouldbenotedthatthisisnotbecauseofabelief
