PRINCIPIUM

™

INS

TI T

UT E

F OR I N T E R

ST

ELLA

R

S T U D I E S

The Newsletter of the Institute for Interstellar Studies™

Letter from the Director

News from the Institute

‘Advances’

Cubesats

Retrospective: Daedalus

Book Reviews

www.I4IS.orgScientia ad sidera

Knowledge to the Stars

Principium | Issue 1 | December 2012 Page 2

Dear friends,

We live in exciting times. In recent yearsmany planets have been detected orbitingaround other stars. This is helping us torealise that there are places to go, aspredicted in the many works of sciencefiction over the last century. In addition,we are now witnessing the emergence ofthe commercial space sector and spacetourism. This gives us hope and optimismthat despite the challenges we face downhere on Earth, better times lay ahead forour space-aspiring society. A keycomponent of this is learning how to worktogether in a spirit of co-operation andfriendship and this is precisely whatinterstellar societies tend to encourage.With optimism, hope and an inspirationalvision, we can reach those distant stars.

The oldest interstellar society today isthe London-based British InterplanetarySociety (BIS), founded in 1933 and fastapproaching its 80th anniversary.Although it examines the broad issuesassociated with robotic and humanspaceflight, interstellar has always been acore component of its work, with studieslike Project Daedalus in the 1970s and thefamous ‘red cover’ issues of the Journal ofthe BIS that were published between 1974and 1991. These considered subjects suchas the design of World Ships, interstellarprecursor missions and the prospect forintelligent life in the Universe. The BIShas been the torch-holder for theinterstellar vision for many decades.

In the last few years many others havedecided to address the interstellarproblem, by the formation oforganisations or societies. This includesVision 21, PI Club, the InterstellarPropulsion Society, the Tau ZeroFoundation, Icarus Interstellar and 100Year Starship. The latest entry into thisgroup is the Institute for InterstellarStudies™. Our main focus is the nurturingof people through our educationalacademy and the fostering of starship-related research and development.

I am proud to have been the originatorof this organisation and I am deeplyhonoured that many others have shared inthat vision and are actively assisting withits foundation. My colleagues and I willwork to make the Institute a success in thecoming years. This excellent newsletterrepresents our first publications outreachactivity, other than the Institute blogpage. In time we hope this newsletter willserve as an exciting information source forthe community. I want to personally thankKeith Cooper for taking on this role ofEditor and Adrian Mann for assisting withthe editorial graphics and production. Ihope you enjoy this first issue ofPrincipium and keep an eye on theInstitute’s website as we graduallyannounce more activities in the comingmonths.  Scientia ad sidera.

Kelvin F. Long

Executive DirectorThe Institute for Interstellar Studies™

A letter from Kelvin F. Long

Principium | Issue 1 | December 2012 Page 3

I4IS blasts off!The Institute for Interstellar Studies™(I4IS) was launched on 14 September2012. Founded in the United Kingdom,it ultimately aims to have a globaloutreach. Executive Director KelvinLong says, “I am very excited about thisopportunity, for which the time has nowcome. Many have worked towards thefulfillment of an interstellar vision overthe past decades, and it is hoped that theinstitute will pull the communitytogether behind a common purpose anda bold enterprise.”

Learn more in Kelvin’s introduction to this issue on page 2.

Spaced-upDr Chris Welch, the deputy chair for I4IS’Senior Advisory Council, gave apresentation about the Institute to theSpaceUp ‘unconference’ (whereparticipants decide the agenda) inStuttgart in September. Introducing theInstitute for the packed audience, hedescribed I4IS as “a nexus for theactivities related to the challenges ofachieving robotic and human interstellarflight.” He recounted the BritishInterplanetary Society’s Daedalus project(see elsewhere this issue) and how I4ISplans to build on that work by seeking toconduct credible research into the scienceand technology of starships, ultimatelyprogressing towards a capable andconfident human species in interplanetaryspace, with benefits for life back hometoo. Welch also gave special mention tothe prospect of the I4IS Academy(directed by Rob Swinney), which will seestudents takes MSc projects with theInstitute through the International SpaceUniversity near Strasbourg.

The first four students to have signedup to the projects are investigating topicsas varied as designing interstellar probes;learning how to decelerate an interstellarprobe from a tenth of the speed of light asit approaches its destination star; andexploring agricultural techniques for adeep space microgravity environment,perhaps in a space station or a worldship,populated by a thousand people.

On the road to the starsThe I4IS held its inaugural planning andprogress meeting in the fitting setting ofthe British Library in London on 29September 2012. Discussing everythingfrom the Institute’s priorities during thecoming years to Institute-led projects andrevenue generation, the conversationsduring the workshop were abuzz withgreat ideas and a tremendous amount ofhope for the future.

I4IS members present included KelvinLong, Rob Swinney, Jeremy Clark,Jonathan Brooks, Richard Osborne,Stephen Ashworth and Keith Cooper.Look out for some of the things theInstitute has planned coming over thenext twelve months – the road to the starsstarts here!

Creating an interplanetarycivilisationI4IS team-member Stephen Ashworth hasdetailed his path for society to become aninterstellar civilisation. Inspired by aposting on the Centauri Dreams website,he describes on his blog a “creativecommunity of public and privateinstitutions acting in concert... and a setof new technologies which both multiplywealth and introduce new problems.”From thereon he describes a 14-pointscenario, starting with governmentexploration of low-Earth orbit and thefoundation of outposts there (alreadyachieved) followed by the onset of spacetourism and private space enterprises thatwe are seeing today, leading to solar powersatellites to energise the burgeoninginterplanetary civilisation that couldembark on new Moon missions and alunar colony by 2050, Mars and Venus by2080 and bonafide colonies on or in orbitaround numerous planets by thebeginning of the 22nd century. By thebeginning of the 23rd century theinterplanetary economy could have grownby ten billion compared to today’seconomy, writes Ashworth, with asteroidmining in particular contributing to it andmost of our descendants living in space.

Do you agree with Stephen Ashworth'sroadmap? write to us and tell us yourvisions of the future.

News from the Institute

Dr Chris Welch introduces the Institutefor Interstellar Studies at the SpaceUp‘unconference’ in September.

I4IS members, with Executive DirectorKelvin Long on the left, discussinterstellar matters at the British Library.

To keep up to date with the latest I4IS news, check out the Starship Log on the Institute’s Interstellar Index

http://www.interstellarindex.com/ blog/

or follow the Institute on Facebookhttp://www.facebook.com/InterstellarInstitute

and LinkedInhttp://www.linkedin.com/groups?home&gid=4640147&trk=anet_ug_hm

Principium | Issue 1 | December 2012 Page 4

Could we warp space to ourwill, reducing interstellar traveltimes to just weeks ratherthan years? It seemsfantastical, but a newexperiment may just be theturning point needed totransform fantasy into reality.

A laboratory experiment to testwhether space can be artificially ‘warped’,potentially leading to a ‘warp drive’ forstarships, has been designed by Dr Harold‘Sonny’ White and his team at theadvanced Eagleworks Labs at NASA’sJohnson Space Center in Houston.

When limited to conventional physics,interstellar travel is really going to be agame for the patient explorers amongstus. Chemical rockets and gravitationalslingshots would propel probes oninterstellar journeys that take tens tohundreds of thousands of years. Even themighty blast of a fusion-powered enginelike Daedalus’ (see Page 9 for more) wouldstill lead to journeys lasting decades orcenturies. Those are realisticexpectations, but science fiction has givenus the dream of travelling from star tostar in a few weeks. Such dreams can behard to shake.

Albert Einstein showed that nothingcan travel faster-than-light through space– but relativity doesn’t rule out space itselfmoving at incredibly fast speeds. We’rewitnessing it today – dark energy iscausing the expansion of the Universe toaccelerate faster than the speed of light.In the very first fractions of a second afterthe big bang, the Universe experiencedanother burst of runaway growth thanksto inflation. In 1994, influenced by thescience behind inflation, physicist MiguelAlcubierre, who was at Cardiff Universityat the time and today is at the NationalAutonomous University of Mexico,derived solutions to Einstein’s GeneralTheory of Relativity that suggested it waspossible to warp space for very rapid andperhaps near instantaneous travel across

the Universe. There was only onedrawback: you would have to convert everyatom in the visible Universe into pureenergy to obtain the required power.

Less energy to warp spaceIt seemed like the dream of faster-

than-light travel had died. Inflation, darkenergy, the entire rest-mass energy of thevisible Universe – these are forces ofnature wildly bigger than anything we cancontrol but since 1994 there has been adetermined downsizing effort going on. Byrevisiting Alcubierre’s calculations,successive physicists have been able totwiddle with the initial conditions of theequations and reduce the amount ofenergy required, first down to the mass-energy of a galaxy, then a star and a gasgiant planet. Now White has reduced theenergy requirements to an amount that,at first glance, seems eminentlyobtainable: about 500 kilograms, the massof the small family car that you drove towork this morning.

What would that energy do? Imagineyou have a starship moving away fromEarth under conventional propulsion atsome sub-light speed – call it impulsepower. Then the starship uses the energyto activate its warp engine to create a‘bubble’ of warped space around it. Insidethe bubble, everything is normal, with

space-time flat. The bubble, however,causes space in front of the craft tocontract, in essence pulling the targetdestination towards it. Behind the vesselthe bubble allows space-time to relax andexpand again, giving the starship a boostof many orders of magnitude in thedirection the craft had been moving underimpulse power. It’s like a rug being pulledunderneath you or, as physicist Eric Davisat the Institute of Advanced Studies atAustin, Texas describes it, surfing on awave of space-time where the wave isdoing the work, not the surfer. So a warpbubble could turn a velocity of a tenth thespeed of light into ten times the speed oflight, making a journey to alpha Centauri4.3 light years away last a mere 0.43 years,or just over five months.

The reduction in the required energyfrom the days of Alcubierre is a result oftoying with the thickness of the warpbubble. The thicker this bubble is, thelower the energy density required,although this reduces the volume insidethe bubble and the optimum trade-offbetween volume and bubble thickness hasyet to be determined. However, before weget too excited, there are some quiteformidable obstacles to overcome, notleast the energy requirements. Althoughthe mass-energy of a car doesn’t sound toobad, in real terms it amounts to 1019

Ahead Warp Factor One!ADVANCES

Could a warp drive enable faster-than-light travel? Image: NASA.

Principium | Issue 1 | December 2012 Page 5

joules, which is almost equivalent to theannual energy expenditure of the UnitedStates. However, a civilisation that uses allavailable energy falling onto its planetfrom the Sun, boosted perhaps withwidespread use of fusion reactors, wouldfind such an amount of energy to be muchmore realistic.

More problematic is the type of energy,and this is why we describe warp drive asunconventional physics – the warp bubbleonly works if negative mass and energy,produced by some exotic form of matter, isused. We have experienced negativeenergy both cosmologically, in the shape ofinflation and dark energy, and closer tohome in the Casimir Effect (the slightrepulsive force created as a result ofvacuum energy – produced by virtualparticles popping in and out of existencethanks to the uncertainty principle ofquantum mechanics – between two metalplates marginally separated). Butaccessing large quantities of negativeenergy, storing it and then utilising it areall currently problems without answers.

Lab experimentsNevertheless, White has come up with

a way to test his theories in the lab. He’sdesigned an experiment called theWhite Juday Warp Field Interferometerthat will use a helium-neon laser todetect an artificially-created warping ofspace across a diameter merely onecentimetre across. The interferometerwill be able to detect a perturbation inspace-time as small as one ten-millionthof a centimetre by monitoring the timingof the laser reflecting off mirrors andpassing through the warped space. If thewarp bubble created in the experimentwere around a spacecraft, it would boostits velocity by 1.0000001 times.

The beauty of a warp drive, if it couldwork, is that there would be no relativistic

effects – no time dilation or lengthcontraction. Inside the bubble the starshipwould experience the same frame ofreference as we do here on Earth (or atleast one close to it if the starship werealready moving at a small fraction of thespeed of light before engaging the warpbubble). Astronauts would not venture offto the stars and return only to find thatcenturies or perhaps millennia havepassed on Earth as the soldiers in JoeHaldeman’s novel The Forever Warexperienced. Instead they could returnhome to find their loved ones have barelyaged at all.

It’s still early days and nothing has yetbeen proven in the laboratory; somephysicists are sceptical that Alcubierre’ssolutions would even work in real life. Yetif the solutions do work and if the hugeproblem of the large quantities of exoticnegative energy can be solved, perhaps ourprivate fantasies of a Star Trek future canbe achieved after all.

It’s like a rug being pulledunderneath you, or a surfer on a waveof space-time where the wave is doingthe work, not the surfer.

News from alpha CentauriNews of the nearest exoplanetto home has raised the stakesamong hunters of alien worlds.Have starship, will travel – but to where?The destination for our intendedinterstellar craft is going to be a crucialpiece of the jigsaw – too far away and wewon’t be able to get there, too inhospitableand there will be little to attract us. A potentially habitable planet orbiting oneof the Sun-like stars in the alpha Centaurisystem, the closest to our Sun at a ‘mere’4.3 light years distant, would by theculmination of two decades of exoplanet-hunting and now a new discovery takes uspart of the way there; a planet, slightlymore massive than Earth, orbiting thestar alpha Centauri B.

“There’s not been a more excitingresult for an individual star, even with thelong line of spectacular results from thelast two decades,” says Professor DebraFischer of Yale University. “The indicationthat our nearest neighbour has rockyplanets is incredible!”

Fischer leads a team that has beenhunting for planets around alphaCentauri for several years, but her group

An artist’s impression of the alpha Centauri system. Alpha Centauri B and its attendantplanet are in the foreground, with alpha Centauri A to the lower left and our Sun abright star in the upper right, 4.3 light years away. Image: ESO/L Calçada/N Risinger (skysurvey.org).

Principium | Issue 1 | December 2012 Page 6

were beaten to the discovery by Europeanastronomers mostly based at GenevaObservatory using the HARPS (HighAccuracy Radial velocity Planet Searcher)instrument fitted on the 3.6-metretelescope at the European SouthernObservatory in Chile, which has pushedour exoplanet detection abilities to thelimit. HARPS is a spectrometer that isable to detect slight ‘wobbles’ in the starcaused by the gravitational perturbationsof accompanying planets. In the case ofalpha Centauri Bb, as the new planet isknown, the wobble it induces in its parentstar amounts to a movement of no morethan 51 centimetres.

Lava oceansAlpha Centauri Bb orbits its star at adistance of just 5.98 million kilometres –close enough to fall into gravitational stepwith its sun and become tidally locked sothat it always shows the same face to itsstar. Consequently there is no hope foroceans of water; the dayside will bear thebrunt of the star’s heat, its surface meltingin temperatures up to 1,220 degreesCelsius. Rather, oceans of lava will be theorder of the day. Such worlds, where themolten surface evaporates to form a thinsilicate atmosphere, or exosphere, havebeen found by the Kepler space mission to

be common, points out Professor GregLaughlin of the University of California,Santa Cruz.

“There is nothing unusual about thisplanet,” he says. “Around fifty percent ofthe stars in the solar neighbourhood haveclose planets smaller than Jupiter so, nooffense to the Geneva team, but thisplanet is completely run of the mill!”

So why does it excite those of us whoshare an interstellar vision? It’s not theplanet itself, but what its presencepotentially promises. “It turns out thatmost of the low mass planets are insystems of two, three or more planets, allthe way out to the habitable zones,” saysStephane Udry of Geneva Observatory.“So there is a very large probability thatthere are more planets around alphaCentauri B.”

Reasons to goIf indeed more planets exist, possibly inthe habitable zone, alpha Centauribecomes a hugely attractive destination.“If a potentially habitable planet is foundwe might see a groundswell of excitementto look towards new propulsiontechnologies that can get a probe therewithin a human lifetime,” says Laughlin.

“It’s twice as easy to get there than other stars.”

In our neighbourhood of the Galaxystars are, on average, distributed four lightyears from one another, but most of thosestars are cool red dwarfs or dim, drearybrown dwarfs. It is quite unusual for twoSun-like stars to be so close – and in thealpha Centauri system we have the bonusof two Sun-like stars.

“The odds that we would have such anextraordinary star so close to us is one in athousand,” says Laughlin. “A million years ago alpha Centauri was far away and not visible; in another million years it will have passed by. Right now is itsclosest approach.”

Naturally any potentially habitableworlds will also be of interest to SETI, the Search for ExtraterrestrialIntelligence. “At just four light years away a technological civilisation, if itexisted, would be watching recent newsfrom Earth,” says Fischer. So as wewatched President Obama being re-elected, denizens of Alpha Centauri wouldbe witnessing the run-up to his triumph in 2008, and watching Spain beat allbefore them in the UEFA EuropeanFootball Championships.

A possible planet, seven times moremassive than Earth, has been foundsitting smack-bang in the habitable zoneof a star 42 light years away. The system,HD 40307, is home to six planets, allrocky ‘super-earths’, but it is planet g thathas captured the imagination the most.Discovered through re-analysis of datafrom the world’s greatest radial velocityplanet detector – the HARPS instrumentat the European Southern Observatory inChile – by a team led by Mikko Tuomi ofthe University of Hertfordshire, 40307gorbits its orange K-class star (which iscooler than the Sun) every 198 days at anaverage distance of 90 million kilometres,or about 0.6 astronomical units (whereone astronomical unit is the meandistance from the Sun to Earth, 149.6.million kilometres). Althoughunconfirmed at present until otherastronomers are able to detect itindependently, if it does exist it may bethe closest thing to Earth found so far.

The star’s habitable zone existsbetween 0.43 and 0.85 astronomical unitsand planet 40307g will receive 62 percent

of the solar heating that Earth receivesfrom the Sun. In order to be potentiallyhabitable, it will need an atmospherethicker than Earth’s to trap the heat, butsuch a massive planet (the surface gravitywould be almost twice that of Earth)should have no problem retaining athicker atmosphere to ensuretemperatures appropriate for liquidwater. The main problem may be that the

planet is too massive – recent work byMIT’s Vlada Stamenkovic indicates thatsuch super-earths could possess interiorsthat have not separated into a core andmantle, therefore ruling out protectivemagnetic fields created by a dynamoeffect within the planet, and the churningof continents through plate tectonics thatis vital for recycling carbon andregulating planetary temperature.

All the potentially habitable exoplanets discovered thus far, compared to Earth andMars. Image: PHL@UPR Arecibo.

Second Earth?

Principium | Issue 1 | December 2012 Page 7

Spectroscopic SETIDuring our interstellar travels it is

feasible that we’ll bump into otherintelligent species out there, but perhapswe will have discovered their existencebeforehand. One way to do this could beto detect signals from them, perhaps inthe form of powerful laser pulses.Currently, unlike searches for radiosignals from extraterrestrialcivilisations in the form of all-skysurveys, optical searches for lasers haveto take the slow road, going from star tostar. Now Ermanno Borra of UniversitéLaval, Québec, might have a solution.He points out that a pulsating lasersource modulating its frequency overperiodic time periods as small as 10–10 to10–15 seconds would be detectable asfrequency shifts in astronomical spectra,of the kind routinely taken by all-skyspectroscopic surveys of stars such as theSloan Digital Sky Survey in New Mexico.These surveys produce huge amounts ofdata, much of it barely analysed, whichscientists could sift through searching foranomalous frequency patterns thatmight be indicative of an alien callingcard. Borra’s report is published in theAstronomical Journal and a pre-print canbe found here:

http://arxiv.org/abs/1210.5986v1

The 2.5-metre telescope of the Sloan Digital Sky Survey (SDSS) at Apache Point inNew Mexico could theoretically discover laser signals from intelligent extraterrestrialsduring its all-sky spectroscopic surveys designed primarily to measure the redshiftand hence distance of galaxies and stars. Image: Fermilab Visual Media Service.

The billion-year planMaybe the century-long outlook of I4ISand other interstellar groups is too short?Writing on the website KurzweilAI.net,Lt Col Peter Garretson, Chief of FutureScience and Technology Exploration forthe United States Air Force, believes weshould start planning now for the farfuture and the billions and trillions ofyears to come.

“It isn’t enough just to plan for two or20, or even the fabled Chinese 100 yearperiods,” he writes. “We need to bethinking and planning on the order ofbillions of years. Our civilisation needsinter-generational plans and goals thatspan as far out as we can forecastsignificant events.”

The first of those events include theuninhabitability of Earth within a billionyears as the Sun warms. Garretsonproposes that we build giant O’Neillcolonies (named after the NASAastrophysicist Gerard O’Neill whopopularised the idea in the 1970s in hisbook, The High Frontier) from material

in the Asteroid Belt that couldpotentially become home to 100 trillionhumans. However, it’s a more pressingrace against time than it at first glanceappears – with just a few hundred yearsof natural resources remaining on Earth,and other looming crises such as theenvironment or war, we need to develop aspace programme based around the long-term survival of humanity now, before itis too late.

Even the Sun won’t last forever, withGarretson recognising the need forinterstellar colonisation – the further wespread ourselves, the greater theprobability that some will survive. He even speculates towards the end ofthe Universe, when the stars go out,atoms decay and the black holesthemselves begin to evaporate, leavingone possible door open to us – thecreation of new, baby universes intowhich we could escape.

You can read the full article athttp://www.kurzweilai.net/what-our-

civilization-needs-is-a-billion-year-plan

When the Sun goes out and expandsinto a red giant before billowing awayinto a planetary nebula some fivebillion years into the future, such as theHelix Nebula pictured here, humanitywill have to move on to other stars tosurvive. Image: NASA/ESA/C R Dell(Vanderbilt University)/ M Meixner/PMcCullough.

Principium | Issue 1 | December 2012 Page 8

Tiny cube-shaped satellitesweighing just a kilogram aremaking space explorationaffordable and they mayultimately provide the firstprecursor missions for whatwill eventually be a voyage toanother star system.

Big dreams start small. The first spacemission that the Institute for InterstellarStudies™ will launch won’t be a fusion-powered starship to Fomalhaut; it won’tbe a graceful solar sail to Sirius; it won’teven be an automated probe to alphaCentauri. In fact, the Institute’s firstmission won’t even reach beyond Earth orbit or be larger than a few bags of sugar.

Project CATSTAR is the Institute’sprogramme to launch a cubesat, which aresmall satellites built from off-the-shelfelectronic components, no larger than 10centimetres cubed and sometimes stackedin twos or threes, piggybacking on rocketlaunches delivering other satellites intospace to keep launch costs down. The ideais to use the cubesats – built by Institutescientists, engineers and team-members –to test new technologies necessary tobegin building the foundations of aninterstellar craft and, by doing so,increasing what is termed theirTechnological Readiness Level (TRL).

Get readyThe TRL is a measure of how advanced

a specific technology is. An ion drive, forinstance, has the highest TRL rating ofnine, implying it has been fully tested onsuccessful missions, such as the EuropeanSpace Agency’s SMART-1 mission to theMoon or, more recently, NASA’sextraordinarily successful Dawn missionto the asteroids Vesta and, in 2015, Ceres.Solar sails have a TRL of eight, indicatingthey have been flight tested but not put towork on any real missions yet. At the other

end of the scale a fusion-based propulsionsystem only rates a two and a warp drive,where not even the theory is nailed down,has a TRL of one. The only way we canincrease their TRL is by testing,experimenting and optimising them foruse in future missions and, perhaps oneday, an interstellar voyage.

That’s where cubesats come in. Wemight not be able to test an antimatterdrive in a cubesat, but we can test solarsails for example – NASA’s NanoSail-D2mission in 2010 utilised a cubesat-likesatellite from which unfurled a ten-metresquare sail made from kapton film justtwo microns thick. There are also other,less dramatic, applications, from testingradiation shielding, communicationssystems and software, or even used as atelescope for detecting transitingexoplanets as in the case of MIT’sExoplanetSat launching some time in thenext 12 months.

Mission trainingCubesats had a modest beginning.

Initially developed by Jordi Puig-Suari atthe California Institute of Technology andBob Twiggs at Stanford University in thelate 1990s, they were intended as trainingplatforms to give students the opportunityto practice building, testing and operatinglow-cost spacecraft. A single cubesat canset you back as little as £50,000 and eventhe most expensive rarely top a quarter of

a million pounds. Basically launching acubesat is like sending a bag of sugar intospace – similar size, same mass – exceptthat the cubesats can be combined intoconfigurations of two or three ‘units’, or2U or 3U in the shorthand notation of thegrowing cubesat community.

The first cubesat to reach orbitlaunched on a Russian Soyuz rocket inJune 2003 and since then another 74 havefollowed it into space. Far from thetraining exercises they were envisaged as, scientists are now using them as low-budget options for their research. The first British cubesat, a 3Uconfiguration called UKube-1, will carryfive experiments including one todemonstrate the feasibility of using cosmicray hits to generate random numbers thatcan be used to secure communicationlinks. It will blast off on a Soyuz rocket inMarch 2013.

Project CATSTAR seeks to takecubesat technology and apply it todeveloping the science for interstellartravel, but there is no need to rush.Cubesats fall into the natural scheme ofscience and engineering, coming aftertheory, table-top experimentation andfully-fledged ground demonstrations. If a cubesat mission is successful the nextstep is to utilise the technology in aprecursor missions to the other planets inthe Solar System or perhaps to the outerboundary of the Sun’s influence in thedistant Oort Cloud of icy cometarybodies. From there it is but a giant leapfor a real mission to the stars. From small seeds do great things growand, if the first interstellar missions do carry technology that was initiallytested in diminutive cubesats, it will be symbolic of our growth from small scale space missions to conqueringinterstellar distances.

THE GREAT CUBESAT REVOLUTION

NASA’s NanoSail-D2 cubesat was atestbed for solar sail technology thatone day may aid the voyage of aninterstellar craft. Image: NASA.

Three small CubeSats are deployedfrom the International Space Station on4 October, 2012. Image: NASA

Principium | Issue 1 | December 2012 Page 9

The greatest starship designisn’t the Enterprise or a StarDestroyer, but Daedalus – areal attempt at creating ablueprint for a vessel thatcould travel to one of thenearest stars and beyond at 12percent the speed of light.

We at the Institute for InterstellarStudies™ fiercely believe that starshipbuilding will be a major part of the futureof humankind, but what many may notrealise is that to reach the future much ofour inspiration is going to come from thepast. For in the 1970s, members of theBritish Interplanetary Societyaccomplished something that had neverbefore been achieved, somethingrevolutionary: the design of a starship.

Interstellar dreamsIt was 1973 and the promised land of

regular spaceflight throughout the SolarSystem and the untold riches that it couldbring were still in sight. Apollo had endeda year previous, with the United Statesembroiled in a war it could ill afford, butthe talk was of more ambitious missions:permanent space stations, colonies on theMoon and flights to Mars. Such talk led todreams of how far we humans could go.

Dreams, however, are not particularlyscientific. Led by Alan Bond, a group ofskilled enthusiasts sought to remedy this.Science fiction, from the popcorn GoldenAge classics of E E ‘Doc’ Smith to themore refined ‘hard’ SF of Arthur C Clarkeor Isaac Asimov, regularly portrayedinterstellar travel as a natural progressionof human ingenuity, but was it reallypossible to go galavanting around theGalaxy like Captain Kirk? Moreover, theanswer would solve some riddles about ourown future and the apparent absence ofextraterrestrial life in the Galaxy; ifinterstellar travel was inordinately hard,we could not reasonably have expectedaliens to have reached our planet, neatlyanswering the puzzle of why we see noevidence of intelligent extraterrestriallife close to Earth. On the other hand, ifinterstellar flight was achievable, it couldraise more concerns about whereeverybody is.

And so Project Daedalus was born: afive-year study to produce a solid, scientificdesign for an interstellar craft, bringingthe dreams of SF into the realm of hardcalculations using 1970s technology ornear-future tech, extrapolated from wherescience and engineering was at in 1973.Beyond this the only other requirementfor any mission launched based on the

Daedalus blueprints was for it to becompleted within the working lifetime of a mission scientist. To these ends,Daedalus was designed to keep thingssimple, with an unmanned probe thatwould accelerate to 12 percent of thespeed of light, whizzing past its targetdestination (Barnard’s Star) and returningdata to Earth.

Fusion power to the starsNuclear fusion was the power system of

choice for the spacecraft in the 1970s andeven today, when interstellar spacecraftdesigns are discussed, fusion propulsion isoften top of the list. Daedalus was to carryten tanks of tiny pellets composed ofdeuterium and helium-3, around 54,000tons in total, equating to a total of 30billion pellets. When bombarded withelectron beams these pellets wouldundergo nuclear fusion, producing energy,helium-4 and protons that would bedirected by magnetic nozzles out throughthe engine to provide thrust. By igniting250 pellets per second Daedalus wouldproduce 1013 watts – around onemegajoule per pulse – to power thestarship out of the Solar System.

The tank layout is a vital part ofDaedalus’ design. Like the Saturn V or thespace shuttle’s external tank and solidrocket boosters, Daedalus would be amulti-stage system. Six tanks, in totalcarrying 50,000 tons of pellets, would formthe first stage, with two tanks droppingaway after 250 days of powered flight,having reached a distance of 0.0039 lightyears from the Solar System. Another tankis left behind at 0.0178 light years, anotherat 0.0503 light years and then just overtwo years into the mission the entire firststage is discarded into interstellar space,having driven the starship up to sevenpercent of the speed of light. Without theredundant mass of the first stage and itsempty tanks, the 4,000 tons of propellantin the second stage doesn’t have to work ashard, burning for 320 additional days,ending three years after leaving the SolarSystem at a distance of 0.21 light years.Daedalus would then continue the rest ofthe way coasting at 12.2 percent of thespeed of light (36,500 kilometres persecond) for around 46 years. There is no

Retrospective: Project Daedalus

An unmanned probe that wouldaccelerate to 12 percent of the speed of light, whizzing past Barnard’s Star.

Principium | Issue 1 | December 2012 Page 10

reason why the starship could not haveeven more stages, producing highervelocities, but even then we are stilllooking at many decades travel time withDaedalus before we reach the neareststars. As the Daedalus report described in a special edition of the Journal of theBritish Interplanetary Society in 1978, “A complete mission would involve about20 years design, manufacture and vehiclecheckout, 50 years flight time and six tonine years of transmitting informationback to the Solar System. Therefore, it appears that even the most simpleinterstellar missions will require acommitment of support for 75–80 years...Even if the exhaust velocity of the rocketcould be doubled, thus permittingdeceleration at the target, flight timeswould still be measured in decades and somanned interstellar flight does not lookvery promising.”

Problems with powerEven unmanned interstellar flight usingthe Daedalus system currently faces twobig problems. The first is nuclear fusionitself. Regardless of the type of fusion –whether it be electron beams, inertialconfinement fusion (ICF) with high-powered petawatt (1015 watts) lasers or a magnetic confinement reactor withtokamaks containing a plasma ofdeuterium and tritium that is heated to a million degrees until the atoms fuse – no fusion reactor has yet produced moreenergy than is put into the system. For example, the best the Joint EuropeanTorus magnetic confinement reactor inOxfordshire, UK has achieved is a 16megawatt output for two secondsfollowing an input of 25 megawatts.However, technological advances intokamaks and ICF should remedy thisproblem within the decade and it isexpected that by 2050 a substantialproportion of the energy on the National Grid will come from commercialfusion reactors.

So that’s one problem solved; the other is going to take a bit more work.You’ll notice that in Earth-based reactorsdeuterium and tritium are used as thereactants, whereas in Daedalus deuteriumand helium-3 is preferred. That’s becausehelium-3 is a more efficient fusion fuel.However, it is rarely found on Earth. If wewant access to helium-3 we must either

produce it ourselves in reactors on Earth(through deuterium/deuterium orlithium-6/neutron reactions, but this iscostly and time-consuming), collect itfrom the solar wind (where we would needan enormous and impractical collectingarea) or on the Moon where the solarwind deposits it (but the concentrationsare low), or head out to Jupiter and mineit from its atmosphere (requires a space-based society and an interplanetaryinfrastructure). Perhaps surprisingly,Jupiter was the preferred choice of theDaedalus team, who imagined that thestarship could be built nearby the Jovianfuel depot, the manifestation of a wealthy,Solar System wide society mining andtransporting helium-3 for use in fusionreactors on Earth and in various colonies.

The study concluded that, “If we canrealise the technological steps in nuclearfusion and electronics, predicted byreasonable extrapolation of today’stechnology, then interstellar missions of alimited type will be possible.” This modestjudgement perhaps belies their ambitionand optimism in embarking on the project– the degree to which we can become aninterstellar civilisation remains to be seen,but Project Daedalus certainly bolsteredhopes rather than constrained them.

Barnard’s Star, which is a red dwarfstar 5.9 light years away and which hasthe highest proper motion of any star onthe sky, seemed a good choice ofdestination in the 1970s as circumstantialevidence pointed to the existence ofplanets in orbit around the star. Alas, thatevidence turned out to be false, but withplanets now being discovered in the alphaCentauri system our nearest star systemis looking a much more promising target.

Wherever its destination, after the fly-by Daedalus was fated to never returnhome. It would carry on deep intointerstellar space, continuing to doscience in the interstellar medium as longas power and communication with Earthheld out. Had it flown to Barnard’s Star,its trajectory would eventually have takenit about 13,500 light years above theGalactic Centre in about 180,000 yearstime and ultimately out of the Galaxy –from being our first interstellar explorerto becoming lost in intergalactic space,Daedalus’ voyage would become thegreatest adventure of all time.

If we can realise the technologicalsteps in nuclear fusion and electronics,predicted by reasonable extrapolationof today’s technology, then interstellarmissions of a limited typewill be possible.

Project IcarusIn Greek mythology Daedalus had ason, Icarus. Both built wings of wax,but Icarus flew too close to the Sunand the wax melted, sending himplummeting to the sea below.Project Daedalus has alsobequeathed Project Icarus, atwenty-first century design-study foran interstellar vehicle.Once again initiated by members ofthe British Interplanetary Society,originally headed up by I4ISExecutive Director Kelvin Long,Icarus began as a five-year study –now in its penultimate year – but hassince taken on a life of its own asthe foundation for a non-profitorganisation called IcarusInterstellar, dedicated to interstellarflight and initiating many projectsinto deep space propulsion. To findout more, visit

www.icarusinterstellar.org.

Jargon Buster

Helium-3/helium-4

These are differing isotopes of atomichelium. Helium-3 has one neutron andtwo protons; helium-4 has twoneutrons and two protons.

Nuclear fusion

The process by which two atomicnuclei are fused together to form alarger nucleus, releasing energy in the process

Fermi Paradox

This conundrum asks, if intelligentextraterrestrial life exists and ifinterstellar travel is possible, why hasEarth not been already colonised byaliens at some point in its 4.5 billionyears history? Where is everybody?Project Daedalus aimed to inform theFermi Paradox discussion by showingwhether interstellar flight was possibleor not.

Light year

The distance light travels in one year,which is 9.46 trillion kilometres.Barnard’s Star is 5.9 light years away,or 55.8 trillion kilometres.

The British Interplanetary Societyhttp://www.bis-space.com

DimensionsOne hundred and ninety metres

long, Daedalus would not be an especially giantstarship – the fictional starship Enterprise was

300-metres long – but it is still far larger thanany spacecraft or space station built to date. Itssheer size requires that Daedalus would have to

be assembled in space.

Principium | Issue 1 | December 2012 Page 11

Self-repairsEven the most sophisticatedsystems with built-in redundancywill inevitably suffer breakdownsat some stage during such a longand arduous mission. Without humans on hand to make repairs, two robotic wardens, armed with a degree of artificialintelligence necessary to be able to functionautonomously six light years from home, will patrol the starship during the voyage to maintain the vehicle and implement repairs.

Deflector shieldPowering through space at 12 percent of the speed of light requires a clearpath – hitting even the tiniest piece of space dust at that velocity wouldpack the punch of an atomic bomb.

In order to protect the ship a deflector shield must be employed in front ofthe vessel in the form of a cloud of micron-sized dust particles that wouldintercept anything from dust to small asteroids up to 500 kilograms andvapourize it on contact.

ProbesDaedalus wasn’t designed to slow down,so its visit to Barnard’s Star would befleeting, passing through at 12 percent thespeed of light. In order to better study thestar system, Daedalus would deploy 18scientific probes to investigate the starand any attendant planets closer up.

StagesThe Daedalus starship is divided into two stages toallow increased velocity by losing mass during thejourney. The first stage consists of six tanks ofpropellant and is discarded after two years; the secondstage has four smaller tanks that provide addedpropulsion for a further 320 days.

The Daedalus Starship

PowerSuperconducting coilsgenerate a magnetic field intowhich the deuterium/ helium-3pellets are injected to collidewith beams of electrons insidethe reaction chamber andfuse, the products of whichare magnetically driven out toprovide thrust.

CommunicationFor short range signalling, either with its daughter probesor with Earth during the first stage of propulsion, Daedaluswas to be armed with a high-power laser. A radio antenna– made out of the parabolic dish of the second stage’sreaction chamber – would be used for longer distancecommunication. However, during the 1970s lasers werestill an immature technology, less than two decades old.Today lasers are considered a far superior mode of longdistance communication.

Principium | Issue 1 | December 2012 Page 12

Book ReviewsGoing InterstellarEdited by Les Johnson and Jack McDevitt

This isn’t the firststarship anthology toput the science intothe fiction, and itwon’t be the last, butit is certainly one ofthe best. Proclaiming‘Build StarshipsNow!’, every pagefizzes with bold ideasand clever use ofimagination.

Which you would expect from thepedigree on show. Les Johnson is DeputyManager for NASA’s Advanced ConceptsOffice at the Marshall Space FlightCenter; Jack McDevitt is a celebrated SFauthor with Nebula and Philip K Dickawards under his belt. Together they’veaccumulated some of the best starshipfiction around, headlined by the great SFveteran Ben Bova and including CharlesGannon, Louise Marley, Michael Bishop,Sarah Hoyt and Mike Resnick.Interspersed between are essays on realstarflight concepts from I4IS’ Advisory

Council Chair Dr Gregory Matloff, IcarusInterstellar’s Richard Obousy and Johnsonhimself. Indeed, amidst all these stellarnames it’s Johnson who gets the book offthe starting block with a contender for thebest short story within its pages, ‘Choices’,where the use of virtual reality as a tool tostimulate the mind during hibernationthreatens to derail an interstellar colonymission. The main character’s solution isingenious, to say the least.

Also worthy of mention is McDevitt’s‘Lucy’, a charming tale of artificialintelligence and curiosity versusstagnation. Bova equips himself well in ‘ACountry for Old Men’ in which an oldscientist feeling redundant onboard astarship crewed by young people and an AIfinds a new reason for existence innavigating the hydrogen fields of theinterstellar medium. Meanwhile, Gannon’s‘Lesser Beings’ exists in a Universe wherehumans have already colonised the starsand oligarchic houses engage in conflictand introduces a new motivation forinterstellar travel: expulsion. Sarah Hoyt’s‘The Big Ship and the Wise Old Owl’ is aslightly contrived look at ensuring thecrews of generation ships don’t lose sight oftheir goal while Michael Bishop’s ‘Twenty

Lights to the Land of Snow’ is the only realletdown, a meandering and unfocusednovella about the reincarnation of theDalai Lama onboard a Tibetan colony shipthat lacks a strong climax.

The accompanying essays arecomparatively brief and are aimed mostlyat the newcomer to starship andpropulsion physics, but they are conciseand surprisingly comprehensive overviewsof solar sails, antimatter and fusionstarships. Overall, Going Interstellar’sinnovative and engaging prose and essaysare packed with enough thoughtprovoking ideas to make it a real winner.

Going Interstellar

Authors: Michael Bishop, Ben Bova, CharlesE Gannon, Sarah A Hoyt, Les Johnson,Louise Marley, Gregory Matloff, JackMcDevitt, Richard Obousy, Mike Resnick

Published by Baen (paperback, 416pp)

ISBN: 978-1-4516-3778-6

Available from Amazon.

Deep Space PropulsionKelvin F. Long

The first few chaptersmove rapid-firethrough manydifferent propulsionsystems (21 variationsin all) and reasonswhy we should dreamof interstellar travel.In subsequentchapters Kelvin Long,

I4IS’ Executive Director, expands on thesesystems, rigorously describing theworkings of electric and nuclear-basedpropulsion, fusion drives, solar sails andthe possibilities of antimatter and Bussardramjets, charting their development allthe way back to basic flight principles.These rigorous workings include manymathematical proofs, but the non-mathematical enthusiast shouldn't be putoff - it’s good to try and follow the maths,although for the general reader it isn'tessential and can be skipped over.

Long goes beyond propulsiontechnologies to look at general missiondesign and architecture, which is where

the book really earns its stars to becomethe very roadmap that Long asks forwithin its pages. His (self-confessed)optimistic timeline on page 321 hastechnology demonstrator missions blastingoff in the next few decades, sending apathfinder probe to 1,000 astronomicalunits (the outer edge of the ‘focal pointzone’ where the Sun can be used as agravitational lens); the first interstellarprobe launches in 2100 to arrive at anearby star (possibly the alpha Centaurisystem) by 2160 and the launch of the firsthuman interstellar colonising mission by2250. To put this into context, popularscience fiction such as the original StarTrek and Babylon 5 are set around the 2250sand Long notes that without abreakthrough discovery that couldrevolutionise space travel, such as warpdrive or wormholes, meeting theexpectations of those SF tales is going tobe difficult.

Long hits his stride best whendiscussing the overall structure ofmounting an interstellar mission; on theother hand, some early chapters aboutexploring the Solar System and beyondseem rather incongruous amidst thediscussion of propulsion and mission

technologies and, as a result, the text herefeels uneasy, listing facts about the planetsthat needn't be in a book about propulsion.That aside, Deep Space Propulsion is anotherwise excellent guide to starshipdesign and the chapters, replete withpractice exercises at the end of eachchapter (and not all of them aremathematical, giving readers of allabilities a chance at having a go) almostseem to have been arranged to suitably fit a lecture course on the topic. If youhave the time, this ‘homework’ is wellworth the effort and is a really nifty ideaon behalf of Long.

For anyone with a serious interest inthe subject, Kelvin Long's essential bookmay be the best around.

Deep Space Propulsion

Author: Kelvin F. Long

Published by Springer (paperback, 367pp)ISBN: 978-1-4614-0606-8e-ISBN: 978-14614-0607-5

Available from Amazon.

The young star cluster NGC 3603 inCarina. Image: NASA/ESA//R O’Connell(University of Virginia)/F Paresce (NationalInstitute for Astrophysics, Bologna) / E Young (Universities Space ResearchAssociation/Ames Research Center) /WFC3 Science Oversight Committee /Hubble Heritage Team (STScI/AURA).

™

INS

TI T

UT E

F OR I N T E R

ST

ELLA

R

S T U D I E S

www.I4IS.org

We'd love to hear from you, our readers,about your thoughts on Principium, theInstitute or interstellar flight in general.Join us on our Facebook page to join inthe conversation!

Editor: Keith CooperLayout: Adrian Mann