[WIND WHISTLING] PATRICK STEWART: WE ARE A RESTLESS SPECIES, FOREVER DRIVEN BY DREAMS OF WHAT LIES BEYOND THE HORIZON, IN SEARCH OF NEW LANDS TO EXPLORE, NEW WORLDS TO DISCOVER.

IT'S A SPIRIT WHICH HAS CARRIED US OFF THE PLANET, TO NEW FRONTIERS WHICH ONE DAY MAY MAKE US A MULTIPLANETARY SPECIES, BUT THE STORY OF HOW WE LEFT EARTH IS NOT WHAT YOU MIGHT EXPECT.

IT WOULD TAKE AN EXPLOSIVE EXORCISM IN THE ANCIENT WORLD, A LEAP IN TECHNOLOGIES FOR FIGHTING FIRE, THE MECHANIZATION OF DAIRY FARMS, A PLOT TO KILL THE KING OF ENGLAND, OH, AND SOME ELABORATE SOVIET SUBTERFUGE TO CREATE A MACHINE WITH THE POWER TO BREAK FREE FROM EARTH'S GRAVITY AND HURL US TOWARDS OTHER WORLDS-- THE ROCKET.

THESE ARE THE INVENTIONS THAT DEFINE OUR AGE AND HAVE CHANGED OUR WORLD FOREVER, THAT HAVE ALLOWED US TO MOVE ON THE GROUND AND IN THE AIR, TO CONNECT TO EACH OTHER, AND CREATE MIRACULOUS MACHINES, EACH A STORY OF INGENUITY, OF WONDER, OF BREAKTHROUGH.

MAN: T-MINUS 20 SECONDS.

STEWART: TODAY WE'RE ON THE BRINK OF SOMETHING THAT PROMISES TO TRANSFORM CIVILIZATION.

MAN: IGNITERS HAVE BEEN LIT.

STEWART: A NEW GENERATION OF ROCKETS ARE BEING DESIGNED TO CARRY HUMANS BACK INTO DEEP SPACE FOR THE FIRST TIME IN ALMOST 50 YEARS.

MAN: AND LIFT-OFF, THE DAWN OF ORION AND A NEW ERA OF AMERICAN SPACE EXPLORATION.

DIFFERENT MAN: SPACE BEGAN AS A BINARY EFFORT.

THERE WERE ONLY TWO PLAYERS-- THE SOVIET UNION AND THE UNITED STATES.

THAT HAS CHANGED.

THE WORLD IS DIFFERENT.

STEWART: A ROCKET REVOLUTION IS UPON US, WITH MORE COMPANIES BUILDING AND LAUNCHING THEIR OWN ROCKETS THAN AT ANY OTHER TIME IN HUMAN HISTORY.

MAN: NO ONE DOUBTS THAT COMPANIES LIKE SPACE X AND BLUE ORIGIN ARE THE FUTURE.

WE ARE NOW ABSOLUTELY IN AN INNOVATIONS RACE TO HELP HUMANITY REALLY GO BEYOND AND, YOU KNOW, BE A MULTIPLANET SPECIES.

STEWART: THIS IS THE STORY OF HUMANITY'S GREATEST ADVENTURE AND OUR GRANDEST DREAMS.

GARRIOTT: IT'S ACTUALLY QUITE DIFFICULT TO OVERSTATE HOW FAST AND HOW TRANSFORMATIVE THIS IS GOING TO BE.

MAN: 20 YEARS FROM NOW, SPACE TRAVEL IS GONNA BE LIKE AIR TRAVEL TODAY, AND THEN HUMANITY WILL HAVE TRULY BECOME A SPACEFARING SPECIES.

STEWART: THE STORY OF HUMANITY'S QUEST TO LEAVE THE EARTH, IN FACT, BEGINS DEEP WITHIN IT, IN A NETWORK OF CHINESE CAVES OVER 1,000 YEARS AGO, WHERE A MONK NAMED LI TIAN WAS BATTLING SUPERNATURAL SPIRITS.

MAN: THE STORY GOES THAT LI TIAN IS THIS SEVENTH-CENTURY MONK, AND HIS EMPEROR HAS CHARGED HIM WITH FINDING A WAY OF WARDING OFF EVIL SPIRITS THAT ARE PLAGUING SOCIETY WITH DROUGHTS AND FLOODS.

LI TIAN'S SEARCH TOOK HIM DEEP UNDERGROUND, TO CAVES WHERE BATS WERE ROOSTING.

ON THE FLOORS OF THESE PASSAGES AND CHAMBERS, HE FINDS THEIR DROPPINGS, KNOWN AS GUANO, WHICH ARE RICH IN POTASSIUM NITRATE.

NOW, THIS HAS BEEN USED SINCE ANCIENT TIMES FOR PRESERVING FOOD AND FOR FERTILIZING CROPS, BUT LI TIAN IS INTERESTED IN GUANO FOR OTHER REASONS.

A BORN PIONEER WITH AN INTEREST IN ALCHEMY, HE BEGINS TO COLLECT IT TO TAKE BACK HOME TO TEST.

IT WAS KNOWN AT THE TIME THAT BY WASHING AWAY IMPURITIES IN THE GUANO AND THEN MIXING IT WITH CHARCOAL AND SULPHUR, IT ACQUIRED MAGICAL PROPERTIES...

THE PERFECT TOOL TO SCARE OFF EVIL SPIRITS.

WHAT LI TIAN HAS, IN EFFECT, IS WHAT WE WOULD TODAY CALL GUNPOWDER, THE FIRST MIXTURE THAT BURNS WITHOUT NEEDING EXTERNAL AIR.

HE'S NOT THE FIRST TO USE IT, BUT, BECAUSE IT'LL BURN IN CONFINED SPACES, LI TIAN TRIES SOMETHING NEW, SOMETHING THAT HE THINKS WILL CREATE A MUCH BIGGER SHOW FOR HIS EMPEROR.

HE STUFFS BAMBOO SHOOTS WITH THIS GUNPOWDER, AND LEGEND HAS IT THAT WHEN SOMEONE THREW THEM ONTO THE FIRE, THE BAMBOO TUBES SHOT OUT ACROSS THE GROUND.

A LOT OF GAS IS BEING PRODUCED IN THIS CHEMICAL REACTION WITH A TREMENDOUS AMOUNT OF ENERGY, SO IF THE GUNPOWDER IS CONFINED INTO A TIGHT PLACE AND LIT, THE GAS THAT'S RELEASED PROVIDES THRUST THAT PUSHES THE BAMBOO SHOOT, IN THIS CASE, IN THE OPPOSITE DIRECTION, AND THIS IS THE PRINCIPLE OF THE ROCKET, A FORCE IN ONE DIRECTION PRODUCING A FORCE IN THE OPPOSITE DIRECTION.

IN THIS CASE, HOT GASES EXPELLED BACKWARDS PUSHED THE ROCKET FORWARDS.

IN SUCCEEDING TO SCARE OFF EVIL SPIRITS, LI TIAN HAD INADVERTENTLY DISCOVERED HOW TO TURN CHEMICAL ENERGY INTO THRUST.

WHAT WOULD EVENTUALLY BECOME THE ROCKET HAD TAKEN ITS FIRST FLIGHT.

STEWART: LI TIAN IS CREDITED WITH THE CREATION OF THE FIREWORK, A DEVICE DREAMED UP TO AMAZE AND DELIGHT AN EMPEROR, BUT SADLY, AS WOULD OFTEN HAPPEN WITH THIS PARTICULAR INVENTION, OTHERS WOULD SEE DARKER USES.

THE ROCKET MADE A FEARSOME WEAPON.

IT COULD UNLEASH THE FIRES OF HELL, WREAKING DESTRUCTION AND INTIMIDATING AN ENEMY MORE USED TO SPEARS AND ARROWS.

HERE IN THE GREEK TOWN OF VRONTADOS, AN EERILY SIMILAR ROCKET BATTLE IS UNLEASHED EVERY EASTER IN THE STRANGEST OF TRADITIONS.

ACROSS ONE HIGHLY CHARGED NIGHT, TWO PARISHES UNLEASH TENS OF THOUSANDS OF HOMEMADE ROCKETS, EACH TRYING TO HIT THE OTHER'S CHURCH TOWER.

IT'S A SPECTACULAR SHOW, AND THE PARTICIPANTS MEAN NO HARM, BUT JUST IMAGINE WHAT IT MUST HAVE LOOKED LIKE IN THE FIRST MILLENNIUM WHEN, INSTEAD OF BEING A FESTIVE CELEBRATION, THESE WERE ROCKETS OF WAR.

THE IDEA THAT A ROCKET COULD BE USED FOR MORE PEACEFUL MEANS TO TRAVEL TO DISTANT WORLDS WAS A LUDICROUS DREAM BECAUSE FOR MOST OF HISTORY, THE IDEA OF DISTANT WORLDS WAS LUDICROUS, TOO.

THEN A LITTLE-KNOWN MATHEMATICIAN LIVING IN LONDON MADE A MOMENTOUS DISCOVERY, DESPITE BEING CAUGHT UP IN A PLOT TO KILL THE KING.

WOMAN: THE YEAR IS 1605, AND ENGLISH POLYMATH SCIENTIST THOMAS HARRIOT IS LIVING WITH THE ARISTOCRATIC PERCY FAMILY AND TUTORING THEIR CHILDREN IN MATHEMATICS, BUT HARRIOT'S GOT A PROBLEM.

HIS EMPLOYERS, THE PERCY FAMILY, HAVE BECOME EMBROILED IN A TREASONOUS PLOT.

THEIR ASSOCIATES HAVE STASHED 36 BARRELS OF GUNPOWDER IN THE VAULTS BENEATH THE PALACE OF WESTMINSTER TO BLOW UP ENGLAND'S PARLIAMENT, KILLING PROTESTANT KING JAMES I...

BUT THINGS DON'T GO TO PLAN, AND WITH JUST DAYS TO GO, THE AUTHORITIES ARE TIPPED OFF.

THE GUNPOWDER PLOTTERS, INCLUDING THE FAMOUS GUY FAWKES, ARE ROUNDED UP AND EXECUTED.

THEIR FAMILIES AND ASSOCIATES ARE CAPTURED AND IMPRISONED.

AMONGST THEM IS THOMAS HARRIOT.

HARRIOT PLEADS FOR HIS LIFE AND IS RELEASED 3 WEEKS LATER, BUT HIS BOSS AND PATRON HENRY PERCY WILL SPEND THE NEXT 16 YEARS IN JAIL.

SHAKEN BY THESE EVENTS BUT RELIEVED TO HAVE HIS FREEDOM, HARRIOT THROWS HIMSELF INTO HIS STUDIES.

HIDDEN AWAY AND AVOIDING FURTHER TROUBLE, HE DEVOTES ALL HIS TIME TO UNDERSTAND THE NATURAL WORLD, AND IN 1609, HE GETS HIS HANDS ON A DUTCH SPYGLASS, ONE OF THE FIRST IN THE WORLD.

6 MONTHS BEFORE GALILEO'S FAMOUS OBSERVATIONS OF THE NIGHT SKY, HARRIOT POINTS IT AT THE MOON AND DRAWS WHAT HE SEES.

THESE ARE THE FIRST DRAWINGS OF THE MOON SEEN THROUGH A TELESCOPE.

WHAT THEY SHOW IN EXQUISITE DETAIL ARE THE MOON'S MOUNTAINS, VALLEYS, AND CRATERS.

IT'S AN ASTONISHING DISCOVERY, PROVING THAT THE MOON IS A SOLID CELESTIAL BODY IKE EARTH.

AL-KHALILI: HARRIOT'S TELESCOPIC OBSERVATIONS OF THE NIGHT SKY WERE THE VERY FIRST IN HISTORY, AND THEY WERE THE FIRST TO SHOW US THAT OUT THERE WERE WORLDS BEYOND OUR OWN, WORLDS TO STUDY, TO EXPLORE, AND MAYBE EVEN TO VISIT.

STEWART: HARRIOT'S OBSERVATIONS MARKED THE START OF A MOVEMENT WHICH SWEPT EUROPE.

WITHIN MONTHS, GALILEO MADE HIS OWN TELESCOPIC OBSERVATIONS OF THE MOON AND PLANETS, OBSERVATIONS OF SUCH PROFOUND SIGNIFICANCE THAT THEY INSPIRED THE NEXT GENERATION TO LOOK BEYOND THE CONSTRAINTS OF OUR OWN PHYSICAL WORLD AND IMAGINE WHAT LAY BEYOND.

IN 1634, PUBLISHERS RELEASED WHAT MAY BE THE FIRST PIECE OF SCIENCE FICTION, A WORK BY GERMAN ASTRONOMER JOHANNES KEPLER IN WHICH HE IMAGINED A TRIP TO THE MOON PROPELLED BY MAGICAL BEINGS, BUT THE STORY WAS SIMPLY TOO OUTLANDISH TO BE TAKEN SERIOUSLY.

250 YEARS LATER, HOWEVER, THE IDEA WOULD RESURFACE IN ANOTHER CAPITAL CITY, AND THIS TIME, IT WOULD TAKE OFF.

AT 20 YEARS OLD, A YOUNG MAN TRAVELED TO PARIS.

HIS FATHER INSISTED THAT HE FINISH A LAW DEGREE IN THE CITY...

BUT THE CITY FUELED OTHER AREAS OF HIS IMAGINATION.

INSTEAD OF STUDYING THE HUMDRUM TEXTS OF LAW... [APPLAUSE] HE FILLED HIS MIND WITH MARVELOUS TALES OF DERRING-DO AND FANTASTICAL, FAR-OFF DISCOVERIES, ALL FOUND IN THE THOUSANDS OF BOOKS IN THE FRENCH NATIONAL LIBRARY.

HERE, HE IMMERSED HIMSELF IN THE LEADING SCIENTIFIC IDEAS OF THE AGE, AND THEY IGNITED A DESIRE IN THE YOUNG MAN, THE DESIRE TO WRITE, HIS NAME--JULES VERNE, AND HIS STORIES WERE THE GRANDEST ADVENTURES IMAGINABLE-- VOYAGES WHICH CROSSED AFRICA IN A BALLOON... EXPEDITIONS WHICH TRAVELLED 20,000 LEAGUES UNDER THE SEAS, AND A JOURNEY UP A VOLCANO THAT LED TO THE CENTER OF THE EARTH.

HIS STORIES WERE PURE FANTASY, BUT THEY WERE BELIEVABLE BECAUSE THE IDEAS WERE BASED IN REALITY, AND THEY WERE A HUGE SUCCESS, MAKING VERNE RICH AND FAMOUS.

BY 1865, HOWEVER, HE'D EXHAUSTED THE POSSIBILITIES OF THIS PLANET AND STARTED TO LOOK BEYOND IT FOR NEW EXPLOITS.

"FROM THE EARTH TO THE MOON" IS THE STORY OF THE BALTIMORE GUN CLUB AND 3 MEN DETERMINED TO BUILD A CRAFT THAT CAN CARRY THEM TO THE MOON FIRED FROM A GIANT CANNON TO BLAST THEM INTO SPACE.

THIS BOOK CAUSED A SENSATION AND TRIGGERED PUBLIC DEBATE ACROSS THE WORLD ON THE POSSIBILITY OF BLASTING A MAN TO THE MOON AND BEYOND.

COULD SUCH A THING BE ACHIEVED?

MOST THOUGHT IT WAS PURE FICTION, BUT THE BOOK FELL INTO THE HANDS OF A YOUNG BOY LIVING IN THE MIDDLE OF RURAL RUSSIA WHO COULD SEE A WAY TO TURN FICTION INTO FACT.

HIS NAME WAS KONSTANTIN TSIOLKOVSKY.

GARRIOTT: A LOT OF US MAKE INCREMENTAL STEPS BASED UPON THE ADVANCEMENTS OF OTHERS, BUT TSIOLKOVSKY IS ONE OF THESE PEOPLE WHERE YOU'RE GOING, "YOU KNOW WHAT?

HE JUST MADE THAT FIRST PILLAR ON HIS OWN."

HE WAS ONE OF THOSE GIANTS UPON WHOSE SHOULDERS THE REST OF US WERE STANDING.

10 YEARS AGO, I BEGAN TO COLLECT SOME OF THE ORIGINAL DRAWINGS THAT TSIOLKOVSKY CREATED COMING UP WITH MANY OF THE BREAKTHROUGHS FOR HOW ROCKETS MIGHT ESCAPE THE EARTH AND TRAVEL OUT INTO THE STARS.

KONSTANTIN TSIOLKOVSKY CAME DOWN AT A YOUNG AGE WITH SCARLET FEVER AND LOST MOST OF HIS HEARING, AND THERE'S GOOD ODDS THAT KIND OF DROVE HIM TO BE A BIT OF THIS BOOKISH, INTROSPECTIVE PERSONALITY.

SAT IN HIS DESK IN KALUGA IN HIS MODEST HOME, IT IS HARD TO IMAGINE THAT HE WOULD HAVE VERY MUCH INSPIRATION OF TECHNOLOGY AROUND HIM.

IT SURELY HAD TO COME FROM THE THINGS HE COULD FIND IN BOOKS AND, THEREFORE, WHAT WOULD BE SPARKED IN HIS OWN IMAGINATION.

READING JULES VERNE, "FROM THE EARTH TO THE MOON," KONSTANTIN WAS INSPIRED TO SIT DOWN AND GO, "WELL, YOU KNOW, HOW FAST DO YOU ACTUALLY NEED TO GO TO LEAVE THE EARTH?"

HE QUICKLY RECOGNIZED THAT TO ACCELERATE AN ARTILLERY SHELL TO REACH SPACE, THIS CANNON MIGHT BE AS LARGE AS THE EIFFEL TOWER AND WOULD HAVE THOUSANDS OF Gs OF G-FORCES WHICH WOULD CRUSH ANY PASSENGER WITHIN IT, SO THAT MIGHT NOT BE PARTICULARLY PRACTICAL A WAY TO LEAVE THE EARTH.

STEWART: THEN TSIOLKOVSKY HAD A MOMENT OF INSPIRATION.

HE THOUGHT, "WELL, WHAT IF I USE A VEHICLE "THAT RELEASED ENERGY MORE GRADUALLY FROM WITHIN LIKE A MASSIVE FIREWORK?"

SO IN A FARMER'S HOUSE IN RURAL RUSSIA, TSIOLKOVSKY SETS OUT TO DO THE MATH.

GARRIOTT: AND PRIOR TO THE WRIGHT BROTHERS EVER FLYING AN AIRPLANE, TSIOLKOVSKY WOULD BECOME THE FIRST PERSON TO WORK OUT WHAT IT WOULD TAKE TO PUT THESE ROCKETS ALL THE WAY INTO SPACE.

STEWART: TSIOLKOVSKY'S VISIONARY WORK ON ROCKETS WOULD EVENTUALLY UNDERPIN ALL MODERN SPACE FLIGHT, BUT EVEN TSIOLKOVSKY'S VISIONS COULDN'T PROPEL US TO THE STARS.

STRANGELY, THAT WOULD RELY ON A BREAKTHROUGH IN BUTTER MAKING.

[COW MOOS] [MOO] [BIRDS CHIRPING] [MOO] IN THE LATE 19th CENTURY, DAIRY FARMING WAS BEING TRANSFORMED WITH HUNDREDS OR EVEN THOUSANDS OF CATTLE REPLACING TINY FAMILY FARMS, BUT THE JOB OF SEPARATING MILK FROM CREAM TO MEET THE DEMAND FOR BUTTER WAS STILL PAINFULLY SLOW.

IT TOOK SO LONG THAT IN HOT WEATHER, THE MILK OFTEN SOURED DURING THE PROCESS.

THEN ONE DAY, AN ENTERPRISING SWEDISH ENGINEER NAMED KARL GUSTAF DE LAVAL READ ABOUT THE PROBLEM AND WAS INSPIRED TO DEVISE A SOLUTION.

[TEA KETTLE WHISTLING] HE DESIGNED A SPINNING MACHINE WHICH COULD CONTINUOUSLY SEPARATE CREAM FROM MILK USING CENTRIFUGAL FORCE.

NEXT, HE POWERED IT WITH A STEAM TURBINE OF HIS OWN DESIGN, PAVING THE WAY FOR MASS PRODUCTION.

NOT CONTENT WITH REVOLUTIONIZING THE BUTTER INDUSTRY, DE LAVAL NOW TURNED HIS ATTENTION TO IMPROVING STEAM TURBINES, TOO.

IN A BID TO MAKE THEM SPIN AS FAST AS POSSIBLE, HE CAME UP WITH A SPECIALLY SHAPED CONVERGING, THEN DIVERGING NOZZLE WHICH FOCUSED THE STEAM INTO A SUPER FAST JET, SO WHAT DOES ALL THIS BUTTER AND STEAM HAVE TO DO WITH ROCKETS?

IT WOULD TAKE A VISIONARY AMERICAN PHYSICIST WHO DREAMED OF THE STARS TO MAKE THE CONNECTION.

ON OCTOBER 19, 1899, A 17-YEAR-OLD BOY CLIMBED TO THE TOP OF A CHERRY TREE IN HIS FAMILY'S YARD, LOOKED OUT OVER THE NEW ENGLAND FIELDS, AND DREAMED OF THE POSSIBILITY OF TRAVELING INTO SPACE.

FROM THAT MOMENT ON, HIS PASSION FOR BUILDING ROCKETS WAS IGNITED.

HE WOULD BECOME AMERICA'S GREATEST ROCKET PIONEER, AND HIS NAME WAS ROBERT GODDARD.

WOMAN: BY THE 1920s, ROBERT GODDARD WAS WORKING ON SOMETHING THAT THE WORLD HAD NEVER SEEN BEFORE-- LIQUID-FUELED ROCKETS, BUT HIS EXPERIMENTS WERE KIND OF HOMESPUN.

HIS ROCKETS WERE ONLY ABOUT A METER OR SO LONG, AND THEY COULDN'T REALLY GET OFF THE GROUND.

WHAT GODDARD WAS FACING WAS THAT HE WAS ONLY GETTING 2% THRUST OUT OF THE ROCKET FUEL THAT HE IGNITED, SO HE REALLY HAD TO FIGURE OUT HOW TO INCREASE THE ROCKET EFFICIENCY.

AS A ROCKET SCIENTIST, I FEEL HIS PAIN.

WHAT YOU REALLY WANT TO DO IS TRY AND GET SO MUCH OUT OF EVERY PIECE OF THE PROPELLANT MASS THAT YOU'RE PUSHING INTO SPACE, AND THAT'S WHY WE STILL PUT SO MUCH TIME AND EFFORT INTO TESTING EVERY SINGLE ROCKET ENGINE THAT WE MAKE.

WOMAN: AND WE ARE STANDING BY FOR RS-25 ENGINE TEST HERE AT STENNIS SPACE CENTER.

FLETCHER: ON THIS TEST STAND TODAY IS ONE OF NASA's LATEST ROCKET ENGINES WHICH WILL POWER THEIR NEW SPACE LAUNCH SYSTEM, WHICH IS WHAT I'M HELPING THEM TO BUILD.

WOMAN: AUTO SEQUENCE HAS STARTED.

FLETCHER: THE EXHAUST IS COMING OUT AT 13 TIMES THE SPEED OF SOUND.

[WHOOSHING] IT'S REMARKABLY EFFICIENT.

OVER 90% OF THE ENERGY RELEASED IS TRANSFERRED INTO THE SPEED OF THE EXHAUST GASES, CREATING ENOUGH UPWARD FORCE TO LIFT ALMOST 250 TONS, AND THE KEY TO THIS EXTRAORDINARY EFFICIENCY IS SOMETHING THAT ROBERT GODDARD INCORPORATED IN A ROCKET ENGINE FOR THE VERY FIRST TIME-- DELAVAL'S SPECIAL CONVERGENT-DIVERGENT NOZZLE.

IT WORKS LIKE THIS.

AS HOT BURNING GAS IS SQUEEZED INTO THE CONVERGING SECTION OF THE NOZZLE, THERE IS LESS SPACE FOR IT TO OCCUPY, SO IT ACCELERATES.

IT MIGHT SEEM THAT AS THE NOZZLE WIDENS, THE GAS WOULD SLOW DOWN, BUT BECAUSE IT'S SO HOT, WHEN RELEASED INTO THE LOW-PRESSURE ENVIRONMENT OF THE DIVERGENT SECTION, THAT HEAT CAUSES IT TO EXPAND RAPIDLY AND SHOOT OUT.

IT MAKES USE OF FAR MORE OF THE FUEL'S STORED CHEMICAL ENERGY.

THUS THE SPEED INCREASES.

THUS MORE THRUST.

IT'S EXACTLY WHAT GODDARD NEEDS IN ORDER TO GET HIS ROCKETS INTO THE AIR.

HIS TESTS SHOW THAT WITH DE LAVAL'S NOZZLE, HE COULD INCREASE HIS EFFICIENCY FROM 2% ALL THE WAY TO 63%.

BY MARCH 16, 1926, GODDARD IS READY TO FLY HIS FIRST LIQUID-FUELED ROCKET.

HE NAMES IT AFTER HIS DAUGHTER NELL.

THE FLIGHT IS BRIEF.

THE ROCKET DOESN'T GO FAR OR FAST, REACHING A MAXIMUM SPEED OF 100 KILOMETERS PER HOUR AND 41 FEET, BUT HUMANITY'S FIRST LIQUID-FUELED ROCKET MAKES IT FROM THE EARTH INTO THE SKY.

AL-KHALILI: GODDARD'S FIRST LIQUID-FUELED ROCKET FLIGHT IS A COLOSSAL MOMENT IN HISTORY BECAUSE IT LAYS THE FOUNDATIONS FOR US TO LEAVE THE PLANET.

STEWART: BUT FOR ALL HIS PIONEERING WORK, THERE IS ONE FAMILIAR PROBLEM THAT GODDARD NEVER MANAGED TO SOLVE--MONEY.

WITHOUT THE FUNDS TO DEVELOP AND BUILD THEM, GODDARD'S ROCKETS WOULD NEVER REACH SPACE.

TO GET THE KIND OF INVESTMENT THAT COULD SEND A ROCKET TO THE LIMIT OF EARTH'S ATMOSPHERE, IT WOULD TAKE A LOOPHOLE IN AN INTERNATIONAL TREATY.

[CHEERING] AT THE END OF THE FIRST WORLD WAR, ALLIED POWERS FORCED A BROKEN GERMAN NATION TO THE NEGOTIATING TABLE.

IN THE TOWN OF VERSAILLES IN 1919, GERMANY SIGNED A TREATY INTENDED TO ENSURE THAT NEVER AGAIN WOULD THEY THREATEN ANOTHER NATION WITH THEIR MILITARY MIGHT.

THE TREATY BANNED THE GERMAN MANUFACTURE OF BIG GUNS, TANKS, AND PLANES, BUT NO ONE THOUGHT TO STOP THE GERMANS FROM BUILDING ROCKETS BECAUSE NO ONE IMAGINED THAT ROCKETS WOULD EVER POSE A THREAT.

GEORGE: THEN IN 1930, A YOUNG ENGINEER JOINS A BERLIN SCIENCE CLUB-- THE SOCIETY FOR SPACE TRAVEL.

HIS NAME IS WERNER MAGNUS MAXIMILIAN FREIHERR VON BRAUN, AND HE'S BEEN DEVOTED TO ROCKETRY SINCE FIRST DREAMING OF SETTING FOOT ON THE MOON AFTER HIS MOTHER GAVE HIM A TELESCOPE FOR HIS 13th BIRTHDAY.

STEWART: VON BRAUN HAD THROWN HIMSELF INTO THE STUDY OF AEROSPACE ENGINEERING.

HIS ROCKET DESIGNS OFTEN OUTSHONE HIS PEERS, SO MUCH SO THAT AT JUST 22 YEARS OLD, HE CAME TO THE ATTENTION OF THE GERMAN HIGH COMMAND.

GEORGE: THE ARMY BEGIN FUNDING HIS WORK, AND WITHIN MONTHS, VON BRAUN IS REACHING RECORD NEW HEIGHTS, LAUNCHING LARGE, LIQUID-FUELED ROCKETS UP OVER TWO MILES.

THEY ECLIPSE THE WORK OF HIS CHILDHOOD HERO ROBERT GODDARD.

STEWART: BUT WHILE VON BRAUN'S DREAM WAS TO CARRY MEN TO THE MOON, THE GERMAN ARMY WANTED A ROCKET TO CARRY SOMETHING FAR MORE SINISTER.

THROWING MONEY AT THE PROJECT, THEY BUILT A SECRET RESEARCH BASE NEAR THE REMOTE VILLAGE OF PEENEMUNDE ON THE NORTH COAST OF GERMANY.

AT THIS HUGE SITE, VON BRAUN, NOW A MEMBER OF THE SS, WAS PLACED IN CHARGE OF 350 ENGINEERS AND ORDERED TO PRODUCE A ROCKET THAT COULD CARRY A BOMB MORE THAN 150 MILES.

GENERATING ENOUGH THRUST WOULD BE THE PRIMARY TASK.

GEORGE: WHEN IT COMES TO INCREASING A ROCKET'S THRUST, DA LAVAL'S NOZZLE, WHICH ROBERT GODDARD APPLIED, CAN ONLY GET YOU SO FAR.

THE ONLY WAY TO ACHIEVE EVEN MORE THRUST IS TO INCREASE THE AMOUNT OF FUEL YOU'RE BURNING, AND THAT MEANS FORCING MORE OF IT INTO THE ENGINES EACH SECOND.

IT SOUNDS SIMPLE IN THEORY, BUT IN REALITY, VON BRAUN'S ARMY PAYMASTERS HAVE SADDLED HIM WITH A COLOSSAL CHALLENGE.

AT THIS TIME, THE BEST ROCKET HE HAS CAN GENERATE 1 1/2 TONS OF THRUST.

HE SETS A GOAL OF BUILDING A NEW ROCKET THAT CAN GENERATE A STAGGERING 25 TONS OF THRUST, WHICH HE CALCULATES WILL BE NEEDED TO CARRY THE BOMBS THE GERMAN ARMY ARE DESIGNING.

THE OBVIOUS ENGINEERING SOLUTION TO INCREASING THE PRESSURE OF THE FUEL IS TO PRESSURIZE THE TANKS, BUT A PRESSURIZED TANK MEANS THICKER WALLS.

THICKER WALLS MEANS MORE WEIGHT.

[WHOOSHING] SEEKING ANOTHER WAY TO GET MORE FUEL INTO THE ENGINES, VON BRAUN PLACES HIS FAITH IN A TECHNOLOGY FROM AN ALTOGETHER DIFFERENT VEHICLE.

IN THE 1930s, FIRE ENGINES ARE EQUIPPED WITH A HIGH-POWERED PUMP, AND THEY'RE STILL IN USE TODAY.

STEWART: A 1930s FIRE TRUCK PRESSURIZED WATER USING SOMETHING CALLED A TURBO PUMP, AND IT WORKS ON A SIMPLE CONCEPT.

THESE SUPER EFFICIENT PUMPS PRESSURIZE THE WATER BY HURLING IT TO THE EDGES OF A SPINNING DISK INSIDE HERE.

THIS SPINNING DISK THROWS LOW-PRESSURE WATER OUT TO ITS EDGE USING CENTRIFUGAL FORCE.

HERE, THE NOW-FAST-MOVING WATER IS COLLECTED INTO A HIGH-PRESSURE FLOW, SO AT A 1,000 REVOLUTIONS PER MINUTE, WE HAVE AROUND 20 LITERS OF WATER EVERY SINGLE SECOND, SO NOW IF WE SPIN THE DISK FASTER, MORE AND MORE WATER IS BEING HURLED TO THE EDGES, MAKING THAT WATER HIGHLY PRESSURIZED COMING OUT OF THE PUMP.

THAT'S 2,000... 2,500... 3000.

OK?

3,500 REVOLUTIONS PER MINUTE.

THAT'S ABOUT 45 LITERS PER SECOND.

THIS IS APPROXIMATELY THE RATE AT WHICH THE ROCKET NEEDS TO CONSUME FUEL.

A LIGHTWEIGHT CENTRIFUGAL PUMP IS THE SOLUTION THAT VON BRAUN'S LOOKING FOR TO PRESSURIZE HIS FUEL, ALTHOUGH IT TAKES ALMOST A DECADE OF DEVELOPMENT AND FUNDING BEFORE THE DEVICE CAN COPE WITH THE EXTREME TEMPERATURE AND VIBRATIONS OF A MOVING ROCKET, BUT BY 1944, VON BRAUN'S TEAM HAS BUILT A PUMP THAT CAN MAKE THE MAGIC 25 TONS OF THRUST POSSIBLE FOR THE ROCKET NOW CALLED THE V2... AND HERE IT IS, THE WORLD'S FIRST CENTRIFUGAL FUEL PUMP CAPABLE OF POWERING A ROCKET MOTOR, AND INCREDIBLY, THIS PUMP WOULD HAVE PUSHED THROUGH 3,000 LITERS OF ETHANOL AND 6,000 LITERS OF LIQUID OXYGEN IN JUST 60 SECONDS.

VON BRAUN IS A STEP CLOSER TO HIS DREAM.

IN 1944, A TEST FLIGHT FROM HERE IN PEENEMUNDE PROVES THAT, FOR THE FIRST TIME, A ROCKET IS CAPABLE OF REACHING THE LIMIT OF OUR ATMOSPHERE AND TOUCHING THE EDGE OF SPACE, BUT THIS IS NOT A MOMENT TO CELEBRATE.

ON SEPTEMBER THE 8th, 1944, THE FIRST ONES TAKE TO THE SKIES IN ANGER.

ONE OF THEM LIFTS OFF FROM WASSENAAR IN THE NETHERLANDS AND HEADS FOR ITS TARGET.

WITHIN MINUTES, IT BREAKS THE SOUND BARRIER, AND WITHIN ANOTHER 60 SECONDS, IT REACHES A HEIGHT OF 100 KILOMETERS, BURSTING OUT OF THE EARTH'S STRATOSPHERE.

FREED OF ATMOSPHERIC DRAG, IT POWERS DOWN ITS ENGINES.

IT'S NOW FLYING AT 4 TIMES THE SPEED OF SOUND AS IT DESCENDS IN A GRACEFUL, PARABOLIC CURVE, BREAKING THROUGH THE CLOUD LINE HERE OVER WEST LONDON.

IT'S FLIGHT TO SPACE AND BACK HAS TAKEN LESS THAN 5 MINUTES.

THE ROCKET IS TRAVELING SO FAST THAT IT ARRIVES SILENTLY AHEAD OF THE BOOM OF IT BREAKING THE SOUND BARRIER.

THE BLAST FROM ITS WARHEAD DESTROYS THE HOUSES HERE, HURLING 3,000 TONS OF RUBBLE AND DEBRIS INTO THE AIR.

BY SOME MIRACLE, ONLY 3 PEOPLE ARE KILLED HERE, BUT IN THE MONTHS WHICH FOLLOW, 1,500 MORE V2s WILL RAIN DOWN FROM THE EDGE OF SPACE ONTO LONDON, KILLING ANOTHER 7,250 PEOPLE BEFORE THE END OF THE WAR.

IT'S AN UNCOMFORTABLE FACT THAT A WEAPON OF WAR KILLING THOUSANDS OF PEOPLE, INCLUDING SOME 20,000 VICTIMS OF THE SLAVE-LABOR FACTORIES WHERE IT WAS BUILT, WAS ALSO HUMANKIND'S FIRST SPACE ROCKET.

STEWART: WITHIN MONTHS OF THIS FIRST V2 FLIGHT, A FAR GREATER THREAT TO HUMANKIND EMERGED.

THE FIRST NUCLEAR WEAPONS WERE DROPPED ON JAPAN, BRINGING ONE WAR TO A HORRIFIC CLOSE BUT IGNITING A NEW CONFLICT-- A COLD WAR IN WHICH THE U.S. AND THE SOVIET UNION RACED TO BUILD BIGGER AND HEAVIER NUCLEAR BOMBS.

BY NOW, BOTH SIDES HAD GOTTEN THEIR HANDS ON V2 ROCKET PARTS CAPTURED FROM A RETREATING GERMAN ARMY, AND EACH SUPERPOWER SOON REALIZED THE POTENTIAL OF ROCKETS TO DELIVER THEIR NEW WEAPONS OF MASS DESTRUCTION.

THE PROBLEM WAS THAT NOT EVEN THE MIGHTY V2 WAS CAPABLE OF CARRYING A 5-TON NUCLEAR WARHEAD, BUT AMERICA HAD CAPTURED AN EVEN BIGGER PRIZE.

WERNHER VON BRAUN HAD SURRENDERED TO THEM AND WAS SOON AT WORK IN THE NEW MEXICO DESERT DEVELOPING NEW VERSIONS OF HIS ROCKET.

ON ONE TEST FLIGHT IN 1946, A 35-MILLIMETER CAMERA CAPTURED THIS FOOTAGE.

IT WOULD BE THE FIRST TIME THAT WE HAD EVER SEEN OUR PLANET FROM THE EDGE OF SPACE...

BUT HUMANS MIGHT NEVER HAVE FOLLOWED THESE FIRST ROCKETS WITHOUT AN ACCIDENT OF GEOPOLITICS AND A PRISONER FROM A SIBERIAN GULAG.

GARRIOTT: DURING THE COLD WAR, U.S. HAD ALLIES IN EUROPE THAT WERE MUCH CLOSER TO THE SOVIETS, AND SO THE SOVIETS FELT PARTICULAR PRESSURE TO HAVE THE ABILITY TO HAVE RANGE, HAVE A GLOBAL REACH WITH THEIR MISSILE SYSTEMS.

THE SOVIETS WERE EXTREMELY MOTIVATED TO DELIVER WARHEADS TO LITERALLY THE OPPOSITE SIDE OF THE WORLD IN ORDER TO DETER THE THREAT THEY FELT FROM THE UNITED STATES.

STEWART: THEY WERE SO MOTIVATED, IN FACT, THAT THEY TURNED TO A POLITICAL PRISONER, HIS NAME--SERGEI KOROLEV.

GARRIOTT: KOROLEV DREAMED OF SPACE FLIGHT AS A CHILD, BUT IN THE 1930s, HE FELL FOUL OF THE SOVIET AUTHORITIES AND WAS EXILED TO A GULAG IN SIBERIA.

[WIND WHISTLING] THEN IN 1945, KOROLEV GOT A REMARKABLE PROMOTION FROM POLITICAL PRISONER TO COLONEL IN THE RED ARMY.

THE REASON IS SIMPLE.

KOROLEV IS A BRILLIANT ROCKET SCIENTIST AND THE ONLY MAN CAPABLE OF EVOLVING INTERCONTINENTAL BALLISTIC MISSILES THAT CAN LIFT THE HEAVY NUCLEAR WARHEADS BEFORE THE AMERICANS DO.

STEWART: SUDDENLY, THE SOVIETS NEEDED HIM.

NOW, YOU MIGHT THINK THE WAY LIFT A HEAVY PAYLOAD IS TO BUILD A HUGE ROCKET WITH A MASSIVE SUPPLY OF FUEL, BUT IT'S NOT THAT SIMPLE BECAUSE THERE'S A FUNDAMENTAL PROBLEM TO THIS CHALLENGE, ONE THAT STILL TAXES ROCKET ENGINEERS AND ASTRONAUTS TO THIS DAY.

I'VE FLOWN IN SPACE 7 TIMES, AND I KNOW ONLY TOO WELL HOW DIFFICULT IT IS TO BUILD A SPACESHIP THAT CAN TRANSPORT YOU INTO ORBIT, AND PART OF THE PROBLEM IS THAT MOST OF THAT SPACESHIP IS FUEL.

NOW, THIS IS NOT A PROBLEM THAT ALL VEHICLES SUFFER FROM.

TYPICALLY ON A LARGE SHIP LIKE THIS, ABOUT 3% OF YOUR MASS IS FUEL... AND A CAR IS ABOUT THE SAME, POWERED BY A FUEL TANK WHICH TAKES ABOUT 3% TO 4% OF ITS MASS.

A LIGHT AIRCRAFT NEEDS A BIT MORE ENERGY TO LEAVE THE GROUND... WITH ITS FUEL TAKING UP 25% OF ITS MASS.

CARS AND SHIPS AND EVEN PLANES PROPEL THEMSELVES AROUND THE WORLD RATHER EFFICIENTLY, BUT WHEN IT COMES TO ROCKETS, I STILL FIND THE AMOUNT OF FUEL THEY NEED ASTOUNDING.

TYPICALLY, 85% TO 90% OF THE ROCKET NEEDS TO BE FUEL IN ORDER FOR THE ROCKET TO BE ABLE TO TAKE FLIGHT.

THE REASON IS BECAUSE, UNLIKE ANY OTHER VEHICLE, A ROCKET MOVES BY EXPELLING ITS OWN MASS.

THE ROCKET HAS TO THROW OUT PART OF ITSELF TO BE ABLE TO MOVE THE OTHER PART IN THE OPPOSITE DIRECTION, AND THAT MEANS THERE'S ONLY 10% TO 15% LEFT FOR THE ACTUAL ROCKET--THE TANKS, THE MOTORS, THE PIPES-- AND IF YOU'RE NOT CAREFUL, THERE'S NOTHING LEFT FOR THE PAYLOAD, THE STUFF THAT YOU REALLY WANT TO LAUNCH.

THE TRUTH IS THAT HERE ON EARTH, CHEMICAL ENERGY IS ONLY JUST ENOUGH TO BEAT THE FORCE OF GRAVITY.

THE ENERGY THAT'S PACKED IN A GALLON OF FUEL IS WHAT IT IS, AND YOU CAN'T DO MUCH MORE THAN THAT.

IF YOU WANT TO FLY MORE MASS INTO ORBIT, THEN THE ONLY SOLUTION IS A BIGGER ROCKET.

STEWART: IN FACT, IN THE 1950s, SERGEI KOROLEV'S CHALLENGE TO BUILD SOMETHING CAPABLE OF CARRYING 5-TON NUCLEAR WARHEAD ALL THE WAY TO AMERICA WOULD HAVE RESULTED IN A ROCKET THE SIZE OF THE EMPIRE STATE BUILDING.

KOROLEV NEEDS ANOTHER APPROACH TO ROCKET SCIENCE.

HIS SOLUTION WOULD COME FROM A RADICAL IDEA FROM THEIR OLD COMRADE KONSTANTIN TSIOLKOVSKY-- THE IDEA THAT A ROCKET CAN BE MADE UP OF SEVERAL ROCKETS ALL STRAPPED TOGETHER.

GARRIOTT: WHAT KOROLEV FIGURES OUT THEY HAVE TO DO IS TO SHED WEIGHT, AND SO THEY COME UP WITH THIS PLAN WHERE THEY TAKE THESE 4 OUTER STRAP-ON BOOSTERS THAT NATURALLY, AS THEY DRAIN THE FUEL THAT'S WITHIN THEM AND NO LONGER ARE PUSHING, WILL DROP AWAY AND FALL OFF, AND THEN THAT CENTRAL CORE CONTINUES TO BURN AND MAKES IT ALL THE WAY INTO SPACE.

STEWART: KOROLEV DREW UP PLANS FOR A MASSIVE NEW ROCKET KNOWN AS THE R-7.

IT WOULD BE THE WORLD'S FIRST MULTISTAGE DESIGN CAPABLE OF TRAVELING BETWEEN ENTIRE CONTINENTS.

IT WAS TWICE AS BIG AND 20 TIMES HEAVIER THAN THE V-2, BUT GETTING SUCH A ROCKET OFF THE GROUND WAS NOT EASY.

GARRIOTT: KOROLEV, AFTER 3 FAILED ATTEMPTS, ON THE 21st OF AUGUST, 1957, LAUNCHED A 5.4-TON WARHEAD FROM KAZAKHSTAN THAT WENT 6,500 KILOMETERS.

IT WAS A MONUMENTAL SUCCESS THAT CLEARLY PUT THE SOVIET UNION WELL AHEAD OF ANY OTHER COUNTRY.

THERE WAS NOW NOWHERE ON EARTH THAT THEY COULD NOT TOUCH, THAT THEY COULD NOT BRING DEVASTATION THAT WOULD BE UNSTOPPABLE AT THE PUSH OF A BUTTON.

STEWART: THIS DESTRUCTIVE MOMENT MARKED THE BEGINNING OF A NEW SURGE IN ROCKET DEVELOPMENT.

NOW NO EXPENSE WAS TOO GREAT AS BOTH AMERICA AND RUSSIA RACE TO BUILD BIGGER ROCKETS THAT COULD CARRY HEAVIER BOMBS.

IN THE SCRAMBLE THAT FOLLOWED, KOROLEV SPOTTED AN OPPORTUNITY TO REALIZE A MORE PEACEFUL AMBITION, BUT IT WAS GOING TO TAKE A PIECE OF RISKY SUBTERFUGE TO PULL IT OFF.

GARRIOTT: KOROLEV, WHO HAD LONG DREAMED OF SPACE FLIGHT, BELIEVES HIS R-7 HAS GREATER POTENTIAL.

WITHOUT THE HEAVY NUCLEAR WARHEAD, HE BELIEVES IT CAN BE THE FIRST-EVER ROCKET TO REACH EARTH ORBIT.

THE PROBLEM IS, THE SOVIET PREMIER NIKITA KHRUSHCHEV ISN'T INTERESTED IN SPENDING MILLIONS TO EXPLORE SPACE, SO KOROLEV TAKES A RISK.

IN 1954, HE PLANTS A FAKE NEWS STORY IN THE SOVIET NEWSPAPERS CLAIMING THE NATION IS PREPARING TO LAUNCH A SATELLITE INTO EARTH ORBIT.

BELIEVING THE STORY, THE AMERICAN NEWSPAPERS RUN IT, TOO.

PRESIDENT EISENHOWER FEARS THE SOVIETS ARE TAKING A TECHNOLOGICAL LEAD AND RETALIATES, ANNOUNCING THE UNITED STATES WILL SEND THEIR OWN SATELLITE INTO SPACE.

WITH AMERICA NOW PUBLICLY WORKING TOWARDS THE WORLD'S FIRST SATELLITE LAUNCH, KOROLEV WRITES A LETTER TO THE SOVIET GOVERNMENT DEMANDING THEY TAKE ACTION TO SAVE FACE.

THE AUTHORITIES AGREE, AND SUDDENLY, KOROLEV'S LIFELONG DREAM OF SPACE FLIGHT IS WITHIN REACH.

STEWART: BUT IF HIS R-7 COULDN'T CARRY A WARHEAD INTO ORBIT, WHAT COULD IT CARRY?

GARRIOTT: KOROLEV TAKES OUT THAT 5.4-TON WARHEAD AND PUTS IN A 184-POUND SATELLITE, AND THAT CHANGE IN MASS TAKES THIS POWERFUL ROCKET WHICH PREVIOUSLY COULD NOT REACH ORBIT, AND NOW IT HAS THE POWER FOR THE FIRST TIME TO TAKE THIS MODEST PAYLOAD AND FIRE IT AT 17,210 MILES AN HOUR, WHICH IS THE VELOCITY THAT ONE NEEDS TO BE GOING TO REMAIN IN ORBIT AROUND THE EARTH, AND SO ON OCTOBER 4, 1957, THE FIRST ARTIFICIAL SATELLITE SHOCKS THE WORLD.

STEWART: IT WAS NAMED SPUTNIK, AND IT WAS ONLY NOW ORBITING THE EARTH THANKS TO KOROLEV'S CUNNING AND HIS REVOLUTIONARY BREAKTHROUGH IN ROCKET SCIENCE.

GARRIOTT: THIS CONCEPT OF DROPPING YOUR OUTER BOOSTERS, OR THE FIRST STAGE, IS THE ESSENTIAL SOLUTION FOR ANY CHEMICAL ROCKET TO BE ABLE TO REACH ORBIT.

MAN: AND JUST THERE, WE SEE THE FIRST STAGE SEPARATING.

STEWART: KOROLEV'S DESIGN WOULD FORM THE BASIS OF ALMOST ALL RUSSIA'S MANNED ROCKETS, INCLUDING THE SOYUZ, WHICH IS STILL USED TODAY, THE WORKHORSE ROCKET THAT HAS TAKEN HUNDREDS OF PEOPLE INTO SPACE.

GARRIOTT: THAT'S WHY I'M AN ASTRONAUT, SO THAT'S THE CONNECTION.

HA HA HA!

STEWART: IT'S ONE THING TO REACH ORBITAL SPEED AROUND EARTH WITH A SMALL PAYLOAD BUT QUITE ANOTHER TO FLING A GIANT SPACESHIP INTO ORBIT OR TO LEAVE EARTH COMPLETELY AND HEAD FOR, SAY, THE MOON.

TO DO THAT REQUIRED ROCKET SCIENTISTS TO HARNESS A FUEL THEY COULD SQUEEZE EVEN MORE ENERGY OUT OF, AND ONCE MORE, THEY WOULD LOOK TO THE WRITINGS OF KONSTANTIN TSIOLKOVSKY.

WELL, HE'S NOT KNOWN AS THE FATHER OF ROCKETRY FOR NOTHING.

GARRIOTT: WHEN TSIOLKOVSKY WAS CALCULATING HOW TO GET OFF THE EARTH, HE THOUGHT THROUGH EVERY COMBUSTIBLE REACTION HE COULD THINK OF, BURNING EVERY MIXTURE HE COULD IMAGINE, AND ULTIMATELY, HE ARRIVED AT HYDROGEN.

STEWART: THIS IDEA TO USE HYDROGEN TO POWER ROCKETS WAS AS PROFOUND A BREAKTHROUGH AS THE DISCOVERY OF OTHER WORLD'S BEYOND EARTH, AS IT WOULD PROVE TO BE THE KEY TO EVENTUALLY CARRY US TO THEM.

AL-KHALILI: BUT WHY HYDROGEN?

TO ANSWER THAT QUESTION, WE NEED TO RECREATE TSIOLKOVSKY'S THOUGHT EXPERIMENT, WHICH WEIGHED UP THE OPTIONS.

ALL RIGHT.

THAT'S GOT IT.

SO WE'VE PLACED TWO GRAMS OF GUNPOWDER, TWO GRAMS OF GASOLINE, AND TWO GRAMS OF HYDROGEN IN THOSE 3 BARRELS.

THEY'RE ALL MIXED WITH OXYGEN, AND ALL 3 BARRELS WEIGH THE SAME.

POWER IT UP.

POWER IT UP.

PRESS ON.

AS SOON AS THAT RED LIGHT GOES SOLID, WE'RE READY TO FIRE.

RIGHT.

HERE WE GO.

AL-KHALILI: FIRST UP, THE GUNPOWDER... [PING] HA HA!

HA HA HA!

AL-KHALILI: JUST A TINY PUFF OF SMOKE BUT BARELY ANY EFFECT.

NEXT, IT'S THE GASOLINE, WAY BETTER, ENOUGH THRUST TO GET THIS 44-POUND BARREL ROCKET A FEW FEET OFF THE GROUND, BUT WHAT ABOUT THE HYDROGEN?

HA HA HA!

WHOA!

HA HA!

THAT'S BRILLIANT.

AL-KHALILI: HYDROGEN IS THE CLEAR WINNER, WITH JUST TWO GRAMS CARRYING ITS BARREL UP OVER 30 FEET, BUT WHY SUCH A BIG DIFFERENCE IF EACH BARREL WEIGHS THE SAME AND CONTAINS THE SAME AMOUNT OF FUEL?

WHEN IT COMES TO MAXIMIZING ENERGY RELEASE AND ENGINE EFFICIENCY, THEN SIMPLICITY IS BEST.

FUELS LIKE GUNPOWDER, OR EVEN GASOLINE AND KEROSENE, ARE MADE UP OF A NUMBER OF DIFFERENT ELEMENTS WHICH, WHEN THEY BURN, THEY RELEASE CHEMICALS AND THAT WASTES ENERGY, BUT HYDROGEN'S COMBUSTION ONLY PRODUCES WATER, THUS RELEASING MORE ENERGY THAN THE OTHER REACTIONS, IN FACT, THE MOST ENERGY OF ANY COMBUSTION WE KNOW, AND THAT, TSIOLKOVSKY CONCLUDED, WAS WHY IT WOULD BE THE ULTIMATE ROCKET FUEL.

CHANG-DIAZ: TSIOLKOVSKY REALIZED THAT IN THE CASE OF HYDROGEN, THE REACTION IS VERY POWERFUL, HYDROGEN AND OXYGEN, AND THIS IS THE BASIS FOR TODAY'S CHEMICAL ROCKETS THAT PRODUCE A LOT OF HEAT AND, THEREFORE, EJECT THE MATERIAL AS FAST AS POSSIBLE.

MAN: VELOCITY-- 1,300 FEET PER SECOND.

NEIL ARMSTRONG: THAT'S ONE SMALL STEP FOR MAN... STEWART: HYDROGEN FUEL HAS CARRIED US ALL THE WAY TO THE MOON.

ARMSTRONG: ONE GIANT LEAP FOR MANKIND.

STEWART: IT'S LIFTED 400 TONS OF SUPERSTRUCTURE INTO EARTH ORBIT TO BUILD US AN INTERNATIONAL SPACE STATION.

TODAY'S ROCKETS ARE MORE EFFICIENT THAN EVER, THE STAGES DESIGNED TO RETURN TO THE EARTH TO BE USED AGAIN AND AGAIN, BUT WHEN IT COMES TO CHEMICAL ROCKETS, WE'RE AT THEIR LIMIT.

NO FUEL CAN PROPEL US FASTER THAN HYDROGEN.

TO GO FASTER, TO GO FURTHER, THE ROCKET NEEDS A NEW REVOLUTION, AND IT'S A REVOLUTION THAT'S JUST AROUND THE CORNER.

CHANG-DIAZ: WHEN YOU ARE TALKING ABOUT SHOOTING MATERIAL FAST, YOU'RE TALKING ABOUT MAKING THAT MATERIAL HOT.

MAN: 40 SECONDS IN.

CHANG-DIAZ: PROBLEM IS, YOU COME TO A POINT WHERE IF YOU MAKE THE EXHAUST TOO HOT, THEN YOU MELT THE ROCKET.

ENGINEERS HAVE WORKED REALLY HARD TO IMPROVE ON THE MATERIALS, BUT YOU STILL GET TO THE POINT THAT YOU CAN'T GO ABOVE A FEW THOUSAND DEGREES, AND YOU WANT TO GO TO MILLIONS OF DEGREES.

YOU NEED SOMETHING DIFFERENT, SO WE'VE MOVED AWAY FROM CHEMISTRY, AND WE'VE MOVED INTO PLASMA PHYSICS.

STEWART: PLASMA IS ONE OF THE FUNDAMENTAL STATES OF MATTER.

NEITHER A SOLID, A LIQUID, OR A GAS, PLASMAS OCCUR NATURALLY ON EARTH IN THE FORM OF LIGHTNING.

THESE ULTRA HOT SOUPS OF CHARGED PARTICLES ARE USUALLY FOUND IN THE HEART OF STARS...

BUT IN THESE RESEARCH LABS IN HOUSTON, THEY USE ELECTRICAL POWER TO FIRST CREATE PLASMAS AND THEN CONTAIN AND MANIPULATE THEM.

THE REASON THEY DON'T MELT THE MACHINERY IS DUE TO THE FACT THAT THE ELECTRICALLY CHARGED PARTICLES IN THE PLASMA RESPOND TO A MAGNETIC FORCE.

AND WE TAKE ADVANTAGE OF THAT PROPERTY BY CREATING AN INVISIBLE, MAGNETIC PIPE, AND THIS IS ABLE TO HOLD THIS PLASMA AT MILLIONS OF DEGREES, AND THIS PLASMA DOESN'T TOUCH THE SURROUNDING STRUCTURE, SO THE MATERIALS ARE HAPPY.

STEWART: AND THAT MEANS THAT WE CAN DEVELOP NEW ROCKETS, ONES THAT DON'T BURN CONVENTIONAL CHEMICAL FUELS, BUT INSTEAD USE SOLAR POWER TO FIRE ULTRA HOT, ULTRA FAST JETS OF PLASMA TO PROPEL THEMSELVES.

CHANG-DIAZ: AS LONG AS THE MAGNETIC FIELD IS ABLE TO CONTAIN IT, THEN YOU REALLY HAVE NO LIMIT AS TO HOW HOT YOU CAN MAKE IT, WHICH MEANS THAT IT'S MANY MORE TIMES AS FAST AS THE BEST CHEMICAL ROCKET.

STEWART: SOME BELIEVE WE COULD USE PLASMA ROCKETS TO CUT DOWN THE RETURN TRIP FROM MARS FROM 3 YEARS TO JUST 39 DAYS.

CHANG-DIAZ: AND THEN WE WILL HAVE ACCESS TO THE ENTIRE SOLAR SYSTEM.

HUMANITY WILL BE TOTALLY FREE TO GO ANYWHERE THEY WANT.

STEWART: OUR FIRST STEPS INTO THE COSMOS HAVE ONLY JUST BEGUN, BUT WE HAVE ALREADY LIVED CONTINUOUSLY BEYOND EARTH THROUGHOUT THE ENTIRE 21st CENTURY ONBOARD THE INTERNATIONAL SPACE STATION, THE ROCKET TECHNOLOGY WHICH HAS TAKEN US THERE BORN INITIALLY FROM AN AGE OF WARFARE AND FEAR, THE INGENUITY TO OUTRUN EARTH'S GRAVITY BORROWED FROM OTHER INDUSTRIES TO REALIZE THE DREAMS OF SCIENTISTS AND SCIENCE FICTION WRITERS THROUGH THE CENTURIES, AND IN DOING SO, IT HAS CHANGED THE STORY OF WHO WE ARE.

THE ROCKET IS AN INVENTION THAT'S EVOLVED US INTO A SPECIES WHICH IS NO LONGER CONFINED TO EARTH.

BREAKTHROUGHS DON'T GET ANY BIGGER THAN THAT.

STEWART: NEXT TIME ON "BREAKTHROUGH," THE STORY OF THE DEVICE THAT TRANSFORMED THE MODERN WORLD.

IT WOULD TAKE A ROMAN SIEGE, AN UNTIMELY DEATH, A HOLLYWOOD STAR WITH A BRILLIANT MIND, THE CLOAK-AND-DAGGER COMMUNICATIONS OF WORLD WAR II, AND A MISSED VACATION TO CREATE A DEVICE THAT PUT THE WHOLE WORLD IN OUR HANDS--THE SMARTPHONE.

TO ORDER "BREAKTHROUGH: THE IDEAS THAT CHANGED THE WORLD" ON DVD, VISIT SHOPPBS OR CALL 1-800-PLAY-PBS.

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