[dramatic percussion music]
- HI THERE, AND WELCOME TO "NASA LAUNCHPAD."
I'M YOUR HOST, MOLLY.
WHAT DO YOU KNOW ABOUT RADIOISOTOPE POWER SYSTEMS?
[crickets chirping]
NOT EVEN SURE WHAT AN R.P.S. IS?
WELL, YOU MAY HAVE HEARD OF
THE VOYAGER MISSION TO THE OUTER PLANETS
OR THE ONGOING CASSINI MISSION TO SATURN.
AND WE CAN'T LEAVE OUT NEW HORIZONS,
THE NASA SPACECRAFT
THAT IS SPEEDING ON ITS WAY TO PLUTO.
ALL OF THESE AMAZING NASA MISSIONS
TO EXPLORE THE SOLAR SYSTEM
HAVE BEEN MADE POSSIBLE
BY THE USE OF RADIOISOTOPE POWER SYSTEMS,
OR R.P.S. FOR SHORT.
AN R.P.S. IS A UNIQUE POWER SYSTEM
THAT PROVIDES ELECTRICITY
USING HEAT FROM THE NATURAL DECAY
OF THE RADIOISOTOPE PLUTONIUM-238.
RADIOISOTOPE POWER CAN SIGNIFICANTLY ENHANCE
THE ABILITY OF SOLAR SYSTEM EXPLORATION MISSIONS
TO MEET THEIR SCIENTIFIC AND OPERATIONAL GOALS.
USUALLY THESE POWER SYSTEMS ENABLE SPACE MISSIONS TO HAPPEN
THAT JUST WOULDN'T WORK WITHOUT THEM.
IN PARTICULAR, AN R.P.S. PROVIDES A CONTINUOUS,
LONG-LIVED POWER SOURCE
THAT'S IDEAL FOR MISSIONS TO PLACES THAT ARE DARK, DUSTY,
OR HAVE EXTREME TEMPERATURE FLUCTUATIONS,
WHERE SOLAR PANELS OR BATTERIES ALONE
MIGHT NOT BE THE BEST CHOICE.
- WELL, RADIOISOTOPE POWER SYSTEM TECHNOLOGY
ALLOWS US TO GO TO THE FURTHEST REACHES OF THE SOLAR SYSTEM
AS WELL AS OTHER PLACES IN THE SOLAR SYSTEM
WHERE THE SUN'S ENERGY
JUST CAN'T BE USED FOR SPACECRAFT POWER.
SO WE WANT TO BRING A DIFFERENT ENERGY SOURCE WITH US.
SO OUT IN THE JUPITER, SATURN, URANUS, NEPTUNE RANGE,
YOU WOULD WANT TO USE RADIOISOTOPE POWER.
- SO KNOWING THAT,
YOU MIGHT NOT BE SURPRISED
THAT WE HAVE BEEN USING THIS TECHNOLOGY
TO POWER SPACE PROBES FOR 50 YEARS.
- SPACECRAFT THAT ARE POWERED BY RADIOISOTOPE POWER SYSTEMS
HAVE BEEN AN INTEGRAL PART OF OUR EXPLORATION
SINCE THE VERY BEGINNING.
AND THIS IS BECAUSE THEY PROVIDE SUCH STEADY AND RELIABLE POWER
OVER THE COURSE OF AN ENTIRE MISSION,
WHICH CAN GO BEYOND 30 YEARS.
WE LIKE TO SEND SPACECRAFT WITH RADIOISOTOPE POWER SYSTEMS
INTO THE PLACES OF THE SOLAR SYSTEM
WHERE THERE'S VERY LOW LIGHT.
WHEN WE WANT TO GO FAR AWAY FROM THE SUN,
THE SUNLIGHT IS GONNA GET DIMMER AND DIMMER.
IT'S JUST LIKE WHEN YOU LEAVE YOUR HOUSE AT NIGHT,
WHEN YOU SEE YOUR PORCH LIGHT
AND IT GETS DIMMER AND DIMMER AS YOU DRIVE AWAY.
THAT'S JUST HOW IT IS AS THE SPACECRAFT TAKES OFF
TOWARDS JUPITER, SATURN, URANUS, AND NEPTUNE.
SO WE NEED RADIOISOTOPE POWER SYSTEMS
TO PROVIDE A RELIABLE, STEADY SOURCE OF HEAT
THAT WE THEN CONVERT INTO ELECTRICITY
THAT PROVIDES THE POWER FOR THESE MISSIONS
AS THEY GO ON THEIR OUTWARD JOURNEY
ACROSS THE SOLAR SYSTEM.
- THE POWER SOURCE FOR AN R.P.S. PRODUCES HEAT FOR A LONG TIME.
THAT MEANS AN R.P.S. CAN PROVIDE POWER
FOR LONG-LASTING SPACE MISSIONS,
LIKE THE VOYAGER SPACECRAFT.
LAUNCHED BACK IN 1977,
THE TWO VOYAGERS ARE THE LONGEST CONTINUALLY OPERATING SPACECRAFT
IN DEEP SPACE.
AFTER TRAVELING AT TENS OF THOUSANDS OF MILES PER HOUR
FOR MORE THAN 30 YEARS,
THEY'VE ACTUALLY REACHED, WELL,
BASICALLY THE EDGE OF OUR SOLAR SYSTEM.
BOTH CRAFT ARE STILL SENDING BACK DATA
AS THEY HURTLE TOWARD INTERSTELLAR SPACE--
THE SPACE BETWEEN THE STARS.
THESE SPACECRAFT REALLY HAVE GONE
WHERE NO ONE HAS GONE BEFORE.
AND RIGHT NOW, THEY'RE HELPING US
LEARN MORE ABOUT THE EDGES OF OUR SOLAR SYSTEM.
NASA GROUND CONTROLLERS
RECENTLY COMMANDED ONE OF THE VOYAGERS
TO ROTATE IN SPACE FOR THE FIRST TIME IN 20 YEARS
TO MAKE A CERTAIN KIND OF SCIENTIFIC MEASUREMENT,
AND THE SPACECRAFT RESPONDED PERFECTLY.
THE REASON THEY STILL HAVE POWER IS THANKS TO R.P.S. TECHNOLOGY.
TRY FINDING A BATTERY
THAT'LL HOLD A CHARGE AFTER THREE YEARS OF USE,
LET ALONE THREE DECADES.
VOYAGER 1 AND 2 ARE NOT THE FIRST SPACECRAFT
TO USE R.P.S. TECHNOLOGY,
NOR ARE THEY THE LAST.
MORE THAN 20 NASA MISSIONS HAVE USED THIS TECHNOLOGY.
PIONEER 10 USED AN R.P.S.
TO FLY THROUGH THE ASTEROID BELT,
MAKING OUR FIRST DIRECT OBSERVATIONS OF JUPITER.
AND GALILEO GAVE US
OUR FIRST CLOSE-UP RENDEZVOUS WITH AN ASTEROID
AND WAS NEARBY TAKING PICTURES
WHEN A COMET SMASHED INTO JUPITER.
THE ULYSSES MISSION FLEW OVER THE SUN'S POLES
TO HELP US LEARN MORE ABOUT SOLAR FLARES.
EVEN THE APOLLO ASTRONAUTS USED R.P.S. TECHNOLOGY
TO POWER SCIENCE EXPERIMENTS THEY LEFT BEHIND
ON THE SURFACE OF THE MOON.
AT SATURN, THE CASSINI MISSION ALSO MAKES USE OF R.P.S.
AT SATURN'S DISTANCE FROM THE SUN,
WHICH IS TEN TIMES FARTHER AWAY THAN EARTH,
SOLAR POWER ISN'T A PRACTICAL OPTION--AT LEAST NOT YET.
BUT THANKS TO R.P.S. TECHNOLOGY,
WE CAN CONTINUE TO RECEIVE AMAZING IMAGES LIKE THESE.
CASSINI'S INCREDIBLY SUCCESSFUL MISSION HAS BEEN EXTENDED TWICE,
AND IT STILL HAS POWER TO EXPLORE.
IT WILL HAVE OPERATED IN SPACE FOR 20 YEARS
BY THE TIME THE MISSION ENDS IN 2017.
THERE'S ANOTHER BENEFIT TO USING R.P.S.
SOME OF THE EXCESS HEAT FROM THE POWER SYSTEM
CAN BE USED TO KEEP VITAL PARTS OF A SPACECRAFT WARM
SO THEY CAN OPERATE IN COLD PLACES LIKE DEEP SPACE
OR THE FRIGID SURFACE OF MARS.
OF COURSE NASA WANTS TO USE THE BEST POWER SYSTEM
FOR ANY MISSION IT LAUNCHES,
AND SAFETY IS THE FIRST OF NASA'S CORE VALUES.
RADIOISOTOPE POWER SYSTEMS
ARE A TYPE OF NUCLEAR TECHNOLOGY,
SO HOW SAFE ARE THEY?
- SAFETY IS A KEY FACTOR IN THE DESIGN
OF ALL RADIOISOTOPE POWER SYSTEMS.
WE DESIGN SAFETY FROM THE INSIDE OUT
AND THE OUTSIDE IN
OF ALL RADIOISOTOPE POWER SYSTEMS.
WE BEGIN WITH THE RADIOISOTOPE FUEL ITSELF,
PLUTONIUM-238 DIOXIDE,
WHICH IS A CERAMIC MATERIAL.
IT'S INSOLUBLE AND BREAKS INTO LARGE PIECES WHEN IMPACTED.
NEXT, WE HAVE THE IRIDIUM CLADDING,
WHICH SURROUNDS THE PLUTONIUM FUEL.
THE IRIDIUM IS DUCTILE.
IT'S VERY STRONG, AND IT HAS A HIGH MELTING TEMPERATURE.
SURROUNDING THE IRIDIUM IS A CARBON MATERIAL.
IT'S VERY TOUGH,
AND IT ALSO PROTECTS AGAINST FIRES
AND THE HEAT OF REENTRY.
THE DEPARTMENT OF ENERGY AND ITS PREDECESSOR AGENCIES
HAVE BEEN INVOLVED WITH-- FOR OVER 50 YEARS
IN DEVELOPING SPACE R.P.S. WITH NASA AND NAVY, AIR FORCE.
- COMBINING TECHNOLOGY WITH KNOW-HOW--
AND THE RESULT IS AN R.P.S.
THAT MAKES POWER USING THE HEAT FROM ITS PLUTONIUM FUEL SOURCE,
WORKS IN ALL KINDS OF EXTREME ENVIRONMENTS,
AND LASTS A REALLY LONG TIME.
AND FOR SOME OF NASA'S MOST POPULAR
AND EXCITING SPACE MISSIONS,
R.P.S. TECHNOLOGY HAS BEEN AND REMAINS
AN ABSOLUTE NECESSITY.
- I THINK THE FUTURE FOR US
IS VERY BRIGHT, VERY INTERESTING.
WE HAVE A LOT OF PLACES TO GO IN THE SOLAR SYSTEM.
WE NEED TO BRING RADIOISOTOPE POWER SYSTEMS ALONG
TO BE ABLE TO GO UNDERSTAND
THE ICE SURFACE OF JUPITER'S MOON EUROPA.
WE'D LIKE TO GO OUT TO THE ICY MOON OF SATURN
THAT'S KNOWN AS ENCELADUS.
WE WOULD THINK THAT WOULD BE A FROZEN BALL OF ICE,
BUT WE FIND IT'S ACTUALLY GEOLOGICALLY ACTIVE
AND THERE'S WATER AND VOLATILE SPEWING OUT OF ITS SOUTH POLE.
ALSO OUT AT SATURN IS THE GIANT MOON TITAN,
WHICH HAS A HAZY ATMOSPHERE AND LIQUID HYDROCARBON LAKES.
WE'D LIKE TO SEND A SPACECRAFT THERE.
AND THEN AS WE TRAVEL EVEN FURTHER OUT,
WE COME TO THE KUIPER BELT
WHERE THERE'S A MYRIAD OF SMALL BODIES
THAT ARE VERY PRIMITIVE LEFTOVER BUILDING BLOCKS
FROM THE FORMATION OF THE SOLAR SYSTEM.
- SOME PAST NASA MISSIONS
WOULD NOT HAVE BEEN THE SUCCESS THEY WERE
WITHOUT THE USE OF R.P.S.
IN FACT WITHOUT IT,
WE WOULDN'T HAVE HAD THIS REVEALING PICTURE
OF MARS' SURFACE IN 1976
OR THIS PANORAMIC VIEW FROM THE FAR SIDE OF SATURN
OR EVEN THIS GLIMPSE OF EARTH FROM 4 BILLION MILES AWAY
OR ANY OF THESE DOZENS OF IMAGES.
WE WOULDN'T HAVE ANY OF THESE WITHOUT R.P.S.
SO RADIOISOTOPE POWER SYSTEMS LEAD TO ANOTHER KIND OF R.P.S.,
REALLY PRODUCTIVE SPACECRAFT.
THAT'S IT FOR THIS EPISODE.
THANKS FOR WATCHING.
I'M MOLLY,
AND I'LL CATCH YOU NEXT TIME ON "NASA LAUNCHPAD."