[dramatic percussion music]
- HI. WELCOME TO "NASA LAUNCHPAD."
I'M YOUR HOST, VINCE WHITFIELD.
THERE ARE ALL SORTS OF SCIENCES OUT THERE,
MOST OF WHICH YOU HAVE TAKEN IN SCHOOL:
CHEMISTRY, BIOLOGY, ASTRONOMY, PHYSICS.
WELL, YOU GET THE POINT.
BUT THERE'S A NEWCOMER TO THE WORLD OF SCIENCE,
AND IT GOES BY THE NAME OF ASTROBIOLOGY.
AND AS THE NAME SORT OF IMPLIES,
IT'S THE SCIENCE CONCERNED WITH LIFE BEYOND EARTH
BUT ALSO THE ORIGIN AND EVOLUTION OF LIFE ON EARTH.
SINCE THERE IS CURRENTLY NO PROOF OF LIFE
ANYWHERE OTHER THAN EARTH
AND ASTROBIOLOGY IS A STUDY OF LIFE OFF-WORLD,
SCIENTISTS WANT TO SEARCH FOR IT.
BUT HOW?
WELL, THERE ARE CERTAIN INDICATORS
THAT SCIENTISTS LOOK FOR
THAT MAY POINT TO LIFE ELSEWHERE IN THE COSMOS.
ONE YOU'VE PROBABLY HEARD US TALK ABOUT
A LOT HERE ON "NASA LAUNCHPAD" IS WATER.
BUT A SPECIAL INDICATOR
YOU MAY NOT KNOW MUCH ABOUT IS METHANE.
ON EARTH, A HUGE PORTION OF METHANE, OVER 95%,
IS FORMED BY BIOLOGICAL PROCESSES,
AND THE REST OF THE METHANE IS FORMED GEOLOGICALLY,
LIKE WITHIN A VOLCANO.
SO YOU MIGHT BE ASKING YOURSELF,
"WHERE IS ALL THIS METHANE ON EARTH?
COWS, SWAMPS?"
WELL, THOSE ARE SOME OF THE CLICHE ANSWERS.
SO LET'S CHECK IN WITH SOMEONE
WHO HAS A BETTER TAKE ON THE WHOLE THING,
DR. MICHAEL MUMMA, SENIOR SCIENTIST
IN THE SOLAR SYSTEM EXPLORATION DIVISION OF NASA,
WHO CAN FILL US IN ON SOME OF THE BIOLOGICAL REASONS
FOR METHANE ON EARTH.
- ONE OF THE STANDARD QUESTIONS PEOPLE ASK IS,
"HOW IS METHANE FORMED ON EARTH,
AND IS IT ALWAYS COMING FROM COWS?"
[laughs]
ABOUT 95% OF METHANE FOUND IN EARTH'S ATMOSPHERE
ACTUALLY COMES FROM BIOLOGICAL PROCESSES,
NOT NECESSARILY FROM LIVING CREATURES
BUT ALSO FROM DECAY OF THEIR RESIDUE.
THE BURIED ORGANICS--
LIKE, COAL HAS A LOT OF METHANE IN IT,
AND THAT METHANE WAS BIOLOGICALLY PRODUCED.
- PRETTY MUCH ANY LIFE, BE IT PLANT LIFE OR ANIMAL LIFE,
CREATES METHANE AS IT DECAYS.
SO BURIED ORGANICS
LIKE COAL OR ORGANIC WASTE IN LANDFILLS
PRODUCE METHANE AS THEY BEGIN TO BREAK DOWN.
AND, YES, COWS DO PRODUCE METHANE,
AS DO OTHER HOOVED ANIMALS AND EVEN YOU.
METHANOGENS, A SPECIAL TYPE OF EXTREMOPHILE,
OBTAIN THEIR ENERGY
BY MAKING METHANE GAS FROM OTHER ORGANIC COMPOUNDS.
IN YOUR CASE,
THE HARSH CONDITIONS WHERE THESE BACTERIA LIVE
JUST HAPPEN TO BE IN YOUR DIGESTIVE SYSTEM.
THESE PROKARYOTES ARE ALSO FOUND IN DIFFERENT ENVIRONMENTS,
SUCH AS SWAMPS.
COWS AND SWAMPS, JUST LIKE I SAID.
BUT WHAT ABOUT THE OTHER 5% OF METHANE ON EARTH?
WHERE DOES THAT COME FROM?
- YOU CAN ALSO PRODUCE METHANE ON EARTH
BY MEANS OF HOT WATER REACTING WITH HOT ROCK
IN THE MANTLE OF THE EARTH,
DEEP BELOW THE SURFACE, WHERE THE TEMPERATURES ARE HIGH.
- SO IF 95% OF METHANE ON EARTH
IS PRODUCED BY BIOLOGICAL PROCESSES,
IT STANDS TO REASON THAT IF WE FIND METHANE ON ANOTHER PLANET,
WE HAVE INCREASED CHANCE OF FINDING LIFE, RIGHT?
WELL, GUESS WHAT.
SCIENTISTS HAVE RECENTLY FOUND METHANE ON MARS.
- WE'VE ACTUALLY DETECTED METHANE
FROM THREE DISCRETE SOURCE REGIONS ON THE PLANET.
WE DON'T KNOW AT PRESENT
WHICH OF SEVERAL PROCESSES IS RESPONSIBLE FOR THE METHANE,
BUT THERE CAN REALLY ONLY BE TWO PRINCIPAL CANDIDATES.
ONE POSSIBILITY IS THAT THE METHANE,
LIKE MOST METHANE ON EARTH,
IS PRODUCED BY MICROBIAL ACTIVITY.
THESE WOULD BE BACTERIA OR MICROBES, AS WE CALL THEM,
OR ANOTHER DOMAIN OF LIFE CALLED ARCHAEA
THAT MIGHT STILL BE LIVING BELOW THE SURFACE OF MARS,
WHERE THEY'RE PROTECTED
FROM THE INTENSE RADIATION FIELD OF THE SUN
AND ALSO FROM COSMIC RAYS
AND COULD NOW BE PROSPERING AND RELEASING METHANE
INTO THE ATMOSPHERE.
ON THE OTHER HAND, IT COULD BE THAT MARS
IS NOT A TOTALLY DEAD PLANET GEOCHEMICALLY.
IT MAY STILL HAVE SOME INTERNAL ACTIVITY.
ONE SIGNATURE OF SUCH ACTIVITY
WOULD BE TO SEE METHANE THAT'S BEING PRODUCED
BY A CHEMICAL PROCESS
IN WHICH ONE FORM OF IRON OXIDE IS CONVERTED TO ANOTHER.
THIS HAPPENS ON EARTH IN SEVERAL DISCRETE PLACES.
AND SO WE ARE LOOKING DISTINCTLY FOR THIS ON MARS.
- SO HOW IS IT THAT SCIENTISTS LIKE DR. MUMMA
ARE ABLE TO FIND METHANE
IN THE ATMOSPHERE OF A DISTANT PLANET?
WELL, IT'S A VERY INVOLVED PROCESS,
BUT THE SIMPLE ANSWER IS SPECTROSCOPY.
WHEN LIGHT FROM THE SUN HITS THE PLANET'S SURFACE,
SOME OF THAT LIGHT IS REFLECTED BACK INTO SPACE.
SPECTROMETER INSTRUMENTS ATTACHED TO TELESCOPES IN HAWAII
CAPTURED SOME OF THAT REFLECTED LIGHT
AND SEPARATED IT INTO ITS COMPONENT COLORS.
THE RESULT WAS A SPECTRUM WITH MISSING WAVELENGTHS
WHERE GASES IN MARS' ATMOSPHERE ABSORBED EXTRA SUNLIGHT.
AS A RESULT, THE SCIENTISTS HAVE OBSERVED AND MAPPED
SEVERAL METHANE PLUMES ON THE RED PLANET.
BECAUSE METHANE IS QUICKLY DESTROYED
IN THE MARTIAN ATMOSPHERE,
THE DISCOVERY OF THESE PLUMES MEANS THAT SOME ONGOING PROCESS
IS RELEASING THE GAS.
USING SPECTROSCOPY,
SCIENTISTS CAN THEORETICALLY DETERMINE
WHAT THE ATMOSPHERE ON ANY PLANET IS MADE OF
BY SEEING WHICH KEY WAVELENGTHS
IN THE REFLECTED LIGHT ARE MISSING.
BUT THE ANSWERS FOR WHERE THE GASES ARE COMING FROM
WILL BE LEFT UP TO FUTURE NASA MISSIONS
LIKE THE MARS SCIENCE LABORATORY
AND ITS ROVER, APPROPRIATELY NAMED "CURIOSITY."
THIS IS SOME PRETTY EXCITING STUFF, FOLKS,
AND IT'S ONLY GOING TO GET MORE INTERESTING.
SCIENTISTS ARE LOOKING FOR ANSWERS TO QUESTIONS
THAT COULD POTENTIALLY CHANGE THE WAY WE VIEW LIFE
AS WE KNOW IT.
- OF COURSE, LIKE MOST PEOPLE ON EARTH
WHO EVER THINK BEYOND THEIR OWN LOCAL ENVIRONMENT,
ONE ALWAYS WONDERS, "HOW DID LIFE COME TO BE?
"WHAT WAS THE PATH OF EVOLUTION OVER TIME?
HOW DID WE EVOLVE?" AND SO FORTH AND SO ON.
BUT THE OTHER QUESTION IS, HOW DO PLANETS EVOLVE?
WHICH ONES WILL BE LIFE-BEARING?
WERE MICROBES TRANSFERRED FROM MARS TO EARTH
OR EARTH TO MARS
IN THE EARLY PHASE OF OUR SYSTEM,
WHEN PLANETS WERE BEING BOMBARDED BY LARGE BODIES
AND TRANSFERRING MATERIAL BACK AND FORTH?
SO IF I WERE A HIGH SCHOOL STUDENT TODAY
AND I HAD AN INTEREST IN THE ORIGIN OF LIFE,
I WOULD HAVE TO THINK THAT ONE OF THE MOST COMPELLING THINGS
THAT ONE COULD IMAGINE IS TO BE A PART OF THAT SEARCH.
- WOW, COUNT ME IN.
BUT THAT'S ALL THE TIME WE HAVE NOW
FOR THIS EPISODE OF "NASA LAUNCHPAD."
UNTIL NEXT TIME, I'M VINCE WHITFIELD.
CHEERS.