FINALLY, THIS PAST WEEK ASTRONOMERS AT CAMBRIDGE UNIVERSITY MADE HEADLINES WHEN THEY SAID THEY'D SPOTTED INDICATIONS OF POSSIBLE LIFE ON A DISTANT PLANET, USING DATA FROM THE JAMES WEBB SPACE TELESCOPE.

NOW ANOTHER SPACE-BASED OBSERVATORY THAT'S CHANGED WHAT WE KNOW ABOUT THE UNIVERSE IS RETIRING.

THE EUROPEAN SPACE AGENCY'S CRAFT KNOWN AS GAIA IS LEAVING BEHIND A LEGACY OF STUNNING DISCOVERIES.

GAIA BEGAN ITS WORKING LIFE IN 2013 LAUNCHED WITH A CLEAR MISSION, MAP OUR GALAXY AND TELL ITS STORY THE SPACE OBSERVATORY IS EQUIPPED WITH AN ARRAY OF TELESCOPES AND INSTRUMENTS.

FOR MORE THAN A DECADE IS SLOWLY SPUN ABOUT A MILLION MILES FROM EARTH CHARTING THE PRECISE LOCATIONS OF NEARLY 2 BILLION STARS.

>> I DON'T THINK ANYONE CAN IMAGINE LIVING WITHOUT GAIA.

JOHN: ASTRONOMER ANTHONY BROWN FROM THE NETHERLANDS LEADS GAIA 'S DATA PROCESSING AND ANALYSIS.

>> BECAUSE WE HAVE THE POSITIONS, BRIGHTNESS AND COLOR OF 2 BILLION STARS IN THE SKY, WE CAN MAKE A BEAUTIFUL ALL SKY MAP OF THE MILKY WAY.

JOHN: BUT GAIA HAS CREATED MORE THAN BEAUTIFUL MAPS.

ITS DATA LED TO THE REVELATION THAT 10 BILLION YEARS AGO THE YOUNG MILKY WAY COLLIDED AND MERGED WITH A SMALLER GALAXY.

SCIENTISTS ARE STILL EXPLORING THE COSMIC FALLOUT.

>> A LOT OF STARS ARE STILL AROUND AND WE CAN IDENTIFY THEM THINGS TO GAIA.

JOHN: GAIA COMPLETED ONE OF THE MOSTOMPLICATED CELESTIAL CATALOGS IN HISTORY, REVEALING MORE THAN HALF A MILLION NEW STARS IN A CLUSTER KNOWN AS OMEGA CENTAURI.

MANY ZIPPED THROUGH SPACE AT SEVERAL HUNDRED MILES PER HOUR.

SO FAR GAIA'S DATA HAS BEEN USED IN MORE THAN 13,000 STUDIES.

BROWN USED IT TO CHART THE PATH OF STARS IN OUR NIGHT SKY AND PREDICT THEIR MOVEMENTS FOR THE NEXT 1.6 MILLION YEARS.

ITS DETECTION OF A FAINT WOBBLE AND A STAR L L TO AN ASTROPHYSICIST'S DISCOVERY OF A MASSIVE PLANET MANY LIGHT-YEARS AWAY.

>> STARS ARE MASSIVE AND DO NOT MOVE MUCH IN RESPONSE TO THE GRAVITY OF THE PLANET, BUT THE GAIA SPACECRAFT IS PROVIDING JUST THE KIND OF DATA WE NEED.

JOHN: A CORNELL ASTRONOMER USED THESE FINDINGS TO DETERMINE WHAT PLANETS OUTSIDE OUR SOLAR SYSTEM WOULD HAVE A CLEAR VIEW OF EARTH, PART OF THE SEARCH FOR LIFE ELSEWHERE.

>> MORE THAN 1000 STARS COULD SEE US AND WE KNOW WHICH ONES THERE ARE BECAUSE THE GAIA MISSION GIVE US THAT INFORMATION.

ONE OUT OF FIVE STARS HAS A PLANET THAT IS NOT TOO HOT OR TOO COLD TO POTENTIALLY BE LIKE OURS.

JOHN: A DECADE OF HARD WORK NEARLY EXHAUSTED GAIA'S FUEL.

IT WAS TIME TO SAY GOODBYE.

ITS TEAM ON EARTH SENT THE FINAL COMMANDS TO SHUT IT DOWN AND ALSO SEND PHARAOH MESSAGES WHICH WILL FOREVER BE STORED ON THE SPACECRAFT'S ONBOARD MEMORY.

>> WE ARE HUNDREDS OF PEOPLE, THOUSANDS WHO WORKED TOGETHER.

JOHN: THIS PHYSICIST IS THE PROJECT SCIENTIST.

>> WE ARE WITNESSING SOMETHING DEEP THAT IS ENDING.

THERE WERE MANY EMOTIONS, TEARS.

JOHN: GAIA'S WORK MAY BE DONE, BUT IT LEFT PLENTY TO DO ON EARTH.

RESEARCHERS PROCESSED ONLY ABOUT A THIRD OF THE DATA GATHERED.

>> NEXT YEAR WE WILL PUBLISH ANOTHER BIG DATA RELEASED AND THIS WILL OPEN ANOTHER TREASURE TROVE FOR SCIENTISTS TO EXPLORE.

JOHN: LAST MONTH GAIA'S THRUSTERS FIRED ONE LAST TIME TO SEND IT TOWARD THE MOST FAMILIAR STAR, THE MILKY WAY'S PREMIER CARTOGRAPHER WILL SPEND THE REST OF ITS DAYS ORBITING THE SUN, TAKING A PLACE OF ITS OWN IN OUR NIGHT SKY.

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