Curious About Satellites

PODCAST 213: CURIOUS ABOUT SATELLITES

RELEASE DATE: SUNDAY, OCTOBER 30TH, 2022

D:  HELLO, AND WELCOME BACK TO THE CURIOUS KID PODCAST.  BELIEVE IT OR NOT, THERE ARE OBJECTS THAT WE CAN’T SEE FROM HERE ON EARTH THAT HELP US DO THINGS EACH AND EVERY DAY.  WHEN YOU WOKE UP THIS MORNING, CHANCES ARE THAT YOU OR A GROWNUP CHECKED THE FORECAST TO SEE WHAT YOU SHOULD WEAR TODAY.  WILL IT BE WARM OR COLD?  WILL YOU HAVE RAIN OR SNOW?  IF YOU ARE LISTENING TO THIS EPISODE WHILE ON A LONG CAR DRIVE, AS MANY OF OUR LISTENERS LOVE TO DO, PERHAPS YOU ARE USING GPS TO GET YOU WHERE YOU NEED TO BE.  WELL, THERE ARE THESE AMAZING OBJECTS RESPONSIBLE FOR WEATHER FORECASTS AND FOR GPS THAT WE CAN’T SEE.  NOT BECAUSE THEY AREN’T THERE, BUT BECAUSE THEY ARE REVOLVING AROUND EARTH HIGH IN THE SKY.  LET’S LEARN MORE.

O:  DOUBLE-MAILBAG!

D:  DOUBLE-MAILBAG!

“HI OLIVIA AND JACOB, OUR NAMES ARE NOLAN (9), EASTON (8), AND JACKSON (6).  WE LIVE IN CANTON, MICHIGAN.  WE LOVE YOUR SHOW SO MUCH.  WE LISTEN TO YOU EVERY DAY ON THE WAY TO SCHOOL.  WE ARE VERY CURIOUS ABOUT SATELLITES.  HOW DO THEY GET UP THERE?  WHAT DO SATELLITES DO UP THERE?

THANK YOU, FROM NOLAN, EASTON, AND JACKSON”

“HI, MY NAME IS YVES AND I AM FOUR YEARS OLD.  I’M CURIOUS ABOUT SATELLITES.  HOW DO SATELLITES SEE?  HOW DO YOU LAUNCH THEM INTO SPACE?  AND WHAT MATERIALS ARE THEY MADE OF?  I WOULD LOVE IF YOU COULD DO A PODCAST ABOUT THIS.  I LOVE YOUR PODCAST.  

YVES, OF SAN FRANCISCO, CALIFORNIA”

O:  WHAT AN AWESOME EPISODE TOPIC SUGGESTION.  WE CAN’T WAIT TO LEARN MORE ABOUT SATELLITES FOR NOLAN, EASTON, JACKSON, AND YVES.  

D:  THERE IS SO MUCH TO LEARN ABOUT SATELLITES, SO LET’S KICK THINGS OFF WITH THE QUESTION OF THE WEEK.

O:  IN ORDER FOR SATELLITES TO STAY IN SPACE, THEY NEED TO TRAVEL REALLY FAST.  THE SPEED THEY NEED TO MAINTAIN IS CALLED A SATELLITE’S ORBITAL VELOCITY.  CAN YOU GUESS HOW FAST SATELLITES NEED TO TRAVEL IN ORDER TO STAY UP IN SPACE?

D:  WHILE YOU’RE THINKING ABOUT THE ANSWER, LET’S START LEARNING ABOUT SATELLITES.  I THINK THE DEFINITION OF A SATELLITE WOULD BE A GREAT PLACE TO START.

O:  A SATELLITE IS AN OBJECT THAT ORBITS, OR TRAVELS AROUND, ANOTHER OBJECT.  THERE ARE NATURAL SATELLITES, WHICH ARE SATELLITES THAT WEREN’T CREATED BY HUMANS.  THE MOON IS A NATURAL SATELLITE, BECAUSE IT IS AN OBJECT THAT TRAVELS AROUND THE EARTH.

D:  AND THERE ARE ALSO ARTIFICIAL SATELLITES, WHICH ARE SATELLITES THAT WERE MADE BY HUMANS.  MANY ARTIFICIAL SATELLITES ALSO ORBIT THE EARTH, BUT THERE ARE ALSO SATELLITES THAT ORBIT OTHER PLANETS LIKE MARS AND VENUS.

O:  THE FIRST ARTIFICIAL SATELLITE WAS CALLED SPUTNIK.  IT WAS LAUNCHED BY THE SOVIET UNION 65 YEARS AGO, BACK ON OCTOBER 4TH, 1957.  JUST A MONTH LATER, THEY LAUNCHED ANOTHER SATELLITE, CALLED SPUTNIK 2.  THE SECOND SATELLITE WAS MUCH DIFFERENT FROM THE FIRST, BECAUSE THERE WAS A LIVING PASSENGER ON THAT SATELLITE.  IT WAS A DOG NAMED LAIKA.

D:  THE REST OF THE WORLD WAS SHOCKED WHEN THE SOVIET UNION STARTED LAUNCHING SATELLITES INTO SPACE.  OTHER COUNTRIES WERE VERY EAGER TO GET THEIR FIRST SATELLITES INTO ORBIT.  

O:  THE UNITED STATES LAUNCHED IT’S FIRST SATELLITE JUST THREE MONTHS AFTER THE ORIGINAL SPUTNIK, IN JANUARY OF 1958.

D:  AND THEN, JUST FOUR YEARS LATER, THE UNITED KINGDOM LAUNCHED IT’S FIRST SATELLITE AS WELL.  IN THE 65 YEARS SINCE SPUTNIK WAS LAUNCHED, THOUSANDS AND THOUSANDS OF SATELLITES HAVE BEEN LAUNCHED INTO ORBIT BY MORE THAN 50 DIFFERENT COUNTRIES, AND MANY OF THEM STILL ORBIT THE EARTH.        

O:  OF THE THOUSANDS OF SATELLITES IN SPACE RIGHT NOW, ONLY A FEW HUNDRED ARE CURRENTLY BEING USED.  THE OTHER ONES ARE NOT BEING USED ANY MORE, BUT THEY CONTINUE TO ORBIT EARTH.

D:  THE LARGEST ARTIFICIAL SATELLITE IS THE INTERNATIONAL SPACE STATION.  AT ANY GIVEN TIME, THERE ARE USUALLY SIX ASTRONAUTS AT THE INTERNATIONAL SPACE STATION, ALTHOUGH THE CREW CHANGES OFTEN.  

O:  MANY OF THE MAN-MADE SATELLITES ARE LOCATED IN WHAT IS CALLED LOW EARTH ORBIT.  DON’T BE FOOLED BECAUSE THEY ARE STILL WAY UP THERE IN THE SKY.  LOW EARTH ORBIT JUST MEANS THAT THEY ARE LESS THAN ONE THOUSAND KILOMETERS ABOVE GROUND.  

D:  LIKE WE SUGGESTED IN THE QUESTION OF THE WEEK, SATELLITES HAVE TO TRAVEL SIDEWAYS AT A REALLY FAST SPEED TO AVOID THE FORCE OF GRAVITY TAKING THEM DOWN.

O:  SATELLITES IN LOW ORBIT ARE GOOD FOR LOTS OF DIFFERENT TASKS, INCLUDING TAKING STUNNING PICTURES OF EARTH.  IT TAKES THESE SATELLITES LESS THAN TWO HOURS TO ORBIT THE EARTH.   

D:  BEYOND LOW ORBIT SATELLITES ARE MEDIUM ORBIT SATELLITES.  SATELLITES IN MEDIUM ORBIT ARE ABOUT TEN TIMES HIGHER UP THAN LOW EARTH ORBIT SATELLITES.  GPS SATELLITES ARE USUALLY IN MEDIUM ORBIT.    

O:  THE COOL THING ABOUT MEDIUM ORBIT SATELLITES IS THAT THEY PASS ABOVE THE SAME POINTS ON THE EQUATOR AT THE SAME TIMES EACH DAY.  

D:  THAT MAKES THEIR ORBITS SEMI-SYNCHRONOUS.  THEY ARE ABLE TO TRAVEL ABOVE THE SAME SPOTS AT THE SAME TIMES EACH DAY BECAUSE IT TAKES THEM 12 HOURS TO ORBIT EARTH.

O:  FINALLY, THERE ARE HIGH EARTH ORBIT SATELLITES THAT TRAVEL ABOUT 22,000 MILES, OR 36,000 KILOMETERS ABOVE THE EARTH’S SURFACE.  THAT ALLOWS THEM TO TRAVEL AROUND EARTH EXACTLY ONCE A DAY, RETURNING TO THE SAME SPOT AT EXACTLY THE SAME TIME EACH DAY.  WEATHER SATELLITES ARE OFTEN IN HIGH ORBIT.  

D:  OUR LISTENERS FROM MICHIGAN AND CALIFORNIA WANTED TO KNOW HOW THE SATELLITES GET INTO SPACE.

O:  THEY USUALLY GET THERE BY BEING LAUNCHED ON ROCKETS.  EVEN THOUGH MORE THAN 50 COUNTRIES HAVE PUT SATELLITES INTO SPACE, THERE ARE ONLY 11 COUNTRIES THAT ARE CAPABLE OF LAUNCHING THEM.  

D:  THE 11TH COUNTRY TO LAUNCH A SATELLITE INTO SPACE DID IT FOR THE FIRST TIME IN JUNE OF THIS YEAR.  THAT COUNTRY WAS SOUTH KOREA.  

NOW THAT WE’VE LEARNED ABOUT WHAT SATELLITES ARE AND SOME OF THE HISTORY ON SATELLITES, LETS LEARN MORE ABOUT THE PARTS OF A SATELLITE AND HOW THEY WORK.

O:  ARTIFICIAL SATELLITES USUALLY HAVE TWO MAIN COMPONENTS.  ONE IS THE ANTENNA.  THE ANTENNA ALLOWS THE SATELLITE TO SEND AND RECEIVE INFORMATION.  THE OTHER MAIN COMPONENT IS A POWER SOURCE.  

D:  THAT’S RIGHT.  YOU CAN’T PLUG YOUR SATELLITE INTO THE WALL WHEN IT’S TRAVELING SUPER FAST IN SPACE.  TYPICAL BATTERIES ALSO WOULDN’T LAST VERY LONG.  FOR THAT REASON, SATELLITES USE DIFFERENT POWER SOURCES, LIKE SOLAR POWER, TO KEEP THEM WORKING.  

O:  DIFFERENT SATELLITES WORK IN SLIGHTLY DIFFERENT WAYS.  WE ARE GOING TO LEARN HOW COMMUNICATIONS SATELLITES WORK, BECAUSE THEY ARE USED TO BOUNCE IMPORTANT INFORMATION LIKE RADIO, TV, AND INTERNET DATA FROM ONE SIDE OF THE EARTH TO THE OTHER.  

D:  HAVE YOU EVER WONDERED HOW YOU ARE ABLE TO WATCH A SPORTING EVENT HAPPENING FAR FAR AWAY FROM YOUR HOME AS IT’S HAPPENING?  

O:  WELL, FIRST, THERE’S SOMETHING CALLED AN UPLINK.  DATA IS BEAMED FROM THE SOURCE ON THE GROUND UP TO THE SATELLITE.  

D:  THE SATELLITE WILL THEN PROCESS THE DATA USING TRANSPONDERS.  THE TRANSPONDERS ARE ABLE TO BOOST THE SIGNALS AND ALSO CHANGE THEIR FREQUENCY.  IT’S IMPORTANT FOR THE FREQUENCIES TO BE CHANGED, SO THAT THE INCOMING SIGNALS DON’T GET MIXED UP WITH OUTGOING SIGNALS.

O:  AFTER THAT, THE DOWNLINK SENDS DATA BACK TO ANOTHER GROUND STATION ON EARTH.  

D:  THIS MEANS THAT THERE IS USUALLY ONLY ONE UPLINK, WHILE THERE COULD BE MILLIONS OF DOWNLINKS, IF MILLIONS OF TELEVISIONS ARE TUNED INTO THE SAME SATELLITE TV SIGNAL.  

O:  AND ALL OF THIS HAPPENS SUPER QUICK, ALLOWING PEOPLE TO WITNESS SOMETHING HAPPENING ON THE OTHER SIDE OF THE EARTH ALMOST IN REAL TIME, AS IT’S HAPPENING.

D:  SO, WE’VE ALREADY LEARNED THAT THE PARTS OF A SATELLITE CAN BE BROKEN DOWN INTO TWO MAJOR GROUPS, THE ANTENNA AND THE POWER SOURCE.  THERE IS ANOTHER WAY OF GROUPING THE PARTS OF A SATELLITE.

O:  YOU CAN THINK OF A SATELLITE AS HAVING A VEHICLE AND A PAYLOAD.  THE VEHICLE OF A SATELLITE, WHICH IS ALSO CALLED THE BUS, INCLUDES THINGS LIKE THE OUTER CASE, THE POWER SOURCE, AND ROCKET THRUSTERS THAT HELP KEEP THE SATELLITE IN POSITION.  THE BUS HOLDS EVERYTHING TOGETHER, AND IT ALSO NEEDS TO BE STRONG ENOUGH TO SURVIVE THE LAUNCH. 

D:  THE PAYLOAD IS THE PART OF THE SATELLITE WHICH HELPS IT DO IT’S UNIQUE JOB.  IT INCLUDES THINGS LIKE CAMERAS AND COMPUTERS.  

O:  SATELLITES CAN BE MADE FROM LOTS OF DIFFERENT MATERIALS, BUT THE TWO MATERIALS YOU WILL SEE MOST FREQUENTLY IN SATELLITES ARE ALUMINUM AND TITANIUM.  THESE MATERIALS ARE USED BECAUSE THEY ARE LIGHTWEIGHT, AND THEY ARE ALSO ABLE TO SURVIVE THE HARSH CONDITIONS IN SPACE.

D:  YOU MAY BE WONDERING WHAT HAPPENS TO SATELLITES THAT ARE NO LONGER IN USE.  AFTER ALL, MOST OF THE SATELLITES IN SPACE ARE NO LONGER ACTIVE.

O:  ONE OF THE THINGS WE CAN DO WITH INACTIVE SATELLITES IS SLOW THEM DOWN SO THAT THEY FALL BACK TO EARTH.  WHEN THIS HAPPENS, THE SATELLITE WILL ACTUALLY BURN UP IN THE ATMOSPHERE AS IT’S FALLING.  THAT’S PRETTY NEAT.

D:  THIS IS DONE BY ENGINEERS THAT CHANGE THE ORBIT OF THE SATELLITE A LITTLE SO THAT THE SATELLITE FALLS AND BURNS ON IT’S OWN OVER THE COURSE OF 25 YEARS AFTER IT’S MISSION IS COMPLETE.  IF THE SATELLITE IS TOO BIG TO DO THIS, THE SATELLITE IS DE-ORBITED, SO THAT IT FALLS BACK TO EARTH IN AN AREA FAR FROM CIVILIZATION.  ONE SUCH AREA EVEN HAS THE NICKNAME “THE SPACECRAFT CEMETERY”.  IT’S LOCATED IN THE SOUTHERN PART OF THE PACIFIC OCEAN.  

O:  A SECOND THING WE CAN DO IS PUSH THE SATELLITE INTO A HIGHER ORBIT, KEEPING IT FAR AWAY FROM THE SATELLITES THAT ARE STILL WORKING.  THIS HELPS PREVENT COLLISIONS IN THE INCREASINGLY CROWDED ORBITS WHERE MANY SATELLITES TRAVEL.  

D:  THE ORBIT WHERE THE INACTIVE SATELLITES ARE PUSHED TO ALSO GOES BY SOME INTERESTING NICKNAMES, SUCH AS JUNK ORBIT, DISPOSAL ORBIT, OR GRAVEYARD ORBIT.  IT’S LOCATED WELL OVER 22,000 MILES, OR 36,000 KILOMETERS, ABOVE EARTH.  THAT MEANS THAT IT’S FAR FROM ANY ACTIVE SATELLITES.  

ALRIGHT OLIVIA, IT’S TIME TO ANSWER THE QUESTION OF THE WEEK.   ORBITAL VELOCITY DESCRIBES HOW FAST A SATELLITE NEEDS TO BE MOVING TO FIGHT THE DOWNWARD PULL OF GRAVITY.  WHAT’S THE CRAZY, TOTALLY INSANE, SPEED THAT SATELLITES NEED TO ACHIEVE TO STAY IN ORBIT?

O:  ORBITAL VELOCITY IS ABOUT 17,000 MILES PER HOUR, OR 27,000 KILOMETERS PER HOUR.  JUST TO GIVE YOU AN IDEA OF HOW FAST THAT IS, AIRPLANES USUALLY FLY AT A CRUISING SPEED OF ABOUT 550 MILES PER HOUR, OR 900 KILOMETERS PER HOUR.  

D:  MAINTAINING ORBITAL VELOCITY IS VERY IMPORTANT.  IF A SATELLITE’S SPEED IS TOO SLOW, GRAVITY WILL PUT IT DOWN TO EARTH.  IF IT’S TOO FAST, THE SATELLITE WILL FLY OFF INTO SPACE, LEAVING THE GRAVITATIONAL PULL OF EARTH.  WELL, THAT’S A WRAP FOR THIS WEEK’S EPISODE.

O:  213 - SATELLITES

D:  GREAT JOB OLIVIA, AND GREAT JOB NOLAN, EASTON, JACKSON, AND YVES FOR THE SPACY EPISODE TOPIC SUGGESTION.  BEFORE WE SAY GOODBYE, WE HAVE SOME AWESOME PEOPLE TO THANK.

O:  WE WANT TO THANK OUR NEWEST PATREON SUPPORTERS, CHARLOTTE D. AND OLIVER B.

D:  A BIG THANKS TO CHARLOTTE AND OLIVER FOR THE SUPPORT.  OUR PATREON SUPPORTERS HAVE ACCESS TO HOURS OF EXTRA CURIOUS KID PODCAST CONTENT, AND THEY ALSO GET MONTHLY NEWSLETTERS LETTING THEM KNOW WHAT WE’RE WORKING ON AT CURIOUS KID PODCAST HEADQUARTERS.  JOIN US NEXT WEEK, WHEN WE WILL GET CURIOUS ABOUT CHOCOLATE FOR LISTENERS IN MASSACHUSETTS, CALIFORNIA, AND INDIA.  AS ALWAYS, THANK YOU SO MUCH FOR LISTENING AND GETTING CURIOUS WITH US.