Jet, Sydney, Sean, and Sunspot join Celery as she competes against her brother, Uncle Zucchini, in an "Earthie-style race with a winner"! The race is tight until Celery uses the kids' proposed secret "strategy" - a "gravity assist" off of Jupiter, to increase their saucer speed, and win! / Jet uses his Bortronian skills to test his first experimental Time Machine so he and his Earthie friends can go back to an exact time - 3 minutes earlier - in order to see a spectacular moment in a meteor shower that they missed. A mistake happens the first time, so he keeps trying to go back in time to fix the first mistake, but more mistakes keep happening and snowball into hilarity.

Sydney shows Jet and Sean a cool experiment - dropping different items from the same height to see which reaches the ground first. That reminds Sean of a video he watched of an astronaut on the Moon dropping a hammer and a feather from the same height. They reach the ground at the same time. And the reason is atmosphere - or lack of it - on the Moon. Jet laughs - really? Wait, what's atmosphere? Well, the kids know the best way to find out - into the wagon/saucer! Our kids and Celery fly to the edge of the Earth's atmosphere to learn what it does... and then go to the Moon. Is the atmosphere around the Moon the same as the Earth's? And what happens when our kids do the hammer-feather drop on the lunar surface? / Sydney brings Jet and Sean to the DSA to visit her mom, DR. AMY SKELLEY, and check out her work. Dr. Skelley is a robotics engineer who makes outer space robotic and gadget dreams a reality.

Sydney shows Jet and Sean a cool experiment - dropping different items from the same height to see which reaches the ground first. That reminds Sean of a video he watched of an astronaut on the Moon dropping a hammer and a feather from the same height. They reach the ground at the same time. And the reason is atmosphere - or lack of it - on the Moon. Jet laughs - really? Wait, what's atmosphere? Well, the kids know the best way to find out - into the wagon/saucer! Our kids and Celery fly to the edge of the Earth's atmosphere to learn what it does... and then go to the Moon. Is the atmosphere around the Moon the same as the Earth's? And what happens when our kids do the hammer-feather drop on the lunar surface? / Sydney brings Jet and Sean to the DSA to visit her mom, DR. AMY SKELLEY, and check out her work. Dr. Skelley is a robotics engineer who makes outer space robotic and gadget dreams a reality.

After an afternoon on the Moon, Celery, Jet, and Sunspot discover, as they fly to Earth, that they have mistakenly left Carrot on the Moon! Then the saucer malfunctions and they receive news of a possible solar storm headed their way. In a nail-biter, Jet and Sunspot do a mid-outer space repair job - as per Celery's instructions -with Carrot comically adapting to the Moon environment. In the end, the saucer is fixed, Carrot is rescued, and the solar storm heads in the opposite direction of the Moon. / When a loud thunderstorm hits the neighborhood one evening, the Propulsions are woken up. They gather in the kitchen as the noisy storm rages on, and Jet is too excited to get back to sleep. Carrot, Celery, and Sunspot are sympathetic - they're in the same boat! During the night they all learn about Earth storms as compared to storms on other planets. And then they all try to get Jet to fall back asleep, a seemingly impossible task. They use more and more absurd methods, until Celery has a conventional Earthie solution: sing a lullaby.

It's Mothers Day, and Jet wants to do something special for Celery, who just wants to finish her book. She suggests a day where Jet finds his own missing things. Jet agrees it would be the perfect gift, but first he needs her to fly them to Mars, so he can find his missing robot, Jet 2, that he left there!It's the first windy day of spring at Boxwood Terrace, and the kids are all trying out their new kites - all but Sean, who's stuck in his room with a cold. Sunspot joins Sean and helps him work out engineering problems so he can entertain himself - and even fly a kit from his room!

It's Mothers Day, and Jet wants to do something special for Celery, who just wants to finish her book. She suggests a day where Jet finds his own missing things. Jet agrees it would be the perfect gift, but first he needs her to fly them to Mars, so he can find his missing robot, Jet 2, that he left there!It's the first windy day of spring at Boxwood Terrace, and the kids are all trying out their new kites - all but Sean, who's stuck in his room with a cold. Sunspot joins Sean and helps him work out engineering problems so he can entertain himself - and even fly a kit from his room!

The kids get information from Dr. Rafferty and then travel to outer space to confirm the amazing fact that there is no sound in outer space... even though Jet is convinced he's heard sounds all over the solar system. / After Mindy laments the fact that she's still only 4 and still can't go to space with the other kids, Sydney, Jet, Sean, and Sunspot plan a full makeshift, cobbled together "Day in Space" right there in Jet's yard. Mindy's day ends on a nearby hilltop where they all watch a real, amazing, actual space event - the Leonid Meteor Showers shooting across the sky!

Mindy's mom has gradually been giving Mindy permission to go a little bit farther in the neighborhood on her own, and Mindy is trying to map out exactly what her boundaries are. Sean compares her "Mindyspere" to the helisophere-the boundaries of the Sun's influence. The kids get Celery to fly them out past the heliosphere into true interstellar space. Back on Earth, they make their own Voyager 1 (out of a wagon) and take Mindy to the outermost edges of the Mindysphere! / Sydney knows a lot about Boxwood Terrace's early history, and she tells Jet stories about a local pioneer who went by the nickname "Lone Star." He got that name because he was an early astronomer who liked the hills of Boxwood Terrace for their excellent views of the night sky, and built the first Observatory on the hill that now sits at the center of the Deep Space Array. As Jet imagines Sydney's story of Lone Star, the kids turn the story into a Western-flavored musical.

Mindy's mom has gradually been giving Mindy permission to go a little bit farther in the neighborhood on her own, and Mindy is trying to map out exactly what her boundaries are. Sean compares her "Mindyspere" to the helisophere-the boundaries of the Sun's influence. The kids get Celery to fly them out past the heliosphere into true interstellar space. Back on Earth, they make their own Voyager 1 (out of a wagon) and take Mindy to the outermost edges of the Mindysphere! / Sydney knows a lot about Boxwood Terrace's early history, and she tells Jet stories about a local pioneer who went by the nickname "Lone Star." He got that name because he was an early astronomer who liked the hills of Boxwood Terrace for their excellent views of the night sky, and built the first Observatory on the hill that now sits at the center of the Deep Space Array. As Jet imagines Sydney's story of Lone Star, the kids turn the story into a Western-flavored musical.

Jet is fascinated by the Earthie potatoes that the kids have grown in the backyard garden. Now he wants to try to grow potatoes on Mars! They take several plants to Mars and try, but learn that potatoes need the right air, temperature, water, and even the right soil.Jet is fascinated by his first Earthie rainbow. He wants to know all about them! Sydney tells Jet about the mythical Leprechauns that keep a pot of gold at the end of the rainbow, and even though they explain that it's only a story, Jet insists on following the rainbow to its end and meeting a magical leprechaun.

Sean's nervousness about flying out to visit the remote Neptune is soothed by Jet's suggestion - an improvised, fun "Neptune tune." It works as our kids, Sunspot, and Celery fly to the faraway eighth planet! / When the kids discover that they've missed all 63 of Jet's Bortronian birthdays, they decide to celebrate the one-year anniversary of him landing on Earth instead... with an "Earthday birthday" surprise party!

Sean's nervousness about flying out to visit the remote Neptune is soothed by Jet's suggestion - an improvised, fun "Neptune tune." It works as our kids, Sunspot, and Celery fly to the faraway eighth planet! / When the kids discover that they've missed all 63 of Jet's Bortronian birthdays, they decide to celebrate the one-year anniversary of him landing on Earth instead... with an "Earthday birthday" surprise party!

As the kids get ready for Valentines Day by making their own valentines out of paper, Mindy continues to feel sad that little, frozen Pluto is so far out at the edge of the solar system. When Sydney shows Mindy a newly-downloaded, full-color image of Pluto as seen by the New Horizons spacecraft, Mindy is intrigued by Pluto's "heart" of ice. Mindy once again feels that Pluto deserves our love, since it's no longer considered a planet, but is orbiting out there at the edge of our solar system, like a big frozen Valentine. She asks Sydney to bring her own little hand-made Valentine to Pluto on her behalf. Sydney leads an expedition of the kids to Pluto to bring Mindy's Valentine, experience the frozen dwarf planet themselves, and bring back their report to Mindy. / Sydney is directing the kids in a backyard movie, making her version of a Commander Cressida story about the formation of a star. The other kids all have parts, but Sunspot has the lead - as the star! The kids' movie coincides with the celebration of a star being born near (a.k.a. 10 light years away from) Bortron 7!

Each kid brings their personal project up to the tree house, and each contributes to a huge mess. Now they can't do anything in the tree house because it's too messy, but none of them want to clean up the other's mess. They have to learn to share the responsibility and clean it together.When Mindy tells Jet that clouds are made of cotton candy, and defends this idea because she heard a friend say so, Sean and Sydney set out to show her how to separate fact from fiction through research! Celery takes them up into the clouds to see for themselves.

Each kid brings their personal project up to the tree house, and each contributes to a huge mess. Now they can't do anything in the tree house because it's too messy, but none of them want to clean up the other's mess. They have to learn to share the responsibility and clean it together.When Mindy tells Jet that clouds are made of cotton candy, and defends this idea because she heard a friend say so, Sean and Sydney set out to show her how to separate fact from fiction through research! Celery takes them up into the clouds to see for themselves.

"Sunday Drive" Parts 1 & 2 - After the Propulsions download their new version of their saucer dashboard operating system, things are out of whack. Their test drive to Mars - usually a simple trip - is complicated by the new dashboard. They zip to Venus and Saturn instead... and then finally land on Mars, so they think. They're actually in an Earth desert, Mars-like at first (hot, red soil, lack of water), but soon they realize where they are. A desert vs. Mars comparison is made. Before heading home, the family decides that the old, dependable saucer operating system works just fine for them. Curriculum: An Earth desert and a Mars desert have some similarities, but are also very different. A comparison is made between the two, including life or lack thereof, temperature, water, and soil.

The kids can't play shadow tag because the Sun keeps going behind clouds. Mindy wants the sun to be out all the time! Face 9000 tells them about a system with not one, but three suns! That sounds like a place where there would be shadows all the time. Celery takes them to visit in the family saucer.Sean becomes an amateur magician called the Great Seanzo, dazzling the other kids with magnet tricks. Jet becomes fascinated by magnets, and they all explore the various things magnets can do, culminating in a magic magnet show for Carrot.

The kids can't play shadow tag because the Sun keeps going behind clouds. Mindy wants the sun to be out all the time! Face 9000 tells them about a system with not one, but three suns! That sounds like a place where there would be shadows all the time. Celery takes them to visit in the family saucer.Sean becomes an amateur magician called the Great Seanzo, dazzling the other kids with magnet tricks. Jet becomes fascinated by magnets, and they all explore the various things magnets can do, culminating in a magic magnet show for Carrot.

Mindy has to go to bed when the Sun goes down, but she's having such a fun day with her friends. She asks Jet and the others to help her keep the Sun from going down. The older kids humor Mindy and try to help "slow down the Sun." All their efforts make Mindy so sleepy that she decides to go home and sleep.Sydney and Jet are having a hard time explaining to Mindy that the Sun doesn't move - the Earth is moving around the Sun, so the Sun seems to move. Then Sean comes over dressed as his science hero Galileo, getting ready to do a school report. Mindy asks "Galileo" to explain why the Sun seems to move, and Sean practices for his report by explaining how the planets move, in character as Galileo!

It's evening at the cul-de-sac, and the kids are looking at two asteroids through Sean's telescope - one is light-colored and one is dark. Meanwhile, Mitchell's dog Cody seems to have run away because he doesn't like the black sweater Mitchell put on him. The kids learn about how, just like asteroids, some things are easier to see in the dark than others, like a white card is easier to see than Cody's black sweater. This amount of brightness is called "albedo."The kids go to their local beach to surf, but notice that the beach looks completely different from the last time they stood there. There's way more sand, and the ocean is far away! They decide to be detectives and study what has happened, and learn that the larger and smaller beach is caused by the tides - the rising and falling of the ocean.

It's evening at the cul-de-sac, and the kids are looking at two asteroids through Sean's telescope - one is light-colored and one is dark. Meanwhile, Mitchell's dog Cody seems to have run away because he doesn't like the black sweater Mitchell put on him. The kids learn about how, just like asteroids, some things are easier to see in the dark than others, like a white card is easier to see than Cody's black sweater. This amount of brightness is called "albedo."The kids go to their local beach to surf, but notice that the beach looks completely different from the last time they stood there. There's way more sand, and the ocean is far away! They decide to be detectives and study what has happened, and learn that the larger and smaller beach is caused by the tides - the rising and falling of the ocean.

While making a cake, Carrot and Mindy find they are one are short one ingredient, so they head to the store. But Carrot accidentally pushes a wrong button on the wagon's newly-updated control panel, and they take off into outer space! Using a diagram, methodical experimentation, and record keeping, Mindy and Carrot figure out how to properly fly the saucer back home, where they finally finish the cake. Mindy has a problem: now that she's been to space with the bigger kids, she realizes how much there is out there to see! How can she decide where to explore next? Sydney asks her mom, Dr. Skelley, who presents them with the very first edition of Commander Cressida comics! In reading the comic book, Mindy comes to appreciate that she, like Commander Cressida, can explore space "one adventure at a time."

Jet is amazed to find out that the entire Earth doesn't have the same season at the same time. So he flies with Sydney and Sean from the northern hemisphere to the southern hemisphere to compare and experience holidays in winter and summer...all in one day!Mindy feels bad that she's the smallest kid in the group, so sympathetic Jet and friends use a shrink-ray and become her size. The plan goes awry, and Jet, Sean, Sydney, and Sunspot become the size of mice. Mindy has to follow intricate diagrams to reverse the shrink-ray!

Jet is amazed to find out that the entire Earth doesn't have the same season at the same time. So he flies with Sydney and Sean from the northern hemisphere to the southern hemisphere to compare and experience holidays in winter and summer...all in one day!Mindy feels bad that she's the smallest kid in the group, so sympathetic Jet and friends use a shrink-ray and become her size. The plan goes awry, and Jet, Sean, Sydney, and Sunspot become the size of mice. Mindy has to follow intricate diagrams to reverse the shrink-ray!

Sunspot begins acting strangely, and Jet fears that he is sick. Carrot and Celery examine him, and decide that he's acting strange because of a large sunspot on the Sun. The only way to cure him is to bring him to the Sun, and get him close to the huge sunspot.Mindy wants to have a sleepover outside with her friend Lillian, but it's winter and too cold to sleep outside under the stars. Sean points out that they are under the light of a star all the time - our Sun! Mindy learns that our Sun is a star, just like the tiny ones we see at night.

Each kid brings their personal project up to the tree house, and each contributes to a huge mess. Now they can't do anything in the tree house because it's too messy, but none of them want to clean up the other's mess. They have to learn to share the responsibility and clean it together.When Mindy tells Jet that clouds are made of cotton candy, and defends this idea because she heard a friend say so, Sean and Sydney set out to show her how to separate fact from fiction through research! Celery takes them up into the clouds to see for themselves.

Each kid brings their personal project up to the tree house, and each contributes to a huge mess. Now they can't do anything in the tree house because it's too messy, but none of them want to clean up the other's mess. They have to learn to share the responsibility and clean it together.When Mindy tells Jet that clouds are made of cotton candy, and defends this idea because she heard a friend say so, Sean and Sydney set out to show her how to separate fact from fiction through research! Celery takes them up into the clouds to see for themselves.