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, 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.

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!

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!

Sydney, Sean, and Mindy help Jet experience his first Halloween. They come up with a list of classic Halloween to-dos, including carving Jack-o-lanterns, dressing up in costumes, and collecting candy. Celery takes the kids on a quick trip to space to see what causes a lunar eclipse. Meanwhile, Mitchell Petersen is on the case to figure out what exactly is going on with that strange Propulsion family... / Sydney, Sean, and Mindy take Jet trick-or-treating, and along the way, they learn about the Red Moon effect from some of the neighborhood scientists. Carrot and Celery turn their garage into a haunted house, which is an unexpected hit with the neighborhood. Jet and Sunspot even make Mindy's Halloween wish come true by flying across the Red Moon as a witch and her cat on a broom.

"More than One Moon" - Mindy is shocked to learn that there is more than one moon in the solar system. Celery flies the kids out to Mars so they can see what its two moons look like compared to ours. Curriculum: There is more than one moon in the Universe; in fact, there are hundreds of moons in our own Solar System. Mars has 2 moons, Phobos and Deimos, which are unusual in that they are not round like our moon, but oddly shaped, like battered potatoes. "Visit to Mom's Office" - Sean and Sydney take Jet to meet Sean's mom, a scientist, at the Deep Space Array. She explains that they're looking for stars with their own systems of exoplanets to detect if there might be any that contain life. But will taking Jet out in public expose his secret identity? Curriculum: An exoplanet is a planet that doesn't orbit the Earth's sun, but instead orbits a different star in the Universe.

When a strange bird lands in Jet's yard, the kids learn it is a migrating Snow Goose who is using Jet's yard as a temporary stopping-off place. Several more Snow Geese arrive, and the kids set up an "observation station" to make notes about their migrating habits. Sean accidentally drops his beloved Neil Armstrong action figure into a large crack in the ground in the woods behind his house. The kids all work together to engineer some kind of robotic arm to reach down into the crack and rescue Neil!

Mindy is impatient for winter, because she wants to ice skate. So Jet, Sean, Sydney, and Celery fly to Saturn's icy rings to gather ice from them and return to build a Saturn-ringed skating rink around Jet's house. Jet, Sydney, Sean, Mindy, and Sunspot decide to make a scaled replica of the solar system using found items in their own neighborhood and in doing so learn that an Astronomical Unit is the distance from the Earth to the Sun.

Mindy has finally turned five and is super excited that she is now old enough to go to space. But she's planned a tea party in the back yard. The kids convince Mindy to move her tea party to the Moon! In her first trip to space ever, Mindy gets to board the Propulsion family saucer and experience space travel, rounding out their Moon tea party with a quick trip out to Pluto and back.

"Which Moon is Best?" - Sean wants to be the first to walk on a moon, like his hero Neil Armstrong. When Sydney points out that 12 astronauts have already walked on our Moon, Sean thinks that rather than be the 13th to walk on OUR moon, why not be the first to walk on ANOTHER moon in our solar system? Sure, but which moon? The kids decide to compare the frozen moons Europa, which orbits Jupiter, and Enceladus, which orbits Saturn. They get help from Carrot and Celery, who fly them to each one, and Sean gets to walk on them. Curriculum: The gas giants Jupiter and Saturn each have around 60 moons - each of them unique. Interestingly, each gas giant has a frozen ice moon that contains a warmer liquid ocean under the surface: Jupiter's moon Europa, and Saturn's moon Enceladus. Each moon has its own similarities and differences. "Detective Mindy" - When Mitchell's mother declares the kitchen counter a "black hole" because she can't find her sunglasses and she's sure she left them there, Mitchell takes up the case of the black hole kitchen counter. As he's investigating, one by one, all the other kids get involved in his process. As they learn about what a black hole really is, Mitchell discovers that science holds enough mysteries to keep him busy for many years. Curriculum: Black holes are strange little holes in space that are like vacuum cleaners that use gravity (instead of suction) to suck things in. A black hole is what remains when a massive star dies. They send out no light and have very strong gravity. Once a planet or star has been sucked into the black hole, it cannot escape, and compresses to a very small size.

Jet's robot Jet 2 needs new wheels if he's going to be able to rove over the surface of Mars. Jet and the kids try a bunch of different wheels, without success. In the end, they borrow the wheels from Mitchell's scooter, so Jet 2 can successfully navigate on Mars. The kids enter their karts in the big kid-kart derby, but this year they all have to design solar powered karts. Jet learns how solar panels work, and how batteries save up the energy so you can race even when clouds cover the Sun.

Mission to Mars - When Jet and Sydney interrupt Sean doing some training in his backyard to eventually lead a mission to Mars, Jet suggests they just have his mom fly them out to Mars. Is Sean's concern about Martian dust devils legitimate? Curriculum: The next big frontier for human space flight is Mars. We have long range plans to get humans to Mars, but still have not solved some of the challenges, like what human inhabitants will do about the lack of oxygen and water, and the extreme temperatures. Sounds Abound - Sean is trying to work on a science project for Space Troops, but is interrupted by his friends' constant noise. His search for a quiet place to conduct his experiment leads him to the realization that sound is exactly what his experiments needed all along. Curriculum: Sound travels in waves like light or heat, but unlike them, sound travels through vibration. So, in order for sound to travel, there must be something for sound to travel through. Sound can travel through air, water, and solid objects, but not through space.

When Astronaut Ellen Ochoa comes to visit the DSA and review an engineering project, she runs into the kids, who are running Sean's lemonade stand to raise money for a rocket to Mars. They end up hanging out with her before her DSA meeting. They solve an engineering problem together, which inspires Ellen to use the same solution with the engineering project at the DSA.

A Visit from Uncle Zucchini - Celery's brother, Zucchini, and his pet, Moonbeam, decide to visit the Propulsions, but get lost along the way. The kids have to figure out where on Earth he is. As it turns out, Uncle Zucchini never made it to Earth, but has landed on a place that sort of resembles Earth - Titan, Saturn's largest moon! Titan has Earth-like features such as oceans, mountains, and an atmosphere. Curriculum: Titan is Saturn's largest moon, and the second largest in the solar system. Titan has lots of conditions that make it similar to Earth, including an atmosphere with clouds and a golden haze, and liquid oceans. Mindy's Weather Report - Mindy and Sunspot, watching a weather report broadcast on FACE 9000's screen, learn of a huge storm system on Saturn. When the other kids hear about it, they mistakenly assume the storm is somewhere local. Mayhem ensues as the misinformation spreads and everyone rushes around to prepare, while Mindy meanwhile "broadcasts" her own weather report from Jet's house. Curriculum: Earth is not the only planet with storms! Although we have big hurricanes here that typically last up to a week, Saturn is home to a hexagonal group of hurricanes locked into place around Saturn's north pole, that may have been going on for hundreds of years.

Sean is planning his first sleepout under the stars with his Space Scouts troop, but the weather is threatening, and it looks like his sleepout will be rained out. The kids get help from Mitchell , building a weather observation station to make a weather prediction, and visit the DSA for further help by tracking the weather with satellites. A total eclipse of the Sun is coming to Boxwood Terrace! The kids prepare a Total Eclipse song and dance to perform at the DSA, where the whole town is gathered for the event. Meanwhile, Sunspot attempts to explain the eclipse to all the local animals so they won't think it's night and sleep through it.

Carrot is about to turn 250 Bortronian years old, and the kids have set up a backyard circus to help him celebrate. They all notice that Earth's gravity makes it hard to perform their circus stunts, so they take the whole circus to the Moon, where its 1/6th gravity makes all their stunts much easier! It's Earth Day, and the kids are preparing posters for the big community celebration at the DSA. They decide to research their posters by traveling all around the Earth in Jet's family saucer and observing all the things that make Earth so special.

The Grandest Canyon - When the Propulsions are forced to watch a slide show of the Petersen's vacation to the Grand Canyon, they're inspired to take their own trip to Mars to explore Valles Marineris-the largest canyon in the Solar System! Curriculum: Mars has deeper canyons than our own Grand Canyon on Earth. The deepest canyon in our solar system exists on Mars, called Valles Marineris. A Visit to the Planetarium - Sean and Sydney take Jet to the DSA to see a show at the Planetarium. But things take a fun turn when Jet decides to upgrade the show with some Bortronian technology and sings a song explaining how to find Earth in the Milky Way galaxy! Curriculum: Our sun is actually a bright star out on a spiral arm of the Milky Way Galaxy, which is made of billions of other stars, and our galaxy is just one of billions of galaxies.

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.

Ice Moon Enceladus - Sean sets up a sno-cone stand to help raise money to send a spaceship to Mars. But it's the hottest day of the year and he quickly runs out of ice, and he can't find any nearby. Then Jet has an idea where they can go to get some ice-Saturn's ice moon, Enceladus! Curriculum: Enceladus is a small moon of Saturn that contains a liquid ocean underneath an outer layer of ice. It has "ice volcanoes" that shoot geyser-like jets of water vapor into space. Some of the water vapor falls back as "snow" and the rest escapes, which supplies most of the material making up Saturn's E ring. What Goes Up... - Jet builds a mini-flying saucer in his garage and wants to test it, but to succeed, he has to learn what gravity is and how it works. Curriculum: Gravity is an invisible pulling power that every object has-planets, moons, stars, and YOU. Gravity pulls all objects in the universe toward one another. The bigger and heavier an object is (the more mass it has), the more gravity it has.

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."

Solar System Bake-off! - Mindy and Carrot are entering a cooking competition and are making desserts representing the different planets of the Solar System. But they hit a bump when they can't remember if Saturn is cold on the inside and hot on the outside... or the other way around. Jet, Sydney, and Sean fly with Celery out to Saturn to find out before the competition begins, so Mindy and Carrot can finish their entry in time! Curriculum: The planets in our solar system can be divided into two categories -- terrestrial (inner planets) and gas (outer planets). Saturn is a gas planet that seems to have a hot solid inner core of iron and rocky material surrounded by an outer core probably composed of ammonia, methane, and water. Kid-Kart Derby - Jet builds an electric engine from scratch for the annual soapbox derby competition, but Mitchell, determined to win the derby, is suspicious that Jet is using some alien technology. Curriculum: An ion drive engine is a very fuel-efficient engine for space vehicles. Ion beams are capable of propelling spacecraft at up to 10 times faster than ships propelled by chemical rockets.

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.

Mindy Pet-sits Sunspot - Sean, Sydney, Jet, and Carrot head out to view the Northern Lights. Mindy, upset she can't go, gets a boost - Sunspot stays back and agrees to let her be his pet-sitter. As the group in the saucer searches for, yet can't find, the Northern Lights, Sunspot and Mindy work on a backyard project - making their own amazing backyard "Northern Lights" display! Curriculum: Northern lights (aka, aurora borealis) are a natural, awesome phenomenon. The origin of the aurora begins when a cloud of gas is ejected from the Sun's surface. When it collides in Earth's atmosphere with oxygen and nitrogen, it produces dazzling auroral light. Treehouse ISS - When the kids realize that they all want to use the treehouse at the same time for different activities, arguments break out. Mindy tries to help by creating a schedule for each kid to use the treehouse alone. In the end, the kids realize they need each other's company and ideas in order to be successful in their own projects. In resolving their problem, the kids learn to think like the scientists on the International Space Station, who have to find a solution to the problem of getting along while doing different projects in a small space. Curriculum: The International Space Station (ISS) program is a great global human achievement in international cooperation. Countries work in partnership to support the experiments of scientists on the ISS, including observing space, growing plants in micro-gravity, and recording observations.

"What's a Satellite?" - An Earth-orbiting "telecom" communications satellite breaks down, and satellite TV service in Boxwood Terrace stops working. Three people can't watch their favorite shows and consequently get very upset. Jet decides to fly up to space and see what the problem is with the satellite, and hilarity ensues. Curriculum: A satellite is an artificial object that has been intentionally placed into orbit. Satellites are used for a large number of purposes. Communications satellites receive signals from Earth and bounce them back to other locations, for everything from GPS to cell phone service to TV shows. Satellites are usually semi-independent computer-controlled systems. "Satellite Selfie" - The kids learn that they can use links to different websites to see a satellite view of their house. Mindy notices that Jet's house is not in the image. That's because these images are from sometime over the past 2 years, and not live images from space. With Dr. Rafferty's help, the kids identify the next time a satellite will pass over their neighborhood, and try to gather for a "space selfie" next to Jet's house. Curriculum: Satellites are objects that humans have placed into orbit around the Earth. Many have cameras in them. Some of these satellite cameras look "up" at the outer areas of space, and some look "down" at the Earth - they can even see our houses and cars!

Asteroids, Meteors, and Meteorites - Sean is determined to beat his mystery competitor at a video game of "Astro-Tracker." When Face 9000 tells the kids about the Asteroid Belt, Sean realizes that the best way to learn about asteroids is to see them for himself. Celery flies them out to space, and the kids learn the difference between an asteroid, a meteor, and a meteorite. Worried at first, Sean learns that only the rare asteroid (called a meteorite) makes it all the way to Earth, so he decides that he'll become really good at "Astro-Tracker" to prepare for the future when he can be on a team of scientists who track rogue asteroids. Curriculum: Asteroids are small solar system bodies that orbit the Sun. Asteroids are similar to comets but do not have a visible coma (fuzzy outline and tail) like comets do. A meteor is a small asteroid that burns up as it passes through the Earth's atmosphere. A meteorite is a piece of asteroid that survives falling through the Earth's atmosphere and collides with the Earth's surface. Mindy's Meteorite Stand - When Mindy and Sunspot are digging in the yard, they discover a unique rock that Mindy is convinced is a meteorite. The kids conduct a series of tests to find out and amazingly the rock passes each test. "Meteorite fever" grips the neighborhood, as Mindy sets up a stand so people can see her meteorite, and bring her rocks to assess. In the end, a DSA scientist confirms that Mindy's rock actually isn't a meteor... but, wait, the random rock Mindy's sitting on is! Curriculum: Meteorites are pieces of space rocks (asteroids) that break up when they hit the Earth's atmosphere and fall in small pieces. Meteorites are older than any rock from Earth, and share certain characteristics: density (high), attraction to a magnet, and rust.

"Space Junk" - After learning about space junk, the kids are determined to help do their part to clean up their "space neighborhood." They meet up with Uncle Zucchini, a long-time galaxy garbage man! Using Bortronian technology, they start a cleanup. During the course of the day, our kids learn that recycling is necessary both on Earth and in space! Curriculum: The outer space region around Earth swarms with millions of pieces of man-made space junk that create potential hazards. Objects as small as 4 inches can be seen by radar or optical telescopes on Earth. Cleaning the debris is a challenge. Trips to larger objects could remove them from orbit, but that's expensive. Another proposal is using lasers to provide a path-changing push that wouldn't damage the object. "Scientific Sean" - Jet is fascinated by Earth paper airplanes when he watches Sean casually fold one. Jet suggests that the kids challenge each other to build the plane that will fly the farthest, and still carry the payload of a message. Sean wants to use the Scientific Method to solve the distance/size issues. CURRICULUM: The Scientific Method is a simple set of rules that scientists use the world over, to make sure that they are doing their experiments correctly and in a way that they can repeat. But great science comes from both the application of this simple set of rules AND from imagination and inspiration.

Comet Fever - The neighborhood is having a star gazing party when Mindy discovers what may be a new comet. While Celery takes Jet, Sean, and Sydney out to space to get a close-up look at the comet, Carrot and Mindy decide to surprise the others and make their very own comet in the backyard using ingredients from home! Curriculum: A comet is an icy body that releases gas or dust. Comets are often compared to dirty snowballs. Occasionally a comet streaks through the inner solar system, creating quite a show! Asteroid Patrol - When Sean learns that asteroids are floating around the solar system (potentially), he decides to set up a homemade asteroid watch-station in the treehouse, and gets all the other kids involved. Eventually, Sean's mother and her colleague at the DSA help Sean and the others understand how scientists monitor the skies for asteroids, a job that Sean doesn't need to do all by himself. Curriculum: Asteroids are mostly found in the Asteroid Belt. Occasionally an asteroid can break away from the gravity of the Asteroid Belt and intersect with the orbit of the Earth. When a small asteroid enters the Earth's atmosphere, it becomes a meteor and burns up.