A father takes his son on a once-in-a-lifetime trip to Saturn. If you have or know children over the age of three you’ll be able to relate.
“But it’s not really a train then, is it?” Aiden asked as he watched the Earth rise through the shuttle window.
Aiden’s father slumped further into his seat. He had been answering questions about the so-called “space train” for most of the morning and they were at least another day’s travel from Saturn. “What do you mean?”
“Trains run on tracks but this one doesn’t, does it? I mean, sure, it goes on the rings but it doesn’t really go on them. They’re not even in one piece!”
“That’s true, but–”
“And they’re not even flat, dad! How can a train go on tracks that aren’t even flat?!”
A few weeks ago, Aiden’s family had won a luxury ride for two aboard the Saturn Space Train, valued at approximately $80,000. Aiden’s mother got spacesick so she wasn’t especially upset that she’d miss this opportunity. “Besides, it’ll be a chance for you two to spend some quality time together.” she’d said. From the moment they arrived at the launchpad Aiden’s father realized that what she really meant was that it would be a chance for her to spend some quality time alone.
Truth be told, Aiden’s father was excited too—he’d dreamt of traveling into space since he was a boy—he just wished his son would give him a minute to appreciate it. Still, the boy’s enthusiasm made him smile too.
Aiden’s father took a deep breath as he collected his thoughts and tried to simplify his explanation. “You’re right, it’s not really a train; it’s a long space station that kind of looks like a train. Its orbit, the path it takes around the planet, is just above the rings. It pretends they’re a track but the ‘train’ doesn’t come within 100 meters of them or it might hit something. That’s about the distance from our front door to the slide in the park across the street.”
“Oh.” said Aiden. He was almost ready to lose interest in the space station orbiting just above another planet’s rings because it wasn’t really a train. He tried his best to salvage the mental image rather than ruin his once-in-a-lifetime trip. “Does it have cars at least?”
“It has modules, yes. Some spin to maintain gravity, some don’t so you float, and at least one looks like a balloon.” As his father expected, the space balloon got Aiden’s interest back on track. So to speak.
“Wait, what about fuel? That thing’s been out there forever and nobody’s ever brought fuel!”
“They don’t need to; it fuels itself.”
Aiden’s jaw hung low as his eyes widened. “Wow… how does it do that?”
“Every so often it will scoop up some of the ice from the rings with a special net. Then it zaps it with electricity from the solar panels to break it into hydrogen and oxygen. The train uses some of the oxygen to make the air safe for people to breath and the hydrogen goes through a process called the Sabatier reaction with the air people breath out to turn it into fuel. Then that fuel gets used to make small changes to the path the train is following, like if it needs to avoid an upcoming chunk of ice.”
Aiden tried to imagine how zapping a chunk of ice would turn it into air but the image was interrupted by another thought. “Dad, if it keeps scooping ice won’t the rings disappear eventually?”
Aiden’s father smiled; he had anticipated this question. “They would, but did you know that everyone breathes out a bit of water too? The train also collects that water and uses some of it for fuel, but when it has more than it needs it releases the extra water into space so the rings get some ice back.” He skipped over mentioning urine collection and recycling since he didn’t want his son to worry about what the water they drank on board used to be.
“And dad, how were the rings formed?”
“You know what? I don’t know!”
“C’mon, dad, I thought you knew a lot about this stuff!”