The Manessa Kwi remained on the hilltop for the remainder of that day as the crew chatted about all the things that had happened since Rini spotted the shipwreck and the rock hut on the ice continent, and how they might do it differently next time.
When one or two of them would go for a stroll outside the ship, they would look at the trail that wound through the trees, half-expecting to see Risan Gor coming up, looking for her gold and trying to explain that Timod Gor had already spent his share.
Ilika remembered Kodi.
The following morning, after a filling breakfast of fried cakes topped with stewed fruit, Ilika could see in the faces of his crew that they were ready to move on, so he put their next task on the large display screen above Kibi’s station.
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“You have completed your basic planetary flight training. You will learn new things every time we are on the surface of a world, from tiny asteroids to gas giants. As your language skills improve, I will give you advanced training materials and exercises. Eventually you will begin cross-training to learn the other stations during planetary flight.
“All that will come in time. Right now we are ready to leave the surface of this world. Our next stop is planetary orbit. It may sound strange, but when a ship is in orbit, it is constantly falling, but it is also the only place a ship in flight can rest without using any engines.”
Frowns all around the table told Ilika that it did, indeed, sound strange.
“The formula on the screen gives us the most important information about orbit. During the next few days, you will come to know this formula well, and it will become your best friend. In space, it is life, more important than food and water.”
He looked around the table. Every pair of eyes was glued to the screen.
“V is velocity, the speed of the ship. M is the mass of the planet you are orbiting. R is the radius, your current distance from the center of the planet.
A is the semi-major axis of the ellipse of your orbit, in other words, half the long diameter of the ellipse. If your orbit is circular, R and A are the same.”
He gave them a moment to absorb that much.
“In every group of students, there is always someone who thinks orbit isn’t important. When I first learned about orbit, that someone was me.”
“I was just thinking that,” Boro admitted. “Can’t we just use the anti-mass drive?”
Ilika suppressed his temptation to smile. “Usually we will. But imagine what would happen if we needed to go out onto the hull in a space suit. How far out does the anti-mass field extend?”
“Um . . . one meter.”
“Correct. If a person is on the hull and accidentally gets more than one meter from the ship, he or she drops like a rock toward the nearest gravity mass, which might be a planet, and it might be the sun.”
Boro
swallowed.
“Look at the orbit formula. Is the mass of the orbiting ship a factor?”
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“N . . . no?” Rini answered with an unsure expression.
“That’s right. Everything orbits together, regardless of how big it is — the ship, the engineer out on a safety line, his tools, everything.”
Boro
nodded.
Sata’s hand came up. “What’s the little two in the big V-thingy?”
“Root, the opposite of power. Three to the second power is . . .”
“Nine . . . I mean eleven in base eight,” Sata said.
“So the second root of eleven is three.”
“Okay, that’s easy.”
Boro moaned under his breath.
When Ilika announced an hour of free time, Sata made sure everyone understood the root operation. She had to spend most of the hour with Boro.
Rini was the first to realize that the bigger the planet, the faster the ship had to orbit. Ilika nodded, but also did a mini-lesson to make sure they knew the difference between size and mass, pointing out that some small, rocky planets had more mass than much larger gas giants, which could be lighter than water.
A little later, Sata lit up with a huge grin when she figured out that the ship would orbit at different speeds at different places in an elliptical orbit, faster when close to the planet, slower when farther away.
Ilika smiled, and asked her to explain her discovery to the others.
When everyone understood, both Mati and Kibi still wore slight frowns, but didn’t know how to put their concerns into words. All Mati could say was,
“We can’t be just anywhere above the planet, can we?”
“No. We must be outside the atmosphere, or the friction would slow us down, cause our orbit to decay, and eventually we’d crash. On this planet, that’s about a thousand kilometers from the surface.”
“Wow,” Boro breathed.
Ilika nodded. “The outer limit of usable orbit is different for each planet, as you must avoid the gravity of any moons, rings, or other planets.”
The questions and insights continued during lunch, and Ilika let his students take the discussion wherever they wanted.
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“Are there any . . . monsters in space?” Mati asked as she nervously pushed a dumpling around in her soup bowl.
“Oh, yes,” Ilika replied, “but they are creatures of light and energy that Manessa knows well. Rini will learn how to find them. They are often very beautiful, like the aurora.”
Mati took a deep breath, joined the others in smiles of anticipation, and spooned the dumpling into her mouth.
“It’s dark out there, isn’t it?” Sata asked with a shaking voice.
“In orbit, we’ll get more daylight than we do on the planet . . .”
Sata relaxed a little.
“. . . but in deep space between solar systems, it can be very dark.”
She
frowned.
“We’ll jump over most of those dark, interstellar voids.”
The navigator slowly brightened and glanced at Boro.
“Will I . . . get seasick?” Kibi asked with a slightly sour expression.
“I don’t think so. Orbit and space flight are completely smooth, and it never feels like you’re falling, even when looking down at a planet. But there is something I have to warn you about . . . especially you, Kibi.”
Kibi looked at her captain and waited.
“When we depart for orbit, we will be taking a couple of weeks to visit several planets and a number of smaller objects. You will all get space suit time, but none of the worlds we will visit have breathable air. The next time we can open the hatch is at Satamia Star Station. It will be physically impossible to . . . um . . . run away.”
Kibi gave Ilika a smile and a dirty look at the same time, then needed a moment to put her thought into words. “I . . . never thought I’d hear myself say this, but . . . sometimes not having choices is . . . okay.”
Rini grinned at her and nodded.
The afternoon was devoted to getting Sata and Mati completely comfortable with the elliptical geometry of orbit, and the tools they had at their stations to perform the necessary calculations and navigation plots.
Sata learned she could just enter the parameters, and Manessa would draw the resulting orbit. Of more concern to Mati were the transitions from the
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surface to orbit, and from one orbit to another, which the ship could also calculate and draw.
Rini watched and listened for the entire afternoon. Kibi and Boro came and went, but also wanted to keep an eye on the landing site and start cooking dinner.
The navigator and pilot spent time learning about all the forces that could cause their orbit to decay, from the very thin atmosphere at those heights, to the magnetic field of the planet itself. “Remember, even though orbit is a place of rest, it is unstable by nature. If you speed up, but don’t get the ship into a lower orbit, you’ll spiral out into space. If you slow down, but don’t get the ship into a higher orbit, you’ll spiral in.”
At first they were worried, but when Ilika showed them how Manessa could monitor the orbit and make tiny corrections automatically, they relaxed.
“Going into space is pretty complicated,” Boro admitted with big round eyes from where he sat at his station, listening.
“Yes. It’s one of the biggest tests a civilization goes through before . . .
growing up. For you five, it will mark the end of your lives as simple people from a little kingdom, and the beginning of your adventures in the vast universe.”
All five crew members took slow, deep breaths for courage.
Deep Learning Notes
There are many other things anyone who goes into space must learn about orbit, but the ship’s velocity is probably the most important. When Ilika declared “it is life,” he is echoing what fixed-wing airplane pilots learn about air speed, and what helicopter pilots learn about rotor speed.
The next time you do an orbit excursion (we call them “space walks”), remember that even though your tools will generally orbit with you, they will slowly wander away unless tied down somehow.
In our mathematics, the “2” is implied with the root operation when not
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specified.
Root operations of even powers (2, 4, 6, etc.) actually have two answers. The second root (also called the “square root”) of 4 is 2 and -2. Only the positive answer is important for most situations.
Rini’s realization that the bigger the planet, the faster the ship has to orbit, was because the Mass of the planet is being multiplied in the formula. If Mass goes up, Velocity goes up, and if Mass goes down . . .
Size or volume is the amount of space something take up. Mass is the total amount of matter present, and is related to weight. Mass / Volume = Density, a measure of how “tightly packed” the atomic particles are. If you take a certain volume of water, then freeze it, the mass remains the same, but the volume increases, which means the density does down. It will now float on liquid water.
In our solar system, Saturn is an example of a gas giant that’s average density is less than water. That only happens because we are counting the entire volume of the “visible” Saturn, much of which is atmosphere.
Sata’s realization that the ship would orbit faster when close to the planet, slower when farther away, was because Radius is a divisor in the formula.
When we divide by a number, the greater the number, the smaller the result.
Mati was showing a different kind of intelligence when she realized they couldn’t just orbit anywhere. She was using her natural “pilot’s instincts.”
What is a “monster”? Hint: the same creature would be a “monster” to a 3-month-old baby, and a “cute puppy-dog” to a 5-year-old child.
Sata was still aware of her claustrophobia. Even though she had made great progress at mastering it, deeply-rooted fears rarely go away completely.
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What was it about that situation that made Kibi willing to risk motion sickness in space?
As Mati sensed, changes in orbit are tricky because they involve both the maneuvers to change altitude, and changes in velocity (“delta V”).
In systems science, there are basically two kinds of feedback. (These two terms are mathematical in nature, and are completely unrelated to the use of the same terms in human social situations.) Negative feedback occurs when imperfections in the system lead to greater stability. Positive feedback occurs when imperfections lead to collapse of the system. Imperfections in the orbit of a ship, as Ilika explained, have positive feedback. The following number series illustrate both ideas:
Negative Feedback: 15, 5, 14, 6, 13, 7, 12, 8, 11, 9, 10, 10, 10, 10 . . .
Positive Feedback: 10, 10, 10, 11, 9, 12, 8, 13, 7, 14, 6, 15, 5, 17, 3, 20, 0 . . .
If going into orbit is “one of the biggest tests a civilizations goes through before growing up,” what might be other big tests for a civilization “growing up”?