Prof. Nerva Regis 's Stories

[Nerva Regis]

The Cross-Vandermeer comet from O3 - part 1

I should make this one just like when I was writing papers in college.


If I remember correctly, the word comet derives from the Old English cometa from the Latin comēta or comētēs. That, in turn, is a latinisation of the Greek κομήτης ("wearing long hair"), and that the term (ἀστὴρ) κομήτης already meant "long-haired star, comet" in Greek. Κομήτης was derived from κομᾶν ("to wear the hair long"), which was itself derived from κόμη ("the hair of the head") and was used to mean "the tail of a comet"

So... I started what we all knew: A very large comet, possibly a rogue planetoid, caught in the gravitational well of the Omega 3 star. Initial scans have revealed immense quantities of Cobalt locked under it's icy crust. Due to it's proximity to the star, the comet cannot be mined directly, but the star is slowly eroding the comet. The comet's tail contains small quantities, easily retrievable Cobalt.


Unity parking near the comet.


First we deployed three of our new terrain satellites.




Physical characteristics:
Nucleus - after deep scans, it seems that is formed out of pure cobalt.
Coma - the streams of dust and gas released form a huge and extremely thin atmosphere around the comet.
Tails - the cloud from which miners get the cobalt ore is actually the tail of the comet that behaves like the coma.

And now the weird part - the comet is sniping around its axis, but it does not move around its star in an orbit. No, it just stays there... and revolves...
and it does that really fast.

Here is what it should look like.


The comet should revolve around the host star. If it does not do that, it should crash into the star.

An object's momentum and the force of gravity have to be balanced for an orbit to happen. If the forward momentum of one object is too great, it will speed past and not enter into orbit. If momentum is too small, the object will be pulled down and crash. When these forces are balanced, the object is always falling toward the planet, but because it's moving sideways fast enough, it never hits the planet. Orbital velocity is the speed needed to stay in orbit.

How orbits work
The drawings below simplify the physics of orbiting a Planet. We see a Planet with a huge, tall mountain rising from it. The mountain, as Isaac Newton first envisioned, has a cannon at its summit. When the cannon is fired, the cannonball follows its ballistic arc, falling as a result of Planet's gravity, and it hits the Planet some distance away from the mountain. If we put more gunpowder in the cannon, the next time it's fired, the cannonball goes halfway around the planet before it hits the ground. With still more gunpowder, the cannonball goes so far that it just never touches down at all. It falls completely around a planet. It has achieved orbit.



If you were riding along with the cannonball, you would feel as if you were falling. The condition is called free fall. You'd find yourself falling at the same rate as the cannonball, which would appear to be floating there (falling) beside you. You'd just never hit the ground. Notice that the cannonball has not escaped the Planet's gravity, which is very much present--it is causing the mass to fall. It just happens to be balanced out by the speed provided by the cannon.
In the third drawing in the figure, you'll see that part of the orbit comes closer tot he Planet surface that the rest of it does. This is called the periapsis of the orbit. It also has various other names, depending on which body is being orbited. In the drawing, the mountain represents the highest point in the orbit. That's called apoapsis (apogee, apojove, aposelene, apolune, aphelion). The time it takes, called the orbit period, depends on altitude. At space a altitude of, let's say 200 kilometers, it's 90 minutes.

The cannonball provides us with a pretty good analogy. It makes it clear that to get a spacecraft into orbit, you need to raise it up (the mountain) to a high enough altitude so that the Planet's atmosphere isn't going to slow it down too much. You have to accelerate it until it is going so fast that as it falls, it just falls completely around the planet. In practical terms, you don't generally want to be less than about 150 kilometers above the surface of the Planet. At that altitude, the atmosphere is so thin that it doesn't present much frictional drag to slow you down. You need your rocket (or cannon) to speed the spacecraft up to the neighborhood of 30,000 kilometers (about 19,000 miles) per hour. Once you've done that, your spacecraft will continue falling around the Planet. No more propulsion is necessary, except for occasional minor adjustments. These very same mechanical concepts apply whether you're talking about orbiting the Planet the moon, the sun, or anything. Only the terms and numbers are different. The cannonball analogy is good, too, for talking about changes you can make to an orbit. Looking at the third drawing, imagine that the cannon has still more gunpowder in it, sending the cannonball out a little faster. With this extra speed, the cannonball will miss the Planet's surface by a greater margin. The periapsis altitude is raised by increasing the spacecraft's speed at apoapsis.

This concept is very basic to space flight. Similarly, decrease the speed when you're at apoapsis, and you'll lower the periapsis altitude. Likewise, if you increase speed when you're at periapsis, this will cause the apoapsis altitude to increase. Decelerating at periapsis will lower the apoapsis.

Professor, I have started creating a model of the comet.
Put it on my screen.

This is fascinating.