Comet iOS

[Roger Jolly]

This isn’t cheating, it’s an act of God

First try I went looking for the Sun’s parabolic limit, I didn’t find it

And sorta broke things...

My comet jumped back and froze at the peri apsis, but went back into orbit when I reboot the game for a second attempt though the crude angular path marker remained

Second insertion was a bit more reasonable, somewhere around Neptune and Pluto I guess

I got a proper peri#...so voila, I got a wild target to rendezvous

Maybe should put a port on it so I could anchor a lander be a good idea...Anyway, there’s a new sort of challenge needs no mods

 

[Altaïr]

Oh, well done!

But what do you mean by "Sun's parabolic limit"? An object with a parabolic trajectory will escape the solar system, so that's probably not what you want...

Now if your comet happens to meet Earth, you will have a free Armageddon recreation

 

[Roger Jolly]

Oh, well done!

But what do you mean by "Sun's parabolic limit"? An object with a parabolic trajectory will escape the solar system, so that's probably not what you want...

Now if your comet happens to meet Earth, you will have a free Armageddon recreation

Isn’t escape a hyperbolic?
What I meant was just short of escape from the sun, that comet got all jumpy as it got away from the sun so I deleted it...
The other looks ok as I launch my first test craft, going to take some long trial looking for options

If it ever makes an encounter it’ll be a reverse Armageddon where I save the comet from a menacing Earth
Or I could try and force it into a collision

 

[Altaïr]

Isn’t escape a hyperbolic?
What I meant was just short of escape from the sun, that comet got all jumpy as it got away from the sun so I deleted it...

Ah, you meant highly elliptical then (the term "quasi-parabolic" also applies). Both parabolic and hyperbolic lead to an escape. A trajectory is hyperbolic if its eccentricity is greater than 1, and elliptical if it's lower than 1. Parabolic means that eccentricity is exactly 1. It also means that speed is exactly the liberation speed. If it differs by a very small value, then it's either elliptical or hyperbolic. For this reason the parabolic case is never considered in practice, it's mostly a theoretical case.

 

[Roger Jolly]

Ah, you meant highly elliptical then (the term "quasi-parabolic" also applies). Both parabolic and hyperbolic lead to an escape. A trajectory is hyperbolic if its eccentricity is greater than 1, and elliptical if it's lower than 1. Parabolic means that eccentricity is exactly 1. It also means that speed is exactly the liberation speed. If it differs by a very small value, then it's either elliptical or hyperbolic. For this reason the parabolic case is never considered in practice, it's mostly a theoretical case.

Sooo...by “eccentricity is exactly 1” means perfect circle?
I clearly need to read of this subject later,
Starting here:

 

[Altaïr]

Sooo...by “eccentricity is exactly 1” means perfect circle?

No, eccentricity is 0 for a circle. It's difficult to explain exactly what eccentricity is, as it's originally a mathematical parameter. The type of the curve depends on it.

For an ellipse, eccentricity = (A-P)/(A+P), where A and P are apoapsis and periapsis. It works for a circle (A=P, so e = 0), and an ellipse, it roughly works for a parabola (A is infinite, e=1), but it doesn't work for an hyperbola. There are other formulas (based on velocity for example), but nothing as visual as the elliptical case.

 

[Roger Jolly]

No, eccentricity is 0 for a circle. It's difficult to explain exactly what eccentricity is, as it's originally a mathematical parameter. The type of the curve depends on it.

For an ellipse, eccentricity = (A-P)/(A+P), where A and P are apoapsis and periapsis. It works for a circle (A=P, so e = 0), and an ellipse, it roughly works for a parabola (A is infinite, e=1), but it doesn't work for an hyperbola. There are other formulas (based on velocity for example), but nothing as visual as the elliptical case.

Yes of course...
eccentricity 0=O eccentricity
Damn my American public education, lol

Been driving having vague flashbacks to long ago intro calc, thanks for clueing me in

 

[Altaïr]

Yes of course...
eccentricity 0=O eccentricity
Damn my American public education, lol

Been driving having vague flashbacks to long ago intro calc, thanks for clueing me in

You're welcome
And don't blame yourself, it's not common knowledge after all.

 

[Roger Jolly]

You're welcome
And don't blame yourself, it's not common knowledge after all.

Ya, I remember those formulas up there from the tail end of high school algebra, or was it geometry?...the “and if you like this maybe you should try calculus next year” finale

They threw some other class in my way I stumbled over and never made it to calc, so never put any velocity into the equations; I should google learn some of that stuff