Jump to content

Pushing planets?


Recommended Posts

Nope, can't be done. The planets have a set orbit which they follow, and no forces are ever actually calculated for them. The planets obey the mathematical equations for 2-body gravity, as do the moons, each calculated only between it and its parent body using the same parameters. It follows its path, never shifting. They are "on rails", so to speak.

Link to comment
Share on other sites

Even if it were possible in the realm of the game...

Gilly is the smallest (lightest) body, at a whole 1.2420512×1014 t. To deorbit it at its slowest, that would take ~274 m/s of ÃŽâ€V.

We'll use the motor with the largest Isp, the PB-ION, and assume we'll burn all of our fuel to perform the deorbit.

ÃŽâ€V = Isp * g0 * ln (m0/mf)

274 = 4200 * 9.82 * ln (m0/1.2420512×1014)

274 = 41244 * ln (m0/1.2420512×1014)

.007 = ln (m0/1.2420512×1014)

1.007 = m0/1.2420512×1014

1.250×1014 = m0

EDIT: Forgot to subtract. lol. Anyway, that's 794,880,000,000 t of fuel. Or, 159 trillion litres. Good luck assembling a rocket that large. :D

Edited by zeppelinmage
Link to comment
Share on other sites

Actually, it depends on a comet's trajectory. Redirecting a comet can be done rather cheaply if the thrust is applied in a correct point in orbit. We're talking a few meters per second of dV. It's still take quite a push, but it could be achieved with a specially designed nuclear warhead. Of course, that only works if the comet's trajectory already passes near what we want it to hit.

Link to comment
Share on other sites

Even if it were possible in the realm of the game...

Gilly is the smallest (lightest) body, at a whole 1.2420512×1014 t. To deorbit it at its slowest, that would take ~274 m/s of ÃŽâ€V.

We'll use the motor with the largest Isp, the PB-ION, and assume we'll burn all of our fuel to perform the deorbit.

ÃŽâ€V = Isp * g0 * ln (m0/mf)

274 = 4200 * 9.82 * ln (m0/1.2420512×1014)

274 = 41244 * ln (m0/1.2420512×1014)

.007 = ln (m0/1.2420512×1014)

1.007 = m0/1.2420512×1014

1.250×1014 = m0

EDIT: Forgot to subtract. lol. Anyway, that's 794,880,000,000 t of fuel. Or, 159 trillion litres. Good luck assembling a rocket that large. :D

Wouldn't it make more sense to use the most powerful? Your burn time would be considerably less and as a result you would need a lot less fuel tonnage. Might not be the most efficient, but would it be doable?

Link to comment
Share on other sites

Wouldn't it make more sense to use the most powerful? Your burn time would be considerably less and as a result you would need a lot less fuel tonnage. Might not be the most efficient, but would it be doable?

You might think the more powerful would be better but you're wrong.

If you would use an engine that has double the strength but half the efficiency you would indeed reach your target dV in half the time. But it would require double the amount of fuel. Actually, it would require MORE than double the amount of fuel since you'd need to move all that extra fuel too.

Long story short: Time is irrelevant. Efficiency is the only thing that matters.

Link to comment
Share on other sites

Soda Popinski and Dragon01, I've been fascinated recently by the idea of "weapons of mass creation", Terraforming using nuculear weapons, :D and I've found the major snag to be chemistry: sure you could in theory nuke one atmospheres worth of martian soil, creating one kilo-pascal of pressure, and crucially an atmosphere of 40% oxygen, but whenever it cools down again its just going to re-bond with the constituents in the air that where solid before hand due to there low boiling points, and rain as solids, going back to square one.

In the same vein firing comets into a planet won't introduce a noticeable quantity of gas into the atmosphere unless the compounds that form, have boiling points below the planets mean temperature (Mars mean is 210kelvin), it'll just solidify after a while. so sending over an ice comet wont work, as the vapor will freeze after a while (mars already has ice at the poles). It might work if the gas introduced could raise the minimum temperature of the planet above its own boiling point by a safe margin. or try sending something over from the outermost rims of the system

Link to comment
Share on other sites

What you need for Gilly is to ferry over a whole bunch of Kerbals with shovels, get them to stand on the prograde face and start throwing dirt into the sky...

With the gravity on gilly, those kerbals would probably propel themselves into orbit when they try to stick the shovel in the dirt.

Link to comment
Share on other sites

I was thinking about this a while back so I went on Youtube, and wouldn't you know it that there was a video about this very thing.
I was just watching a Scott Manley clip that talks about this:

As it turns out, the planets in KSP are not bound by gravity, they are set on rails that keep them in their orbits no matter what.

Impressive how in a thread barely three pages long the exact same video gets posted three time.

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...