Pushing planets?

[Ariel4]

A random thought came to my mind...

What if you built a rocket big enough, with enough deltaV - would it be able to push/deorbit small bodies like Minmus, Bop etc?

Anyone tried this one yet?

[vexx32]

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.

[DonLorenzo]

Also, even if it were simulated it'd require unfathomable rockets. Which is why it isn't simulated

[lajoswinkler]

Unfathomable is such a weak word for describing such rocket.

[zeppelinmage]

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 I_sp, the PB-ION, and assume we'll burn all of our fuel to perform the deorbit.

ÃŽâ€V = I_sp * g₀ * ln (m₀/m_f)

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.

Edited January 11, 2014 by zeppelinmage

[zeppelinmage]

Oh, and that burn would take 6.624×10¹⁶ s, or two billion years!

[Richy teh space man]

Nova did a rendezvous with Roche scenario a while back where you had to push a small asteroid from Eve to Kerbin, not tried it to see if it works on this version though.

[lajoswinkler]

[Commissioner Tadpole]

Nova did a rendezvous with Roche scenario a while back where you had to push a small asteroid from Eve to Kerbin, not tried it to see if it works on this version though.

It probably was part of the Asteroids mod.

[Soda Popinski]

I made a Terraforming mod suggestion, and thought it would be pretty useful if you could deorbit comets to provide water. I guess it would take a LOT of delta-V to do so.

[Captain Sierra]

I made a Terraforming mod suggestion, and thought it would be pretty useful if you could deorbit comets to provide water. I guess it would take a LOT of delta-V to do so.

It would be far more efficient to mine the water on the asteroid and transfer it back to the terraforming planet.

[Guest]

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.

[Richy teh space man]

It probably was part of the Asteroids mod.

afaik they were separate mods.

Novas scenario is here for anyone interested:

http://forum.kerbalspaceprogram.com/threads/33693-Scenario-Rendezvous-With-Roche

Moving that thing was hard enough, never mind an entire planet or moon.

[metl]

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 I_sp, the PB-ION, and assume we'll burn all of our fuel to perform the deorbit.

ÃŽâ€V = I_sp * g₀ * ln (m₀/m_f)

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.

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?

[Tex_NL]

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.

[Rondon]

Soda Popinski and Dragon01, I've been fascinated recently by the idea of "weapons of mass creation", Terraforming using nuculear weapons, 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

[Silverchain]

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...

[Liowen]

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.

[spudcosmic]

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.

[tntristan12]

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

Get the kerbal mafia to supply them all with concrete boots!

[Markus Reese]

Meh, time is irrelevant. Debug them infinite fuel, and have mega strength 10000000 thrust engines!

[Capt. Hunt]

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.

[SSSPutnik]

Kerbals could shift dirt from one side of the planet to the other, this would change the CoM and shift the planet slowly

[Tex_NL]

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.