Question Moving planets with rocket engines; is it possible?

Is it possible to move planets in orbiter with insanely powerful rocket engines?


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SlyCoopersButt

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I think using a vessel for a planet is your only option. But it can't be landed on or orbited though.
 

JamesG

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Are the orbital data for planets from the solarsystem file variables that can be accessed and changed at run time?

In real life:
Assides from all of the Newtonian problems, for all thier massive size, planets are very delicate. All but the smallest cold asteroids have the integrity of a falling drop of water. The Earth would crumple and distort like the surface tension on water, probably completely destroying its crust if you had something as crude as a bunch of giant rocket motors attached to it. Even the moon would probably break up into pieces from the sheer forces of any kind of noticeable thrust.

The only "practical" way would be to somehow steer one of the more solid dwarf planets or very large asteroids (my pick would be Ceres) on an an elliptical trejectory that passes close to and accellerates or slows down your target planet to change its orbit by tiny amounts each pass. You use the sun and your motor to replenish its energy (and prevent it from carreening out of the solar system) and you repeat this process until the desired orbit is accieved.
Very slow process but the only way to "safely" do this without being able to place an order for an ACME "Instant Black Hole" that you can place and turn on and off to move things around.
;)
 

Linguofreak

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Even though no engine could be used for it, Would de-orbiting Jupiter into the sun perhaps add a few extra thousand years to of cool time down here? Jupiter has lots of hydrogen. My best guess would be to use millions or even billions of Anti-matter bombs for de-orbiting it. Might be safer than moving Earth.

More likely, if you de-orbited jupiter into the sun, you would cause a massive, if short-lived, flare-up that would obliterate all life on Earth. Assuming that we de-orbit jupiter quickly (i.e. we stop it in its orbit and it falls straight into the sun) and ignoring the energy release required to perform the de-orbit burn, which is likely substantial, we find that by the time it touches the surface of the sun, it has acquired a velocity such that its kinetic energy is equal to the gravitational potential energy difference between its own orbit and the surface of the sun. Gravitational potential energy, U, is defined by the equation U=-G*((m1*m2)/R). For the sun and jupiter, m1 is the mass of the sun and m2 is the mass of jupiter. Since we're finding the energy released by falling from Jupiter's orbit to the solar surface, we run the equation twice, once with R=radius of Jupiter's orbit, and once with R=radius of the sun. We then take the difference between the two. The first time we get U=-3.2367*10^35 joules, the second time we get U=-3.6232*10^38 joules. The difference is 3.6200*10^38 joules, or 8 trillion megatons. Divide that by the mass of Jupiter and we get the energy per kilogram, 190,657 megajoules/kg (one megajoule/kg is equal to 1 km^2/s^2). The energy per kilogram is the square of Jupiter's velocity at the end of its fall, so sqrt(190,657 km^2/s^2) = 436.64 km/s. So you have Jupiter smashing into the sun at over 400 km/s. Since Jupiter is about the same density as the sun, it probably won't go straight through. Rather, it will stop, probably fairly quickly, and all of that 3.62*10^38 joules will be released as heat. It will probably stop before it reaches the center, but I don't know exactly how far in will go, so I'll be conservative and say it stops at the exact center of the sun. So it will decelerate from 436 km/s to zero over a distance of one solar radius. Assuming this acceleration is uniform, the average velocity will be 218 km/s. Thus it will take 3190 seconds, or 53 minutes and ten seconds to reach the center. The average power released over this time period will be the energy released over the time, or 3.62*10^38 joules / 3190 seconds, which comes out to 1.13 * 10^35 Watts, or 335 million solar luminosities. Now, a fair portion of this energy would end up trapped fairly deep within the sun and would be delayed in its release, so the observed brightening would be less, but we would definitely observe the Sun to brighten by a factor of at least a few thousand for a short time. This would not create friendly conditions for life on Earth.

EDIT: Oops. v= sqrt(2*kinetic energy/m), so velocity is 616 km/s. Average velocity over the deceleration period after hitting the Sun is 308 km/s. Time to decelerate is 37.6 minutes, or 2,255.67 seconds. Power is 474 million solar luminosities.
 

Hielor

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Ok, since almost everyone is saying no to this, I have a new question, is it possible to do this with a DLL?

If you made your own planet, it may be possible to have the ephemerides dynamically change in response to some event, eg. a vessel on the surface with its engines on.

It would not be possible to write a DLL that would move the existing planets. If you wanted to, say, move the Earth, you would need to replace the existing Earth dll with a new custom one.
 

Kaito

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More likely, if you de-orbited jupiter into the sun, you would cause a massive, if short-lived, flare-up that would obliterate all life on Earth. Assuming that we de-orbit jupiter quickly (i.e. we stop it in its orbit and it falls straight into the sun) and ignoring the energy release required to perform the de-orbit burn, which is likely substantial, we find that by the time it touches the surface of the sun, it has acquired a velocity such that its kinetic energy is equal to the gravitational potential energy difference between its own orbit and the surface of the sun. Gravitational potential energy, U, is defined by the equation U=-G*((m1*m2)/R). For the sun and jupiter, m1 is the mass of the sun and m2 is the mass of jupiter. Since we're finding the energy released by falling from Jupiter's orbit to the solar surface, we run the equation twice, once with R=radius of Jupiter's orbit, and once with R=radius of the sun. We then take the difference between the two. The first time we get U=-3.2367*10^35 joules, the second time we get U=-3.6232*10^38 joules. The difference is 3.6200*10^38 joules, or 8 trillion megatons. Divide that by the mass of Jupiter and we get the energy per kilogram, 190,657 megajoules/kg (one megajoule/kg is equal to 1 km^2/s^2). The energy per kilogram is the square of Jupiter's velocity at the end of its fall, so sqrt(190,657 km^2/s^2) = 436.64 km/s. So you have Jupiter smashing into the sun at over 400 km/s. Since Jupiter is about the same density as the sun, it probably won't go straight through. Rather, it will stop, probably fairly quickly, and all of that 3.62*10^38 joules will be released as heat. It will probably stop before it reaches the center, but I don't know exactly how far in will go, so I'll be conservative and say it stops at the exact center of the sun. So it will decelerate from 436 km/s to zero over a distance of one solar radius. Assuming this acceleration is uniform, the average velocity will be 218 km/s. Thus it will take 3190 seconds, or 53 minutes and ten seconds to reach the center. The average power released over this time period will be the energy released over the time, or 3.62*10^38 joules / 3190 seconds, which comes out to 1.13 * 10^35 Watts, or 335 million solar luminosities. Now, a fair portion of this energy would end up trapped fairly deep within the sun and would be delayed in its release, so the observed brightening would be less, but we would definitely observe the Sun to brighten by a factor of at least a few thousand for a short time. This would not create friendly conditions for life on Earth.

EDIT: Oops. v= sqrt(2*kinetic energy/m), so velocity is 616 km/s. Average velocity over the deceleration period after hitting the Sun is 308 km/s. Time to decelerate is 37.6 minutes, or 2,255.67 seconds. Power is 474 million solar luminosities.

My brain just shut down.
This would be an interesting thing wtih a .dll: put a docking port on a planet sized ship, and get a OMFG big rocket, and see what happens
 

Linguofreak

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My brain just shut down.

In other words, Jupiter falling into the sun would create an explosion that would, for a short period of time, make the sun a whole heck of a lot brighter.

My back of the envelope calculation says about 500 million times brighter for about 40 minutes, though that's almost certainly wrong one way or the other. This would not be a happy event for anyone living on Earth.

Jupiter would probably stop faster than I'm assuming, making things brighter for a shorter period of time, but on the other hand, the bulk of the sun would probably delay some of the energy from getting out, which would make things dimmer for a longer period of time. I'm just not sure which effect is bigger.
 

SlyCoopersButt

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I had thought about that. Much like stoking a fire. like if you throw fuel into a fireplace. I expect it would be significant. So much for that being a safer alternative!
 

JamesG

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To add even more fun to the scenario, the gravitational effect of having Jupiter suddenly plunge into the sun would be to play cosmic billiards with the other planets in the solar system.
Presuming you achieved this bullying of Jupiter by enacting some sort of force field that suddenly nullified its gravity and inertia (zapping it out of the universe momentarily?) This by itself will make the sun "snap" in its orbit from the suddenly gone gravitational influence Jove had on it. Its too late/early for me to even contemplate the math, but this shock would probably be enough to disrupt the sun's internal fusion system, and either cause it "go out" (core disruption) or explode (expell its outer layer).
 

Linguofreak

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To add even more fun to the scenario, the gravitational effect of having Jupiter suddenly plunge into the sun would be to play cosmic billiards with the other planets in the solar system.
Presuming you achieved this bullying of Jupiter by enacting some sort of force field that suddenly nullified its gravity and inertia (zapping it out of the universe momentarily?) This by itself will make the sun "snap" in its orbit from the suddenly gone gravitational influence Jove had on it. Its too late/early for me to even contemplate the math, but this shock would probably be enough to disrupt the sun's internal fusion system, and either cause it "go out" (core disruption) or explode (expell its outer layer).

Jupiter wouldn't have too much effect on the other planets before it hit unless it passed really close to one. I've tried putting a second Jupiter in Jupiter's orbit going the other way before in gravitational simulators, so that they slingshotted each other onto highly elliptical orbits that went far into both the inner and outer systems, and it generally takes a few passes before anything really crazy happens to the inner planets. If it's just falling straight in, it won't get more than one pass.

And I doubt that Jupiter would have much effect on the sun either before it actually hit. The gravitational effect on the sun of Jupiter stopping like that would be negligible. The sun's orbital velocity due to Jupiter's gravity is only about 12.5 m/s, or about 28 mph.

However, when Jupiter actually *hit* the sun, the resulting energy release would fry the inner solar system, and probably seriously upset the sun in the short term (say for a few thousand or million years). But eventually things would calm down, and there wouldn't be much to say that the sun had eaten a gas giant except for the effects that the cataclysm had on the various objects in the solar system. (The sun is big. It's hard to permanently disrupt.)

It would be a big event though. Just for a sense of scale on exactly how big, Jupiter falling straight in to the sun would release about as much energy as the sun does in 30,000 years.
 

James.Denholm

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Heh. Now, imagine being able to harness such power, to be able to convert and store the energy from such an event, and you've got a very attractive reason to travel the galaxy, frying gas giants.
 

Agra Barecasco

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what if we try it to the moon?

If it is impossible to move the earth because it is fixed by the program, why don't you try to tweak it's orbit/ephemeris ? (I don't know about the programming though)
think of a new challenge having home planet as close as mercury to the sun..., or orbiting jupiter,:p

Okay, I now know it is impossible using a rocket because of the escape velocity problem....and ion thruster would become great waste of time..

about the asteroid idea, it's quite possible, changing some asteroids trajectory from afar, then after some asteroids pass by, the earth trajectory will change for sure,

If sun is getting older and become a red giant, it's mass will have been decreased because of ejected material from it's outer layer,
the decrease of it's mass will affect earth trajectory too, so earth will go higher automatically from sun...

how about using the rockets to moon, eject it from it's orbit,,, will it affect the earth trajectory?


-----Post Added-----


Jupiter is getting it's fame....
 

Usquanigo

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Speaking of moving planets (and related).... what about the moon? From what I recall hearing, it's actually going away. Slowly of course, but fast enough to be measured, which I would call a concern.

If it gets too far out, it would be very bad for the planet, it's environment, and all life on it.

And perhaps best of all, it's rotation is such that if one did use the OMFG sized rocket, it should be more or less pointed retro-grade all the time due to the rotation/revolution sync it has going on.
 

sputnik

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If you made your own planet, it may be possible to have the ephemerides dynamically change in response to some event, eg. a vessel on the surface with its engines on.

It would not be possible to write a DLL that would move the existing planets. If you wanted to, say, move the Earth, you would need to replace the existing Earth dll with a new custom one.

Hielor,

I'd be very interested in doing this to make a movable asteroid. The problem I found when last I looked at it was, there's no timestep function in a planet's .dll, so I was unable to conceive of a way to describe the orbit based on arbitrary events in the future.

Am I wrong? Is this possible? I'd really like to do that.
 

Imagineer

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Hi there! I was wondering, is it possible to move planets in orbiter with HUGE and powerful rocket engine at the back of the planet? For example, a ship 1/3 of the size of the Earth, pointing downward at the Earth, and has a thrust setting of 10e100000. Is it possible to do something like that in orbiter?

1) In simulation:
a) Due to the way that planets are implemented in Orbiter, no.
b) If you replace the planet with a massive planet-shaped space ship, yes.

2) In real life, The Sierra Club will sue you senseless :p.
 

Linguofreak

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Speaking of moving planets (and related).... what about the moon? From what I recall hearing, it's actually going away. Slowly of course, but fast enough to be measured, which I would call a concern.

I believe it's about 4 cm/year. In the next million years its orbit will only have moved outwards by 40 km.
 

Hielor

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Hielor,

I'd be very interested in doing this to make a movable asteroid. The problem I found when last I looked at it was, there's no timestep function in a planet's .dll, so I was unable to conceive of a way to describe the orbit based on arbitrary events in the future.

Am I wrong? Is this possible? I'd really like to do that.

According to the documentation, clbkFastEphemeris is called on each simulation step.

YMMV, though--I've never written a planet DLL.
 

Linguofreak

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I had thought about that. Much like stoking a fire. like if you throw fuel into a fireplace. I expect it would be significant. So much for that being a safer alternative!

No, more like whacking the sun with a really big, really fast bullet.
 

Andy44

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Funny you should mention the growth of the Moon's orbit; at mindnight tonight you will witness the byproduct of this effect when the IERS adds a leap second to the clock.

Because the Moon's orbit period is more than 1 day, tidal forces cause the Moon to speed up and the Earth's rotation to slow down. Phobos, on the other hand, revolves about Mars in less than one Martian day, and tidal forces slowly cause it's orbit to shrink.

So someday in the far distant future, Phobos will crash into Mars. Panic now! We need to do something to prevent this catastrophe! ;-)
 

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You can't do it in Orbiter and you can't do it in reality with any planet that has at least some amount of atmosphere...

Even if you point a huge rocket down and fire it.... even if it's an incredibly powerful ion engine with the nozzle velocity of ~50 km/s, the particles won't make it through the atmosphere. They'd be slowed down by the atmosphere and stay on the planet. And the law of conservation of momentum dictates that you cannot move a body's center of mass without "throwing" something off you or "being hit" by something.
 

Linguofreak

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You can't do it in Orbiter and you can't do it in reality with any planet that has at least some amount of atmosphere...

Even if you point a huge rocket down and fire it.... even if it's an incredibly powerful ion engine with the nozzle velocity of ~50 km/s, the particles won't make it through the atmosphere. They'd be slowed down by the atmosphere and stay on the planet. And the law of conservation of momentum dictates that you cannot move a body's center of mass without "throwing" something off you or "being hit" by something.

Well, a powerful enough rocket (probably not an ion engine) might get through the atmosphere, but it would probably disrupt the local climate pretty badly...
 
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