Question Moving planets with rocket engines; is it possible? - Orbiter-Forum

Talon1 · 12-30-2008, 10:25 PM

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?

Also, I've added a poll for this question.

**Piper** · 12-30-2008, 10:32 PM

Essentially no, not in Orbiter anyways. Technically, in real-life, any-time a rocket lifts off from Earth, or a spacecraft does a fly-by of Earth, there is a minuscule effect on the orbit of Earth (or whatever object it happens on). However in Orbiter, planets/asteroids can not be changed in game, unless they are declared as a spacecraft themselves.

Jarvitä · 12-30-2008, 10:51 PM

Real life: Yes, with OMFG-sized rockets. (or a certain ancient Greek philosopher with a fulcrum and a very long lever)

Orbiter: No.

Arrowstar · 12-30-2008, 11:06 PM

I was going to say what Piper said, so.

Linguofreak · 12-30-2008, 11:21 PM

Quote:

Originally Posted by Talon1

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?

Also, I've added a poll for this question.

In Orbiter, no, as has been said.

In real life, it depends: How much does the planet's orbit have to change before you consider it "moved," how long are you willing to wait, and how much damage are you willing to do to the planet?

Andy44 · 12-31-2008, 12:00 AM

Orbiter's planets' ephemeris is fixed and they cannot be accelerated by rockets.

In real life, it is theoretically possible, but if you simply put a conventional rocket nose-down in your back yard and light it up it won't move the Earth, because the exhaust won't be able to reach escape velocity. It isn't going that fast at the nozzle to begin with, and even if it is it has to go even faster to overcome atmospheric resistance. You might have better luck on the Moon, but even that requires a very high exhaust velocity. Any exhaust that doesn't reach escape velocity is technically still part of the planet.

Jarvitä · 12-31-2008, 12:11 AM

Quote:

Originally Posted by Linguofreak

In Orbiter, no, as has been said.

In real life, it depends: How much does the planet's orbit have to change before you consider it "moved," how long are you willing to wait, and how much damage are you willing to do to the planet?

1. The average planet-sun distance should change by one diametre of the planet.
2. Let's say...the time it takes to complete one half of it's orbit around the Sun
3. in the case of Earth, the surface should still be habitable for humans after the orbit change.

Now someone get your astrodynamics equations out and calculate the mass/force/size of the rocket needed to do this to Earth.

P.S.:Andy44, so "all" you have to do to move Earth is to put together a giant (which is a giant understatement in itself) ion thruster that reaches outside of the Earth's atmosphere? If I remember correctly, Ion thrusters typically have exhaust velocities in the 10-20 km/s range, which is easily above the Earth's escape velocity. The fuel mass would be negligible compared to a conventional rocket engine, and since it's on Earth, you can always build a few dozens of giant nuclear power-plants around it for power. The thruster would be located on the equator and only fired for a few hours a day when the Earth is positioned properly to give it a prograde boost. In a few months, the delta-V should built up even with a relatively low acceleration - say, on the order of .1 to 1 m/s^2.

Disclaimer: This is a semi-drunk 2am post, please go gentle on any obvious errors. I didn't do any calculations and I acknowledge that this could never work.

P.P.S.:Ok, math time:

If we assume 1 m/s^2 acceleration for 6 hours a day (with thrust vectoring to somewhat compensate for the Earth's rotation or something) for six months, the total deltaV would be 1080 m/s, which is quite a chunk of the Earth's orbital velocity, 29783 m/s.

Zatnikitelman · 12-31-2008, 12:16 AM

Well, I don't know aobut Earth, but I calculated a plane change of Phobos once from its slightly inclined orbit to 0 degree. Even using an Ion engine, you'd need something like 13*10^24 kg of propellant.

**pete.dakota** · 12-31-2008, 12:17 AM

Someone back on M6 (may have been DaveS) crunched the numbers regarding how many SSMEs would be required to burn for 8 minutes and move the Earth a notable distance. Might still be able to find the thread on Google's cache if you know how to search for it.

Suzy · 12-31-2008, 01:33 AM

I did see a plan somewhere to move the Earth further from the Sun (when the Sun was becoming a red giant) using an asteroid's orbit - there's an article here: Moving the Earth: a planetary survival guide - so that's another way of doing it!

Andy44 · 12-31-2008, 01:51 AM

To accelerate the Earth at 1 m/s^2 would require a HUMONGOUS array of ion thrusters! Perhaps if you could find a way to turn the Earth's magnetic field into a gigantic Bussard ramjet...yeah, good luck with that!

I remember an episode of Salvage once in which Andy Griffith's crew dismantled the Salvage 1 spacecraft and used the super-high Isp rockets to move an iceberg from the Arctic Circle to the West Coast of the US and sold it to Los Angeles for fresh water. Seems to me a squadron of tugboats would've been an easier way...

SlyCoopersButt · 12-31-2008, 01:54 AM

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.

RocketMan_Len · 12-31-2008, 02:22 AM

Larry Niven did it with Neptune, in his novel 'A World Out of Time'. He proposed a BIG fusion ramjet that used atmospheric gases as propellant.

Step 1 - stick a BIG tube into the atmosphere, let the hydrocarbons collect
Step 2 - light it off with a laser cannon. The exhaust pushes the tube back into the atmosphere. This action imparts a velocity vector onto the planet, and replenishes the fuels in the combustion chamber.
Step 3 - Go back to Step 1

To move the Earth, he brought Neptune into close proximity, and let gravity do the moving. (The idea being that you DO NOT use reaction drives on inhabited worlds...)

Andy44 · 12-31-2008, 02:37 AM

Quote:

Originally Posted by RocketMan_Len

To move the Earth, he brought Neptune into close proximity, and let gravity do the moving. (The idea being that you DO NOT use reaction drives on inhabited worlds...)

Well, that was certainly nice of Mr. Niven...

Mandella · 12-31-2008, 02:52 AM

In Larry Niven's World Out of Time, somebody built one very big fusion ramscoop and dropped it into Uranus' atmosphere. It grabbed compressed hydrogen on the way down, then "bounced" back up to the upper atmosphere where it fired it all off in a directed fusion blast, which pushed it back down into the lower atmosphere where the whole process was repeated. Uranus was thus turned into a planetary gravity tug which was used to move Earth and Mars around (sun was heating up, I think -- it's been a few years).

Good old Niven, thinking big...

But back on topic, one *could* declare a planet as a spaceship, as long as it didn't have moons, couldn't one?

EDIT: Rocketman beat me by minutes! But was it Neptune and not Uranus? Like I said, been a few years...

View Poll Results: Is it possible to move planets in orbiter with insanely powerful rocket engines?
Yes	8	16.33%
Mabye	3	6.12%
No	32	65.31%
I don't know	7	14.29%
Multiple Choice Poll. Voters: 49. You may not vote on this poll

12-30-2008, 10:25 PM	#1
Talon1 Semi-Intermediate Add-on Dev.	Moving planets with rocket engines; is it possible? 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? Also, I've added a poll for this question.

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12-30-2008, 10:32 PM	#2
Piper Orbiting Space Addict	Essentially no, not in Orbiter anyways. Technically, in real-life, any-time a rocket lifts off from Earth, or a spacecraft does a fly-by of Earth, there is a minuscule effect on the orbit of Earth (or whatever object it happens on). However in Orbiter, planets/asteroids can not be changed in game, unless they are declared as a spacecraft themselves.

12-30-2008, 10:51 PM	#3
Jarvitä Orbinaut	Real life: Yes, with OMFG-sized rockets. (or a certain ancient Greek philosopher with a fulcrum and a very long lever) Orbiter: No.

12-30-2008, 11:06 PM	#4
Arrowstar Probenaut	I was going to say what Piper said, so.

12-30-2008, 11:21 PM	#5
Linguofreak Orbinaut	Quote: Originally Posted by Talon1 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? Also, I've added a poll for this question. In Orbiter, no, as has been said. In real life, it depends: How much does the planet's orbit have to change before you consider it "moved," how long are you willing to wait, and how much damage are you willing to do to the planet?

12-31-2008, 12:00 AM	#6
Andy44 owner: Oil Creek Astronautix	Orbiter's planets' ephemeris is fixed and they cannot be accelerated by rockets. In real life, it is theoretically possible, but if you simply put a conventional rocket nose-down in your back yard and light it up it won't move the Earth, because the exhaust won't be able to reach escape velocity. It isn't going that fast at the nozzle to begin with, and even if it is it has to go even faster to overcome atmospheric resistance. You might have better luck on the Moon, but even that requires a very high exhaust velocity. Any exhaust that doesn't reach escape velocity is technically still part of the planet.

12-31-2008, 12:11 AM	#7
Jarvitä Orbinaut	Quote: Originally Posted by Linguofreak In Orbiter, no, as has been said. In real life, it depends: How much does the planet's orbit have to change before you consider it "moved," how long are you willing to wait, and how much damage are you willing to do to the planet? 1. The average planet-sun distance should change by one diametre of the planet. 2. Let's say...the time it takes to complete one half of it's orbit around the Sun 3. in the case of Earth, the surface should still be habitable for humans after the orbit change. Now someone get your astrodynamics equations out and calculate the mass/force/size of the rocket needed to do this to Earth. P.S.:Andy44, so "all" you have to do to move Earth is to put together a giant (which is a giant understatement in itself) ion thruster that reaches outside of the Earth's atmosphere? If I remember correctly, Ion thrusters typically have exhaust velocities in the 10-20 km/s range, which is easily above the Earth's escape velocity. The fuel mass would be negligible compared to a conventional rocket engine, and since it's on Earth, you can always build a few dozens of giant nuclear power-plants around it for power. The thruster would be located on the equator and only fired for a few hours a day when the Earth is positioned properly to give it a prograde boost. In a few months, the delta-V should built up even with a relatively low acceleration - say, on the order of .1 to 1 m/s^2. Disclaimer: This is a semi-drunk 2am post, please go gentle on any obvious errors. I didn't do any calculations and I acknowledge that this could never work. P.P.S.:Ok, math time: If we assume 1 m/s^2 acceleration for 6 hours a day (with thrust vectoring to somewhat compensate for the Earth's rotation or something) for six months, the total deltaV would be 1080 m/s, which is quite a chunk of the Earth's orbital velocity, 29783 m/s.

12-31-2008, 12:16 AM	#8
Zatnikitelman Wandering lonely as a cloud	Well, I don't know aobut Earth, but I calculated a plane change of Phobos once from its slightly inclined orbit to 0 degree. Even using an Ion engine, you'd need something like 13*10^24 kg of propellant.

12-31-2008, 12:17 AM	#9
pete.dakota Donator	Someone back on M6 (may have been DaveS) crunched the numbers regarding how many SSMEs would be required to burn for 8 minutes and move the Earth a notable distance. Might still be able to find the thread on Google's cache if you know how to search for it.

12-31-2008, 01:33 AM	#10
Suzy Orbinaut	I did see a plan somewhere to move the Earth further from the Sun (when the Sun was becoming a red giant) using an asteroid's orbit - there's an article here: Moving the Earth: a planetary survival guide - so that's another way of doing it!

12-31-2008, 01:51 AM	#11
Andy44 owner: Oil Creek Astronautix	To accelerate the Earth at 1 m/s^2 would require a HUMONGOUS array of ion thrusters! Perhaps if you could find a way to turn the Earth's magnetic field into a gigantic Bussard ramjet...yeah, good luck with that! I remember an episode of Salvage once in which Andy Griffith's crew dismantled the Salvage 1 spacecraft and used the super-high Isp rockets to move an iceberg from the Arctic Circle to the West Coast of the US and sold it to Los Angeles for fresh water. Seems to me a squadron of tugboats would've been an easier way...

12-31-2008, 01:54 AM	#12
SlyCoopersButt Orbinaut	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.

12-31-2008, 02:22 AM	#13
RocketMan_Len Orbinaut	Larry Niven did it with Neptune, in his novel 'A World Out of Time'. He proposed a BIG fusion ramjet that used atmospheric gases as propellant. Step 1 - stick a BIG tube into the atmosphere, let the hydrocarbons collect Step 2 - light it off with a laser cannon. The exhaust pushes the tube back into the atmosphere. This action imparts a velocity vector onto the planet, and replenishes the fuels in the combustion chamber. Step 3 - Go back to Step 1 To move the Earth, he brought Neptune into close proximity, and let gravity do the moving. (The idea being that you DO NOT use reaction drives on inhabited worlds...)

12-31-2008, 02:37 AM	#14
Andy44 owner: Oil Creek Astronautix	Quote: Originally Posted by RocketMan_Len To move the Earth, he brought Neptune into close proximity, and let gravity do the moving. (The idea being that you DO NOT use reaction drives on inhabited worlds...) Well, that was certainly nice of Mr. Niven...

12-31-2008, 02:52 AM	#15
Mandella Space Cultist	In Larry Niven's World Out of Time, somebody built one very big fusion ramscoop and dropped it into Uranus' atmosphere. It grabbed compressed hydrogen on the way down, then "bounced" back up to the upper atmosphere where it fired it all off in a directed fusion blast, which pushed it back down into the lower atmosphere where the whole process was repeated. Uranus was thus turned into a planetary gravity tug which was used to move Earth and Mars around (sun was heating up, I think -- it's been a few years). Good old Niven, thinking big... But back on topic, one could declare a planet as a spaceship, as long as it didn't have moons, couldn't one? EDIT: Rocketman beat me by minutes! But was it Neptune and not Uranus? Like I said, been a few years...