Full Version: Help.
I am planning on bringing one of Mars two moons to a stable orbit around earth. I was wondering what the effects on the tides would be, as well as any other major effects. Don't ask why. Its a bit of insanity my runners started on, that I felt I had to run to its end.
Um, the energy involved to do that would be at least a few trillion H bombs worth, and it would have very, very significant and far reaching impacts on the earth.
I am aware of both. I just want to know what the impacts would be.
Cats sleeping with dogs, ya know, the sorta stuff the apoclypyse is made outta.
Dogs and cats living together, Mass hysteria.
On a slightly more serious note, it depends on the location of the new moon in relation to the one we currently have.
Place it directly opposite and for a few months we have newar catestrophic weather as the climate is wrenched into the new pattern. After it settles down (and life has to start over) there would be more mild tidal effects as the gravity of one would counteract the gravity of tghe other, however some areas would see a reduction of ocean levels as the gravity pulled water away from those areas. I think seismic activity would also increase as the magma would be effected the same way.
Also, weather would shift, as one of the biggest drivers is the ocean and it's currents. Weather patterns would be unrecognizable until a few hundred years had passed.
Now, put the new moon in a closer, less balanced position, you have more viokent long term effects. The tides would be stronger, weather more violent, earthquakes and volcanoes more prevalent. Soon the world would cease to be habitable by humanity, but it would take more time than the other way. Also, the earth would suffer more meteor activity as the double moons would pull our relatively small planet in a more erratic micro orbit around the sun, exposign us to more of the van Allen belt, life would evolved on a different scale as organisms were forced to adapt to more radical shifts. life might not be able to adapt, this could become a dead world.
All in all, it's a bad idea to go swapping the moons around, m'kay?
On a slightly more serious note, it depends on the location of the new moon in relation to the one we currently have.
Place it directly opposite and for a few months we have newar catestrophic weather as the climate is wrenched into the new pattern. After it settles down (and life has to start over) there would be more mild tidal effects as the gravity of one would counteract the gravity of tghe other, however some areas would see a reduction of ocean levels as the gravity pulled water away from those areas. I think seismic activity would also increase as the magma would be effected the same way.
Also, weather would shift, as one of the biggest drivers is the ocean and it's currents. Weather patterns would be unrecognizable until a few hundred years had passed.
Now, put the new moon in a closer, less balanced position, you have more viokent long term effects. The tides would be stronger, weather more violent, earthquakes and volcanoes more prevalent. Soon the world would cease to be habitable by humanity, but it would take more time than the other way. Also, the earth would suffer more meteor activity as the double moons would pull our relatively small planet in a more erratic micro orbit around the sun, exposign us to more of the van Allen belt, life would evolved on a different scale as organisms were forced to adapt to more radical shifts. life might not be able to adapt, this could become a dead world.
All in all, it's a bad idea to go swapping the moons around, m'kay?
| QUOTE (Jari_Kafghan) |
| I am planning on bringing one of Mars two moons to a stable orbit around earth. I was wondering what the effects on the tides would be, as well as any other major effects. Don't ask why. Its a bit of insanity my runners started on, that I felt I had to run to its end. |
The technical term for the effects of a tiny little lump like Phobos or Deimos going into Earth orbit is "Diddly Squat." There will be NO disturbance of terrestrial tides or weather. They're just too small.
Further, the Martian moons need to be kept above about 30,000 miles (48000km) from Earth, minimum. Closer than that and they'll break up (See: Roche limit.) That's a really bad problem for the Martian moon, a major problem for satellites, and a minor problem for anyone on Earth. The break-up will result in a brief (centuries, millennia) ring system that gradually peppers Earth with minor debris over a few thousand years.
Finally, the Martian moon (assuming it stays intact) will probably only be stable around Earth for a few millennia, or maybe a few million years, before interactions between the Earth, moon, and Sun either sling it out of Earth orbit or into the Earth or moon.
While Phobos and Deimos are too small to bother Earth from orbit, they're a helluva lot bigger than the Dino Killer asteroid (which was about 5 miles across). Deimos is about twice as big (8x as massive) while Phobos is about three times as big (27x as massive). They'd make a splash on Earth that, as they say, you could see from the moon.
Probably there'd be minor effects- weather isn't really understood that well, and minute changes in basic factors like tides and gravity might produce some unexpected changes.
Didn't you play Doom? It would open the gates of hell...
| QUOTE (Toptomcat) |
| Probably there'd be minor effects- weather isn't really understood that well, and minute changes in basic factors like tides and gravity might produce some unexpected changes. |
Well.
Tidal force is related to the inverse cube of the separation, and linearly related to mass.
Phobos, the bigger Martian moon, is 1/7,000,000th as massive as Luna. If located just above its Roche limit at 50,000km, it's about 8x as close as Luna. Therefore, Phobos (at a 50000km orbit) would exert 1/13000th the tidal effects of Luna on Earth.
For comparison, the Sun exerts about 1/2 the tidal effects of the moon.
| QUOTE (Jari_Kafghan) |
| I am planning on bringing one of Mars two moons |
Thats no moon. Its a space station.
Luna's size (fifth-largest moon in the system, and actually bigger than Pluto) makes putting a second moon into long-term stable orbit around Earth difficult. Luna's big enough, relative to Earth, that its gravity would seriously perturb the second moon's orbit. That's why all the multiple-moon planetary systems we know of are made up of moons that are tiny relative to the planet... the gas giants have multiple Luna-sized moons, but they're much, much more massive than Earth, and Mars, which is smaller than Earth, has just a couple of glorified boulders. The best bet would be to park your stolen moon at one of the Earth-Luna Lagrange points... either L4 or L5 (in the same orbit as Luna, sixty degrees ahead or behind).
Effects on Earth would be basically nil. Phobos, the larger of the pair, is under 30km across (compare to Luna's 3500km), and has a surface gravity so low that you could jump off the thing. I'm not sure it'd even be visible to the naked eye from Earth... it wouldn't be more than a speck if it were. Its gravity certainly wouldn't produce any noticable effects on either Earth or Luna.
Effects on Earth would be basically nil. Phobos, the larger of the pair, is under 30km across (compare to Luna's 3500km), and has a surface gravity so low that you could jump off the thing. I'm not sure it'd even be visible to the naked eye from Earth... it wouldn't be more than a speck if it were. Its gravity certainly wouldn't produce any noticable effects on either Earth or Luna.
So what if you put Phobos in orbit around Luna? What would that do? Would it even be noticed with the naked eye from Earth?
Then you could orbit a shotput around that, and a speck of dust around that!
...what?
...what?
| QUOTE (Gem the Troll) |
| So what if you put Phobos in orbit around Luna? What would that do? Would it even be noticed with the naked eye from Earth? |
You could probably get a stable orbit for a new moon if it was close (within a few hundred miles) of either the Earth or moon, where the effects of the other body (moon or Earth) would be reduced.
BUT then you run into the Roche limit problem, where the asteroid gets pulled apart by the gravity of the larger body.
Sounds like Saeder-Krupp's new trid ad for Ultra Glue showing the destruction of Deimos from gravital forces and a perfectly stable Phobos thanks to it's Ultra Glue coating. I've heard they've got a simsense ad coming out where you can actually feel Demios coming apart; can't wait to get my hands on the beetle version.
kanada - Thats not horribly far off.
| QUOTE (Kanada Ten) |
| Sounds like Saeder-Krupp's new trid ad for Ultra Glue showing the destruction of Deimos from gravital forces and a perfectly stable Phobos thanks to it's Ultra Glue coating. I've heard they've got a simsense ad coming out where you can actually feel Demios coming apart; can't wait to get my hands on the beetle version. |
Ultra-Glue (or just melting Phobos/Deimos into a solid rock) would defeat the Roche limit problem. An adequately strong material can survive the tidal forces that would tear the new moon apart.
There's a Jovian or Saturnian satellite observed within the Roche limit of that planet. Presumably, it's a solid object rather than a "rubble pile" or cluster of fragments.
You spelled physicist wrong.
/feels like being picky today.
/feels like being picky today.
Well, the answer from my girlfriend (a physicist) was basically "It won't work too well, and if you do manage to get it into stable orbit, which is unlikely, you won't notice too much because they're small."
JaronK
JaronK
How big would phobos's face be seen from earth at its minimum altitude?
Would it even present a visible disk?
Would it even present a visible disk?
Phobos is 13.5 km radius at 50,000 km distance.
| QUOTE (http://chandra.harvard.edu/photo/scale_distance.html) |
| The moon is about 0.51 degree across, and is about 384,000 kilometers from Earth. Using Equation (1), we calculate that the diameter of the moon is approximately: S =( 0.0175) x (384,000) x (0.51) = 3430 kilometers. |
So let us reverse that: (13.5*2) = .0175 x 50,000 X A
27/(.0175 x 50000) = 27/875 = 0.031 degrees = A
So take the moon's face and divide it by 17... we should still see it.
| QUOTE (Rev) |
| How big would phobos's face be seen from earth at its minimum altitude? Would it even present a visible disk? |
As Kanada calculated, it probably wouldn't be a dot.
Think of a 1.7-foot object seen at 3000ft distance (or 1.7cm object seen at 30m).
Here is what it would look like as it passed near the moon.
Waaaaaaait… is Saeder-Krupp building Colony Ship Marathon?
~J
~J
| QUOTE (Kagetenshi) |
| Waaaaaaait… is Saeder-Krupp building Colony Ship Marathon? ~J |
Erm...huh?
Marathon reference.
Because I got a shotgun and you don't got one.
Because I got a shotgun and you don't got one.
Do you know what kind of hat I'm wearing?
A party hat; you don't get one. An honor will this party be, a party in your honor, for your honor. Some of Tfear's personal guards are going to be there. You'll be introduced shortly.
Prepare to die.
~J
A party hat; you don't get one. An honor will this party be, a party in your honor, for your honor. Some of Tfear's personal guards are going to be there. You'll be introduced shortly.
Prepare to die.
~J
I say again, "Erm...what?"
Marathon as in "The Battle of...?" Is it anime?
What shotgun, dude?
Edit: Oh.
Marathon as in "The Battle of...?" Is it anime?
What shotgun, dude?
Edit: Oh.
All roads lead to Sol.
~J
~J
| QUOTE (Gem the Troll) |
| So what if you put Phobos in orbit around Luna? What would that do? Would it even be noticed with the naked eye from Earth? |
Close orbit around Luna is tricky, because Luna's density is sufficiently irregular to produce significant differences in its gravitational field from point to point in a circular orbit. That pretty quickly makes the orbit non-circular, and eventually results in the satellite either smacking into the moon or escaping completely. Lunar orbiters that have to stay up for more than a few dozen orbits have to make periodic adjustment burns to maintain their orbits. The further out the orbit is, the less of a problem that is, but if you're too far out, Earth becomes an even bigger problem.
Phobos's mean radius is about 11km (I think the 13.5km Kanada Ten is using is the long axis... the thing's not even close to being round). Luna's mean radius is 1737km. In either lunar orbit or at the Earth-Luna L4 or L5 points, it'd have the same average distance from Earth as Luna, so figuring its apparent size is straightforward division. Phobos is about 1/150th Luna's diameter, so, at the same distance, it'd appear about 1/150th as wide. You can eyeball that next full moon, or figure if Luna's half a degree across, Phobos would be... about 12 arc-seconds.
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