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it's because it's moving sideways so fast that it keeps missing the planet it is falling towards

That's an interesting way to put it.

Anyway, eventually the debris of the ship would make planetfall. There is always some drag on the ship while it is in orbit. So without constant corrections and firing the thrusters it will fall even without getting hit with anything. Blowing it up will proly cause it to enter the atmo a lot sooner, therefor causing more drag, slowing the velocity normal to the gravitational pull and leading the debris "falling" faster.

Unless you were able to hit it with something "heavy" (in the sense of having a large mass) and knock it further way from the planet and break orbit. Even so, it wouldnt hit the same place it was in orbit over, it would hit "behind" it (relative to the rotation of the planet) and a bunch of it would burn up (depending on the atm) and hopefully the rest you could mop up with smaller guns

or..................

send a rag tag group of astronauts/scientists/sassy models/and a guy with a troubled past, to stop anything from crashing into the planet by attaching some sort of nuke or other-such equally unbelivable plan to redirect the ships hull into the sun or something. Failing that, a group of over the hill retired astronauts, I have seen that work too, cant remember where, but it has to be based on fact. At worst you can laugh at the hijinks as they try to get along and save the world, but more importantly discover something else......themselves.......

 Grey Templar wrote:
They didn't need to be aggressive. Just not total wussies.

Well, their ships were heavily armed and even the Startfleet pacificsts knew war and conflict. It's just that they didn't like the thought of building an outright warship when their official policy was founded on peaceful compromise and cooperation. If you want true stupidity in Startrek then ask about the exploding consoles and why basic bodyarmour (even if it is just to stop some savages knive...or a thrown rock), helmets and anything more useful than the equivalent of a bolt action rifle are apparently no longer possible in the 24. century.

taurising wrote:

it's because it's moving sideways so fast that it keeps missing the planet it is falling towards

That's an interesting way to put it.

Anyway, eventually the debris of the ship would make planetfall. There is always some drag on the ship while it is in orbit. So without constant corrections and firing the thrusters it will fall even without getting hit with anything. Blowing it up will proly cause it to enter the atmo a lot sooner, therefor causing more drag, slowing the velocity normal to the gravitational pull and leading the debris "falling" faster.

Unless you were able to hit it with something "heavy" (in the sense of having a large mass) and knock it further way from the planet and break orbit. Even so, it wouldnt hit the same place it was in orbit over, it would hit "behind" it (relative to the rotation of the planet) and a bunch of it would burn up (depending on the atm) and hopefully the rest you could mop up with smaller guns

or..................

send a rag tag group of astronauts/scientists/sassy models/and a guy with a troubled past, to stop anything from crashing into the planet by attaching some sort of nuke or other-such equally unbelivable plan to redirect the ships hull into the sun or something. Failing that, a group of over the hill retired astronauts, I have seen that work too, cant remember where, but it has to be based on fact. At worst you can laugh at the hijinks as they try to get along and save the world, but more importantly discover something else......themselves.......

The problem is that debris is a non-issue in terms of "what will hit the planet". The debris will pretty much fall into one of three categories:

-sufficient velocity imparted to break orbit, wherein it's now heading into deep space.
-insufficient velocity imparted, orbit is normalized at a lower altitude; likely decays over the course of several decades (IE, relative non-issue)
-sufficient velocity imparted and at an appropriate vector to cause a "planet strike". Rarely will this be large enough to not burn up during "reentry".

So the problem with debris is not "oh noes, the sky is falling", but more likely to be "we have a lot of garbage in orbit that makes it hard to do STO/OTS runs".

-sufficient velocity imparted to break orbit, wherein it's now heading into deep space.

No, it wouldn't. A ground-based laser cannon, for example, would "peel" parts of the orbiting ship off, which is then in free-fall at the velocity of its parent vessel, +/-

insufficient velocity imparted, orbit is normalized at a lower altitude; likely decays over the course of several decades (IE, relative non-issue)

That is not a non-issue if that chunk of debris is a multi-megaton hunk of adamantine that's going to crash into a populated area. The friction of re-entry is likely insufficient to deplete the mass of, say, half of a cruiser-class starship.

sufficient velocity imparted and at an appropriate vector to cause a "planet strike". Rarely will this be large enough to not burn up during "reentry".

We're talking about entirely-metallic "asteroids" that are comprised of plasma-forged adamantine that are possibly kilometers in length and that are, more or less, semi-aerodynamic in shape. Re-entry will not cause significant burn-off of this material.

 Psienesis wrote:
No, it wouldn't. A ground-based laser cannon, for example, would "peel" parts of the orbiting ship off, which is then in free-fall at the velocity of its parent vessel, +/-

That is not even close to how an efficiently weaponized laser system would work. You'd actually have thousands-to-millions of nano- or micro-second pulses that explosively drill through the target.

 Psienesis wrote:
That is not a non-issue if that chunk of debris is a multi-megaton hunk of adamantine that's going to crash into a populated area. The friction of re-entry is likely insufficient to deplete the mass of, say, half of a cruiser-class starship.

A decades-long decay cycle is a non-issue because it means that you have plenty of time to stabilize the orbital track. This also assumes that the wreckage won't be recovered and reused.

 Psienesis wrote:
We're talking about entirely-metallic "asteroids" that are comprised of plasma-forged adamantine that are possibly kilometers in length and that are, more or less, semi-aerodynamic in shape. Re-entry will not cause significant burn-off of this material.

To be fair, something that I glossed over and that you've completely ignored is that an orbital warship isn't going to go into orbital decay unless there are some very extenuating circumstances. Things doesn't fall out of orbit because just it gets shot at.

What if the ship ignites the atmosphere? I know about O3, which is why you don't want to fly high without a pressured cabin. I would love for a Hawkins-like mathematician to enter this forum and explain stuff.

Extremely unlikely to happen. If the atmo was so volatile in the first place, the battle over the planet that brought the cruiser into orbit, or the lasers firing from the ground at said cruiser, would have ignited it already.

Yeah. Stable atmospheres, which any inhabited planet will have, aren't full of any compounds that would combust.

Our atmosphere isn't capable of igniting. And even a very high oxygen atmosphere is only a fire hazard when you have something that can burn, the oxygen itself just helps any fires that do occur.

 Grey Templar wrote:
Yeah. Stable atmospheres, which any inhabited planet will have, aren't full of any compounds that would combust.

Our atmosphere isn't capable of igniting. And even a very high oxygen atmosphere is only a fire hazard when you have something that can burn, the oxygen itself just helps any fires that do occur.

a high oxygen enviroment would be incredible corrosive. Increase the pressure and it will tear human life apart.

Our Terran atmo isn't even all that high in oxygen. It's, what, ~80% nitrogen, with some ~5% of various trace gases (xenon and argon and such)?

Yeah, but it could be much higher without any danger. Only once you get huge amounts would it be a problem.

 Psienesis wrote:
Our Terran atmo isn't even all that high in oxygen. It's, what, ~80% nitrogen, with some ~5% of various trace gases (xenon and argon and such)?

yup, 21% O 78% N 1% Ar

Good to a pressure of about 4 atmospheres before the nitrogen starts to cook your brain as a hallucinogen.
If you took it to 8 atmoshperes the oxygen will burn(well oxidize) your lungs and kill you pretty quickly.

The ratios are not the only thing that is important, the pressure makes a huge difference. If you take 100% pure O and up it to 2 atmospheres it will kill you.

 Psienesis wrote:
Our Terran atmo isn't even all that high in oxygen. It's, what, ~80% nitrogen, with some ~5% of various trace gases (xenon and argon and such)?

Isn't that about the size of the planet? I have seen the Universe-programs on Discovery.

I'm not sure what you mean about the "size" of the planet? I mean, Earth is like 25k miles around, 8k miles in diameter and like 200m square miles in surface area.

Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

And yet, 40K has demonstrated that the "Goldilocks Zone" is not relevant to human interests or colonization of worlds. This is how Squats and Ogryns both came about.

Actually, low and high-gravity are words used to explain that. Nice try, but no dice.

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

 Grey Templar wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

You really need to watch Discovery Channel. If a planet is too large the gravity goes seriously up, too small and down by a serious degree. Plus you have the magnetic fields which protects the planet. Too much and you are dead meat, too little and the nearby star would kill you.

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

You really need to watch Discovery Channel. If a planet is too large the gravity goes seriously up, too small and down by a serious degree. Plus you have the magnetic fields which protects the planet. Too much and you are dead meat, too little and the nearby star would kill you.

Do you even know what mass is?

 Wyzilla wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

You really need to watch Discovery Channel. If a planet is too large the gravity goes seriously up, too small and down by a serious degree. Plus you have the magnetic fields which protects the planet. Too much and you are dead meat, too little and the nearby star would kill you.

Do you even know what mass is?

You basically seem to fail to even grasp the concept of gravity. Watch Discovery Channel.

 Beaviz81 wrote:

 Wyzilla wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

You really need to watch Discovery Channel. If a planet is too large the gravity goes seriously up, too small and down by a serious degree. Plus you have the magnetic fields which protects the planet. Too much and you are dead meat, too little and the nearby star would kill you.

Do you even know what mass is?

You basically seem to fail to even grasp the concept of gravity. Watch Discovery Channel.

You mean a garbage channel with incredibly basic shows compared to say, textbooks or actual books written by physicists?

Size does not matter if the mass is too low due to less density, or if there is no magnetosphere to prevent solar winds from blowing away the atmosphere entirely (Mars). What you're thinking off is the actual mass of the atmosphere itself.

The atmosphere weights down on a planet of course. So a really big planet has a really big atmosphere which weight down on the ground on the planet. Its the main reason scientists has failed to pierce the atmosphere of Jupiter.

In fluff heavy gravity eventually produced the Squats and Ogryns. Thats canon. It has been stated since the first edition.

 Beaviz81 wrote:

 Wyzilla wrote:

Do you even know what mass is?

You basically seem to fail to even grasp the concept of gravity. Watch Discovery Channel.

Actually Beaviz, it's you who fails to grasp the concept of gravity.

Gravity is a function of mass. Mass is determined via density and volume being multiplied together. By having a very large volume (IE, "size") and a very low density, you can have an Earth-like mass, and therefore, an Earth-like gravity field. As such, yes, you can indeed have very "large" planets that are of comparable gravitational condition to Earth. Whether or not it has a sufficient magnetic field or atmospheric composition for a shirtsleeve-inhabitable environment is a totally separate issue.

EDIT: and as to this:

 Beaviz81 wrote:
The atmosphere weights down on a planet of course. So a really big planet has a really big atmosphere which weight down on the ground on the planet. Its the main reason scientists has failed to pierce the atmosphere of Jupiter.

That's not how atmospheric pressure works. It's a function of atmospheric composition and *gasps* gravity. Jupiter has a very high gravity, due to its large mass. Neutron stars, for example, are incredibly dense and high-gravity objects, to the point that a human would be less than a smear on the surface of such a stellar object. A neutron star is also (relatively) small, but due to its high density (IIRC it's been said that a teaspoon of neutron-star-stuff has a comparable mass to Earth) it has an incredibly "heavy" gravity.

Put simply, Jupiter doesn't have a high density atmosphere that's difficult to penetrate* because it's "big", it's because it has an enormous gravity and a high-density atmospheric composition.

*Part of the problem with 'penetrating' Jupiter's cloud layers has more to do with the extreme turbulence therein. And much more relevantly, the incredible distance and expense of sending a probe mission to Jupiter.

Whiskey144 wrote:

 Beaviz81 wrote:

 Wyzilla wrote:

Do you even know what mass is?

You basically seem to fail to even grasp the concept of gravity. Watch Discovery Channel.

Actually Beaviz, it's you who fails to grasp the concept of gravity.

Gravity is a function of mass. Mass is determined via density and volume being multiplied together. By having a very large volume (IE, "size") and a very low density, you can have an Earth-like mass, and therefore, an Earth-like gravity field. As such, yes, you can indeed have very "large" planets that are of comparable gravitational condition to Earth. Whether or not it has a sufficient magnetic field or atmospheric composition for a shirtsleeve-inhabitable environment is a totally separate issue.

Then give me the nifty links for that since its complete knowledge I have never even heard about. I don't mind a long boring read, but please tell me which pages to look for.

 Beaviz81 wrote:

Whiskey144 wrote:

 Beaviz81 wrote:

 Wyzilla wrote:

Do you even know what mass is?

You basically seem to fail to even grasp the concept of gravity. Watch Discovery Channel.

Actually Beaviz, it's you who fails to grasp the concept of gravity.

Gravity is a function of mass. Mass is determined via density and volume being multiplied together. By having a very large volume (IE, "size") and a very low density, you can have an Earth-like mass, and therefore, an Earth-like gravity field. As such, yes, you can indeed have very "large" planets that are of comparable gravitational condition to Earth. Whether or not it has a sufficient magnetic field or atmospheric composition for a shirtsleeve-inhabitable environment is a totally separate issue.

Then give me the nifty links for that since its complete knowledge I have never even heard about. I don't mind a long boring read, but please tell me which pages to look for.

Well you could just look up how gravity is calculated.

http://en.wikipedia.org/wiki/Gravity

F=G*(M1*M2/r^2)

The force of gravity is entirely dependent on the mass of the two objects in question. A planet with a high volume, but very low density, can easily have lower gravity than a low volume, but high density, planet. See neutron star example, or a black hole.


Say we have two spheres, both the exact size of earth. One is made out of gold, the other is made out of styrofoam. The one made out of gold will have a much higher gravity than Earth does. The one made out of styrofoam will have much less gravity than Earth.

Earth's molten core is made out of mostly iron and nickel. This actually causes Earth to be the densest planet in the solar system. Oddly enough, some of the other planets would actually float if they were submersed in water. So really, for its size Earth is actually pretty high gravity.

If Earth's core wasn't made out of iron and nickles, and was something lighter like Aluminum, or it had no molten core at all and was just some porous rock like pummace, it would be much less.

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:

 Grey Templar wrote:

 Beaviz81 wrote:
Yeah, but too large and pressure basically gets too great and crushes you. I think we can live on a planet a few times the size of Earth, but beyond that and gravity would crush us.

Not necessarily. If the planet isn't as dense as Earth it could be much larger surface area. A molten core of mostly aluminum instead of iron for example.

Do you know about the Goldilocks-hypothesis? Too small and its too light in gravity and we will die from both atrophy and lack of atmosphere. Too large and the atmosphere comes down and crushes stuff on the ground because of pressure. And you likely know enough to know what a too hot or cold planet would do to human physiology. But I will iterate. The planet can not be too cold, nor too warm, nor too small, nor too big. I highly recommend you to watch Discovery channel.

I think you misunderstand.

You can have a planet with a larger surface area, but is less dense, leading to similar gravity to earth. Or at least close enough to allow habitation.

You really need to watch Discovery Channel. If a planet is too large the gravity goes seriously up, too small and down by a serious degree. Plus you have the magnetic fields which protects the planet. Too much and you are dead meat, too little and the nearby star would kill you.

The size of the planet is not directly comparable to its mass. A planet could be large, but comprised mostly of silicate and aluminum, and thus would have less mass than a smaller planet of igneous rock and ferrous metals. The big planet would have less gravitic pull than the smaller in such a case.

How about starting with the Wikipedia pages for "Gravity", "Mass", and "Density"?

Think about it this way: density is an expression of mass per unit volume; for example, kilogram/m^3 would be an unit of density.

Volume is a measure of how much space something takes up, and is express by cubing a unit of length, like so: m^3.

kilogram/m^3 * m^3, would be kilogram*m^3/m^3, in which case the volume unit cancels out (via dividing itself), leaving only kilograms.

Thus, we have determined mass.

Mass is very relevant to gravity, particularly because weight and mass are separate concepts and measures; weight is more accurately applied as a measurement of how much gravity affects a given object, whilst mass is constant even without the influence of gravity.

For example, I weigh ~110 pounds, roughly 50 kilograms. In open space, however, I would weigh 0 lbs, but still mass 50 kilos. This is why weight is not especially relevant when considering gravitational effects, because it is a measure of easily varying value.

Consider Mars and Mercury, two planets whose gravitational values are actually within ~1% of each other. Yet Mars is both larger and more massive, whilst Mercury is much denser. In fact, Mercury has a density of ~98% that of the Earth, whilst Mars is ~71% the density of Earth.

Mars is also ~11% the mass of Earth, whilst Mercury is only ~5.5% the mass of Earth... and yet Mercury and Mars both have a surface gravity of ~0.38 g.

But if what you say is true, that if a planet is too small or too big, its surface gravity goes wildly down or up, respectively, how is that possible?

To cut to the chase, it obviously cannot be possible, as otherwise Mercury would have a vastly lower surface gravity.

Let's look at Jupiter as our final example; Jupiter has a mass of ~3178% that of the Earth, but a density of only ~24% that of the Earth and a gravity field that's ~250% that of the Earth.

In terms of volume, it's ~13213% that of the Earth... but if it's so much bigger, why is gravity only 2.5x heavier?

I submit that mass plays an enormously important role in how gravity works. I admit that I am far from an expert, being at best an amateur in the field.

But overall size (IE, volume/surface area) are only tangentially related to gravitational effects. Mass and density play a much larger role in gravitational effects, considering the "curious" case of Mercury and Mars, wherein they have nearly identical gravity fields.