Would it not eventually get pulled in and hit the surface?
Nope. That's not how orbital mechanics work.
In order for it to "eventually get pulled in"... one of two things have to happen.
1) The initial anti-radial impulse out the airlock would have to have been powerful enough to alter the orbit enough so that the Queen's orbital periapsis is low enough to drag the tenuous upper atmosphere allowing atmospheric drag to pull it down over the course of years, even decades.
But there is about a zero chance that anti-radial force was strong enough. It would need to be several orders of magnitude greater, a couple of minutes of powerful rocket burn, not just a pop of air out a lock.
2) Some sort of continuing force has to be constantly applied to the Queen after it left the lock. And no... not gravity. Gravity is already a constant force acting on it. It's what allows something to be in Orbit in the first place. Some additive force above gravity, like a rocket engine thrusting for example.
Orbital Mechanics is very counterintuitive for those who have never bothered to understand even the basics of it. What a person would thinknis the obvious result of something is nothing like what would actually happen at all.
Take the following example:
You are on EVA just outside the airlock of the ISS.
Below you spins the Earth as you are in orbit.
You have a baseball in hand and you throw it down towards the Earth.
The baseball leaves your hand and travels in the direction of Earth, straight down away from you, receding further and further till you can no longer see it.
Now what the typical person would assume is that the ball continues in a direct line away from you and towards the Earth till it hits atmosphere and burns up like a meteor (The same assumption made with the Queen and power loader). But that actually is just an illusion of relative motion.
The truth is that you are not floating motionless above the Earth as the Earth spins beneath you. You are hurtling sideways to the Earth at over 17,000 mph. Earth's gravity is pulling you down and you are following a curved arc just like a thrown rock. The thing is you are going sideways so fast and Gravity can only pull you down and curve your path only so much, that you miss hitting the Earth and endlessly fall around it. That's what an orbit is.
When you toss the baseball, It only appears to move away from you and towards Earth from your RELATIVE point of view. In reality, it too is still moving in an orbit about Earth at around 17,000 mph.
Your toss (or the impulse of air blasting the Queen out the airlock) only slightly altered it's orbit from that of your own. It has slewed the Apoapsis and Periapsis about a slight ammount. rotating about the point in the orbit at where the thrust took place. Rather than a circular orbit at lets say... 400 km, The ball is now in an elliptical orbit of 398 x 402 km
As the ball drops down towards 398 km, it picks up speed thanks to gravity and moves ahead of the station. Its added speed is what allows it to climb back up to 402 km, losing speed against gravity as it does so, dropping back in orbit relative to the station. once at 402 km, it no longer has the speed to maintain that orbital altitude so it starts falling again back to 398 km, and so on.
The balls orbital period will be slightly different so eventualy it will spread out around the orbit of the ISS, but never vary more than a few km above and below it's orbit.
Eventually though... the possibility exists that in a few years, the ball could once again pose a collision hazard to the station.
I joined the Navy to see the world, only to discover the world is 2/3 water!
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ttaskmaster
8 years ago
I realise the Sulaco probably had to remain geostationary over the colony, for comms purposes.... but is there a particular distance from a planet (relative to gravity, I assume) where you no longer have to orbit it and can just sit there (roughly stationary) while you lob tennis balls and alien queens out the airlock?
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CGSailor
8 years ago
but is there a particular distance from a planet (relative to gravity, I assume) where you no longer have to orbit it and can just sit there (roughly stationary) while you lob tennis balls and alien queens out the airlock?
Yes....
... and No.
Yes, there is an altitude at which you can orbit and remain stationary over a single point on the surface, but only if that point is on the planet's equator.
But you are not stationary relative to gravity, only the planetary surface.
Gravity acts from the center of mass of the planet and cares not a whit whether the planet is rotating or not. When you orbit about a planet, you are orbiting not about its surface but about it's center of mass.
What you are thinking of is a geostationary orbit.
Lower orbits have a higher orbital velocity and a shorter period of time it takes to complete a single orbit.
Higher orbits have a slower orbitital velocity nd a longer period. There will be a soecific orbital altitude where your orbital velocity is such that your period exactly matches the rotation of the planet (24 hours in the case of Earh). At that height and with the plane of your orbit at exactly 0° Inclination, from the perspective of someone on the planet looking up, you would appear to remain stationary.
For Earth, that altitude is roughly 22,000 miles up. ISS is only a couple hundred miles up. This geostationary orbit is very popular and very crowded with communications satellites for ground based communications networks like Satellite TV, Dish Network, DirectTV, etc... because you can have a fixed satellite dish point at a fix spot in the sky and recieve the signal without having to have an antennae try to track the satellites.
So yes, There is an altitude for which you will APPEAR to remain stationary over a fixed point on the planet.
But NO. You are not actually stationary You are still orbiting about the planet at insane orbital velocities and orbital mechanics still apply just as they did in my previous example. Remember, you are orbiting about the mass of the planet, not orbiting about a point on the surface. The planet itself could stop rotating, reverse its rotation, or change its axis of rotation and it would not matter at all to something in orbit.
You ALWAYS have to orbit a planet. Not unless you have some super sci-fi antigravity gadget.
You always have to orbit because gravity exists. Even in space. Even aboard the ISS when you see astronauts floating about in "Zero Gravity" there is still gravity. Pretty much about 98% of the same gravity as felt standing on the surface.
Gravity is always pulling you down.
Orbiting is moving sideways fast enough (orbital velocity) so that gravity pulls you into a ballistic arc (like a thrown rock) but you are moving sideways fast enough that you miss the Earth and fall endlessly around it. You can never be stationary relative to the planet itself. Gravity would pull you straight down.
What you are doing in a geostationary orbit is still orbiting around the planet, but doing so at the same speed as the planet is rotating and in the same axis of rotation. thus you remain over the same fixed point on the planet.
I joined the Navy to see the world, only to discover the world is 2/3 water!
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ttaskmaster
8 years ago
What you are thinking of is a geostationary orbit.
Na na na... I did mean specifically non-geostationary. As in not above a fixed point on the planet's surface, to the point where you appear be as fixed a point in the sky as the constellations.
Can you not maintain position relative to the planet (regardless of attitude, rotation, etc) and not have to orbit at all?
I'd guess that's not easy in practice, given how far Pluto is from, yet still orbiting, The Sun... but in theory if you were completely static (perhaps actively maintaining your exact position using thrusters), what would happen to the ball/alien if you then threw it 100% directly at the planet?
I'm guessing it'd be no different to an asteroid/meteor hurtling directly at Earth (gravity of other nearby bodies aside)?
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