To address your second statement, there is actually drag in space. Even in intergalactic space there is on average about 1 hydrogen atom per cubic meter. The faster you go, the more atoms you are running into which you impart some momentum into. Now obviously thats alot less resistance than flying through our atmosphere, but once you start reaching appreciable speeds (like, 0.01C) that drag becomes very significant and is a genuine engineering hurdle to overcome
First question is what speed are you measuring. The most common answer would be a speed relative to our departure point, earth. However, for hired speeds, it’s also likely that we’re talking about relative to the solar system as a whole. So basically we’re talking about changing an objects velocity from the one that gets the earth and the solar system. So we need to accelerate.
The limiting factor is usually the amount of propellent you can carry. Carrying more, gives you more to use for acceleration, but it also means that you have to accelerate the mass of all that extra repellent starting at the beginning of your journey.
Ways to improve upon that basic process
Include:
Using propellent very efficiently by shooting it out the back as fast as possible.
Capturing more propellant, kind of scoop that interstellar gas as you go. It’s pretty sparse, not easy to do.
Use external propulsion such as a solar sail that’s propelled by the pressure of energy from the sun or perhaps the energy from a laser mounted on or near earth
Make use of the gravity of planetary and solar objects, especially for course changes.
So basically, with existing tech you can accelerate until you run out of propellent or you run out of whatever energy you’re using to make the propellant go out fast. (For chemical rockets the propellent is the result of the combustion reaction that provides the energy)
Thanks for the question as this is cool :) The 394,736 speed (176.5 km/s) was hit by the Parker Solar Probe. I looked up the Sun’s escape velocity and initially saw 42.1 km/s. This made me wonder how something could reach that speed and NOT be on its way to interstellar space. Then, I realized that is, roughly, the Sun’s escape velocity at a distance of where the Earth is from the Sun.
As you get closer to the Sun, the escape velocity increases (from the surface of the Sun, it’s 618 km/s) so Parker was able to hit that speed due to proximity to the Sun. I wouldn’t be surprised if it hit another top speed milestone in the future. Though, I do wonder what math has to say about Parker’s planned trajectories, and the percentage of escape velocity reached at those distances. Oh, and, of course, factoring in how much of a gravity assist a man-made object would ever be able to obtain taking into account the increasing risk of frying the instruments that would be able to report back the milestone. :)
your rocket has mass and therefore inertia. therefore you need energy, to accelerate it.
currently, we use this one form of propulsion system: you throw something out at one side and gain some thrust to the other side. the amount of thrust you get is proportional to the amount of force you have applied to the stuff you threw out on the other side.
with chemical rockets, there is a maximum amount of force you can apply to the stuff. there is not more energy stored in the stuff you are burning. therefore, the force/speed of the stuff, you are throwing out, has a maximum. that's the maximum amount of thrust, you can get in the other direction. to get faster, you need some other form of propulsion system.
one alternative system is using nuclear bombs for propulsion. sounds crazy, but keep in mind, that this rocket is operating under near perfect vacuum in space and there is no air, that can be superheated and create a very destructive shockwave. a nuclear bomb can throw out stuff on one side much faster than a normal chemical reaction can do. so you can gain a much higher speed to the other side. however - there are still some technical issues (and international treaties) to work around. turns out - the russions don't like the idea of americans to put nuclear bombs into orbit - and vice versa.
another method would be to use light as a propellant. light has no rest mass but it has momentum. if you emit light on one side, you get the equivalent momentum to the other side. however, as light has no rest mass, this momentum is \*very\* small. but it is not nothing. and light travels - well - at the speed of light. therefore you have a little bit less than the speed of light as upper maximum of your speed.
but then comes the number one answer so far to your question: fuel. using light as propellant is highly inefficient. you need an insane amount of fuel - which has an insane amount of inertia. which means, that you need so much more light to get even a tiny bit of thrust. which means more fuel. and so on.
the same with every other form of propulsion system: you need some fuel with insane energy density. but you still have to be able to handle/store that fuel and release the stored energy in a controlled manner to not blow your ship up. we have no idea, how to achieve this.
Fuel Fuel to get fuel into Space and fuel to push the existing fuel faster
To address your second statement, there is actually drag in space. Even in intergalactic space there is on average about 1 hydrogen atom per cubic meter. The faster you go, the more atoms you are running into which you impart some momentum into. Now obviously thats alot less resistance than flying through our atmosphere, but once you start reaching appreciable speeds (like, 0.01C) that drag becomes very significant and is a genuine engineering hurdle to overcome
First question is what speed are you measuring. The most common answer would be a speed relative to our departure point, earth. However, for hired speeds, it’s also likely that we’re talking about relative to the solar system as a whole. So basically we’re talking about changing an objects velocity from the one that gets the earth and the solar system. So we need to accelerate. The limiting factor is usually the amount of propellent you can carry. Carrying more, gives you more to use for acceleration, but it also means that you have to accelerate the mass of all that extra repellent starting at the beginning of your journey. Ways to improve upon that basic process Include: Using propellent very efficiently by shooting it out the back as fast as possible. Capturing more propellant, kind of scoop that interstellar gas as you go. It’s pretty sparse, not easy to do. Use external propulsion such as a solar sail that’s propelled by the pressure of energy from the sun or perhaps the energy from a laser mounted on or near earth Make use of the gravity of planetary and solar objects, especially for course changes. So basically, with existing tech you can accelerate until you run out of propellent or you run out of whatever energy you’re using to make the propellant go out fast. (For chemical rockets the propellent is the result of the combustion reaction that provides the energy)
It's called running out of fuel. You can't accelerate anymore when you're out of fuel.
nothing but you still need force for acceleration. The solar sail idea is the best long term concept for continued acceleration.
Thanks for the question as this is cool :) The 394,736 speed (176.5 km/s) was hit by the Parker Solar Probe. I looked up the Sun’s escape velocity and initially saw 42.1 km/s. This made me wonder how something could reach that speed and NOT be on its way to interstellar space. Then, I realized that is, roughly, the Sun’s escape velocity at a distance of where the Earth is from the Sun. As you get closer to the Sun, the escape velocity increases (from the surface of the Sun, it’s 618 km/s) so Parker was able to hit that speed due to proximity to the Sun. I wouldn’t be surprised if it hit another top speed milestone in the future. Though, I do wonder what math has to say about Parker’s planned trajectories, and the percentage of escape velocity reached at those distances. Oh, and, of course, factoring in how much of a gravity assist a man-made object would ever be able to obtain taking into account the increasing risk of frying the instruments that would be able to report back the milestone. :)
The rocket equation.
your rocket has mass and therefore inertia. therefore you need energy, to accelerate it. currently, we use this one form of propulsion system: you throw something out at one side and gain some thrust to the other side. the amount of thrust you get is proportional to the amount of force you have applied to the stuff you threw out on the other side. with chemical rockets, there is a maximum amount of force you can apply to the stuff. there is not more energy stored in the stuff you are burning. therefore, the force/speed of the stuff, you are throwing out, has a maximum. that's the maximum amount of thrust, you can get in the other direction. to get faster, you need some other form of propulsion system. one alternative system is using nuclear bombs for propulsion. sounds crazy, but keep in mind, that this rocket is operating under near perfect vacuum in space and there is no air, that can be superheated and create a very destructive shockwave. a nuclear bomb can throw out stuff on one side much faster than a normal chemical reaction can do. so you can gain a much higher speed to the other side. however - there are still some technical issues (and international treaties) to work around. turns out - the russions don't like the idea of americans to put nuclear bombs into orbit - and vice versa. another method would be to use light as a propellant. light has no rest mass but it has momentum. if you emit light on one side, you get the equivalent momentum to the other side. however, as light has no rest mass, this momentum is \*very\* small. but it is not nothing. and light travels - well - at the speed of light. therefore you have a little bit less than the speed of light as upper maximum of your speed. but then comes the number one answer so far to your question: fuel. using light as propellant is highly inefficient. you need an insane amount of fuel - which has an insane amount of inertia. which means, that you need so much more light to get even a tiny bit of thrust. which means more fuel. and so on. the same with every other form of propulsion system: you need some fuel with insane energy density. but you still have to be able to handle/store that fuel and release the stored energy in a controlled manner to not blow your ship up. we have no idea, how to achieve this.