In space there is a vacum, no atmosphere, no drag?

Question

So why would we need so much fuel to travel to distant places, once you get up to speed you could turn power off and carry on at the same speed until you got to your destination right?

Answer 1

You are correct, however there are a few factors that need to be considered ones we have escaped the Earth's gravitational field. Here is what stands in our way:
1.Overcoming the inertia
The spaceship has a certain amount of mass which must be overcome by trust supplied by the engines. Spaceships weightless in outerapace still have a mass say betwen 1,000 to 100,000 kg. Remember F=ma? That was the Second law of Newton.
2.Limitation of the momentum of propulsion
The mass of the particles escaping the nozzle of the engines generates the trust. Or moment= mass times velocity (p=mV). Based on Newton’s Third Law “…every action has an apposite and equal reaction” we have P(spacecraft) = P(propellant). Note that at this point the speed of the spacecraft is limited to the exiting propellant (see pace propulsion reference below)
3.The practical consideration.
Practically speaking the propellant is a part of the spacecraft and to achieve speed equal to the exiting propellant is impossible since we must the mass of the spacecraft must be equal to the mass of exiting the nozzle propellant. This will lead the speed of the spacecraft to be a fraction of the speed of the exhaust.

Answer 2

It's not the fuel for the travelling that's an issue, it's the fuel used to escape the atmosphere that takes the original toll. Also, you can only bring so much fuel with you before it's too heavy to reach escape velocity, so you have a finite amount of fuel to work with once you actually acheive space. You still need to run the life-support (air!) and all that. Also, if there is a miscalculation by even the tiniest nth degree, you'll wind up missing where you're going, so adjustments would be needed here and there, which also require energy. That's why they're working on perfecting a ship that will run on hydrogen, which is present as free-floating particles in the void.

Answer 3

You are correct - once the massive amounts of fuel have been used to reach escape velocity and get into space away from the gravitational pull of Earth, they will keep on moving at that velocity until some other force comes into play such as the gravity of the next planet or a collision with a rock. Newtons 2nd Law.
Latest research is developing solar sails that will utilise the plasma (photons of light) to accelerate.

Answer 4

I think the amount of time is more of an issue than fuel. Astronauts can only travel so far. They do shut off engines when they reach orbit, stabilizing rockets are only used after that. However, a certain speed is needed to get through the atmosphere and that works both ways.

Answer 5

The thing is, we've never actually travelled to distant places before. However, we would still need fuel to overcome the Earth and Sun's gravitational pull. Also, there are particles in space and that may cause a tiny amount of resistance.

Answer 6

Yes. According to newton's 2nd law. That is correct. This is because an object will continue in motion unless stopped by a oppositing force (like friction which the space do not have)
However, in space, it is not really a vacuum. It is almost a vacuum. The particles (scattered atoms and molecules) are so far apart, it is like a vacuum.

Answer 7

They go bang! when they set off, then they go "chugga chugga chugga" when they get to the atmosphere, and then they go "buzz" with all the lectrical stuff when they reach space, because they dont need to push against all the little atoms and stuff that float around in the earths atmosphere but hardly in space, so they dont need power, and as you said, they flick the BIG RED BUTTON and then use electric to press buttons and turn and miss being pulled to toher planets by their gravity.

Answer 8

like the dude above said, thats what we do. But even in space theres gravity. think of it like holding a blanket out at four corners and putting a weight in the middle, everything else on the blankets going to want to go towards the weight. Thats the way gravity works in space. Anytime you get close to anything, you take lots of gas to stay away from it.

Answer 9

It's called gravity. The fuel is required to overcome gravity; once a craft reaches space with sufficient velocity to escape earth's gravity, it can coast indefinitely because there is no drag.

Answer 10

You are correct, but it takes a massive amount of energy for a craft to escape the earth's gravitational pull. Thats why shuttles are equipped with massive fuel tanks.