Lunar Rover

[Industrial Toys]

What does a rocket push against in the vaccume of space?

I saw a great video of some excursion in their buggy, maybe 5 KM to some crater. There was a lot of video of the two of them, in proper focus, properly framed and zoomed. I am curious how they managed that. It (the camera) would have had to be remote controlled, but from where and how with such real time precision? A camera man standing there holding the camera could not have done a better job.

 

[MossRoad]

What does a rocket push against in the vaccume of space?

I saw a great video of some excursion in their buggy, maybe 5 KM to some crater. There was a lot of video of the two of them, in proper focus, properly framed and zoomed. I am curious how they managed that. It (the camera) would have had to be remote controlled, but from where and how with such real time precision? A camera man standing there holding the camera could not have done a better job.

For every action, there is an equal and opposite reaction. The burning fuel goes one way, the rocket goes the other. It doesn't need any air to push against.

 

[Industrial Toys]

I'm having a hard time understanding that. If I push my hand out quickly into the air, I don't go anywhere. Push it against a wall and different story. Same with a jet ski. Feed it some water when the jet isn't submerged and it won't have (much) forward movement.

 

[/pine]

basically, rockets are only needed to get to space (through the atmospheres)...once in space (vacuum w/no gravity) for simple movement all that is required is a boost...once boosted an object will move basically forever in whatever direction the object was shoved etc...to stop or slow down would require a calculated boost or shove in the opposite direction...

Basically if you could live in a vacuum with no gravity a fart would propel you...

 

[k0ua]

I'm having a hard time understanding that. If I push my hand out quickly into the air, I don't go anywhere. Push it against a wall and different story. Same with a jet ski. Feed it some water when the jet isn't submerged and it won't have (much) forward movement.

When you push your hand into the air you didn't eject any mass and the air moved around your hand. Some small actual thrust was generated by your hand pushing mechanically against the air molecules.. When you pushed into the immovable object, you still didn't eject any mass you used your muscles contractacting to mechanically move your self. The examples you gave have nothing to do with mass ejection as a method of propulsion in space. Nothing. You are trying to draw and inference and there is none. To move yourself in space you must eject something out the "back". That mass could even be a small ion stream. That would be enough. Until you get the warp drive working.

You say "I didn't go anywhere" I say you did. It is just so small you didn't notice it.

 

[bcp]

What a rocket exhaust pushes against is the rocket. Same as a blown up and released balloon.

And there is gravity in space. It just isn't felt when in orbit. If a satellite stopped moving in its orbit, it would fall.

Bruce

 

[k0ua]

What a rocket exhaust pushes against is the rocket. Same as a blown up and released balloon.

And there is gravity in space. It just isn't felt when in orbit. If a satellite stopped moving in its orbit, it would fall.

Bruce

True for LEO (Low Earth Orbiters) but not true for satellites out past the La Grange points. These satellites are influenced by the weak gravity from the Sun and Moon. In deep space there are no gravitational forces.

 

[/pine]

What a rocket exhaust pushes against is the rocket. Same as a blown up and released balloon.

And there is gravity in space. It just isn't felt when in orbit. If a satellite stopped moving in its orbit, it would fall.

Bruce

Technically that's correct but there are places in space that are very far from objects that create gravity so the effect is minimal...may not be total
"zero gravity" but it can come close... FWIW the moon's gravity is 1/6th of the Earths's

 

[Industrial Toys]

So if the exhaust pushes against the rocket, doesn't there have to be the other half of that equasion, the thrust pushing against atmosphere?


If you had a room with a vaccume and released an air filled balloon or lest say a co2 cartridge with a hole poked in the end, would it propel itself?

 

[/pine]

If you had a room with a vaccume and released an air filled balloon, would it propel itself?

For sure...did you happen to see the movie 'The Martian'?