Solar System Question

[MrJim]

I've wondered about this...

The picture given generally is that "outer space" is somewhat elliptical in shape and if you want to travel to a planet it's essentially like driving a car or steering a boat-you travel horizontally.

How come someone just doesn't go straight up or straight down once they've cleared the earth's orbit?

Probably a duh question-probably too much star trek and star wars...

 

[Yamialpha]

They probably would if the planet they wanted to travel to was straight up or straight down relative to the Earth. But seeing as to travel to the spiral arms you'd have to go horizontal, then most would probably do that.

 

[MrJim]

They probably would if the planet they wanted to travel to was straight up or straight down relative to the Earth. But seeing as to travel to the spiral arms you'd have to go horizontal, then most would probably do that.

So what is straight up or straight down?

 

[Stellar Vision]

Good question. The reason why paths are always shown as curved when traveling from planet to planet is because we are always revolving around sun. A space probe trying to get to Mars will leave the Earth's orbit, but it still has that centripetal motion of the Earth with it.

Basically everything in the solar system has to be moving in some sort of elliptical path around the sun or else it will get pulled in. What a space probe does is simply extend its' orbit around the sun from matching that of the Earth's to that of the Martian orbit.

 

[billwald]

Try walking in a straight line on a merry-go-round and you will understand the problem.

The chosen trajectories minimize energy requirements.

 

[Yamialpha]

I think he's talking about when you've left the gravity of the solar system completely.

 

[Stellar Vision]

I think he's talking about when you've left the gravity of the solar system completely.

I'm not so sure. He did mention travel to a planet, unless he was refering to an extrasolar planet.

How come someone just doesn't go straight up or straight down once they've cleared the earth's orbit?

Probably a duh question-probably too much star trek and star wars...

Could you give us an example, perhaps from star trek or star wars, that you might be thinking of which seems contradictory to real world spaceflight?

 

[MrJim]

I'm not so sure. He did mention travel to a planet, unless he was refering to an extrasolar planet.

Could you give us an example, perhaps from star trek or star wars, that you might be thinking of which seems contradictory to real world spaceflight?

The example is any show where the astronaut/space travelers are sitting in a seat like a car or boat. The are going forward-not going straight down or straight up. Imagine being on the space shuttle and the nose was pointed down. Not knowing the true nature of space travel-forget about energy requirements. You can "warp" straight up or down. Imagine looking at a drawing of the solar system and all the orbits/planets are drawn out. So instead of leaving earth and instead of traveling to a planet you continue just going up (or if it's more comfortable down). Imagine a shuttle/space ship that has gravity (like a star trek ship). The people on the ship wouldn't be able to walk because they'd be piled into the nose/front of ship because it's going down (like a sinking ship or crashing aircraft). But you wouldn't hit anything in space ship because you're in space---what is down there and up there?

 

[Stellar Vision]

Ok, well I guess when you're talking about 'up' and 'down' in space it's all relative. Trying to fly a space ship up or down relative to the plane of the solar system would be possible, but you would still be caught in the sun's gravity, and end up in a polar orbit around the sun.

The sci-fi spaceships that have artificial gravity would probably have something that generates a force which is always downward relative to the floor, regardless of what direction the spaceship is pointed. Even while in orbit around a planet, and pointed 'downward' toward the surface, the people would not be pulled to the nose of the craft, because an orbit is like a state of freefall. In other words both the ship and the people are being pulled by the planet's gravity, so they are not being forced anywhere relative to each other.

Real world spacecraft unfortunately don't normally fly like airplanes do. Airplanes control their flight by pushing off of the air around them. In space there is no atmosphere to push off of. Most of the time those sci-fi spacecraft are always pointed in the direction of travel like an airplane, but I think they do that just because we are more familiar with that type of flying.

 

[Yamialpha]

what is down there and up there?

So basically are you asking what is above and below the Earth?