A space vacuum tube from the lower atmosphere? Could this work?

[Lomaser]

If we could build a large tube big enough for a spacecraft to fit through from the lower atmosphere into space and turn it into a vaccum by sucking out the oxygen (Or could we leave it as it is but with airlock doors on either end? ) Held in place by the same technology as the space elevator.

How could we benefit from this? I think that we would be able to stop reentry friction and also within the tube we might eradicate friction and gravity so would be able to travel faster and carry heavier payloads.

What pros and cons can you see with my idea and am i missing anything of relevance?

[Lomaser]

In case you don't understand think a football as the earth and a cardboard toilet tissue tube stuck to it as the space vacuum tube (Not to scale obviously ) so the tube would serve as a portal

[jake-the-peg]

Are you missing anything of relevance? Where do I start!!??

Firstly the suction has a force limited by the amount of air displaced by the capsule.

It's upwared force is given by the weight of air displaced - so unless your capsule is lighter than air it isn't going anywhere

Secondly the air gets thinner as you get higher so by the time you're just a few miles up there's no upward suction at all to tak of

Thirdly you still need to get to a certain velocity to make it into orbit - otherwise you'll just fall back down to Earth same problem as with the elevator, you have to get up high enough to have sufficient rotational speed to do that.

Fourthly the tube has to be much thicker to keep out the atmosphere which means much more mass to support.

[KerrAvon]

You seem to be under the impression that a vacuum is in someway connected to gravity. I'm trying to be as kind as jake with this but really mate you need to read a lot more on this subject.

[KerrAvon]

Any idea what the tube will be made from? There is no known material that would support even it's own weight beyond about 15km. Granted if you make it to Geostationary height (essential to avoid far bigger issues) then the higher bits will be in freefall. Sorry, like the space elevator, it's a non starter! However this idea is a wonderful thought experiment vehicle.

[mibn2cweus]

A balloon filled with helium would drop like a brick in a vacuum.

The atmosphere is a good thing in that it decelerates objects descending through it which would otherwise be further accelerated by gravity.

In low earth orbit a spacecraft is moving >17,000mph in relation to a stationary point on the earth's surface.