# Could a really tall tube suck garbage in to space?

When I was around 10 years old, I had this idea that was supposed to solve our waste problems; I imagined having tubes miles high that would stretch in to space. Every tube would have a door at the bottom that would be initially closed, and all of the atmosphere inside the tube would then be pumped out. A gigantic pile of garbage would be placed underneath the tube, the door would open, and the vacuum would suck the garbage and eject it in to space.

To what extent could this idea work? Putting aside the problems of keeping a large tube of that size stable(or even manufacturing it), I'm wondering if the force created by the vacuum would be enough to send matter into orbit or if it would immediately come back down the tube once the pressure equalizes. I can't imagine there would be enough inertia to break the earth's gravitational pull, but maybe most of the garbage would stay in orbit for a long time or just burn up on re-entry?

• Hold your finger over a straw and push the straw down into water. Then release your finger and watch the water rush up into the straw. Your atmospheric effect would be pretty much the same. Dec 28, 2014 at 7:44
• Did you try to calculate it? The energy needed to evacuate the tube is given by pdV. You can substitute the average height of the atmosphere (8000m) for the integral over the exponential pressure profile. So let's take a $1m^2$ tube. The total energy to evacuate is roughly 1e5Pascal*8e3m=8e8Joule. The total mass in the tube is approx. 1.5kg/m*8000m=12,000kg. If the pressure equalization converts all of the energy into kinetic energy, the resulting velocity is $v=\sqrt{2*8e8J/1.2e4kg}=365m/s$. Sorry! You just barely left the atmosphere! So, no, it won't work. Dec 28, 2014 at 7:50
• So, you are proposing that we fill the horizon with garbage? Please don't, but do keep thinking of ways to save the environment. Dec 28, 2014 at 8:19
• If you could keep the tube from buckling, you might get farther using pulleys :) Dec 28, 2014 at 13:49

I'm not sure why people are posting what they've put into comments and answers. It's quite simple: a "sucking" system can't pull anything higher than one atmospheric pressure equivalent. That's why barometers work: the height of the material in the tube is limited by the existing atmospheric pressure.

If you want to dump garbage to space, you'll have to pump from below, not evacuate from above.

• So am I right in thinking this means that the sucking system will pull material at most to the edge of the atmosphere? In other words Brandon's visualization above is perfect for this problem! Sorry to jump in on this question - it's just a nice thought experiment with an elegant solution. Dec 28, 2014 at 19:01
• @EdwardHughes no -- the sucking system will only draw material until the weight of the material column produces pressure at the ground level equal to one atmosphere pressure. Take a look at any intro to "how a barometer works" Dec 28, 2014 at 19:31
• of course, I was implicitly treating the mass of the material as negligable. So we can say that the material will at most reach the top of the atmosphere (in the massless case) or lower (if it's a massive object), right? Sorry that my intuition has deserted me this evening! Dec 28, 2014 at 19:39

There are a few design issues that would need to be worked out.

First, is structural integrity. We currently don't have any material strong enough to withstand the strain of reaching out into space.

In order to have the tube in a stationary position, the tube is built from geostationary orbit and extended in both directions (to maintain balance and position).

As pointed out in the comments, the vacuum would not be sufficient to eject the payload (garbage) into space. Although an elevator could be used.

Allowing the garbage to fall into the atmosphere to burn up is not a good idea. Since most of the garbage is carbon based, it would create a lot of carbon dioxide in the upper atmosphere. The amount of carbon dioxide would easily turn the planet into a desert.

Allowing the garbage to accumulate in space would probably create a small moon. Which may create more problems in the future.