I have heard some propose the idea of launching trash and refuse into space, or towards the Sun, or what have you. Now, besides the obvious fact that there is a LOT of trash on Earth and that sending rockets into space is really expensive, wouldn’t sending all our trash into the Sun just remove finite resources from the Earth and leave us less to work with in the long run?
Yes?
(Not to be snarky, but yes, if you keep offloading resources off-planet, you’ll eventually run out… was that the extent of your question?)
Yes. I know it was simple, but why don’t people consider that when they propose that idea (and I’ve heard the idea thrown out there a bunch of times).
I guess people don’t think about that the same way I didn’t consider all the challenges associated with throwing trash into volcanoes.
Because the very question betrays lazy thinking. It is hardly surprising that one who can look past the fact that it would take less energy and expense to incinerate the trash on earth than to launch it into space, would also look past the fact that we would be removing earth-bound resources.
I think that the general intent of proposals to send waste into space (whether at the Sun or in a permanent solar orbit) is to dispose of hazardous, non-remediable waste such as depleted nuclear fuel elements or highly toxic chemical waste. Aside from the objection of the hazard of attempting to transport this waste via space launch vehicle–the most reliable SLVs still have a 1-2% catastrophic failure rate and about a 3-4% likelihood of partial or complete mission abort–there is nothing inherently wrong with the suggestion. Although it may be possible to process nuclear waste into usable fuel in the future by using a hybrid fission-fusion or traveling wave reactor, if you have the capability to send waste into interplanetary space reliably you are probably also very close to being capable to mine asteroid in near Earth orbit or the asteroid belt for resources, in addition to the resources available on Earth.
Stranger
I must have missed that thread.
Throwing it into the sun is really expensive, I think - more so than throwing it out of the solar system, or at the moon.
But all of these options are just horribly, prohibitively expensive for any significant volume of waste - it’s hard enough for NASA to get funding to put people, instruments and scientific experiments off the planet. Imagine trying to justify it for a box of trash. Not gonna happen.
Yes. Folks who don’t understand orbital mechanics often don’t realize this, but from an energy standpoint (and energy costs by far dominate the costs of doing anything in space), the Sun is actually the hardest place to get to in the Universe. It would literally be easier (though admittedly a lot slower) to throw trash into alpha Centauri, or the black hole in Cygnus X-1, than into the Sun.
That’s really interesting actually. I have no understanding of orbital mechanics, can you elaborate a little on why that would be?
And you don’t want to thwart future space tourism by reminding people to take a receipt when they’re finished with the loo.
Can you elaborate? I once was supposed to understand some mechanics but probably didn’t do very well in that class. Are you saying it’s cheaper to hit any point outside the solar system or is the choice only hurling something into the sun vs out of the system?
To get something from Earth to the sun, you’re going to have to decelerate it quite a bit. It’s already going about 67,000 mi/h in an orbit around the sun, which is definitely not towards the sun. That momentum is useful when going away from the center of our solar system and works against trying to go towards it.
I’m not sure I agree.
If one has limitless time, then using a low-cost, and low-thrust device like a solar sail would be a relatively low energy way to get something to fall into the Sun.
In order to throw something into the Sun you have to cancel practically all of the orbital momentum; otherwise, the payload will just go into a permanent solar orbit. The Earth has an average orbital speed of nearly 30 km/s. I’ll leave it as an exercise to the reader to calculate the specific kinetic energy, but you have to lose all of it; even 1 km/s left will just have the payload going into a highly elliptical orbit. While you could theoretically transfer this momentum to other planets using repeated swing-by maneuvers, in reality this would take millennia to actually achieve a zero orbital speed, whereas slinging something out of the system just requires picking up enough speed to exceed solar escape speed at a given distance (plus any drag from the interplanetary medium), which we’ve managed to do using modest chemical rockets that barely escape Earth’s sphere of influence plus a couple of planetary swingbys around Jupiter, Saturn, or Uranus.
Hitting an extra-solar target reliably, on the other hand, would be fantastically difficult, especially with a purely ballistic path with no correction. But once we launch crap out into extra-solar space, it will be millions of years before it could ever conceivable return even against fantastic odds.
Stranger
To escape earth’s gravitational field, you need to fire it from your ground-based “garbage cannon” with a muzzle velocity of about 25,000 MPH (disregarding atmospheric drag). That takes a certain amount of energy (a LARGE amount; look how big the Saturn rockets were for a final-stage payload of just a few tons), but once done, you can expect to leave the earth forever. Next stop could be the moon or another planet, but if you’re smart, you can use gravitational slingshot mechanics to suck energy from the other planets and speed your garbage up so much that it leaves the solar system.
The earth (and all of our trash) is orbiting around the sun at about 68,000 MPH. If you want to shoot something from the earth at the sun and actually get it to hit the sun, you have to first escape earth’s gravitational field, and then remove all of the extra kinetic energy that corresponds to orbiting the sun so that your projectile falls straight in (to the sun). In the previous paragraph, you only needed to fire your ground-based garbage cannon at 25,000 MPH; if you want to “drop” your garbage into the sun, you need to fire your ground-based garbage cannon at 93,000 MPH. That’s almost 14 times as much energy.
How 'bout that, hadn’t even thought of that. OK, my ignorance has taken enough of a beating today, I’m going to give it the rest of the day off. Thanks.
Even if you could do this with a solar sail (and I’m not entirely sure you can) it would still take vastly longer than sailing an equal distance away from the sun.
Oh, now I get it. It’s analogous to putting something in LEO counter to the direction of the Earth’s rotation, right?
As for the trash question, again—do you reeelly want NASA handing out contracts to organized crime?
Why would you need to decelerate the trash to zero relative to the sun? Wouldn’t at some point above that speed the gravity of the sun pull the object into itself? My ignorant guess is that the gravity of the sun should actually help you launch objects into it.
And of course there’s always the off chance that a clone of superman will emerge afterward so that’s a negative.