Astronauts Throw Trash Into Space

MattSparkes writes "The International Space Station is home to an increasing amount of unwanted goods, and NASA has just approved a policy where these could be thrown out of the door into space. 'Tools and other gear have accidentally floated away during spacewalks. But NASA has shied away from intentionally jettisoning gear off the ISS in the past because of the threat of space junk hitting the station or other spacecraft.' The loosening of the rules on this comes just as Russian cosmonaut Mikhail Tyurin is about to take a space walk where he will hit a golf ball from the ISS in a promotional stunt for a golf company."

Re:Randomly dump their trash would be stupid

[Noryungi]

Hmmmm... I love the smell of a flame war early in the morning...

Yeah, because see, all these rocket scientists, they are well known for bein' stoopid. Ain't that a shame to pollute them purty stars.

Let me help you understand what's at stake here. This quote is from the TFA, that you obviously haven't read:

Tools and other gear have accidentally floated away during spacewalks. But NASA has shied away from intentionally jettisoning gear off the ISS in the past because of the threat of space junk hitting the station or other spacecraft. Even tiny flecks of paint have cracked the windows of the space shuttle orbiter because they zoom around Earth at thousands of kilometres per hour.

Total cost of the ISS (so far): close to US$35 billions (source [www.abo.fi]). The collective face NASA is going to make when the ISS is made unusable by some medium-sized space junk: priceless. Added points for the irony of being hit by space junk that comes from the ISS itself. So, yes, allow me to say it again: throwing junk overboard without thrusting is bad policy, and it is stupid.

If all you needed to deorbit something thrown from the ISS was a "small amount of thrust", don't you think that atmospheric drag would have already deorbitted the ISS itself?

Oh wait, are you talking about the same ISS that needs an extra orbital boost [sciencedaily.com] from time to time due to atmospheric drag? Hmmm... Interesting... That means the ISS is slowly being dragged toward the earth. Amazing, isn't it? Who would have thought?

In order to deorbit something, you need a very considerable amount of thrust, with an engine and propellant brought up from Earth at enormous cost. Left to its own device, a low-density object such as a bag of trash is going to slowly lose altitude due to atmospheric drag, then burn. No need for propellants. Good old air envelope does the trick.

Which, of course, is in complete contradiction with what you just wrote about the ISS, right? Oh well, what's a few inconsistencies between friends? Besides, the goal is precisely to avoid filling the Earth outer space with dangerous, slow moving bags of trash. If you had read TFA, you would know that the golf ball that was to be putted by a russian cosmonaut is no danger, precisely, because hitting that little golf ball with a gold club is enough to send into the atmosphere, where it will burn harmlessly. Which, again, completely contradicts your previous statement that it takes a lot of thrust to de-orbit trash.

On the other hand, the real heart of the matter is, of course, that even if there is never another rocket launch, the outer space around the Earth will be filled with junk until at least 2055:

The model predicts that even without future rocket or satellite launches, the amount of debris in low orbit around Earth will remain steady through 2055, after which it will increase.

That was one [nationalgeographic.com] of the the links I posted. But, let me guess: you did not read any of these either, right?

(me)there is no reason not to incinerate their trash. Incinerate? Whaaa?? Look, this is space, ok?

Fine, that sentence should have been: ... there is no reason not to incinerate their trash IN THE UPPER ATMOSPHERE . Happy? I may sound dumb, but I am not THAT dumb, thankyouverymuch.

As for reusing it, I'm afraid that a sizeable fraction of the trash is, er, astronaut dung. I doubt the reuse value of human waste is very high in space, until we have complete hydroponic gardens.

Still, there i

Re:Randomly dump their trash would be stupid

[Mindwarp]

Actually, no. If an astronaut were to throw a bag of trash 'downwards' towards the Earth then its orbital velocity relative to the space station would increase (since it is moving into a lower orbit) so it would start to overtake the space station below it. As the orbital velocity increases it would start to again climb to a higher orbit, passing above the space station in front of it. As it gained a higher orbit than the space station its orbital velocity relative to the ISS would drop, causing the trash to drop to a lower orbit. In summary, if you throw anything out of the ISS down towards the Earth it will in fact pull a complete loop and end up impacting the top of the ISS.

There is only one safe direction to throw anything out of an orbiting spacecraft - backwards, in the opposite direction of your orbit. By doing this you reduce the orbital velocity of the object relative to your spacecraft thereby guaranteeing that the object will enter a lower orbit from which it is guaranteed not to climb. At this point atmospheric drag will continue to degrade the objects orbit until it eventually burns up.

Re:Randomly dump their trash would be stupid

[roystgnr]

A person could throw it with the hand towards the earth and have more than enough 'thrust' to 'deorbit' it. Orbit is a VERY precarious balancing act. Just a little higher or lower, faster or slower and you lose it.

No, you don't lose it (otherwise every little tidal perturbation would be knocking satellites from the sky), you just change it. To actually immediately leave orbit from the ISS you'd need more than 100m/s delta V, which you're not going to get from someone throwing a bag of trash by hand even if they're not in a bulky space suit.

So the plan here isn't to throw trash out of orbit, it's to throw it into a slightly lower orbit and let atmospheric drag eventually do the rest. They seem to be relying on the fact that if the trash doesn't break into many small pieces, there's only a tiny probability of it hitting anything during the hundreds of orbits before drag finally wins. Well, best of luck to them, but I'd hate to be the decisionmaker responsible for any accidents.